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Tag: Vitamin D

Published on Leave a comment on Vitamin D and Cancer

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"

Published on Leave a comment on Recent Vitamin D Studies Have Mixed Results

For a few years I've been noticing that studies of vitamin D have had mixed results for a number of medical conditions. A number of times initial studies found an association with low levels of vitamin D and a number of medical conditions, but follow up well-designed studies are just not finding the same results with vitamin D supplementation - or results have been mixed. Also, in some studies, what initially looked like vitamin D being protective for some cancers and multiple sclerosis, now looks like it's sunlight that is giving the protective results. In some cases, vitamin D levels are a proxy for sunlight exposure (the more sunlight exposure, the higher the vitamin D levels in the person). The following 6 studies recently published highlight this same trend of mixed results.

While vitamin D levels increased from high dose vitamin D, there was no change in bone bone mineral density (BMD) in older adults during the 12 months of the study. No adverse effects form the vitamin D supplementation was reported [the older adults received 12,000 international units (IU), 24,000 IU, or 48,000 IU once a month]. From Science Daily: Vitamin D supplements are of no benefit to the over 70s

There is little benefit for those over 70 taking higher dose vitamin D supplements to improve their bone strength and reduce the risk of falls, new research has revealed.

High doses of vitamin D (4000 international units) appeared more beneficial than low dose vitamin D (400 international units) supplements in advanced colorectal cancer patients. From Medical Xpess: High-dose vitamin D shows benefit in patients with advanced colorectal cancer

...continue reading "Recent Vitamin D Studies Have Mixed Results"

Published on Leave a comment on Magnesium Regulates Vitamin D Levels In the Body?

The results of a recent study by Vanderbilt University may help explain why some people have difficulty raising their low vitamin D levels - it may be that their magnesium levels are low. It appears that magnesium may regulate vitamin D levels - when vitamin D levels are low, magnesium supplementation raises vitamin D levels, and when vitamin D levels are high, magnesium supplementation lowers them to a normal level.

What are good food sources of magnesium? Magnesium is found in many plant and animal foods and beverages. Good sources of magnesium include green leafy greens, legumes (beans), whole grains, nuts, dark chocolate, and fatty fish such as salmon. Foods containing dietary fiber generally provide magnesium. By the way, dietary surveys of people in the United States consistently show that intakes of magnesium are lower than recommended amounts. From Medical Xpress:

Study shows magnesium optimizes vitamin D status

A randomized trial by Vanderbilt-Ingram Cancer Center researchers indicates that magnesium optimizes vitamin D status, raising it in people with deficient levels and lowering it in people with high levels. 

...continue reading "Magnesium Regulates Vitamin D Levels In the Body?"

Published on Leave a comment on Vitamin D and Colorectal Cancer Risk

Long-awaited  vitamin D studies are finally appearing this year. A large international study found that higher levels of vitamin D in a person's blood is associated with a lower risk of colorectal cancer. Those with the highest vitamin D levels had a 21% lower risk (compared to the lowest group) of colorectal cancer after an average 5.5 years.

But the researchers generally do not recommend vitamin D supplements - saying that most people had adequate levels from foods and sunshine. However, they suggest that the risk for vitamin D deficiency is higher for those with very dark skin; for older adults (their skin may not be as efficient at synthesizing vitamin D); and for those who do not go outside at all - and that these groups may need supplementation (but not beyond 4000 IU per day - because higher levels have negative health effects). From Medical Xpress:

Large international study links blood vitamin D levels to colorectal cancer risk

A new study authored by scientists from the American Cancer Society, the Harvard T.H. Chan School of Public Health, the U.S. National Cancer Institute, and more than 20 other medical centers and organizations finds that higher circulating vitamin D concentrations are significantly associated with lower colorectal cancer risk. This study strengthens the evidence, previously considered inconclusive, for a protective relationship. Optimal vitamin D concentrations for colorectal cancer prevention may be higher than the current National Academy of Medicine recommendations, which are based only on bone health.  ...continue reading "Vitamin D and Colorectal Cancer Risk"

