- Unless you have a real deficiency or are pregnant, there is likely no benefit in taking vitamin and mineral supplements.
- This is according to an independent panel of US experts, who reviewed a large number of studies.
- In fact, there is evidence that some popular supplements could do more harm than good.
No need to keep buying vitamin and mineral supplements – experts say they're unlikely to protect you from cancer, cardiovascular disease (CVD), or death.
The US Preventive Services Task Force reviewed more than 80 studies testing vitamins in nearly 700 000 people and published an updated guideline in the journal JAMA.
Their last recommendation was in 2014, and the current verdict remains the same: If you are a healthy, non-pregnant adult, there is "insufficient evidence" that taking supplements, including vitamin E, vitamin D, calcium, vitamin B3, and vitamin C can extend your lifespan.
The sales of vitamins, minerals, and nutritional supplements have seen a boom in recent years. Business consulting firm Grand View Research notes that the global vitamin supplements market size was valued at $44.12 billion in 2020 and is expected to grow.
In January, Business Insider SA reported that some families were spending thousands of rands a month on supplements to protect them against Covid-19, with vitamin C, vitamin D, and zinc being the most popular – despite official guidelines suggesting these supplements were not effective.
“At best, current evidence suggests that any potential benefits of a multivitamin on reducing mortality are likely to be small,” three researchers wrote in an accompanying editorial. For example, if a healthy 65-year-old woman, who has a nine-year estimated mortality risk of about 8%, takes a multivitamin for five to 10 years, it might reduce her estimated mortality risk to 7.5%, they explain.
Instead, lifestyle counselling to prevent chronic diseases in patients should focus on evidence-based approaches, they said. These include balanced diets that are high in fruits and vegetables and physical activity. Research has consistently shown that the Mediterranean diet, for example, can reduce one’s risk of CVD and overall mortality.
Beta carotene supplements a big no
The task force also highlighted that there was sufficient evidence to recommend against the use of beta carotene supplements, which converts into vitamin A, as it was found to increase the chance of developing lung cancer in high-risk populations.
The task force team wrote: “[We] conclude with moderate certainty that the harms of beta carotene supplementation outweigh the benefits for the prevention of cardiovascular disease or cancer.”
In another accompanying editorial, one author notes that population surveys demonstrate that people take vitamins either to stay healthy, feel more energetic, or gain peace of mind.
“These evidence-defying beliefs are bolstered by clever marketing campaigns,” writes Peter Ubel, a physician and behavioural scientist at the University of Michigan.
“Essential nutrients plus clever marketing: it is clear why vitamin and mineral supplements are so appealing. But that begs the question of why it is so easy to market the unproven benefits of these products while it is so difficult to convince people to receive life-saving vaccines,” he adds.
In theory, supplements should work
More than half of adults take dietary supplements, and the appeal of supplements is obvious, say the three experts.
In theory, vitamins and minerals have antioxidative and anti-inflammatory effects, and this should work to decrease the development of CVD and cancer, they say.
“Eating fruits and vegetables is associated with decreased cardiovascular disease and cancer risk. It is reasonable to think that key vitamins and minerals could be extracted from fruits and vegetables, packaged into a pill, and people could avoid the difficulty and expense of maintaining a balanced diet,” they write.
But what one needs to bear in mind is that whole fruits and vegetables contain a mixture of vitamins, phytochemicals, fibre, and other nutrients, and these likely act synergistically to deliver health benefits. On the other hand, “micronutrients in isolation may act differently in the body than when naturally packaged with a host of other dietary components”, they clarify.
Supplements can have benefits – for some
The findings don’t suggest that supplements have absolutely no health benefits. Vitamin and mineral deficiencies can cause so many illnesses, and for people who may soon become pregnant, folic acid is recommended to prevent neural tube defects, while iron is recommended to prevent preterm birth, they explain.
As for otherwise healthy, non-pregnant people, the science is clear: “Individual, public health, public policy, and civic efforts should focus on supporting people in regular preventive care, following a healthful diet, getting exercise, maintaining a healthy weight, and avoiding smoking,” they write.