Skip to content

Yesterday's post was about how several well-done large studies did not find the health benefits from vitamin D supplements that the researchers had hoped for. In one of the studies (the VITAL trial) discussed yesterday, Vitamin D supplements did not prevent cancer or cardiovascular events (e.g., stroke, heart attack), which was the focus of the study.

But... one positive finding (in a separate analysis of the study results) did come out of the study: vitamin D supplements reduced the incidence of autoimmune disease by 22% over the 5+ years of the VITAL trial. This included rheumatoid arthritis, polymyalgia rheumatica, autoimmune thyroid disease, and psoriasis.

The more than 25,000 participants (all older than 50 years) took vitamin D 2000 IUs daily or 1 g marine omega-3 fatty acids (fish oil) daily,  or both, or none for more than 5 years. Only the vitamin D supplementation (whether taken alone or with fish oil) had a statistically significant health effect.

From Medical Xpress: Study finds vitamin D supplements with or without Omega-3s decreased risk of autoimmune diseases

Autoimmune diseases (AD) such as rheumatoid arthritis, polymyalgia rheumatica, autoimmune thyroid disease and psoriasis, are a leading cause of morbidity and mortality as people age. Few effective treatments are available for AD, but some preclinical studies have hinted that supplements, including vitamin D and omega-3 (or n-3) fatty acids, may have beneficial effects. In a new study published in BMJ, investigators from Brigham and Women's Hospital evaluated whether taking vitamin D and/or omega fatty acid supplements could affect rates of AD.  ...continue reading "Vitamin D Supplements and Autoimmune Disease"

Several recent articles on Medscape (a site for medical professionals) highlight the debate over vitamin D. The question: Does daily vitamin D supplementation have positive health benefits or not? Everyone agrees that if there is an actual deficiency, then it has positive health effects. But how about the average person with levels above the deficiency level?

Numerous observational studies find that low levels of vitamin D are associated with all sorts of health problems (e.g., cancer, heart disease), but randomly controlled trials (RCT) where people are randomly assigned to different groups with no one knowing what they are getting - just aren't finding health benefits. The strongest evidence so far has been for vitamin D supplementation resulting in lower incidence of upper respiratory illnesses.

What is going on? Some suggest that low vitamin D levels are a marker for ill health (the illness reduces the vitamin D levels), and that vitamin D levels go down when there is chronic inflammation. It could also be a proxy for sun exposure (the more sunlight, the higher the vitamin D levels). Note that sunlight may have additional benefits compared to just vitamin D supplementation (e.g, blue light is immune boosting).

John M. Mandrola, MD writes for Medscape, and his articles tend to be thought-provoking. Some excerpts of a Commentary by Dr. John Mandrola from Medscape: Why Is Vitamin D Hype So Impervious to Evidence?

The vitamin D story exudes teaching points: it offers a master class in critical appraisal, connecting the concepts of biologic plausibility, flawed surrogate markers, confounded observational studies, and slews of randomized controlled trials (RCTs) showing no benefits on health outcomes.

Yet despite the utter lack of benefit seen in trials, the hype continues....

My questions are simple: Why doesn't the evidence persuade people? How many nonsignificant trials do we need before researchers stop studying vitamin D, doctors stop (routinely) measuring levels, and patients stop wasting money on the unhelpful supplement? What are the implications for this lack of persuasion?  ...continue reading "Some Large Studies Find No Benefit From Vitamin D Supplements"

Another study found that increased sun exposure in children and young adults is linked to lower levels of multiple sclerosis. This was the main finding of a study conducted at multiple centers in the United States by a team of American and Australian researchers.

The researchers in the study stated that not only does sunlight boost vitamin D levels, it also "...stimulates immune cells in the skin that have a protective role in diseases such as multiple sclerosis." In addition, they found an association with the intensity of sunlight and estimated that residents of Florida would be 21 percent less likely than residents of New York to have multiple sclerosis. Sun exposure appears to be dose dependent - the longer the exposure, the lower the risk of multiple sclerosis.

