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Tag: Vitamin D

Published on Leave a comment on Regular Exercise In Winter Months Keeps Vitamin D Levels Up

Typically, our vitamin D levels drop in the winter months when we don't get as much sun exposure. After all, it is called the sunshine vitamin. However, a new study found that regular moderate-intensity exercise kept vitamin D levels up in the winter, even without vitamin D supplements or weight loss.

Good reason to exercise - prevent the usual seasonal decline in vitamin D. How much exercise? In the study, overweight adults had four indoor cardiovascular exercise sessions per week for 10 weeks: two treadmill walks, one longer steady-state bike ride, and one high-intensity interval bike session

From Science Daily: Exercise the key to maintaining Vitamin D levels in winter

The sun may be shining now, and our vitamin D levels are getting a natural boost but it wasn't long ago we were in the depths of winter, when sunlight was scarce and vitamin D was in short supply. ...continue reading "Regular Exercise In Winter Months Keeps Vitamin D Levels Up"

Published on Leave a comment on Another Vitamin D Study With Disappointing Results

Recently, another well done study of vitamin D and cancer resulted in disappointing results. Vitamin D supplements showed no benefit in persons with metastatic colorectal cancer (CRC). It did not result in a difference in overall survival outcomes.

In the study, 455 patients with metastatic colorectal cancer were assigned randomly to either high daily vitamin D3 or standard dose vitamin D3, in addition to receiving standard chemotherapy. The high dose vitamin D group received a loading dose of 8000 IU per day for 2 weeks, followed by a maintenance dose of 4000 IU per day until the end of the study. The standard dose vitamin D group received 400 IU per day.

However, there was no difference in "significant progression-free survival benefit". There also was no significant difference in how long people survived in the 2 groups (a median of 25.6 months in the high-dose group, and 27.0 months in the standard dose group).

The study results were disappointing because in laboratory studies vitamin D has anticancer properties. Critics of this study pointed out that vitamin D supplementation may have a role in cancer prevention - but at this point, that is unknown.

From Medscape: High-Dose Vitamin D Disappoints in Metastatic CRC: SOLARIS

The addition of high-dose vitamin D supplementation to standard chemotherapy plus bevacizumab did not result in a significant progression-free survival benefit in patients with metastatic colorectal cancer (CRC) in the SOLARIS study. ...continue reading "Another Vitamin D Study With Disappointing Results"

Published on Leave a comment on Study Found Vitamin D Supplements Do Not Prevent Fractures In Children

Another disappointing result for Vitamin D supplements. A large study, with school-aged children randomly assigned to either a vitamin D supplement group or no supplement, found that vitamin D supplementation had no effect on the number of fractures that occurred in the children. Vitamin D3 supplementation did not prevent fractures or have an effect on bone strength.

Most children were vitamin D deficient at the beginning of the 3 year study (but none had rickets, for which vitamin D is prescribed). The vitamin D supplement (14,000 IU/week for 3 years) group soon had normal levels while the other group stayed at low levels. And yet there were no differences in the percentage getting fractures (6% in both groups) over time.

From Science Daily: Vitamin D supplements do not prevent bone fractures in children

A major clinical trial led by Queen Mary University of London and the Harvard T.H. Chan School of Public Health has found that vitamin D supplements do not increase bone strength or prevent bone fractures in children with vitamin D deficiency. The findings challenge widely held perceptions relating to the effects of vitamin D on bone health. ...continue reading "Study Found Vitamin D Supplements Do Not Prevent Fractures In Children"

Published on Leave a comment on Study Finds Vitamin D Supplements are Linked to Lower Risk of Melanoma

The results from well done studies on vitamin D supplements have frequently been disappointing due to lack of health benefits. However, a recent study found that the risk of melanoma (a skin cancer) was significantly reduced in persons taking vitamin D supplements.

The Univ. of Eastern Finland researchers also found no link between vitamin D supplementation and facial photoaging, actinic keratoses, nevus count, basal cell carcinoma and squamous cell carcinoma.

Just keep in mind that the people were not randomly selected  - these were self-selected groups, and thus this is a correlation study. There could be a reason other than vitamin D for the different outcomes.

From Science Daily: Fewer cases of melanoma among people taking vitamin D supplements

Fewer cases of melanoma were observed among regular users of vitamin D supplements than among non-users, a new study finds. People taking vitamin D supplements regularly also had a considerably lower risk of skin cancer, according to estimates by experienced dermatologists. The study, conducted in collaboration between the University of Eastern Finland and Kuopio University Hospital and published in Melanoma Research, included nearly 500 people with an increased risk of skin cancer. ...continue reading "Study Finds Vitamin D Supplements are Linked to Lower Risk of Melanoma"

Published on Leave a comment on Two Studies Find Vitamin D Doesn’t Prevent COVID

More studies are finding that supplementing with vitamin D is not living up to its original promise - that is, as a supplement that can prevent or treat all sorts of health conditions. Two recent large studies found that daily vitamin D supplementation in persons with or without a vitamin D deficiency didn't reduce the risk of getting COVID-19.

Both studies found that no matter the vitamin D dose - low (800 IU/day), high (3200 IU/day), or even taken as a cod liver oil supplement -  didn't prevent COVID infection, serious COVID, or any other respiratory infection. Very disappointing findings!

The researchers stress that both study results underscore that the COVID vaccines are the best way to protect a person from COVID-19 or a serious COVID illness. They advise that only persons with a vitamin D deficiency need vitamin D supplements. [Note: The best form of vitamin D is D3, which was given to the study participants.]

However, it must be pointed out that some other studies have found that vitamin D does lower how many respiratory infections a person gets each year (while other studies find no effect). So we'll see... more studies are ongoing.

From Medscape: Vitamin D Supplementation Shows No COVID-19 Prevention

Two large studies out of the UK and Norway show vitamin D supplementation has no benefit — as low dose, high dose, or in the form of cod liver oil supplementation — in preventing COVID-19 or acute respiratory tract infections, regardless of whether individuals are deficient or not. ...continue reading "Two Studies Find Vitamin D Doesn’t Prevent COVID"

Published on Leave a comment on Vitamin D Supplements and Autoimmune Disease

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"

Published on Leave a comment on Some Large Studies Find No Benefit From Vitamin D Supplements

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"

Published on Leave a comment on Sunshine and Multiple Sclerosis in Children and Young Adults

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"

Published on Leave a comment on Fewer Respiratory Infections With Vitamin D Supplements

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"

Published on Leave a comment on Vitamin D Levels During Pregnancy Associated With A Child’s IQ

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"