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    • Vitamin D could be a piece of COVID-19's 'complex puzzle,' Israeli scientists say, after a new study finds a link between deficiency and severe illness
    • Vitamin D deficiency tied to increased COVID-19 risk, unique UF data study finds
    • Dr. Zorba Paster: Vitamin D deficiency connected to COVID-19 cases
    • Study suggests high vitamin D levels may protect against COVID-19, especially for Black people
    • 1 in 4 COVID patients hospitalized while vitamin D deficient die – Israeli study
    • Vitamin D and COVID-19 Research
    • Minister urged to recommend vitamin D supplements in Covid-19 strategy
    • Other countries are treating COVID patients with probiotics and vitamin D — why aren’t we?
    • MP David Davis calls for Vitamin D therapy to be rolled out 'immediately' after study finds it can 'reduce Covid deaths by up to 60%'
    • Patients Hospitalized With COVID-19 Have Low Levels of 25-Hydroxyvitamin D
    • Vitamin D, other everyday vitamins could counter coronavirus effects:.
    • Experts send Vitamin D and Covid-19 open letter to world's governments
    • A Functional Medicine Approach To Protect Against the Flu
    • Over 80% of Hospitalized COVID-19 Patients Have Vitamin D Deficiency, Study Finds
    • Vitamin D helps the body fight coronavirus, major Israeli study claims
    • Vitamin D deficiency increased risk of COVID in healthcare workers, new study shows
    • People With Low Vitamin D More Likely to Have COVID, Study Finds
    • Vitamin D for COVID-19: a case to answer?
    • Vitamin D helps the body fight coronavirus, major Israeli study claims
    • Researchers investigating possible link between vitamin D deficiency and COVID-19
    • UK public health bodies reviewing vitamin D's effects on coronavirus
    • Parents can help children deal with coronavirus-related anxiety
    • Does Vitamin D Protect Against More Severe Complications of Coronavirus?
    • Should people take vitamin D to ward off the new coronavirus?
    • Can taking Vitamin D save your life?
    • People with low vitamin D levels more likely to die from coronavirus, study finds
    • COVID-19: Vitamin D Linked to COVID-19 Deaths
    • Vitamin D Defense – Protection against COVID-19
    • GET YOUR VITAMINS Scientists investigate link between coronavirus survival rates and Vitamin D
    • FOODVitamin D and Coronavirus
    • Low Vitamin D Levels Linked To Acute Respiratory Distress Syndrome
    • 'Take Vitamin-D' says government as evidence emerges it could help fight coronavirus symptoms
    • Low Vitamin D linked to poor lung function
    • Study finds Vitamin D can build coronavirus resistance
    • Vitamin D may help reduce the risk of the coronavirus, study says
    • Can Vitamin D Lower Your Risk of COVID-19?
    • A lesson from the 1918 influenza pandemic!
    • Vitamin D: Deficiency May Increase Coronavirus Infection Risk
    • Research finds vitamin D is important for respiratory health
  • Breast Cancer
    • Breast cancer: Vitamin D could lower risk by 21% in Black and Hispanic women
    • Vitamin D and Breast Cancer Survival: What You Should Know
    • High intake of vitamin D, calcium and phosphorus may reduce breast cancer risk
    • Obesity and Vitamin D Deficiency May Indicate Greater Risk for Breast Cancer
    • Women with high levels of vitamin D ‘are almost a third more likely to survive breast cancer’
    • Fact Check: Breast Cancer and Nutritional Supplements
    • Vitamin D Deficiency May Promote Spread of Some Breast Cancers
    • Vitamin D may double chances of surviving breast cancer
    • OMEGA-3s Inhibit Breast Cancer Tumour Growth, U of G Study Finds
    • Probiotics and Cancer
  • News & Information
    • Headline news, the latest stories >
      • 9 things that could happen if you're not getting enough vitamin D
      • Vitamin D: Recent research uncovers new benefits
      • Start the Week Off Right: Get more Vitamin D in your diet
      • Vitamin D deficiency – who is at risk?
      • Men who have good levels of vitamin D in their bachelor years will have healthy and strong kids, study finds
      • Father's pre-conception vitamin D intake linked to child height and weight at 5 years old
      • Nearly 1 billion people lacking vitamin D
      • Vitamin D supplements could improve fertility
      • Vitamin D and probiotics, perfect friends
      • Inflammatory bowel disease: Vitamin D could ease symptoms of Crohn’s, colitis and IBS
      • All Scots advised to take vitamin D says new health guidance
      • Probiotic may boost vitamin D levels
      • Vitamin D can help you be strong and healthy
    • Cancer >
      • Study finds association between vitamin D, BMI and advanced cancer
      • Study Finds Vitamin D Supplements Reduce Risk of Developing Advanced Cancer
      • Effect of serum 25-hydroxyvitamin D level on lung, breast, colorectal and prostate cancers: a nested case-control study
      • Vitamin D cuts colitis risk in cancer patients on immunotherapy by 65%
      • High Dose Vitamin D Beneficial For Colon Cancer
      • Prompting leukemia cells to die
      • Everything You Need to Know About Vitamin D and Cancer Prevention
      • Obesity and Vitamin D Deficiency May Indicate Greater Risk for Breast Cancer
      • Higher Vitamin D Levels Associated With Lower Risks Of Liver Cancer And Death From Chronic Liver Disease
      • More the Vitamin D, lesser the breast cancer risk
      • Scientists detect new ovarian cancer target
      • Higher vitamin D levels cut colorectal cancer risk
      • Vitamin D linked to lower risk of cancer- study
      • More vitamin D may be associated with lower cancer risk
      • New study suggests link between low vitamin D status and increased risk of ovarian cancer
      • Vitamin D relieves joint, muscle pain for breast cancer patients
      • Low Vitamin D Linked to Bladder Cancer
      • Low vitamin D levels increase risk for bladder cancer
      • Can Vitamin D prevent colon cancer?
      • Vitamin D fights pancreatic cancer
      • Vitamin D levels can affect aggressiveness of melanomas
      • Pancreatic Cancer Survical
      • TNBC
      • Vitamin D Melanoma
    • Childrens Health >
      • High-Dose Vitamin D Well Tolerated in Pediatric Patients
      • Why it’s so hard to identify seasonal depression in kids, and how to help
      • Vitamin D During Pregnancy May Benefit Children’s Bones
      • Vitamin D Deficiency linked to Anxiety and depression in Teens
      • Vitamin D During Pregnancy May Improve Dental Health of Babies
      • Newborns with Vitamin D Deficiency Have Higher Risk of Later Schizophrenia
      • Vitamin D-rich Diet May Decrease Cholesterol in Kids
      • Vitamin D Supplements To Curb Rise In Rickets
      • High vitamin D levels linked to lower cholesterol in children
      • Study Links Low Vitamin D Levels with Fracture Susceptibility and Severity
      • Vitamin D deficiency associated with pediatric obesity
      • Can Vitamin D Deficiency in Children Affect the Severity of Illnesses?
      • Can Vitamin D Reduce Risk of Pre-eclampsia in Pregnancy?
      • Warning to pregnant women on vitamin D: Shortages leads to children with poor motor skills
      • Development fears for children of expectant mothers with low vitamin D levels
      • Vitamin D deficiency during pregnancy tied to autism risk
      • Another reason for obese children to go outside: Overweight youngsters with a vitamin D deficiency at risk of heart disease as they grow older
      • Taking Vitamin D During Pregnancy Shows Promise in Preventing Autism
      • Vitamin D deficiency found in children with digestive disorder, UMass study finds
      • Vitamin D deficiency in children exponentially increased in recent years, study finds
      • Maternal Preferences for Vitamin D Supplementation in Breastfed Infants
      • Prenatal Vitamin D Could Lower Baby's ADHD Risk, While Some Diabetes Drugs May do the Opposite
      • Neonatal Vitamin D Levels Appear to Affect MS Risk Later in Life
      • Vitamin D May Improve Symptoms in Children with Autism
      • October is Children’s Health Month
      • Vitamin D Intake During Pregnancy May Protect Against ADHD in Children
      • Regular vitamins likely unnecessary for children with healthy diets, doctor says
      • VITAMIN D DEFICIENCY LEADS TO STRESS FRACTURES IN 15-YEAR-OLD
      • Breastfeeding Moms Aren't Getting Enough of This Essential Vitamin