Earlier studies also found immune boosting properties of sunlight. Sunlight has low levels of "blue light" which energizes T cells that play a central role in human immunity. T cells are a type of white blood cell, are part of the immune system, and help protect the body from infection and cellular abnormalities (cancer). 

Bottom line: In this study getting at least 30 minutes (up to 1 hour) of sunshine daily, especially in the summer, seems to be key in terms of protective effects.

From Medical Xpress: Sunshine may shield children, young adults from MS

Living in sunny locations and spending time outdoors may raise the risk for skin cancer, but a new study led by UC San Francisco and the Australian National University shows that in children and young adults, sun exposure may protect against multiple sclerosis. The study follows previous work by other researchers that has demonstrated an association between increased ultraviolet exposure in childhood and lower odds of adult MS ...continue reading "Sunshine and Multiple Sclerosis in Children and Young Adults"

Many people complain of frequent colds and upper respiratory infections. Perhaps even every month. This is an especially big problem for those suffering from chronic sinusitis, because every cold and sore throat also leads to a sinus infection. So a goal is to try to reduce the number of infections, and daily vitamin D supplements may be the answer.

Many studies have looked at vitamin D supplementation, at all sorts of doses, for all sorts of health conditions, including cancer. Unfortunately, when properly done studies with people randomly assigned to different groups are done, then all sorts of correlations don't hold up, or mixed results. Right now it appears that the main positive benefit of vitamin D supplements is lowering the incidence of upper respiratory illnesses that a person gets. Another study just confirmed this finding.

An international team of researchers reviewed data from 43 studies (48,488 participants), and found a small but significant protective effect of vitamin D supplementation in lowering the risk of getting a respiratory infection (when compared with a placebo). The studies revealed that the protective benefits of vitamin D supplements were strongest in 1 to 16 year olds who took between 400 to 1000 IU daily for up to 12 months.

Interestingly, and this may really bother high dose vitamin D advocates, the researchers found that lower doses (400 to 1000 IU daily) had a positive health effect, but NOT larger daily doses. They found that data from 4 recent good studies (with persons randomly assigned to different groups) in which vitamin D was given at daily dose equivalents of 2000 IU/day or more for 2 to 5 years had NO EFFECT. In other words: null data.

These differing findings suggest that frequency (daily is better then weekly or monthly), dose, and duration (no more than 12 months) of vitamin D supplementation are key to its protective effects against respiratory illnesses. It is unclear why higher doses are NOT protective, while smaller doses are protective. It's like the saying: Less is more.

Excerpts from Medical Xpress, which actually is misleading in how the conclusions of the study are described: New research on vitamin D and respiratory infections important for risk groups

Studies have shown that supplementary vitamin D seems to provide a certain degree of protection against respiratory infections. A new study involving researchers from Karolinska Institute has now made the most comprehensive synthesis to date of this connection. The study, which is published in The Lancet Diabetes & Endocrinology, confirms that vitamin D protects against respiratory infections, a result that can have significance for the healthcare services. [NOTE: Protective effect was seen in the 1 to 16 year old age groups, and not other age groups.] ...continue reading "Fewer Respiratory Infections With Vitamin D Supplements"

Pregnancy is a time when one should try to eat as well as possible, especially for the health of the developing baby. Included in this is the baby's brain development and later intellectual functioning (neurocognitive development). A recent study found that a mother's vitamin D levels during pregnancy are associated with the IQ of the child - that is, higher levels of vitamin D during the second trimester  of pregnancy were associated with higher IQs at age 4 to 6 in the child.

Just keep in mind that it's an association - it does not mean that lower vitamin D levels cause lower IQ. Vitamin D levels go hand in hand with other things - for example, vitamin D levels are lower when a person has chronic inflammation or an underlying health condition. Other studies have had mixed results - some had similar findings of effects on intellectual development, but others did not. Black women are at higher risk of vitamin D deficiencies due to their skin melanin content (harder to get enough vitamin D from the sun).

