Vitamin D supplements may not work if you’re overweight, a study suggests.
Sunshine vitamin supplementation is important for keeping bones strong and the immune system boosted, and may reduce the risk of cancer death.
However, a review of the existing evidence found that the benefits only apply to people of a healthy weight.
People who are overweight or obese – a risk factor for a variety of health problems including cancer, heart disease and stroke – had a “minimal” benefit from the pills.
Vitamin D supplements may help ward off cancer and autoimmune diseases, but only if you’re at a healthy weight, study suggests (file photo)
Scientists believe that people who have too much fat in their bodies have trouble metabolizing vitamin D supplements for use in the body.
The study found that they had significantly lower levels of vitamin D in their blood compared to healthy people taking the same pills.
dr Deirdre Tobias, an epidemiologist at Brigham and Women’s Hospital who led the research, said: “We found striking differences at two years that indicate a blunted response to vitamin D supplementation with a higher body mass index (BMI) indicate.
“Something different appears to be happening with vitamin D metabolism as body weight increases, and this study may help explain the diminished outcomes of supplementation for those with increased BMI.”
For the study, published today in the JAMA Network Open, researchers analyzed data from one of the largest and longest-running vitamin D studies to date, the US-based VITAL study.
It tracked 26,000 people who took daily vitamin D supplements for about five years between 2010 and 2018.
All participants were over 50 years old and had neither cancer nor cardiovascular disease at the start of the study.
Half were taking pills containing 2,000 International Units (IU) of vitamin D per day, or five times the U.S. health officials’ recommended daily dose of 400 IU.
The other half were put in the placebo group, which took a dummy pill.
The results showed that the overall risk of cancer death was 20 percent lower, although this was not significant.
Brigham researchers wanted to see if body weight played a role in this reduction.
They then reanalyzed data from a smaller subset of 16,000 participants who also had blood tests at baseline and for up to two years after the study began.
The sample included 6,600 people with a body mass index (BMI) in the overweight category and 4,400 people who were obese or morbidly obese.
The results showed that both groups saw an increase in the levels of vitamin D in their blood during the study.
But the increase was significantly higher in the group that was not overweight or obese.
dr Tobias added, “This study sheds light on why we are seeing 30 to 40 percent fewer deaths from cancer, autoimmune diseases and other outcomes with vitamin D supplementation in people with lower BMI.
“But minimal benefit in those with higher BMI, suggesting that it may be possible to achieve benefits for the entire population with more personalized dosing of vitamin D.”
She added: “Analysis of the original VITAL data found that vitamin D supplementation was correlated with beneficial effects on multiple health outcomes, but only in people with a BMI below 25.
Scientists suspect that people who are overweight or obese may have lower levels of vitamin D because fat cells absorb the vitamin better than others and may extract more of it from the blood.
They also suggested that being overweight could “impair” the body’s ability to make or process vitamin D, which could lead to lower levels.
The Centers for Disease Control and Prevention (CDC) estimates that about 42 percent of the US population is vitamin deficient.
The VITAL study was a randomized, double-blind, placebo-controlled study conducted in the United States. It was funded by the National Institutes of Health.
If you liked this story, please read…
Research shows that people with more vitamin D in their brain are up to a third less likely to develop dementia
You can overdose on vitamin D: A man who took 20 supplements a day – 375 times more than he needed – was so ill medics feared he had cancer
Does vitamin D work with Covid after all? An Israeli study shows that patients with a deficiency are up to 14 TIMES more likely to become seriously ill
What is vitamin D and how do I get it?
Vitamin D is a type of vitamin that the human body both obtains from food and produces when exposed to sunlight.
what does it do
It helps regulate the amount of calcium and phosphate in the body.
These nutrients are needed to keep bones, teeth, and muscles healthy.
People who don’t get enough vitamin D can suffer from bone deformities such as rickets in children and osteomalacia (a softening of the bones) in adults.
How do I get enough vitamin D?
In the US, most people get the vitamin D they need from sunlight between April and September, as long as they go outside.
The body produces vitamin D naturally when exposed to sunlight.
Vitamin D is also found in foods like oily fish, liver, and egg yolks.
Do I need to take a supplement?
Medical professionals say people should consider taking a vitamin D supplement during the winter months when sunlight is weaker.
Other people may need to take vitamin D year-round because they are housebound or if they have dark skin, which reduces the amount of sunlight their skin absorbs.
Children ages one to four years should also receive a daily vitamin D supplement of 10 micrograms (mcg) year-round.
What happens if I take too much?
Taking too much over a long period of time can lead to a dangerous buildup of calcium in the body, which can weaken bones and also damage the heart and kidneys.
Doctors advise not to take more than 800 International Units (IU) per day.
Vitamin D is often sold in units called IUs. One microgram of vitamin D is equivalent to 40 IU.