Published on Leave a comment on Study Finds No Benefit From Most Supplements

Another study has found that the most common vitamin and mineral supplements (multivitamins, vitamin D, calcium, and vitamin C), don't offer hoped for health benefits, and may actually carry some risks. This latest study was a review of other studies, and examined whether specific vitamins or minerals would  lower the risk of cardiovascular disease (including heart attacks and strokes) and death from any cause (referred to as all cause mortality"). [Posts discussing other research finding problems with supplements.]

In general, the review of studies of popular supplements (multivitamins, vitamin D, calcium, and vitamin C) show no consistent benefit (no significant effect) for the prevention of cardiovascular disease, heart attacks, or stroke, nor any lowering of death (all cause mortality). On the other hand, folic acid and B-vitamins with folic acid, B6, and B12 reduced stroke (folic acid showed a 20% reduction in stroke), but niacin and antioxidants were associated with an increased risk of death from any cause (10% increase). But overall the effects in the studies were small. Vitamin D did not show any benefits in reducing death, but the researchers pointed out that many vitamin D studies are now under way, and the results of vitamin D studies so far are mixed (e.g. 16 showing positive effects from vitamin D, 17 showing a more favorable effect in the control group, and 10 neither).

On the other hand, the researchers stressed that eating a well balanced diet has lots of health benefits and is recommended by the U.S. Dietary Guidelines Advisory Committee. Three dietary patterns are frequently discussed as beneficial: 1) a healthy American diet (sometimes called a "prudent diet") low in saturated fat, trans fat, and red meat, but high in fruit and vegetables, 2) a Mediterranean diet, and 3) a vegetarian diet. All 3 of these diets are rich in fruits and vegetables (which means increased fiber), are relatively rich in vitamins and minerals, and meet Dietary Reference Intake guidelines.  ...continue reading "Study Finds No Benefit From Most Supplements"

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Published on 1 Comment on Five Studies Looking at Vitamin D and Health

The last post was about several reviews of vitamin D studies, and how when people are put randomly into different groups and then followed for a while - that the studies generally are not finding the same wonderful effects of higher levels of vitamin D in the blood that observational studies are finding - instead finding no effect or mixed results. Some issues with observational studies: the groups are self-selected, some are a one time snapshot of a person (thus one can't tell what happens over time); and can't prove cause and effect (can only say there is an association or link). [See all posts about vitamin D.]

But anyway, today's post is about some more vitamin D studies, all published in 2018. All of them find health benefits from higher blood levels of vitamin D. What is an ideal level of vitamin D varies from study to study, and some are observational - thus can only say "find an association with" in the findings. The fifth study finds beneficial effects from higher doses of vitamin D, and the participants were randomly assigned to the groups (good!). Click on links to read details. All excerpts are from Science Daily:

Vitamin D deficiency linked to greater risk of diabetes

An epidemiological study conducted by researchers at University of California San Diego School of Medicine and Seoul National University suggests that persons deficient in vitamin D may be at much greater risk of developing diabetes. The findings are reported in the April 19, 2018 online issue of PLOS One.  ...continue reading "Five Studies Looking at Vitamin D and Health"

Published on Leave a comment on Best to Eat Calcium Rich Foods, Not Calcium Supplements

Once again, a study found an association between a worrisome health problem (intestinal polyps) with a dietary supplement (calcium), but no problems with eating the foods (calcium rich foods). The large multi-center study specifically looked at serrated polyps (SPs) because they are considered precursor lesions for colorectal cancer - that is, that while they are not cancerous, some of them will develop into cancer. Persons invited to join the study had a recent colonoscopy with at least one adenomatous polyp detected and removed, and then were scheduled for another colonoscopy 3 to 5 years later. This was considered a "chemoprevention study" to see if certain supplements help prevent polyps (and thus cancer).