      • Why children’s allergies are on the rise and how dirt may hold key to reducing cases
      • Babies born to mothers with lack of Vitamin D 'more likely to have learning difficulties'
      • Vitamin D reduces Wheezing
      • Vitamin deficiencies may be linked to migraines in children
      • Vitamin D and MS
      • Less body fat for toddlers taking vitamin D
    • Sports & Endurance >
      • How Optimizing Your Vitamin D Status Promotes Muscle Health & Function
      • Reevaluating Vitamin D as a Sports Supplement
      • The Risks of Being Vitamin D Deficient as an Athlete
      • Vitamin D levels in blood tied to cardiorespiratory fitness
      • What We Know About Vitamin D and Performance
      • Girls with high level of vitamin D have stronger muscles
      • Increased vitamin D intake improves muscle strength and athletic performance
      • Low vitamin D levels associated with higher risk of muscle strain among elite-level football players
      • Are athletes realizing the importance of vitamin D before the general public?
      • Why Vitamin D Is Extra Important for Athletes
      • Optimizing athletic performance through research
      • Nearly 60% Of College Football Athletes Don’t Get Enough D
      • A spotlight on vitamin D
      • High levels of vitamin D may improve muscle strength
      • Low levels of vitamin D may increase risk of fractures in active people
      • Why Vitamin D Is Extra Important for Athletes
      • Low Vitamin D weaker athlete
      • Vitamin D profile in National Football League players.
      • Endurance and D
      • Peak Athletic Performance and Vitamin D
    • General Health >
      • Vitamin D Supplements Linked to Slower Epigenetic Aging
      • Many of us have a vitamin D deficiency and don't know it
      • Vitamin D Helps Modulate Blood Sugar & Promotes Metabolic Health
      • Vitamin D and marine omega 3 fatty acid supplementation and incident autoimmune disease: VITAL randomized controlled trial
      • HEALTH AND WELLNESS The 4 vitamins and supplements this immunologist takes every day to strengthen her immune system: ‘Your body will thank you’
      • If You've Hit A Wall Combating Dry Skin, You May Be Lacking This Vitamin
      • Vitamin D supplements lower risk of autoimmune disease, researchers say
      • Vitamin D3, but not D2, linked to improved immunity
      • Vitamin D and fish oil supplements reduce risk of autoimmune conditions
      • Vitamin D deficiency visible for the first time in teeth after cremation
      • Body pain and tiredness? Could be lack of vitamin D
      • This Little-Known Factor Doubles (Or More) Your Vitamin D Needs
      • 5 Vitamin D Benefits You Should Know About
      • Vitamin D Benefits
      • 7 Reasons to make sure you get enough Vitamin D Accoring to the Doctors
      • Very high dosages of vitamin D may delay frailty in old age
      • Vitamin D deficiency: Could a lack of the sunshine vitamin be causing your cold?
      • Hidden hunger: the crucial health role of Omega 3 and Vitamin D
      • Vitamin D: the superstar of prevention
      • Is Dry Skin A Sign Of Vitamin D Deficiency? Know How It Can Affect Your Skin
      • Coping with seasonal affective disorder
      • Skin Warning Signs That May Indicate You Have Vitamin D Deficiency
      • Vitamin D increases protection against infection, new model suggests
      • Vitamin D deficiency linked with increased risk of death, particularly from diabetes: study
      • People with diabetes, hypertension are Vitamin D deficit: Study
      • Intake of vitamin D supplementation may slow diabetes progression
      • New study sheds light on the role of vitamin D in muscle cells
      • Why you can't absorb vitamin D through a sunny window
      • Vitamin D Benefits That’ll Make You Take the Nutrient More Seriously
      • 5 tips to improve your cognitive functions
      • 5 Ways Women Can Keep Their Bones Healthy
      • Flu Prevention Tips
      • Vitamin D Deficiency Linked to Disease Severity, Mortality Risk in IPF Patients
      • 6 Health Problems That Are Caused Due To Vitamin D Deficiency
      • Vitamin D deficiency - does your hair look like this? Warning signs of deficiency revealed
      • Winter Increases Risk Of High Blood Pressure
      • 4 smart tricks to overcome chronic fatigue syndrome without popping pills
      • What can a psychiatrist tell us about vitamin D?
      • Vitamin D for Asthma
      • Researchers discover a new gear in life's clock: Vitamin D
      • Can vitamin D prevent the flu?
      • Vitamin D: It’s that time of the year
      • What's the link between cold weather and the common cold?
      • 11 Sneaky Causes of Vitamin D Deficiency
      • Are you smarter in summer? Brain health changes with the seasons
      • What's the link between vitamin D, gum health, and diabetes?
      • Infection Risk Lower in Dialysis Patients with High, Normal Vitamin D
      • Researchers Find Link Between Vitamin D and Asbestosis
      • We Can Thank Poor Evolutionary Design for Vitamin D Deficiencies
      • Vitamin D deficiency ups diabetes risk in women: Study
      • REASONS WHY YOU SHOULD BE TAKING VITAMIN D SERIOUSLY
      • Is vitamin D deficiency to blame for lung disease?
      • Many people lack Vitamin D — even in the Sunshine State
      • Vitamin D deficiency may up diabetes risk
      • Low Vitamin D Linked to Metabolic Syndrome in Postmenopausal Women
      • Vitamin D deficiency: How to reverse a shortfall and stop painful symptoms
      • Vitamin D could provide psoriasis relief
      • Is vitamin D really a cure-all – and how should we get our fix?
      • Study confirms vitamin D protects against colds and flu
      • The Benefits of Vitamin D – Why It’s the Sexiest Vitamin Around
      • Research finds vitamin D is important for respiratory health
      • Is Vitamin D Really Effective For Cold and Flu
      • Vitamin D deficiency: 6 symptoms
      • Vitamin D could help millions of people with irritable bowel syndrome
      • Frailty not ‘inevitable result of ageing’, can be reversed
      • Should ALL pregnant women take vitamin D?
      • Vitamin D supplementation may be more effective than sun exposure at raising vitamin D levels
      • Study confirms vitamin D protects against colds and flu
      • 7 Benefits of Vitamin D You Might Want to Know About
      • Could Fish Oil, Vitamin D Help Ease Lupus?
      • Study confirms vitamin D protects against colds and flu
      • Are YOU vitamin D deficient? 6 signs even your doctor might miss
      • Top Myths of Vitamin D
      • Vitamin D May Lower Asthma Attack Risks
      • Vitamin D supplements may reduce asthma severity
      • The Shocking Truth About Vitamin D Deficiency And Its Repercussions
      • Vitamin D Might Be The Key Ingredient In Vitiligo Treatment
      • Vitamin D insufficiency linked to lower virologic response in HBV
      • BACK TO SCHOOL COLD PREVENTION
      • Too little vitamin D may hinder recovery of injured corneas
      • Gut reaction to a healthy life
      • Low Vitamin D Levels Increases the Risk for Chronic Headaches
      • Vitamin D Levels Predict Multiple Sclerosis Progression
      • Study Links Certain Jobs to Vitamin D Deficiency
      • Can Vitamin D Improve Sunburn?
      • Vitamin D guidelines need to be updated – here’s why
      • Daily fruit smoothie helps couples trying to start a family
      • Vitamin D deficiency could cause deadly diseases, warn UAE doctors
      • Vitamin D Deficiency May Cause Early Menopause
      • Lactose intolerance linked to lower vitamin D levels
      • Vitamin D Helps Friendly Bacteria Repopulate The Gut, Making It The Perfect Campanion To Probiotic Supplements
      • Sunscreen ‘is making us vitamin D deficient’, controversial study claims
      • Widespread Vitamin D Deficiency Likely Due to Sunscreen Use, Increase of Chronic Diseases
      • Doctor’s Tip: The low-down on vitamin D
      • Pet vet: Understanding the importance of vitamin D for pets
      • Vitamin D could provide psoriasis relief
      • Can A Vitamin Deficiency Cause Depression?
      • Increased Fracture Risk: Seniors Not Taking Vitamin D Supplements
      • 11 surprising things you might not know about vitamin D
      • What is rickets, what causes the condition, is there a cure and how can I prevent Vitamin D deficiency?
      • Sunshine vitamin linked to fewer heart events: Meta­-analysis
      • Study finds link between vitamin D levels and severity of malabsorption issues