However, these results do add support for trying to correct vitamin D deficiencies and keeping vitamin D levels higher during pregnancy - by taking supplements and getting sunlight. Note that it's very hard to get enough vitamin D through food. The researchers said that prenatal supplements typically contain 400–600 IU vitamin D, but this is probably insufficient to correct vitamin D deficiencies, in which case they recommend daily supplementation of 800 to 1000 IU vitamin D.

From Medical Xpress: Vitamin D levels during pregnancy linked with child IQ

Vitamin D is a critical nutrient and has many important functions in the body. A mother's vitamin D supply is passed to her baby in utero and helps regulate processes including brain development. A study published today in The Journal of Nutrition showed that mothers' vitamin D levels during pregnancy were associated with their children's IQ, suggesting that higher vitamin D levels in pregnancy may lead to greater childhood IQ scores. The study also identified significantly lower levels of vitamin D levels among Black pregnant women. ...continue reading "Vitamin D Levels During Pregnancy Associated With A Child’s IQ"

Several studies are now suggesting that low vitamin D levels are linked to increased risk of getting COVID-19. And if you get COVID-19, low vitamin D levels are linked to a higher risk of developing serious symptoms requiring admission to intensive care,  and also not surviving. These studies are observational and don't prove that vitamin D levels are the cause, but a number of studies from countries worldwide and several lines of research are suggesting the same thing.

The best source of vitamin D is sunlight, but if taking supplements - then take vitamin D3. Researchers, doctors, and medical organizations vary in their recommended dosages, but many (such as Mayo Clinic) suggest 1000 to 2000 IU per day. The minimum daily requirement is 600 IU.

Some studies also suggest that having adequate magnesium is needed for vitamin D to be metabolized well. Good food sources of magnesium are nuts, seeds (especially pumpkin seeds), peanut butter, whole grains, beans, leafy vegetables, some fatty fish (halibut, salmon, mackerel), milk, yogurt, dark chocolate, legumes (beans), quinoa, tofu, and bananas. Daily magnesium requirements are 420 mg for men, 320 mg for women. Food is generally considered a better source than supplements.

However, some researchers point out that having a disease (e.g. diabetes) or chronic inflammation results in lowering of vitamin D levels (and not that low vitamin D levels causes disease). We need good double-blind studies (people randomly assigned to groups, and no one knows who is getting what) to understand if it really is vitamin D that's causing beneficial health effects.

Excerpts from Medscape: Low Vitamin D in COVID-19 Predicts ICU Admission, Poor Survival

Having low serum vitamin D levels was an independent risk factor for having symptomatic COVID-19 with respiratory distress requiring admission to intensive care — as opposed to having mild COVID-19 — and for not surviving, in a new study from Italy. ...continue reading "Vitamin D and COVID-19"

A recent study found that giving daily vitamin D supplements to children with severe asthma and low vitamin D levels did not prevent severe asthma attacks, reduce the time to an asthmatic attack, or enable the children to reduce the maintenance dose of an inhaled corticosteroid. Very disappointing!

As of 2018, it is estimated that 5.5 million children in the US have asthma, and that asthma led to more than 546,000 emergency department visits and 80,000 hospitalizations. So the researchers started the study hoping that vitamin D3 supplements could help with asthma attacks.

The well-done year long study recruited children (6 to 16 years old) from 7 US medical centers. They were assigned randomly to different groups (vitamin D or placebo), and with no one knowing who got vitamin D and who didn't. The children took 4000 IU/day of vitamin D3 or a placebo for 48 weeks, and all were maintained with a low-dose of inhaled corticosteroid (fluticasone propionate).

The findings contrast with earlier observational studies (basically a snap-shot of  groups of people) that found a link with severe asthma and lower vitamin D levels. Meanwhile, other well-done studies (women assigned randomly to different groups, etc) have found no protective effect from vitamin D3 supplementation during pregnancy - that is, it did not protect children up to the age of 6 from asthma.

