Vitamin D supplements for muscle health: study finds no benefit

According to National Institutes of Health Office of Dietary Supplements, vitamin D is important for healthy bone growth. It also plays a role in reducing inflammation and affects cell growth, glucose metabolism, and the immune system.

Our body synthesizes vitamin D following direct exposure to the sun. Some foods also contain vitamin D, including oily fish and fish oils, eggs and mushrooms exposed to ultraviolet rays.

In a study based on data in the United States between 2011 and 2014, researchers found that 5% of people over one year of age in the United States were at risk for vitamin D deficiency, while 18.3% were at risk of vitamin D insufficiency.

Speaking on an Endocrine Society podcast, Dr Laurel Mohrmann and Dr Sweta Chekuri, both of Montefiore Medical Center in New York City, say that one of the main reasons for vitamin D deficiency is that people are not sufficiently exposed to the sun to sufficient forces.

“The amount of sun exposure you get is the most important factor because natural sources of vitamin D in foods are very scarce. You don’t really get it from your diet, so you have to be exposed to the sun.

“In our country, a large part of our population lives well above the equator, so there is less sun exposure, and there are extended winter periods with very little sun exposure.”

“People with darker skin, older people, more [body mass index] – all of these things are associated with vitamin D deficiency.

“As a nation, we have also started to supplement our milk with vitamin D. As other forms of milk, such as soy milk and almond milk, become more popular, they are not supplemented. by vitamin D, so that this source has been added to our diet to combat vitamin D deficiency is no longer consumed by a large part of the population, ”explains Dr. Morhmann.

Recently, researchers looked at vitamin D supplementation to see if it protects against COVID-19. However, in an editorial in BMJ, the researchers pointed out that research on the link between vitamin D and COVID-19 is limited. In addition, the evidence that does exist is conflicting as to whether vitamin D is beneficial or not.

Another area that researchers have studied is the possible role that vitamin D supplementation can play in improving muscle performance and health.

Talk to Medical News Today, Dr Lise Sofie Bislev, Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark, and the corresponding author of this study, pointed out that “Vitamin D supplements have in to a large extent have been recommended for people with fatigue. “

However, the researchers noted that the evidence for vitamin D’s effects on muscle performance and health was mixed and limited by the demographics involved in the studies.

In an attempt to get more reliable information, Dr Bislev and his co-authors conducted a meta-analysis of the available research.

The researchers included only double-blind, placebo-controlled, randomized controlled trials in English.

The team drew on data from 54 trials involving a total of 8,747 participants.

According to Dr Bislev, their meta-analysis is important because it offers a rigorous overview of the current literature.

“Most of the previous meta-analyzes report data on grip strength, the Timed Up and Go test or a composite endpoint [such as] overall muscle strength, with wide variation between studies.

“[Our] The study reports effects on the ten most frequently reported outcomes in people treated with vitamin D2 or D3 compared to placebo. Many of these endpoints had not previously been summarized in a meta-analysis. A large number of individuals were included, and the variation between studies [was] moo. “

“Recently, two studies reporting beneficial effects of vitamin D on muscle strength – included in most previous meta-analyzes – were withdrawn due to scientific fraud. In addition, the results of a large number of randomized clinical trials have recently been published, highlighting the importance [of] abstract[ing the] data available. “

Researchers have found no evidence of any benefit that vitamin D supplements provide for muscle strength and health.

Additionally, the team found that vitamin D supplements reduced muscle performance in the Timed Up and Go tests, knee flexion tests, and Short Physical Performance Battery tests.

Dr Bislev said negative knee flexion test results could be due to the type and amount of vitamin D dose.

“For knee flexion, most of the included studies used daily doses of vitamin D greater than 2,800. [international units], and it is possible that the harmful conclusion on this result is caused by the relatively high daily dose. We also speculate [that] high dose bolus therapy may play a negative role compared to daily low dose therapy.

However, for Dr. Bislev, it can still be helpful for people with severe vitamin D deficiency to take a muscle strength supplement.

“Most studies do not include individuals with low levels of vitamin D, and no study only includes individuals with severe vitamin D deficiency. Therefore, we still need to investigate whether vitamin D can exert any effect. beneficial effect in people with very low levels of vitamin D, ”said Dr. Bislev.

According to Dr. Bislev, despite negative results from some muscle strength measurements, this is not a reason people should stop taking vitamin D supplements.

“In general, we need to interpret the results of observational studies – including the results in patients with COVID-19 – with caution. The main conclusion of our study is that vitamin D has no beneficial effect on muscle strength and may even have a small harmful effect.

“The clinical relevance of this small negative result is unknown. People shouldn’t reconsider taking a low-dose supplement to protect or treat osteoporosis, but given the huge public interest in vitamin D, we need to be aware of the possible negative effects of primarily high doses of vitamin D.