      • ‘Proof’ that Vitamin D can fight flu
      • Sunshine Is The Natural Treatment For Preventing Pre-diabetes, Type 2 Diabetes and More In Children and Adults
      • Vitamin D is not just beneficial, it’s a necessity
      • Vitamin D pills 'could stop colds or flu'
      • Vitamin D Supplementation: Protection from Respiratory Infections?
      • Relapse Risk Up With Low Vitamin D Levels in Ulcerative Colitis
      • Supplementation with vitamin D associated with improved testosterone, erectile function among middle-aged men
      • We all need the Vitamin D
      • 7 Signs and Symptoms of Vitamin D Deficiency People Often Ignore
      • 8 Surprising Things You Didn't Know Vitamin D Could Do For You
      • Low vitamin D level predicts CV morbidity, mortality in type 2 diabetes
      • 10 Things That Will Happen If You Lack Vitamin D
      • Vitamin D study outlines impact of supplements in seniors
      • Vitamin D deficiency and the risk of tuberculosis: a meta-analysis
      • Vitamin D improves gut flora and metabolic syndrome
      • Low Levels of Vitamin D May Be Tied to Balance Problems in Fibromyalgia Patients
      • High Levels of Vitamin D Supplements May Help Improve Lung Function in CF Patients, Study Shows
      • Vitamin D Modestly Tied to Sex Hormones in Older Population
      • Sun exposure as kids may prevent nearsightedness in later life
      • Vitamin D reduces respiratory infections, but there's a catch
      • Insufficient Sun Exposure Called Emerging Public Health Problem By World-renowned Researchers
      • Weight loss combined with vitamin D supplements can reduce inflammation linked to cancer and chronic diseases
      • Higher Doses of Vitamin D Can Lower Incidence of Respiratory Infection
      • Poor fertility linked to low vitamin D levels
      • Men and the Power of Vitamin D
      • Vitamin D and Immune Function
      • High quality evidence suggests vitamin D can reduce asthma attacks
      • The association between vitamin D and COPD risk, severity, and exacerbation: an updated systematic review and meta-analysis
      • How to boost your energy levels
      • Low Vitamin D Increases Mortality Risk
      • Air pollution and vitamin D deficiency linked to dementia.
      • The Vitamin D Deficiency Epidemic … 40% World’s Population Low on D
      • Low Vitamin D Linked with All-Cause Death
      • Your Family Doesn't Have To Get Sick This Fall
      • Vitamin D is essential for the elderly living without sunshine in their lives
      • Taking THIS vitamin could protect you against cancer, diabetes and Alzheimer’s
      • Vitamin D tablets may help reduce asthma attacks, review finds
      • Vitamin D Proven More Effective Than Both Anti-Viral Drugs and Vaccines at Preventing the Flu
      • Bring me sunshine: How I beat eczema
      • Insulin Resistance and Vitamin D
      • Diverticulitis risk lower with higher vitamin D
      • Vitamin D deficincy linked to problems in pregnancy.
      • High Doses of Vitamin D Unlikely to Help MS Patients, But Daily Low Dose Good for All,
      • Natural Vitamin D Supplement Effective for Nondialysis CKD-MBD
      • 8 Signs and Symptoms of Vitamin D Deficiency
      • Vitamin D deficiency could increase risk of diabetes related coronary heart disease
      • Low D may increase nonalcoholic fatty liver disease
      • Vitamin D for prostate health
      • Pregnant women with good intake of vitamin D lower risk
      • Fight infection like an Olympic athlete
      • Lack of vitamin D lowering fertility in Gulf, doctors say
      • Rayaldee Approved for Secondary Hyperparathyroidism Vitamin d Deficiency
      • Increase vitamin D levels to cut kidney problems
      • Sunbathers live longer
      • Crohn’s disease causes vitamin D deficiency
      • Taking vitamin D avoid new-onset diabetes risk
      • Vitamin D Deficiency Linked to Diabetic Retinopathy
      • UK sun not enough
      • morbidity and D
      • Macular and D
      • Are You Getting Enough Vitamin D
    • Heart Health >
      • STUDY NAILS DOWN A LINK BETWEEN VITAMIN D AND HEART HEALTH
      • Vitamin D-3 could 'reverse' ​damage to heart
      • Vitamin D and the Heart
      • Vitamin D Can Mend a Broken Heart
      • D deficiency linked to high blood pressure
      • Stress of open-heart surgery significantly reduces vitamin D levels, but supplementation helps
      • Vitamin D reduces early mortality: study
      • Vitamin D-3 could 'reverse' damage to heart
      • High Vitamin D Dose May Rapidly Cut Arterial Stiffness
      • Heart failure 12 times more likely in people with vitamin D deficiency
      • Exercise and vitamin D better together for heart health
      • Sunshine vitamin linked to fewer heart events: Meta­-analysis
      • Vitamin D levels could predict risk of poor cardiovascular health
    • Neurological health >
      • New Research Shows Vitamin D Deficiency Leads to Dementia
      • Vitamin D supplementation may reduce ADHD symptoms, finds study
      • low d linked to fall, sleep problems and depression
      • Potential link between vitamin d deficiency and loss of brain plasticity
      • SUNBATHE AND QUIT SMOKING TO REDUCE MS RISK IN SPAIN’S MALAGA SAY LEADING DOCTORS
      • At risk of getting, or have, multiple sclerosis? Load up on vitamin D: MS Society
      • 4 things you can do to prevent stroke
      • Vitamin D: The Only Dietary Supplement Showing Significant Benefit for MS
      • Vitamin D Supplementation May Help Ease Depression
      • Easing your winter blues this season
      • Reducing Vitamin D Levels in Women May Up the Risk of Multiple Sclerosis
      • UNBC study shows vitamin D boosts brain function
      • Vitamin D Eases Depression, Fatigue in Spinal Cord Patients
      • Sharon Ní Chonchúir on having a baby despite her MS
      • Dutch study confirms link between certain psychiatric disorders and vitamin D deficiency
      • Vitamin D Deficiency and Depression
      • Vitamin D During Pregnancy Reduces ADHD Risk
      • Low Levels of Vitamin D in Patients With Bipolar Disorder
      • Vitamin D Supplements Improve Cognition in Patients With MS
      • Can vitamin D prevent Alzheimers?
      • The signs you might have seasonal affective disorder
      • A deficiency of THIS essential vitamin could lead to MEMORY loss
      • Vitamin D levels predict risk of brain decline in Chinese elderly
      • Vitamin D and MS
      • Alzheimer's Q&A
    • Pain >
      • Vitamin D Reduces Need for Opioid Pain Relief in Cancer Patients
      • The association of calcium and vitamin D use with implant survival of total knee arthroplasty: A nationwide population-based cohort study
      • Vitamin D for Back Pain and Disc Degeneration in Postmenopausal Women
      • Vitamin D may expedite wound healing in burn patients
      • Vitamin deficiency can cause pain
      • What is the link between psoriatic arthritis and depression?
      • Neuropathic Pain in Rheumatoid Arthritis Linked to Vitamin D Deficiency
      • Vitamin D supplements could help pain management
      • Recent clinical trial discovers vitamin D supplementation reduces chronic low back pain
      • Chronic Headache Linked to Vitamin D Deficiency
      • With Vitamin D Deficiency More Prevalent Than Previously Thought, Pain & Stress Center Presents Solution
      • How vitamin D inhibits inflammation
      • Easy ways to relieve crippling knee pain
      • Vitamin D Supplementation and the Progression of Knee Osteoarthritis
      • Migraines Linked to Low Levels of Vitamin D
    • ​Weight Managment >
      • Research links lower vitamin D levels to excess body fat
      • Vitamin D is important for decreasing belly fat
      • Study finds association between vitamin D, BMI and advanced cancer
      • Weight loss combined with vitamin D supplements can reduce inflammation linked to cancer and chronic diseases
      • Vitamin D deficiency can cause weight gain
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  • Vitamin D may get you discharged home sooner! A deficiency in the sunshine supplement trebles the length of time patients stay in hospital
  • 5 Probiotic Benefits That Have Nothing To Do With Digestion
  • Newborns with Vitamin D Deficiency Have Higher Risk of Later Schizophrenia
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  • Exercising and Taking Vitamin D and Omega-3 Supplements May Reduce Your Cancer Risk By 61%, Study Says
Back to Sports & Endurance

