Do we really need to take supplements? It’s complicated

According to the CSIRO, consumer demand for vitamins and supplements in Australia is expected to reach $5.2 billion by 2030. These capsules, powders, gummies and tinctures are often labelled with big – if vague – claims like “supports immune health” or “improves brain performance”.

But most supplements have not been rigorously tested for safety or effectiveness, says Dr JoAnn Manson, a professor of medicine at Harvard Medical School.

Little is known about the risks, benefits or correct dosing of many supplements.Credit: Getty Images

And when researchers have tested them, she adds, they haven’t typically found the health benefits they’d hoped for, and sometimes have even found some risks.

But, she says, there are some instances where taking a supplement may improve your health. Here are some of the main ones.

To treat or prevent a nutrient deficiency

If a blood test reveals that your body is low in a particular vitamin or mineral, such as vitamin D or iron, supplements can be “essential” in correcting that deficiency, says Dr Pieter Cohen, an internist at Cambridge Health Alliance.

People who follow a vegan diet or have a condition called pernicious anaemia are at greater risk of a vitamin B12 deficiency and may benefit from taking a supplement. And breastfed infants should receive vitamin D and iron supplements, according to the American Academy of Pediatrics.

If you have difficulties absorbing nutrients from food, which can happen after you’ve had bariatric surgery or if you have a medical condition like celiac disease, Crohn’s disease or ulcerative colitis, a supplement may be recommended, Cohen says.

If you are or may become pregnant

It’s important to take 400 to 800 micrograms of folic acid per day if you could become pregnant and during the early months of pregnancy to prevent major birth defects, says Dr John Wong, a professor of medicine at Tufts University School of Medicine.

Most prenatal multivitamins, which should be taken throughout pregnancy, contain this amount, and also supply other key nutrients such as iron, calcium and vitamin D.

If you’re in middle or old age

Most older adults usually get enough nutrition from their food. But as you age, your requirements for some nutrients increase while your ability to absorb them and your appetite can diminish, so your doctor may recommend a supplement. Older adults may have trouble absorbing vitamin B12, for example. And you may need a calcium and vitamin D supplement if you’re at risk for bone loss, Manson says.

There are hints from research that a few other supplements may help prevent certain health conditions. In one 2019 study of adults 50 or older, Manson and her colleagues found that for participants who rarely or never ate fatty fish, those who took an omega-3 fatty acid supplement had fewer cardiovascular events like heart attacks or strokes than those who took a placebo. Those who took vitamin D were also less likely to develop autoimmune diseases like rheumatoid arthritis and psoriasis.

Several recent trials have also found that multivitamins may improve memory and slow cognitive decline in older adults, though more research is needed, Manson says.

And there’s some evidence that taking a supplement that contains vitamins C and E, zinc, copper, lutein and zeaxanthin can slow vision loss for those with age-related macular degeneration, Manson says.

In all other cases, use caution

Just because a supplement contains a nutrient or other natural compound doesn’t make it safe, especially if it has amounts far greater than what you would find in food, Manson says. And in some cases, they can even be harmful.

In the 1990s, for example, researchers hoped that antioxidant supplements like beta-carotene and vitamin E would prevent cancer or heart disease. But when tested in large trials, they found that beta-carotene increased the risk of lung cancer in some people, Wong says, and vitamin E increased hemorrhagic strokes in men, Manson adds.

Little is known about the risks, benefits or correct dosing of many supplements, says Dr Mahtab Jafari, a professor of pharmaceutical sciences at the University of California, Irvine.

And what’s listed on the package can also be different from what’s inside the product, Cohen says. For instance, many weight loss and sports supplements have been found to be tainted with unlisted drugs or chemicals.

Always check with your doctor before taking a supplement, Jafari says, because they can interact with certain medications. Vitamin K can interact with a blood thinning medication, for example, and St John’s wort can interfere with antidepressants and the contraceptive pill.

Finally, Manson says, don’t expect supplements to be a substitute for eating well and being physically active.

“There’s no magic pill that is going to provide good health,” she says.

The New York Times

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