People in different parts of the US were randomly assigned to either receive calcium supplements (1200 mg/day of elemental calcium), vitamin D (1000 IU/day of vitamin D3),  both supplements (calcium supplement plus vitamin D), or neither. Supplement treatment continued for 3 to 5 years and then there was an observational period that was 6 to 10 years after the person first started supplementation. The higher incidence of serrated polyps was a "late effect" (6 to 10 years later) and not seen during the treatment time (the first 3 to 5 years). They found that women and current smokers had higher risks of serrated polyps when exposed to supplemental calcium. Vitamin D alone was not linked with polyps.

Other studies have also found an association between calcium supplements and increased risk of certain health problems, and a lower incidence of polyps with a higher intake of dietary calcium (real food). The researchers said: "Patients with a history of premalignant serrated polyps, especially women and smokers, may wish to avoid vitamin D and calcium supplementation." BOTTOM LINE: General guidelines should be to eat foods, not supplements, to get your nutrients, vitamins, and minerals. There are many studies also at this point that a high fiber diet with lots of fruits, vegetables, whole grains, legumes (beans), nuts, seeds are associated with better intestinal health and fewer polyps (here, here). Another way to view it is: feed your beneficial gut microbes with good, real food. And especially not highly processed junk. From Medical Xpress:

Calcium supplements may boost risk of abnormal bowel growths

Calcium supplements, taken with or without vitamin D, may increase the risk of small growths in the large bowel (colon) called polyps, suggest results from a large US trial published online in the journal Gut. Polyps are small growths in the lower part of the large bowel. They are non-cancerous, but some could eventually turn into cancer if they are not removed. Polyps come in different shapes and sizes, and this study specifically focused on the risk of serrated polyps, which are less common than conventional "adenomatous" polyps, but likely have the same risk of developing into cancer. 

...continue reading "Best to Eat Calcium Rich Foods, Not Calcium Supplements"

Published on Leave a comment on Vitamin D, Breast Cancer, and Melanoma

Two more studies found that higher levels of vitamin D in the blood are associated with better health outcomes - one study found a lower risk of breast cancer, especially among postmenopausal women, and in the other - better outcomes after a metastatic melanoma diagnosis.

The breast cancer study suggested that a fairly high blood level of vitamin D (25(OH)D serum level>38.0 ng/mL) was associated with a lower risk of breast cancer. But overall they found that women supplementing with vitamin D (more than 4 times a week) at any dose had a lower risk of breast cancer over a 5 year period than those not supplementing with vitamin D. From Environmental Health Perspectives:

Serum Vitamin D and Risk of Breast Cancer within Five Years

Vitamin D is an environmental and dietary agent with known anticarcinogenic effects, but protection against breast cancer has not been established. We evaluated the association between baseline serum 25-hydroxyvitamin D [25(OH)D] levels, supplemental vitamin D use, and breast cancer incidence over the subsequent 5 y of follow-up. From 2003-2009, the Sister Study enrolled 50,884 U.S. women 35-74 y old who had a sister with breast cancer but had never had breast cancer themselves. Using liquid chromatography-mass spectrometry, we measured 25(OH)D in serum samples from 1,611 women who later developed breast cancer and from 1,843 randomly selected cohort participants.

We found that 25(OH)D levels were associated with a 21% lower breast cancer hazard (highest versus lowest quartile). Analysis of the first 5 y of follow-up for all 50,884 Sister Study participants showed that self-reported vitamin D supplementation was associated with an 11% lower hazard. These associations were particularly strong among postmenopausal women.

In this cohort of women with elevated risk, high serum 25(OH)D levels and regular vitamin D supplement use were associated with lower rates of incident, postmenopausal breast cancer over 5 y of follow-up. These results may help to establish clinical benchmarks for 25(OH)D levels; in addition, they support the hypothesis that vitamin D supplementation is useful in breast cancer prevention.