Peak Athletic Performance and Vitamin D

03/2007
​"No way doc."  I had just finished telling my patient about the benefits of vitamin D, telling him he should take 4,000 IU per day, using all the techniques I had learned in 30 years of medical practice to convince someone proper treatment is important.  But, he knew the U.S. government said he only needed 200 IU per day, not 4,000.  He also knew the official Upper Limit was 2,000 IU a day.  "What are you trying to do doc, kill me?"  I told him his 25(OH)-vitamin D blood test was low, only 13 ng/ml.  He had read about that too, in a medical textbook, where it said normal levels are between 10 and 40 ng/ml.  "I'm fine doc;" adding "Are you in the vitamin business?"  I explained I was not; that the government used outdated values; that recent studies indicate ideal 25(OH)D levels are about 50 ng/ml; and that they indicated that he needed about 4,000 IU per day to get his level up to 50.  "No thanks doc, I'm fine."
 
So I tried a different tact—I brought copies of recent press articles and asked him to take a look at them. Science Newscalled vitamin D the "Antibiotic Vitamin." Janet RaloffThe Antibiotic Vitamin.Science News, Vol. 170, No. 20, p. 312, 2006.11.11. The Independent in England says vitamin D explains why people die from influenza in the winter, and not the summer. Jeremy LauranceBottled sunshine: The value of vitamin D.The Independent, 2006.09.13. U.S. News and World Report says almost everyone needs more. Deborah KotzThe ABCs of D.U.S. News and World Report, 2006.12.10. Newsweek says it prevents cancer and helps fight infection. Meir J. Stampfer MD DrPHVitamin D in the Spotlight.2006 Newsweek, Inc. United Press International says that it reduces falls in the elderly, Vitamin D may reduce falls in elderly.United Press International, 2007.02.22. reduces stress fractures, Calcium, vitamin D reduce stress fractures.United Press International, 2007.02.12. helps heal wounds, Vitamin D needed to heal skin wound.United Press International, 2007.02.09. and that many pregnant women are deficient in the vitamin. Vitamin D deficiency during pregnancy.United Press International, 2007.02.27.
 
He glanced at the articles, showing a little interest in stress fractures.  Then he told me what he was really thinking.  "Look doc, all this stuff may be important to old guys like you.  I'm 22.  All I care about are girls and sports.  When I get older, maybe I'll think about it.  I'm too young to worry about it.  I'm in great condition."  I couldn't argue.  He was in good health and a very good basketball player, playing several hours every day, always on indoor courts.
 
What could I do to open his eyes?  As an African American, his risk of early death was very high, although the risk for blacks doesn't start to dramatically increase until their 40's and 50's.  Like all young people, he saw himself as forever young.  The U.S. government was no help, relying on a ten-year-old report from the Institute of Medicine that is full of misinformation. 
 
I tired to tell him that the 200 IU per day the U.S. government recommends for 20-year-olds is to prevent bone disease, not to treat low vitamin D levels like his.  I pointed out the U.S. government's official current Upper Limit of 2,000 IU/day is the same for a 300 pound adult as it is for a 25 pound toddler.  That is, the government says it's safe for a one-year-old, 25-pound, child to take 2,000 IU per day but it's not safe for a 30-year old, 300-pound, adult to take 2,000 and one IU a day.  I mean, whoever thought up these Upper Limits must have left their thinking caps at home.  Nevertheless, nothing worked.  My vitamin D deficient patient was not interested in taking any vitamin D.
 
What are young men interested in?  I remembered that he had told me: "Sex and sports."  Two years ago I had researched the medical literature looking for any evidence vitamin D enhanced sexual performance.  Absolutely nothing.  That would have been nice.  Can you imagine the interest?
 
