What you should know about supplements

Over the years, many a patient has asked me if they can take “this vitamin” or “that supplement,” thinking that if something is “natural” it will make them healthier or even be better than their prescribed medications.

Photograph Courtesy of Unsplash/Jon Tyson

When COVID-19 happened, the concern was more about supplements that would strengthen their immune system. Unfortunately, even if something is termed as “natural,” this does not guarantee that it is effective or safe.

Photograph Courtesy of Rotary.org | Rotarian Herbert J. Taylor

The desire to be healthier has made the global market for vitamins and supplements grow into a billion-dollar business. Worldwide, the vitamin, mineral and supplements market is expected to reach $186.95 billion by 2025, growing at a rate of 7.3 percent per year.


It appears, however, that most of this money is being wasted.

There is a lot of research out there regarding vitamins and supplements. Observational studies, though, can have “healthy user bias,” meaning individuals who choose to take vitamins often engage in other healthy behaviors, and so the results of the studies always look good. But time and again, vitamins that looked promising in observational studies have failed in large randomized trials.

Photograph courtesy of Unsplash/Rima Kruciene

Randomized trials are the most reliable method available for testing new treatments. The design of this type of research helps prevent the skewing and manipulation of results, and to reduce the chance that the findings are not due to influences outside of the study — in other words, making sure that the results are real.

Photograph Courtesy of Unsplash/Nadine Primeau

Then there are studies that analyze all of these randomized trials. One such analysis included studies of 24 different interventions from 277 randomized trials and nearly a million patients. What it found was that there is no high-quality evidence that any vitamin or supplement has a beneficial effect on overall mortality. So basically, no evidence to strongly advocate for the continued use of these vitamins and supplements if you’re trying to decrease your chances of having a heart attack, stroke or death.

Photograph Courtesy of Unsplash/Dhiren Maru

The reason these studies showed only small effects is because vitamins were, by and large, identified via their deficiency syndromes. For instance, we know that vitamin C is vital for life because, without it, people get scurvy. But there has never been much rationale as to why taking mega-doses of any of these vitamins would give super-benefits to health.

Photograph Courtesy of Unsplash/Winel Sutanto

Taking more than you need is always more expensive and can also raise your risk of experiencing side effects. For example, getting too much vitamin A can cause liver damage and birth defects. Excess iron causes nausea and vomiting and may damage the liver and other organs. Too much vitamin C can give you kidney stones. High doses of vitamin E may lead to stroke caused by bleeding in the brain. Prolonged intake of high amounts of vitamin B6 has been associated with nerve damage.

Photograph Courtesy of Unsplash/I Yunmai

As for vitamins and supplements and COVID-19, there is currently no scientific evidence to suggest that taking vitamin C, zinc or vitamin D is harmful to patients with COVID-19 — but there is also no strong evidence to suggest that they will prevent or treat the disease.

Some scientific evidence does show that some dietary supplements are beneficial for overall health and for managing certain health conditions. Folic acid decreases the risk of certain birth defects. In the right patient, calcium and vitamin D are important for keeping bones strong and reducing bone loss.

You should also be discerning when reading press releases. A study regarding vitamin D was in the news recently, reporting that people should stop taking vitamin D. Hopefully many actually read the full article, which said you should not take vitamin D if you don’t need it, but that you should if you do. It’s been reported that 1 in 3 Filipinos is deficient, which can be checked with a simple blood test.

Some supplements, however, truly need more study to determine their value. Remember that the US Food and Drug Administration and even our local FDA do not determine whether dietary supplements are effective before they are approved, just that these supplements won’t poison you.

If you’re thinking of taking a supplement, ask your doctor first. Please don’t take them to try to treat a health condition that you’ve diagnosed yourself, or from the advice of an unverified blog or TikTok video, or your well-meaning neighbor. Don’t take supplements in place of, or in combination with, prescribed medications without your doctor’s approval.

The bottom line is that supplements can never replace the variety of foods that are important in a healthy diet. If you already eat nutritious foods and have a healthy lifestyle, you may hardly need any supplementation at all.

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