Value of dietary supplements in question

Millions of people around the world supplement their diet with vitamins and minerals to boost their health.

A new study shows that there is little positive effect in taking these nutritional supplements for health and they also do not reduce the risk of death. This latest study titled, “Association Among Dietary Supplement Use, Nutrient Intake, and Mortality Among U.S. Adults: A Cohort Study,” is published in the journal Annals of internal Medicine.

Image Credit: Ronstik / Shutterstock
Image Credit: Ronstik / Shutterstock

According to the researchers from Tufts University in the USA, these nutritional supplements do not help improve health. A healthy balanced diet and an active lifestyle can on the other hand reduce the risk of deaths, the researchers explain. The team looked at 30,899 adults across the United States and found that nutritional supplements as such do not boost health or reduce the risk of cancers and deaths due to other causes. On the other hand, the same nutrients present in food can help improve health and reduce the risk of death due to cancer, heart disease and other causes.

The team looked at American adults over the age of 20 included in the NHANES (National Health and Nutrition Examination Survey) between 1999 and 2010. They looked at the regular nutrient and supplement intake of the participants and alongside compared it with deaths due to cancer and heart disease or any other cause. This data on deaths came from the National Death Index mortality data.

The participants were asked to list the dietary supplements that they have been taking over the past 30 days of the survey. The product name, duration of use and its frequency of use was recorded. To assess nutrient intake from food, a 24 hour recall of diet was used to assess the food based nutrients taken.

The participants were followed up for a period of around 6 years. During this time there were 3,613 deaths which included 945 due to cardiovascular disease and 805 due to cancer. Looking at the association between nutrient intake and deaths, the researchers found that adequate intake of vitamins A and K and zinc and magnesium are associated with lowered risk of death. This beneficial effect holds true only when these nutrients are taken from food rather than nutrition supplements.

The results also revealed that people taking calcium supplements of more than 1,000 milligrams per day may be at risk rather than benefit. This rate of calcium supplement intake was associated with a raised risk (53 percent more) of death due to cancer said the researchers. Calcium intake from food however was not associated with cancer, said the researchers. Taking vitamin D when there was no deficiency was also linked to a greater risk of death, find the researchers.

According to lead researcher Dr Fang Fang Zhang, “It is important to understand the role that the nutrient and its source might play in health outcomes, particularly if the effect might not be beneficial. Our results support the idea that, while supplement use contributes to an increased level of total nutrient intake, there are beneficial associations with nutrients from foods that aren’t seen with supplements.” He added, “This study also confirms the importance of identifying the nutrient source when evaluating mortality outcomes.”

Market research group Mintel says that in the UK there has been a 6 percent rise in sales of nutritional supplements over the last five years. In 2018, the Britons spent around £442million on nutritional supplements. In the US around 50 percent of the population takes some or other form of nutritional supplement. The numbers are around 34 percent in the UK.

Experts on nutrition and health have said that taking supplements by self medicating oneself may cause more harm than good. A healthy diet is one that is rich in fruits and vegetables, whole grains, seeds, legumes and nuts and low fat dairy products. They add that vitamins and mineral supplements are beneficial for those who are deficient and those who are in need for example pregnant women who require folic acid etc.

The study was funded by the National Institutes of Health.

Dr. Ananya Mandal

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.


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