Then I remembered that several readers had written to ask me if vitamin D could possibly improve their athletic performance?  They told me that after taking 2,000 to 5,000 IU per day for several months, they seemed just a little faster, a little stronger, maybe had a little better balance and timing.  A pianist had written to tell me she even played a better piano, her fingers moved over the keys more effortlessly!  Was vitamin D responsible for these subtle changes or was it a placebo effect?  That is, did readers just think their athletic performance improved because they knew vitamin D was a steroid hormone precursor (hormone, from the Greek, meaning "to set in motion")? 
 
The active form of vitamin D is a steroid (actually a seco-steroid) in the same way that testosterone is a steroid and vitamin D is a hormone in the same way that growth hormone is a hormone.  Steroid hormones are substances made from cholesterol, which circulate in the body, and work at distant sites by "setting in motion" genetic protein transcription.  That is, both vitamin D and testosterone regulate your genome, the stuff of life.  While testosterone is a sex steroid hormone, vitamin D is a pleomorphic (multiple function) steroid hormone.
 
All of a sudden, it didn't seem so silly.  Certainly steroids can improve athletic performance although they can be quite dangerous.  In addition, few people are deficient in growth hormone or testosterone, so when athletes take sex steroids or growth hormone they are cheating, or doping.  The case with vitamin D is quite different because natural vitamin D levels are about 50 ng/ml and, since almost no one has such levels, extra vitamin D is not doping, it's just good treatment.  I decided to exhaustively research the medical literature on vitamin D and athletic performance.  It took me over a year. 
 
To my surprise, I discovered that there are five totally independent bodies of research that all converge on an inescapable conclusion: vitamin D will improve athletic performance in vitamin D deficient people (and that includes most people).  Even more interesting is who published this literature, and when.  Are you old enough to remember when the Germans and Russians won every Olympics in the 60's and 70's?  Well, it turns out that the most convincing evidence that vitamin D improves athletic performance was published in old German and Russian medical literature.
 
With the help of my wife and mother-in-law, both of whom are Russian, and with the help of Marc Sorenson, whose bookSolar Power is a must read, I finally was able to look at translations of much of the old Russian and German literature.  When one combines that old literature with the modern English language literature on neuromuscular performance, the conclusion is inescapable.  The readers who wrote me are right. 
 
If you are vitamin D deficient, the medical literature indicates that the right amount of vitamin D will make you faster, stronger, improve your balance and timing, etc.  How much it will improve your athletic ability depends on how deficient you are to begin with.  How good an athlete you will be depends on your innate ability, training, and dedication.  However, peak athletic performance also depends upon the neuromuscular cells in your body and brain having unfettered access to the steroid hormone, activated vitamin D.  In addition, how much activated vitamin D is available to your brain, muscle, and nerves depends on having ideal levels of vitamin D in your blood - about 50 ng/ml, to be precise.
 
Why would I write about such a frivolous topic like peak athletic performance when cancer patients all across this land are dying vitamin D deficient?  Like many vitamin D advocates, I have been disappointed that the medical profession and the public don't seem to care about vitamin D.  Maybe people, like my young basketball player, will care if it makes better athletes.  So, Hey!  You jocks!  Listen up!  I'm talking speed, balance, choice reaction time, muscle mass, muscle strength, squats, reps, etc.  Important stuff.  Here's the Vitamin D Council's first ever sports quiz.
 
1.  Vitamin D-producing UVB radiation improves athletic performance and may have been widely practiced by German and Russian Olympic athletes in the 1960's and 70's.
 
 
True. I found tantalizing evidence the Russians and especially the Germans were on to this during the 60's and 70's when those two nations took turns placing number one and number two in the Olympics every year? 
 
For example, in 1938, Russian researchers reported that a course of ultraviolet irradiations improved speed in the 100-meter dash in college students compared to matched controls, both groups undergoing daily training. Average 100-meter dash times decreased from 13.51 seconds to 13.28 seconds in the non-irradiated controls, but from 13.63 seconds to 12.62 seconds in the irradiated students.  Here we see training improved times but training and irradiation improved times much more.  Obviously, irradiation or vitamin D would not render the same magnitude of improvements in world-class sprinters, but they would be happy with a few milliseconds.
 
Gorkin Z, Gorkin MJ, Teslenko NE. [The effect of ultraviolet irradiation upon training for 100m sprint.]  The Journal of Physiology of the USSR [Fiziol, z. (RSSR)] 1938; 25: 695-701. (In Russian)
 
 
If you want to know what early German thinking was on this, read this summation of the German literature:
 
"It is a well-known fact that physical performance can be increased through ultra-violet irradiation.  In 1927, a heated argument arose after the decision by the German Swimmers' Association to use the sunlamp as an artificial aid, constituting an athletic unfairness, doping, so to speak.  In 1926, Rancken had already reported the improving effect of sunlamp irradiation on muscle work with the hand-dynamo-graph.  Heib observed an improvement in swimming times after repeated irradiations.  In thorough experiments, Backmund showed that a substantial increase in muscle activity happens after radiation of larger portions of the body with an artificial sunlamp; that this performance increase is not caused through local - direct or indirect - effects on the musculature, but through a general effect.  This general effect, triggered by ultra-violet irradiation, is caused by a systemic effect on the nervous system." (p. 17)
 
Parade GW, Otto H. Die beeinflussung der leistungsfahigkeit durch Hohensonnenbestrahlung. Zeitschrift fur Klinische Medizin (Z Klin Med),1940;137:17-21 [In German]
 
In 1945, two Americans measured the cardiovascular fitness and muscular endurance of 11 male Illinois subjects undergoing training in an indoor physical education class, comparing them to 10 matched controls.  Both groups underwent similar physical training.  Treatment consisted of ultraviolet irradiation, given in the nude, up to two minutes per session, three times per week, for ten weeks in the late fall and winter.  After ten weeks, the treatment group had a 19% standard score gain in cardiovascular fitness compare to a 2% improvement in the control students.  To regular readers of this newsletter, it should come as no surprise that the un-irradiated control group reported twice as many viral respiratory infections as the treatment group.
 
Allen R, Cureton T.  Effects of Ultraviolet Radiation on Physical Fitness.  Arch Phys Med 1945: 10: 641-44.
 
In 1952, the German sports medicine researcher, Spellerberg, reported on the effects of wholesale irradiation of athletes studying and training at the Sports College of Cologne - including many elite athletes - with a "central sun lamp."  He irradiated the athletes in their bathing suits, on both sides of their bodies, for up to ten minutes, twice a week, for 6 weeks.  He reported a "convincing effect" on athletic performance and a 50% reduction in sports injuries.  Results were particularly impressive for swimmers, soccer, handball, hockey, and tennis players, as well as for boxers and most track and field athletes.  He reported that irradiation leading to burns, further irradiation of athletes having achieved peak performance, and irradiation within 24 hours of competition, all impaired athletic performance.  Their results were so convincing, the Sports College of Cologne officially notified the "national German and International Olympic committee." (p. 570)
 
Spellerberg AE. [Increase of athletic effectiveness by systematic ultraviolet irradiation.] Strahlentherapie 1952; 88: 567-70. [In German]
 
 
In 1952, Ronge exposed 120 German schoolchildren to UV lights installed in classrooms and compared them to 120 un-irradiated control children.  Over a two-year period - excluding summer vacations - he tested both groups with a series of six cardiovascular fitness tests using a bike ergometer.  Un-irradiated children showed a distinct seasonality in fitness, with the highest values right after summer break and the lowest values in the spring.  Treated children showed no seasonal differences in physical performance.  Differences in work performance between the irradiated and un-irradiated children were most conspicuous in the spring with 56% difference between the two groups.  In a final experiment, he gave 30 children in the control classrooms 6.25 mg (250,000 IU) of vitamin D as a single dose in February and found their performance had "increased considerably," one month later but did not report the actual numbers.  He concluded that vitamin D, either as a supplement or induced via UV irradiation, improved physical performance.
 