Excerpts from Science Daily: Compared to placebo, vitamin D has no benefit for severe asthma attacks, study finds

Contrary to earlier results, vitamin D supplements do not prevent severe asthma attacks in at-risk children, according to the first placebo-controlled clinical trial to test this relationship.  ...continue reading "Children With Severe Asthma Not Helped By Vitamin D Supplements"

2

Disappointing results from a large study of more than 18,000 adults that looked at whether daily vitamin D supplements for 5 years helps prevent depressionThe Harvard Medical School researchers found that vitamin D didn't prevent depression or improve mood.

The study was large (more than 18,000 adults over the age of 50), double-blind (no one knew who was getting what to prevent bias), had people assigned randomly to either getting vitamin D3 (2000 IU/d of cholecalciferol) or a placebo, and lasted 5 years. The researchers summary of findings: "These findings do not support the use of vitamin D3 in adults to prevent depression."

By the way, the results of this well-done study (which was designed to see cause and effect) are in contrast to observational studies that suggested that a person's vitamin D levels and vitamin D supplements are correlated with the risk of depression and depressive symptoms. Once again a well-done vitamin D study did not provide the health benefits that people were hoping for.

From Medical Xpress: Large study confirms vitamin D does not reduce risk of depression in adults

Vitamin D supplementation does not protect against depression in middle-age or older adulthood according results from one of the largest ever studies of its kind. This is a longstanding question that has likely encouraged some people to take the vitamin.  ...continue reading "Study Finds That Vitamin D Supplements Don’t Prevent Depression"

2

The past year has resulted in disappointments for the vitamin and mineral supplement industry as study after study didn't find health benefits from routinely ingesting them. Instead, study after study found health benefits from eating a good diet, specifically one that has as few as possible highly processed foods, but lots of whole foods, and rich in whole grains, fruits, vegetables, nuts, seeds, and legumes (beans). And in this way, also high in fiber. Think along the lines of a Mediterranean diet.

The following are some of the studies finding no benefits to various vitamin and mineral supplements. Many found the results of the vitamin D studies especially disappointing.

1) From Science Daily - Vast majority of dietary supplements don't improve heart health or put off death, study finds

In a massive new analysis of findings from 277 clinical trials using 24 different interventions, Johns Hopkins Medicine researchers say they have found that almost all vitamin, mineral and other nutrient supplements or diets cannot be linked to longer life or protection from heart disease.   ...continue reading "Four Vitamin Studies Have Disappointing Results"

For years researchers have been finding links between vitamin D and all sorts of health benefits, including lower incidence of cancer with higher vitamin D levels. A recent study by Michigan State physicians found that taking vitamin D supplements for at least 3 years resulted in cancer patients living longer, that is, "having significant reduction of cancer-related mortality" . However, it did not prevent cancer.

One issue with much of the vitamin D research that has been done is whether vitamin D is really  causing these health benefits or is it just an association? Perhaps people who take vitamin D are also different in some way from those who  don't, or something else is going on, and this may be confusing the results.What was nice about this  study is that it was a review of studies already done, but the researchers only included vitamin D studies  that used randomly controlled trials (RCT).

In the RCTs  included in the study, people were randomly assigned to different groups and either they were 1) given vitamin D supplements for 3 years or more, or 2) they did not take vitamin D supplements (the placebo group). Thus they evaluated 10 RCT studies with 79,055 persons who were followed for 4 years or more. Vitamin D was associated with significant reduction of cancer-related deaths (when compared with the placebo group). But there was no reduction in cancer incidence. Meaning the vitamin D did not prevent cancer (have a protective effect) in the studies they looked at.

The researchers did not say what they thought was an optimal vitamin D supplement dose or optimal levels in the blood. By the way, keep in mind that vitamin D can easily be gotten from exposure to sunshine. After all, it is called the sunshine vitamin.

From Science Daily: Vitamin D could help cancer patients live longer   ...continue reading "Vitamin D and Cancer"