Lining grocery store shelves are supplements like omega fish oil, goat’s rue and others that sound more like the ingredients of a witch’s cauldron. Social media influencers also push high-tech sounding pills like CoQ10 or plant sterols to their followers. And you can find the classic supplements online or in person — vitamin D, vitamin C or a daily multivitamin.
In the United States, the supplement market was estimated to be worth $42.6 billion in 2022, and it was projected to increase up to $70.8 billion by 2031, according to Statista.
But do any of these so-called health products provide real health benefits? According to long-term studies, the science is unclear on the benefits – or negative impacts – of many supplements. In fact, there is only evidence that a few of them have any benefits at all and are hardly a substitute for eating healthily, exercising, and abstaining from excessive drinking, smoking, or other harmful activities.
Marketing and Research of Supplements
Dietary supplements are any substances that you take in addition to your regular meals and snacks. They can be chemicals, extracts from plants or animal parts, minerals, acids, herbs, or vitamins.
Supplements are typically marketed to provide consumers all kinds of different benefits, whether it’s daily immune system boosts, an increase in milk production for pregnant mothers, or specific conditions.
Part of the issue for the dietary supplement industry is that companies have freedom of what to sell, as “the U.S. Food and Drug Administration (FDA) does not determine whether dietary supplements are effective before they are marketed,” according to the National Institutes of Health’s (NIH) Office of Dietary Supplements.
Actual peer-reviewed studies on the purported effects of supplements are slow to follow the marketing. This is due to a lack of funding and time, and there is difficulty in isolating any one activity as the cause of a positive health outcome — especially when consumers mix supplements to address their health issues.
Read More: It's Tricky to Know Which Supplements Are Safe — Here's What to Avoid
Are There Health Benefits?
As a result, the list of vitamins and supplements that actually have scientific evidence of any real benefit is surprising small, given the number of these products available. NIH’s Office of Dietary Supplements lists just a few positive effects from a handful of supplements.
Calcium and vitamin D can improve your bone health, for example while folic acid can decrease the risk of birth defects. Omega-3 fatty acids from fish oils can help people with heart disease and a combination of vitamins C, E, zinc, copper, lutein, and zeaxanthin may slow down the vision loss of people with age-related macular degeneration.
NIH’s National Center for Complementary and Integrative Health (NCCIH) notes that many vitamins and minerals are essential for our bodies, including vitamins A, C, D, E, K, and various types of vitamin B. Essential minerals include calcium, phosphorus, potassium, sodium, chloride, magnesium, iron, zinc, iodine, sulfur, cobalt, copper, fluoride, manganese, and selenium. But it’s important to note that we get many of these vitamins and minerals through eating healthy food.
Whether taking these as supplements actually helps our bodies still needs more research. Nonetheless, in some cases, taking supplements doesn’t hurt. NCCIH notes that taking your daily dose of multivitamin is unlikely to pose any risks for healthy people, though most studies have shown little or no effects from multivitamins on the risk of health problems.
Read More: Deciding Between Name and Store Brand Supplements? Neither May Be the Answer
The Value of Supplements
Some research has revealed that even some of the most widely marketed supplements have little or no value. A Canadian study published in Current Nutrition Reports in 2013, for example, reported that echinacea had little or no evidence to shorten the symptoms of colds or the flu, despite marketing.
Even primrose oil appeared to have no value in treating eczema, though it may be useful for rheumatoid arthritis and breast pain, and more research is needed. Gingko doesn’t have much evidence of improving memory for Alzheimer’s patients, older adults or those suffering from dementia, and there is little evidence that ginseng does anything.
“[Ginseng] is among the most popular of herbs, and it is used for a variety of reasons, the most common of which are increased sense of well-being, stamina, and improved mental and physical performance,” the authors wrote in the study. “Overall, there is very little solid evidence that ginseng lives up to the many lofty claims of its efficacy.”
Can Supplements Cause Harm?
There are a number of potential ways that supplements can cause harm, directly and indirectly. Taking more minerals, vitamins or other supplements than your liver can handle can cause problems — and it doesn’t matter whether the ingredients are chemical or natural.
“Many dietary supplements (and some prescription drugs) come from natural sources, but ‘natural’ does not always mean ‘safe,’” according to the NCCIH. “For example, the kava plant is a member of the pepper family but taking kava supplements can cause liver disease.”
There are also some specific examples of negative effects from supplements. The Office of Dietary Supplements notes that vitamin K can reduce the ability of some blood thinners to prevent clotting, while St. John’s wort can reduce the effectiveness of medicines like birth control pills, antidepressants, and heart and anti-HIV medicines. Supplements that are antioxidants can reduce the effectiveness of some types of chemotherapy for cancer treatments.
Even daily multivitamins may have negative effects to certain consumers. According to the NCCIH, smokers or former smokers may want to avoid multivitamins with high levels of vitamin A, which some studies have linked to increased risk of lung cancer.
In fact, too much vitamin A can create headaches, liver damage, reduce bone strength, and even cause birth defects. Meanwhile, too much iron can induce nausea and may also cause liver and other organ damage.
More Research Is Needed
Indirectly, reliance on supplements may have a negative effect on the motivation of consumers to engage in other healthy activities like exercising, healthy eating in general, or limiting intake of alcohol, tobacco, or other harmful substances.
One consumer study found evidence that “drug marketing undermines intentions to engage in health-protective behaviors.”
The authors found that essentially, some may believe that supplements can compensate for not going to the gym or drinking too much on the weekends. They also found that, paradoxically, some people who take a lot of supplements may also associate this supplement-taking behavior with their own poor health.
This perception “reduces self-efficacy and perceived ability to engage in complementary health-protective behaviors,” the authors wrote in the study.
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
Statista. Total U.S. dietary supplements market size in 2022, 2023, and 2031
National Institutes of Health. Dietary Supplements: What You Need to Know
National Center for Complementary and Integrative Health. Vitamins and Minerals
Springer Nature. The Marketing of Dietary Supplements: A Canadian Perspective
National Center for Complementary and Integrative Health. Using Dietary Supplements Wisely
Journal of Consumer Research. How Does Drug and Supplement Marketing Affect a Healthy Lifestyle?
Joshua Rapp Learn is an award-winning D.C.-based science writer. An expat Albertan, he contributes to a number of science publications like National Geographic, The New York Times, The Guardian, New Scientist, Hakai, and others.