Ronge HE. [Increase of physical effectiveness by systematic ultraviolet irradiation.] Strahlentherapie 1952; 88: 563-6.  [In German]
 
In 1954, another researcher, at the Max-Planck Institute for Industrial Physiology in Dortmund, Germany, administered three different wavelengths of UV light over 8 weeks to university students.  He found that ultraviolet light in the vitamin D-producing UVB range was consistently effective in reducing resting pulse, lowering the basal metabolic rate, and increasing athletic performance.  UVA had no effect; interestingly, artificial UVC irradiation (the atmosphere normally completely filters out UVC radiation and thus it's not naturally present on earth) also gave some positive results.
 
Lehmann G. [Significance of certain wave lengths for increased efficacy of ultraviolet irradiation.] Strahlentherapie. 1954 Nov;95(3):447-53. [In German]
 
In 1956, Hettinger and Seidel irradiated seven subjects in two different experiments: athletic performance on bike-ergometers and forearm muscle strength.  They found that UV radiation induced a significant improvement in both muscle strength and athletic performance.
 
Hettinger T, Seidl E. [Ultraviolet irradiation and trainability of musculature.] Internationale Zeitschrift für angewandte Physiologie, einschliesslich Arbeitsphysiologie 1956; 16: 177-83. [In German]
 
Another German researcher, at the Institute for Medical Physics and Biophysics at the University of Gottiingen, studied reaction times (the time needed to recognize a light and switch it off) during October and November in a series of controlled experiments on 16 children and an unspecified number of adults.  He first controlled for practice effects (getting better by practicing) and then administered nine full-body UV radiation treatments over three weeks to the two treatment groups, using placebo radiation in the two control groups.  UV radiation improved choice reaction time by 25% in children and 20% in adults while reaction time worsened in controls.  The improvements in the irradiated groups peaked at the end of the three weeks of UV treatments and reverted to baseline levels three weeks later.  In the two control groups, he found distinctly improved reaction times in the sunnier months.
 
Sigmund R. [Effect of ultraviolet rays on reaction time in man.] Strahlentherapie. 1956; 101: 623-9. [In German]
 
The next study threw me because it was very well conducted, meticulously designed, and completely negative.  In 1963, Berven reported on the effects of ultraviolet irradiation and vitamin D supplementation in a group of 30 Stockholm schoolchildren, aged 10 -11, comparing them to appropriate controls. He found no seasonality of fitness in the control group and no effect from either irradiation or two different vitamin D supplementation protocols (1500 IU of cholecalciferol daily for two months and a single dose of 400,000 IU of ergocalciferol) on performance on a bike ergometer.
 
Berven H. The physical working capacity of healthy children; seasonal variations and effect of ultraviolet irradiation and vitamin-D supply. Acta paediatrica. Supplementum 1963; 148: 1-22.
 
 
However, two things were not right and got me thinking.  One, Berven found no seasonality of physical fitness and was the only author who found no such seasonal variations in athletic performance.  Second, he found no effect from irradiation, again, the only author.  Then I realized he was working with Swedish children in the late 1950's.  Supplementation of children with high doses of vitamin D - often as cod liver oil - was routine in Scandinavia in the past, particularly in children.  For example, in neighboring Finland, the official recommended daily dose of vitamin D for children - including infants - was 4,000 IU per day until 1964, when authorities reduced it to 2,000 IU/day.  (That's right, you read that correctly, 4,000 IU per day for infants, which is too much by the way.) 
 
In 1975, Finnish authorities reduced it to 1,000 IU per day, and, in 1992, to 400 IU per day.  I emailed Professor Elina Hypponen who confirmed that the Swedish recommendations were similar to the Finnish ones.  Therefore, it seems highly unlikely that many of Berven's Swedish children, studied in 1958 and 1959, all from "families with a good standard of living," were vitamin D deficient.   Therefore, this study showed that vitamin D will not improve athletic ability in vitamin D replete people.  That's very important because it indicates more is not necessarily better.  More is only better if you are not taking enough.
Hypponen E, et al. Intake of vitamin D and risk of type 1 diabetes: a birth-cohort study. Lancet. 2001 Nov 3;358(9292):1500-3.
In the 1960's, three American researchers conducted experiments with university students. Rosentswieg studied the effects of a single six-minute dose of UV light on each side of the trunk in 23 college women, recording changes in various tests of muscle strength at one and five hours.  He found a trend towards significance after five hours in white but not African American students.  In 1968, Cheatum found that a six-minute administration of UV light, on each side of the trunk, increased the speed of 15 college women in the 30-yard dash.  In 1969, Rosentswieg found a six-minute dose of UV light, on each side of the trunk, finding improved performance on a bicycle ergometer in college women.  However, unlike the Germans and Russians, I could find no evidence that any of these American findings interested any American professionals involved in the care or training of athletes.
 
Rosentsweig J. The effect of a single suberythemic biodose of ultraviolet radiation upon the strength of college women. J Assoc Phys Ment Rehabil. 1967 Jul-Aug;21(4):131-3.
 
Cheatum BA. Effects of a single biodose of ultraviolet radiation upon the speed of college women. Res Q. 1968 Oct;39(3):482-5.
 
Rosentswieg J. The effect of a single suberythemic biodose of ultraviolet radiation upon the endurance of college women. J Sports Med Phys Fitness. 1969 Jun;9(2):104-6.
 
2. Athletic performance peaks in the summer when vitamin D levels peak, and is at its lowest in the winter when vitamin D levels are at their lowest.
 
A. True
B. False
 
True.  The studies below - all I could find in the literature - show tests of physical performance peak in the summer, when vitamin D levels peak, start to decline in early autumn, as vitamin D levels decline, and athletic performance reaches its lowest point in late winter, when vitamin D levels bottom out.   However, it is reasonable to assume that any associations between athletic performance and summer season may be due to "reverse causation."  That is, improved athletic performance in the summer might be secondary to increased outdoor physical and recreational activity in the warmer weather with an indoor sedentary lifestyle during the colder months.  Maybe people have better athletic ability in the summer because they exercise more.  If that is true - and using the same logic - athletic performance should not begin to decline until late autumn, because at most temperate latitudes early fall weather is ideal for outdoor physical activities. 
 
However, some of the studies below controlled for seasonal variations in time spent exercising.  Furthermore, besides a consistent positive association of summer season with improved athletic performance, the below studies found an abrupt - and unexplained - reduction in athletic performance beginning in the early fall - when vitamin D levels decline - but when the weather is ideal for outdoor activities.
 
 
For example, in 1956, German researchers found a distinct seasonal variation in the trainability of musculature, studying wrist flexor strength in 21 German subjects undergoing daily training.  They found highly significant seasonal differences with peak performance during the later part of the summer, nadirs in the winter, and an unexplained sharp autumn decline beginning in October.
 