The first sentence in the melanoma study lays out what is widely known: "Vitamin D deficiency (≤20 ng/mL) is associated with an increased incidence and worse prognosis of various types of cancer including melanoma." Studies show that the relationship between vitamin D, sunlight exposure, and melanoma is complicated in a number of ways, including: sun exposure may be associated with increased survival in patients with melanoma. which may mean that vitamin D has a protective role in patients with melanoma. Several studies suggest that vitamin D may delay melanoma recurrence and improve overall prognosis. The study also found that metastatic melanoma patients with vitamin D deficiency who are unable to or don't raise their vitamin D blood levels (25(OH)D3) have a worse outcome compared to those who are are able to markedly increase (by greater than >20 ng/mL) their 25(OH)D3 levels. From Oncotarget:

Vitamin D deficiency is associated with a worse prognosis in metastatic melanoma

Vitamin D deficiency (≤20 ng/mL) is associated with an increased incidence and worse prognosis of various types of cancer including melanoma. A retrospective, single-center study of individuals diagnosed with melanoma from January 2007 through June 2013 who had a vitamin D (25(OH)D3) level measured within one year of diagnosis was performed to determine whether vitamin D deficiency and repletion are associated with melanoma outcome.

A total of 409 individuals diagnosed with histopathology-confirmed melanoma who had an ever measured serum 25(OH)D3 level were identified. 252 individuals with a 25(OH)D3 level recorded within one year after diagnosis were included in the study .... A worse melanoma prognosis was associated with vitamin D deficiency, higher stage, ulceration, and higher mitotic rate. In patients with stage IV metastatic melanoma, vitamin D deficiency was associated with significantly worse melanoma-specific mortality. Patients with metastatic melanoma who were initially vitamin D deficient and subsequently had a decrease or ≤20 ng/mL increase in their 25(OH)D3 concentration had significantly worse outcomes compared to non-deficient patients who had a >20 ng/mL increase. Our results suggest that initial vitamin D deficiency and insufficient repletion is associated with a worse prognosis in patients with metastatic melanoma.

Published on Leave a comment on Some Health Benefits of Sunlight

 I'm starting to see studies questioning whether some of the beneficial health effects that many attribute to vitamin D may actually be due to sunlight. In the first study, researchers said that sunlight also has low levels of "blue light" which energizes T cells. 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). So the blue light in sunlight had a positive effect on the T cells.

The second study examined whether it was low levels of vitamin D that is linked to multiple sclerosis (which is the widely accepted medical view) or was it low exposure to sunlight? They found that vitamin D is not associated with multiple sclerosis risk in blacks or Hispanics (but is in whites). But sun exposure is protective in all three racial/ethnic groups (blacks, Hispanics, whites). Thus it was the sunlight that was important in protecting against multiple sclerosis rather than vitamin D. Bottom line: for various beneficial health reasons, go out in sunshine frequently (20 minutes a day is fine). Remember, sunlight is the "natural source" for vitamin D (the ultraviolet light hitting our bare skin allows us to make vitamin D).

From Dec. 2016 in Science Daily: Sunlight offers surprise benefit: It energizes infection fighting T cells

Sunlight allows us to make vitamin D, credited with healthier living, but a surprise research finding could reveal another powerful benefit of getting some sun. Georgetown University Medical Center researchers have found that sunlight, through a mechanism separate than vitamin D production, energizes T cells that play a central role in human immunity.

Their findings, published today in Scientific Reports, suggest how the skin, the body's largest organ, stays alert to the many microbes that can nest there. They specifically found that low levels of blue light, found in sun rays, makes T cells move faster -- marking the first reported human cell responding to sunlight by speeding its pace.

"T cells, whether they are helper or killer, need to move to do their work, which is to get to the site of an infection and orchestrate a response," Ahern says. "This study shows that sunlight directly activates key immune cells by increasing their movement."

