Vitamin D helps the body absorb calcium, which improves bone strength
Studies over the years have shown that vitamin D can reduce the risk of developing cardiovascular disease and cancer. Few high-quality and controlled studies have been conducted to confirm these claims.
A recent study in Finland examined the effect of a vitamin D supplement on participants’ health. It has not found a link between its intake and the reduced risk of cardiovascular disease or cancer in people who drank it, writes in its publication the website Medicalnewstoday.com.
Vitamin D helps the body absorb calcium, which improves bone strength. Among other functions, it contributes to the functioning of muscles, nerves and the immune system. Many scientists have set out to understand how a deficiency of this vitamin and taking supplements with it can affect some diseases.
According to the World Health Organization (WHO), there is some evidence that vitamin D can help prevent respiratory infections, for example. Over the past two years, researchers have also studied whether the popular vitamin reduces the risks associated with COVID-19 disease. Although studies are ongoing, there seems to be some evidence that these supplements may reduce the number of people admitted to intensive care units with this infection.
Two other areas of particular interest are the potential effects of vitamin D on the risk of cardiovascular disease and cancer. A recent study published in The American Journal of Clinical Nutrition contributes somewhat to overcoming this lack of knowledge on the subject.
Cancer and heart disease
In a conversation with Vimal Karani, Professor of Nutrigenetics and Nutrigenomics at the University of Reading, UK, it became clear that there was a mismatch between the original research and the results of clinical trials.
Prof. Karani did not participate in the recent study, but worked with some of its authors. He explained that previous major epidemiological studies “have found a link between vitamin D deficiency and the risk of developing cardiovascular disease in different ethnic groups.”
According to him, this suggests that supplements with this vitamin may reduce cardiovascular risk. Although, the scientist added, “clinical trials have not provided convincing evidence of a blood pressure-lowering effect of vitamin D supplements.”
Prof. Karani said there could be a wide range of reasons for this, including “differences in the size of the sample, the duration of the supplement, its dose, the age of the participants, the geographical location, the sun exposure and more.” Further research is needed. “
The Finnish study
It took place between 2012 and 2018 and was double-blind, randomized and placebo-controlled. “When we started planning the study, there was a lot of evidence from observational studies that vitamin D deficiency would be linked to almost all major chronic diseases, such as cardiovascular disease, cancer, type 2 diabetes, and mortality,” said Dr. Jurki. Virtanen.
Dr. Virtanen is an Associate Professor of Nutrition and Public Health at the University of Eastern Finland and one of the main researchers in the study. “We have also shown that among the population of Eastern Finland, low levels of vitamin D in the body are associated with a higher risk of mortality and impaired glucose metabolism.
However, this type of research does not provide evidence of a causal relationship. At the time, there was little evidence from controlled studies that improving the level of this vitamin in the body by adding it reduced the risk of disease. Therefore, our goal was to launch a long-term study on vitamin D supplementation among people living in Finland, where vitamin D deficiency was quite common due to the long winter, and to investigate whether the supplement could reduce the risk of major chronic diseases and death.
The researchers looked at data from 2,495 people, men aged 60 and over and postmenopausal women over 65. The subjects had no history of cardiovascular disease or cancer. Participants received either a placebo or a vitamin dose of 1,600 or 3,200 international units (IU) each day.
No connection found
Compared to placebo, none of the vitamin D doses reduced the incidence of cardiovascular disease or cancer among those studied, the team found.
“The problem with most large studies of vitamin D supplementation is that its initial levels were quite high in a large proportion of the people studied,” explained Dr. Virtanen.
The researchers added that those who could benefit from supplements with this vitamin, ie. have low serum levels, are a minority in the studies. But it would not be ethical for some people surveyed, for example in the placebo group, to be kept vitamin D deficient for several years while the study.