Should I take a supplement?

As a physician who is proactive and data-driven about health, this is one of the most common questions I get asked. My response is going to disappoint a lot of people. My short answer is no. My nuanced answer: it depends. But likely no.

The supplement industry is enormous: Americans spent $60 billion on supplements in 2024. Supplements are easily and widely available. Whole Foods has a huge section in the center of the store dedicated to supplements enticing me to buy something to help boost my immune system, improve my sleep, or help me build muscle. Exercise is hard. Eating healthy is hard. Taking a supplement is easy.

Some of our desire to take a supplement is also driven by fear. Cancer is frightening. Dementia is frightening. Supplements feel like a proactive way to “do something” daily to improve health and prevent scary diseases. So why not take supplements?

First, in the U.S., dietary supplements are not regulated like drugs.The FDA doesn’t approve them for safety or efficacy before they go to market. This leads to a massive variety of products and claims that wouldn’t be allowed elsewhere. The difference between supplements and pharmaceuticals isn’t that one is natural and safe and the other is synthetic with potential side effects - it’s how they are regulated. Unlike a prescription medication, you don’t know exactly what is in that melatonin bottle you bought (third party testing of melatonin found significant under or overdosing -sometimes the actual dose is 4 times that of the label). In addition, you also don’t know if there are contaminants or fillers in the supplement. The clean lab project found that nearly half of the protein powders tested exceeded at least one federal or state regulatory set for safety regarding heavy metals, such as arsenic, lead, and mercury.

Let’s say your supplement brand is 3rd party tested, you are actually ingesting what the bottle says, and there are no significant contaminants. Then you have to ask: Is there evidence that supplement is both safe and effective? I mention safety because sometimes a supplement that is believed to be helping us turns out to be harming us. For example, beta-carotene (a pre-cursor to vitamin A) was thought to prevent cancer back in the 1990’s, but a large randomized trial showed that daily supplementation with beta-carotene and retinol over 4 years resulted in a 28% increased risk of lung cancer and a 17% higher risk of death (CARET study). Other studies have confirmed these results. Needless to say, we no longer recommend beta-carotene supplementation.

Sometimes supplements appear to be safe but are not effective. Studies of anti-oxidant vitamins C and E have not shown benefit in reducing cancer. A systematic review of 84 randomized clinical trials by the US Preventive Services Task Force in 2022 concluded that “vitamin and mineral supplementation was associated with little or no benefit in preventing cancer, cardiovascular disease, and death.”

Let’s do a deeper dive on a few specific and very popular supplements. Every health and fitness influencer I know seems to be recommending vitamin D. It is also one of the most well studied supplements. The VITAL study was an enormous randomized trial of 25,000 people in which supplementation with vitamin D did not result in a lower incidence of invasive cancer, cardiovascular events, or death than placebo. Critics have commented that the 2000 IU dose of vitamin D given (considered a high dose at the time) was too low—5000 IU is more popular now. Most people in the study had a normal level of vitamin D (30 ng/ml) when they entered the study, so it is possible that those who are deficient (<20 ng/ml) may benefit from vitamin D supplementation (a small subgroup analysis of those with low vitamin D levels did not show this, but the study was not designed to answer that question). Some argue that vitamin D supplementation should be based on the blood level of vitamin D and the dosage titrated to the appropriate level. We don’t actually know the optimal vitamin D level; 30 ng/ml is considered sufficient, but is that optimal? These questions may never be answered as clinical trials are very expensive and several trials of vitamin D have already failed to show positive results.

Omega 3 fish oils are another popular supplement that have been well studied. Omega-3 fish oils contain EPA and DHA which are believe to be beneficial for the brain, heart, and eyes. A Cochrane review (a highly respected, independent organization that conducts thorough reviews of the medical literature) evaluated 86 randomized studies and concluded that omega-3 supplementation “has little or no effect on deaths and cardiovascular events (high-certainty evidence).” In the last 20 years, several large randomized trials (VITAL, ASCEND, and STRENGTH) failed to show a cardiovascular benefit to omega-3 fish oils.

I should point out that there have been some exceptions when it comes to trials of omega-3 fish oils for heart disease. The REDUCE-IT trial which showed a significant reduction in a combined endpoint that included cardiovascular death, heart attacks, and strokes compared to people given a placebo. Most of the patients already had heart disease—this was not a trial in healthy people looking to prevent heart disease. In this study patients took 4 grams of pure EPA (16 times more EPA than the Kirkland fish oil at Costco) which is a prescription medication and not an over-the-counter supplement. Critics of this study have commented that the placebo group was given mineral oil which resulted in higher rates of heart disease making the omega-3 arm look more favorable.

Supporters of omega-3 supplementation argue that the 1 gram of omega-3 fish oil dose was too low in most trials - although the STRENGTH trial tested 4 grams of EPA+DHA and was terminated early due to low probability of showing a benefit. Perhaps the typical duration of most trials (5-7 years) is too short to show a benefit. What if someone started taking omega-3 supplements in their 40’s? How would that impact their heart disease risk in their 60’s and 70’s? We do not know. In sum, the extensive data we have failed to show a reduction in cardiovascular events and death from omega-3 fish oil supplementation in healthy people without established heart disease.

What about omega-3 fish oils for other purposes, such as eye and brain health? A large randomized trial (AREDS2 study), failed to show a benefit to omega-3 supplementation in preventing the development of age-related macular degeneration (a leading cause of blindness in the elderly). Studying the effects of omega-3 on the brain is harder. The studies on cognition have been much smaller but showing a possible benefit: a systemic review and meta-analysis of 12 studies showed some benefit on cognition in elderly people with mild cognitive impairment (a pre-cursor to dementia). In my opinion, much more work still has to be done in this area. I would love for omega-3 fish oils to help prevent dementia, but compelling evidence is not there at this time.

There are many other supplements that could be discussed, most of which have been studied much less thoroughly than vitamin D and omega-3 fish oils and therefore have much less evidence supporting their use. If folks are interested in specific supplements, I can write about them in a future post.

When it comes to supplements, I would ask, “Why ?” Is it because you are deficient in a particular nutrient, such as vitamin D? If so, my advice is to correct the deficiency through diet first. You will not only get the particular nutrient, but likely also fiber and other beneficial minerals and vitamins. In the case of vitamin D, try to get more sunlight. Amazingly, your skin is capable of regulating vitamin D production when it comes from the sun (you won’t overproduce vitamin D) but cannot do so when you take a supplement.

If you are seeking a particular benefit, such as lower risk of cancer or heart disease, improved sleep, or increased muscle mass, look for clinical studies that have evaluated for that outcome—not just testimonials from a paid influencer or epidemiological studies showing a correlation.

I tend to agree with an editorial published in the Annals of Internal Medicine back in 2013 which concluded, “Most supplements do not prevent chronic disease or death, their use is not justified, and they should be avoided.” My opinion when it comes to most supplements is first focus on sleep, nutrition, exercise and stress management. If you get all those right, you probably won’t need a supplement.