"We know that blue light can reach the dermis, the second layer of the skin, and that those T cells can move throughout the body," he says. ...."We found that sunlight makes hydrogen peroxide in T cells, which makes the cells move. And we know that an immune response also uses hydrogen peroxide to make T cells move to the damage," Ahern says. "This all fits together." Ahern says there is much work to do to understand the impact of these findings, but he suggests that if blue light T cell activation has only beneficial responses, it might make sense to offer patients blue light therapy to boost their immunity.

From Medscape: Is It Time to Rethink Low Vitamin D as a Contributor to MS?

The idea that vitamin D deficiency may contribute to multiple sclerosis (MS) has been well established in the literature and has, for the most part, been etched into recent neurology dogma. Yet, research by Annette Langer-Gould, MD, PhD—a clinical assistant professor at the University of Southern California's Keck School of Medicine in Los Angeles—suggests that the association might not be that simple. ....As background, the vitamin D–multiple sclerosis hypothesis originated from the observation that the prevalence of MS increases with increasing distance from the Equator, as ultraviolet radiation (UVR) from the sun becomes less intense. But this is also where more white people live.

The main result of our study is that vitamin D is not associated with MS risk in blacks or Hispanics, regardless of genotype. In contrast, sun exposure is protective in all three racial/ethnic groups.

Published on Leave a comment on High Dose Vitamin D Does Not Prevent Cardiovascular Disease

A recent study looking at high dose supplementation of vitamin D found that it did not prevent cardiovascular disease. This study came about because of earlier studies observing that there is a higher incidence of cardiovascular disease in persons with low vitamin D levels (as measured in their blood). But such results from observational studies need rigorous testing in studies where people are randomly assigned to groups, and that are "double-blind" (no one knows who is getting the vitamin D until the end of the study) to eliminate bias. And this is what was done in this study, with the result that monthly high doses of vitamin D3 for 3 years did not prevent cardiovascular disease (including stroke, heart attacks, hypertension, etc) - as seen in that there were no group differences between the vitamin D and placebo groups. Finding no effects are "null findings".

But note that the subjects in the study got monthly high doses, and not daily or weekly vitamin D. It is unknown whether daily dosing would have made a difference in the results. However, the vitamin D levels in the blood soon reached levels (about 51.725 ng/mL) that many view as a desirable "protective" level. So we'll see what other studies find. But these results are definitely disappointing for those wanting an easy "magic bullet" for preventing cardiovascular disease. Bottom line: focus on lifestyle (diet, exercise, not smoking, etc) for heart health. From Science Daily:

Monthly high-dose vitamin D supplementation does not prevent cardiovascular disease

Results of a large randomized trial indicate that monthly high-dose vitamin D supplementation does not prevent cardiovascular disease, according to a study published by JAMA Cardiology. Studies have reported increased incidence of cardiovascular disease (CVD) among individuals with low vitamin D status. To date, randomized clinical trials of vitamin D supplementation have not found an effect, possibly because of using too low a dose of vitamin D. Robert Scragg, M.B.B.S., Ph.D., of the University of Auckland, New Zealand, and colleagues randomly assigned adults (age 50 to 84 years) to receive oral vitamin D3 (n = 2,558; an initial dose of 200,000 IU, followed a month later by monthly doses of 100,000 IU) or placebo (n = 2,552) for a median of 3.3 years.

Of the 5,108 participants included in the primary analysis, the average age was 66 years; 25 percent were vitamin D deficient. Cardiovascular disease occurred in 303 participants (11.8 percent) in the vitamin D group and 293 participants (11.5 percent) in the placebo group. Similar results were seen for participants with vitamin D deficiency at study entry and for other outcomes such as heart attack, angina, heart failure, hypertension, and stroke.

The authors write that the results of this study do not support the use of monthly high-dose vitamin D for the prevention of CVD. "The effects of daily or weekly dosing on CVD risk require further study." [Original study.]