On drugstore shelves, it’s easy to find a variety of colorful bottles with letters that correspond to vitamins and minerals. These products promise substantial health gains, but the reality is not that simple.
New research has noted that vitamin supplements have no proven effectiveness in preventing cancer and cardiovascular disease. On the contrary, one of these substances in excess was associated with the development of lung cancer.
Published in the journal Jama, the article is signed by researchers from the Kaiser Permanente Center for Health Research and the Oregon Health and Science University, institutions in the United States. It is a systematic review –analysis of the results of other research– of 84 publications in English that observed healthy adults without cardiovascular disease and cancer. Participants were not deficient in vitamins and minerals.
The researchers’ goal was to understand the effectiveness of multivitamin supplements and those with only one nutrient in reducing cardiovascular disease, cancer and mortality in adults. It was also seen if the products brought harm.
In the products of isolated substances, those with beta-carotene and vitamin A, calcium (without vitamin D), vitamin E and vitamin D with or without calcium were analyzed. The review was also made up of multivitamins that carry a variety of substances in their formula.
Use of at least one vitamin supplement was reported by 52% of US adults. In Brazil, there is a growth in the consumption of these products, says Maria Eduarda Melo, head of the technical area of Food, Nutrition, Physical Activity and Cancer of Inca (National Cancer Institute), who did not participate in the research.
“Although we have no evidence in terms of health benefits, we see a growing market for sales,” he says.
In the research, the evidence found indicates that there is no benefit of vitamins and minerals for the prevention of cancer, cardiovascular diseases or reduction of mortality from other causes.
This premise is already known and advised by the Inca. “The results of this study are very much in line with what the institute recommends not using food supplements for cancer prevention”, says Melo.
According to her, vitamins and minerals can be important for the prevention of tumors, but most of the population can meet their needs with a balanced diet based on natural foods, such as fruits and vegetables.
The study observed a similar result for cardiovascular disease. “It is very clear that there is no benefit. Sometimes finding out that something doesn’t work is as important as finding out that something works because it avoids wasting money”, says Otavio Berwanger, cardiologist and director of the Academic Research Organization (ARO) at Einstein, who also did not make up the research.
Similarly, Berwanger explains that other published research has also found no benefit from vitamin supplements for treating heart complications. “No multivitamin, from a cardiovascular point of view, should be used,” she says.
He says there are other, more effective ways to prevent cardiovascular problems. The main ones are avoiding smoking, having a balanced diet, low in processed foods and practicing regular physical activity. Controlling blood pressure, cholesterol and diabetes are also important measures.
When using vitamin supplements, these substances come isolated and in greater quantities. This can have no benefit in preventing cancer or even increase the chances of developing the disease.
Published research has found that beta-carotene, an antioxidant found in orange-yellow foods, found in vitamin supplements is associated with an increased risk of lung cancer. But other evidence has already shown that the consumption of this substance only through food can be useful for preventing this type of cancer, especially in the case of smokers and ex-smokers, explains Melo.
Three studies reviewed point to benefits of multivitamins to prevent cancer. However, the authors emphasize that the evidence for these products is small and that the studies did not have a long period of follow-up of the participants, which makes the result not so robust, points also reiterated by Melo.
“In Inca recommendations we did not observe benefits of supplements [para prevenção do câncer]even with these multivitamins”, he says.
Food supplements are recommended in cases where there is a deficiency of vitamins and minerals – which can occur during the treatment of an illness, for example. But ingestion requires medical supervision.
Thus, according to Melo, the use of supplements does not bring positive results for the general population. “The individual who is healthy doesn’t have to use a supplement.”