Hettinger T, Muller EA.  Seasonal course of trainability of musculature.  Int Z Angew Physiol. 1956;16(2):90-4.
 
A study of Polish pilots and crew found physical fitness and tolerance to hypoxia were highest in the late summer with an unexplained sharp decline starting in September.  The authors hypothesized that seasonal variations in an unidentified hormone best explained their results.
 
Kwarecki K, Golec L, Klossowski M, Zuzewicz K. Circannual rhythms of physical fitness and tolerance of hypoxic hypoxia. Acta Physiol Pol. 1981 Nov-Dec;32(6):629-36.
 
Cumulative work ability among 1,835 mainly sedentary Norwegian men during bicycle exercise tests showed an August peak, a sharp decline starting in the autumn, and a wintertime nadir.  There were no seasonal changes in body weights, as might be expected if more caloric-demanding recreational activity during the sunnier months explained their results.
 
Erikssen J, Rodahl K. Seasonal variation in work performance and heart rate response to exercise. A study of 1,835 middle-aged men. Eur J Appl Physiol Occup Physiol. 1979 Oct;42(2):133-40.
 
Koch and Raschka reviewed the mostly German literature on the seasonality of physical performance, discussing studies indicating that muscle strength and stamina peak in the late summer. The authors then attempted to control for seasonal variations in the time spent exercising by instituting a controlled yearlong training regimen, beginning in December.  The training regimen consisted of at least 20 push-ups per day and 2 or 3 long-distances races per week for the entire year.  They found the both the number of push-ups and muscle strength peaked in late summer followed by a rapid decline in the fall, and a nadir in the winter, despite continued training.  They concluded that seasonal variations in an unidentified hormone best explained their results.  In addition, by now we all know that vitamin D is a seasonal hormone, and a steroid hormone precursor to boot.
 
Koch H, Raschka C. Circannual period of physical performance analysed by means of standard cosinor analysis: a case report. Rom J Physiol. 2000 Jan-Dec;37(1-4):51-8.
 
3. Vitamin D has direct muscle-building (anabolic) effects.
 
A. True
B. False
 
 
True, but only in vitamin D deficient subjects. Both animal and human studies have found that vitamin D directly affects muscle.  That is, vitamin D increases muscle mass.
 
For example, Birge and Haddad found that vitamin D caused new protein synthesis in rat muscle.
 
Birge SJ, Haddad JG. 25-hydroxycholecalciferol stimulation of muscle metabolism. J Clin Invest. 1975 Nov;56(5):1100-7.
 
What about humans?  In 1981, Young performed muscle biopsies on 12 severely vitamin D deficient patients before and after vitamin D treatment.  They found type-II (fast-twitch) muscle fibers were small before treatment and significantly enlarged after treatment.  Sorensen performed muscle biopsies on eleven older patients with osteoporosis before and after treatment with vitamin D.  The percentage and area of fast twitch fibers increased significantly after treatment, despite the lack of any physical training.
 
Young A, Edwards R, Jones D, Brenton D. Quadriceps muscle strength and fibre size during treatment of osteomalacia.  In: Stokes IAF (ed) Mechanical factors and the skeleton. 1981. pp 137-145.
 
Sorensen OH, Lund B, Saltin B, Lund B, Andersen RB, Hjorth L, Melsen F, Mosekilde L. Myopathy in bone loss of ageing: improvement by treatment with 1 alpha-hydroxycholecalciferol and calcium. Clin Sci (Lond). 1979 Feb;56(2):157-61.
 
Sato reported that two years of treatment with 1,000 IU of vitamin D per day significantly increased muscle strength, doubled the mean diameter, and tripled the percentage of fast-twitch muscle fibers, in the functional limbs of 48 severely vitamin D deficient elderly stroke patients. The placebo control group suffered declines in muscle strength, and in the size and percentage of fast-twitch muscle fibers.
 
Sato Y, Iwamoto J, Kanoko T, Satoh K. Low-Dose Vitamin D Prevents Muscular Atrophy and Reduces Falls and Hip Fractures in Women after Stroke: A Randomized Controlled Trial. Cerebrovasc Dis. 2005 Jul 27;20(3):187-192 [Epub ahead of print]
 
These studies clearly show that vitamin D when administered to vitamin D deficient people stimulates the growth and number of those muscle fibers critical to athletic ability, type-2, or "fast twitch," muscle fibers.
 
4. Many studies have found direct associations between physical performance and vitamin D levels.  That is, the higher your vitamin D level, the better your athletic performance.
 
A. True
B. False
 
True.  I found 13 positive studies of associations between vitamin D levels and various parameters of neuromuscular performance.  However, they were all in old people.  Of course, old people can be athletes too.  Furthermore, age differences in physiology and pharmacology are quantitative, not qualitative.  That is, what is true in old people will be true in young people, although the magnitude might be different.  Higher vitamin D levels are associated with a wide variety of athletic performance but appear to have the strongest associations with balance, timing, and timed tests of physical performance. 
 
The three largest studies had more than 7,000 elderly subjects.  All found evidence of a vitamin D threshold of between 30 - 50 ng/ml, above which further improvements in athletic performance were not seen.  Wicherts and her colleaguesfound a linear correlation between vitamin D and neuromuscular performance; scores were 78% better for those with vitamin D levels greater than 30 ng/ml compared to those with levels less than10 ng/ml.
 
 
Bischoff-Ferrari HA, Dietrich T, Orav EJ, Hu FB, Zhang Y, Karlson EW, Dawson-Hughes B. Higher 25-hydroxyvitamin D concentrations are associated with better lower-extremity function in both active and inactive persons aged > or =60 y. Am J Clin Nutr. 2004 Sep;80(3):752-8.
 
Gerdhem P, Ringsberg KA, Obrant KJ, Akesson K. Association between 25-hydroxy vitamin D levels, physical activity, muscle strength and fractures in the prospective population-based OPRA Study of Elderly Women. Osteoporos Int. 2005 Nov;16(11):1425-31.

Wicherts IS, et al. Vitamin D status predicts physical performance and its decline in older persons. J Clin Endocrinol Metab. 2007 Mar 6; [Epub ahead of print]
 
Professor Heike Bischoff-Ferrari, now in Switzerland, did the largest study.  She and her colleagues found a strong positive correlation and suggestion of a U-shaped curve with athletic performance on one test peaking with vitamin D levels of 50 ng/ml but deteriorating at higher levels.  It is interesting to speculate that levels around 50 ng/ml may be optimal for athletic performance as such levels are common in humans living in a "natural" state of sun-exposure, such as lifeguards or tropical farmers.
 
Bischoff HA, Stahelin HB, Urscheler N, Ehrsam R, Vonthein R, Perrig-Chiello P, Tyndall A, Theiler R. Muscle strength in the elderly: its relation to vitamin D metabolites. Arch Phys Med Rehabil. 1999 Jan;80(1):54-8.
 
