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  • Covid 19
    • 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

We Can Thank Poor Evolutionary Design for Vitamin D Deficiencies

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My doctor recently declared me deficient in vitamin D and prescribed a weekly pill. Because I take care to eat a healthy and diverse diet, I was a bit annoyed. She said it was no big deal and actually very common, the medical equivalent of a parent telling a child, “Because I said so.” Later on, I was grousing to some of my friends and many of them said they had gotten the same news.  It made me wonder: What is going on with vitamin D?

A Vexing Vitamin

Truth be told, we shouldn’t really need vitamin D in our diets at all. Humans and other animals can synthesize this molecule right from cholesterol, something we always have plenty of. Doing so, however, involves a rather obnoxious biochemical pathway. The synthesis of vitamin D begins in the skin with activation of a precursor molecule by ultraviolet light from the sun. After that, the process moves to the liver for further chemical modification and then on to the kidneys for a final tweak.
This biochemical pathway is really odd and seems unnecessarily complicated. Our bodies are adept at making lots of complex molecules without stops in three different tissues. What’s more, involving the liver and kidneys makes for a huge detour. Because vitamin D and its precursors are fat-soluble molecules, they distribute in tissues throughout the body and especially accumulate in adipose, or fat tissue. It would make much more sense to house the enzymes for the synthesis of vitamin D within fat cells, which are often tucked right underneath the skin anyway, where the UV light is needed for the first step.
Another big problem with our vitamin D synthesis scheme is that, in cold climates, humans must bundle up in order to survive. Since keeping warm wasn’t an issue in Africa, where our ancestors lived for millions of years, we mostly ditched our own fur and instead we now rely on the furs of other animals to keep us warm, thereby blocking the penetration of UV light into the skin and reducing the synthesis of vitamin D.
In warmer regions, humans tend not to cover their skin as much, but this opens them up to skin cancer and also the UV-mediated destruction of folic acid. Skin pigmentation helps mitigate those problems, but at the cost of reduced vitamin D synthesis. The result is a problematic tug-of-war: Skin cancer and folic acid deficiency on the one side and vitamin D deficiency on the other.
There is a way around this problem, of course. Many animals, including humans, can escape this paradox by simply ingesting the activated vitamin D precursor. Dietary vitamin D still requires the activation steps in the liver and kidney, but at least it lets us stay out of the sunlight. Such supplementation has allowed humans to live in frigid climates and it is no coincidence that Arctic diets tend toward fish and whale blubber, two very rich sources of vitamin D.
And yet, despite this, vitamin D deficiencies are still common, and archaeological evidence suggests that they have been for a long time. We know from studying skeletal remains that rickets, caused by childhood vitamin D deficiency, was a common malady in pre-agricultural human populations. The domestication of fowl helped with this, as eggs are rich in vitamin D, and meat and fish are good sources as well. But prior to that, and therefore for most of our evolutionary history, eggs, meat and fish were not in steady supply and still aren’t for many people around the world.
The reason for a continued lack of vitamin D in our lives is that patterns of feast and famine can be effectively managed when it comes to calories, which can be easily stored (too easily, but that’s another story) – but not for vitamins. We don’t store vitamin D for a rainy day, so infrequent large doses do not compensate for weeks of deficiency. While we can get vitamin D in our diet, maintaining a regular supply is difficult. Supplements are often the best option for those who must go without sunlight for long stretches of the year.

What’s It Good for Anyway?

But why do we need vitamin D in the first place? The answer reveals even more poor evolutionary design. While vitamin D has many functions in the human body, the most important, and therefore most sensitive to deficiency, is the absorption of calcium in our intestines.
Humans are notoriously bad at extracting calcium from our food. We start off okay as babies, absorbing a respectable 60% of the calcium we are fed, but our absorption ability steadily drops as we mature. Adults are lucky if we can get 20% of the calcium that we ingest and by middle age, it is often below 10%. You might be happy with the 300mg of calcium in a small cup of milk, but if you’re over 50, you’re probably not absorbing more than 20 or 30mg of that calcium. The rest ends up in the toilet. And that’s the sad state of affairs when we are getting enough vitamin D.
Those deficient in vitamin D cannot absorb calcium from their diets at all. This is why milk is typically supplemented with vitamin D. If we don’t get adequate sunlight – and most of us don’t – we become desperate for calcium, even if we’re consuming plenty of it. Calcium is necessary for more than just healthy bones — it’s crucial for things like flexing our muscles — so our bodies consider the calcium in our bones as reservoirs to be tapped when the need is urgent.
When we don’t get enough vitamin D, we can’t absorb calcium, so we start pulling it out of our bones. If the bones are still growing when that happens, they become misshapen; a condition called rickets. If we’re already fully grown, the lost calcium weakens the bones and they become brittle and easily broken; that’s osteoporosis. All of this because we can’t absorb calcium, even when it’s right there for the taking.

Evolutionary Headache

The fact that vitamin D is required for calcium absorption is the most bizarre part of the whole story. All vitamin D does is signal the cells to absorb calcium. That’s it! Having a switch for calcium absorption is important because having too much can also be unhealthy. But having that switch involve another compound that also must be acquired in the diet is foolish because now there are two ways to suffer from calcium insufficiency: a lack of calcium or a lack of vitamin D.
Since wild animals don’t have the benefit of vitamin D-infused milk in their diet, and are completely covered with thick, light-blocking fur, it seems that they might suffer from similar issues.
Nope, not at all. Other mammals, including our own dogs and cats, synthesize vitamin D just fine because they activate it in their fur instead of their skin. We lost this option when we ditched the fur. Vitamin D deficiency is a uniquely human scourge. So much for being the pinnacle of creation!
So, the bottom line is that some rather glaring design flaws in our bodies have made vitamin D deficiency so common and harmful. Evolution does not produce perfection and nowhere is this clearer than our demanding dietary needs. For many of us, getting a little more direct sunlight would do the trick when it comes to vitamin D, but who really wants to flirt with melanoma? We can also try to eat fish more regularly. Or whale blubber. I think I’ll just stick with the weekly pill.


Nathan H. Lents is professor of biology at John Jay College, CUNY, and the author of Human Errors: A Panorama of Our Glitches, From Pointless Bones to Broken Genes
http://blogs.discovermagazine.com/crux/2018/07/10/vitamin-d-deficiency-evolution/#.W00B21VKiEt

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