Interestingly, all three studies that looked for an association between mental abilities and vitamin D levels found one.  A fourth study, unrelated to athletic function, also found an association.  The obvious explanation for these findings is that cognitively impaired patients do not go outdoors as often as higher functioning patients and thus have lower vitamin D levels.  However, Dhesi found the association after excluding all but mildly demented patients, making such an explanation more difficult.  Flicker and - more recently - Przybelski and Binkley, found the association after controlling for outdoor activities, raising the possibility that the association of vitamin D levels with cognitive abilities is casual.  Both the vitamin D receptor and the enzyme necessary to activate vitamin D are present in a wide-variety of human brain tissue.  If vitamin D deficiency impairs cognitive abilities, it is likely that such deficiencies will also impair the brain's ability to process the complex circuits needed for peak athletic performance.
 
Dhesi JK, Bearne LM, Moniz C, Hurley MV, Jackson SH, Swift CG, Allain TJ. Neuromuscular and psychomotor function in elderly subjects who fall and the relationship with vitamin D status. J Bone Miner Res. 2002 May;17(5):891-7.
 
Kenny AM, Biskup B, Robbins B, Marcella G, Burleson JA. Effects of vitamin D supplementation on strength, physical function, and health perception in older, community-dwelling men. J Am Geriatr Soc. 2003 Dec;51(12):1762-7.
 
Flicker L, Mead K, MacInnis RJ, Nowson C, Scherer S, Stein MS, Thomasx J, Hopper JL, Wark JD. Serum vitamin D and falls in older women in residential care in Australia. J Am Geriatr Soc. 2003 Nov;51(11):1533-8.
[1] 
Przybelski RJ, Binkley NC. Is vitamin D important for preserving cognition? A positive correlation of serum 25-hydroxyvitamin D concentration with cognitive function. Arch Biochem Biophys. 2007 Jan 8;
 
There can be no doubt that higher vitamin D levels are associated with improved athletic performance in the elderly.  From what we know of physiology and pharmacology, the same associations should hold true in young people, including young athletes.
 
5. Numerous studies have found that vitamin D improves physical performance.
 
A. True
B. False.
 
True, but, again, most all the studies are in old persons, not young ones, and none of the studies are in world-class athletes.  However, there is no medical reason why vitamin D would improve the athletic performance of vitamin D deficient old people but not vitamin D deficient young ones.  Eleven studies found vitamin D improved physical performance, mainly on measures of balance and reaction time.  The one study of younger subjects showed dramatic physical performance effects in 55 severely vitamin D deficient women. 
 
Sorensen OH, Lund B, Saltin B, Lund B, Andersen RB, Hjorth L, Melsen F, Mosekilde L. Myopathy in bone loss of ageing: improvement by treatment with 1 alpha-hydroxycholecalciferol and calcium. Clin Sci (Lond). 1979 Feb;56(2):157-61.
 
Gloth FM 3rd, Smith CE, Hollis BW, Tobin JD. Functional improvement with vitamin D replenishment in a cohort of frail, vitamin D-deficient older people. J Am Geriatr Soc. 1995 Nov;43(11):1269-71.
 
Glerup H, Mikkelsen K, Poulsen L, Hass E, Overbeck S, Andersen H, Charles P, Eriksen EF. Hypovitaminosis D myopathy without biochemical signs of osteomalacic bone involvement. Calcif Tissue Int. 2000 Jun;66(6):419-24.
 
Prabhala A, Garg R, Dandona P. Severe myopathy associated with vitamin D deficiency in western New York. Arch Intern Med. 2000 Apr 24;160(8):1199-203.
 
Verhaar HJ, Samson MM, Jansen PA, de Vreede PL, Manten JW, Duursma SA. Muscle strength, functional mobility and vitamin D in older women. Aging (Milano). 2000 Dec;12(6):455-60.
 
Pfeifer M, Begerow B, Minne HW, Abrams C, Nachtigall D, Hansen C. Effects of a short-term vitamin D and calcium supplementation on body sway and secondary hyperparathyroidism in elderly women. J Bone Miner Res. 2000 Jun;15(6):1113-8.
 
Bischoff HA, Stahelin HB, Dick W, Akos R, Knecht M, Salis C, Nebiker M, Theiler R, Pfeifer M, Begerow B, Lew RA, Conzelmann M. Effects of vitamin D and calcium supplementation on falls: a randomized controlled trial. J Bone Miner Res. 2003 Feb;18(2):343-51.
 
Dhesi JK, Jackson SH, Bearne LM, Moniz C, Hurley MV, Swift CG, Allain TJ. Vitamin D supplementation improves neuromuscular function in older people who fall. Age Ageing. 2004 Nov;33(6):589-95.
 
Sato Y, Iwamoto J, Kanoko T, Satoh K. Low-Dose Vitamin D Prevents Muscular Atrophy and Reduces Falls and Hip Fractures in Women after Stroke: A Randomized Controlled Trial. Cerebrovasc Dis. 2005 Jul 27;20(3):187-192 [Epub ahead of print]
 
In summary, five converging - but totally separate - lines of scientific evidence leave little doubt that vitamin D improves athletic performance.  (I actually left out a sixth line of evidence, something a little more complicated, studies of muscle strength and vitamin D receptor polymorphisms; the two studies I could find were both positive.)  Anyway, the scientific evidence that UVB radiation, either from the sun or from sunbeds, will improve athletic performance is overwhelming and the mechanism is almost certainly vitamin D production.  Peak athletic performance will probably occur with 25(OH)D levels of about 50 ng/ml, whether from sun, sunbeds, or supplements.
 
All that is missing is a big-time professional or college team identifying and then treating their elite athletes who are vitamin D deficient. Can you imagine what such performance-enhancing effects would do for basketball players, most of who are African American and who practice and play indoors all winter?  Or gymnasts?  Or weight lifters? 
 
However, a word of caution. The above studies suggest that taking too much vitamin D (more than 5,000 IU per day) may actually worsen athletic performance.  Take the right amount, not all you can swallow.  Take enough to keep your 25(OH)D levels around 50 ng/ml, year round.  Easier yet, regularly use the sun in the summer and sunbeds in the winter - with care not to burn.  Once a week should be about right.
 
When you think about it, none of this should surprise anyone. Every body builder knows that steroid hormones can improve athletic performance, certainly increase muscle mass.  Barry Bonds knows they increase timing and power.  Moreover, activated vitamin D is as potent a steroid hormone as exists in the human body.  However, unlike other steroids, levels of activated vitamin D in muscle and nerve tissue are primarily regulated by sun exposure.  That's right, the rate-limiting step for the cellular function (autocrine) of activated vitamin D is under your control.  It depends on how much you put in your both or go into the sun.  It's ironic that many athletes now avoid the sun, organized baseball is even promoting sun avoidance and sunblocks.  The ancient Greeks knew better; they had there elite athletes train on the beach and in the nude.
 
The medical literature indicates vitamin D levels of about 50 ng/ml are associated with peak athletic performance. Of course, recent studies show such levels are ideal for preventing cancer, diabetes, hypertension, influenza, multiple sclerosis, major depression, cognitive impairments, etc.  But who cares about all that disease stuff old people get,we're talking about something really important: speed, balance, reaction time, muscle mass, muscle strength, squats, reps, etc.  And guess who's now taking 4,000 IU/day?  Yes he is, and he tells me his timing is better, he can jump a little higher, run a little faster, and the ball feels "sweeter," whatever that means.
 
 
John Cannell, MD
 
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