July 29, 2025

5 Supplements That Could Be Harming Your Health

It is astonishing how many commonly used dietary supplements potentially pose serious threats to overall health. Human research studies have identified five dietary supplements that offer little to no benefit. In addition, they may possibly contribute to an individual's risk for developing disease.

Herein lies our analysis of the evidence for each of the five supplements. We will begin with the first of the most commonly consumed.

Calcium

While it is true that humans require sufficient calcium for the proper functioning of muscles, for nerve communication, and for bone density, the current body of evidence indicates that consuming calcium through supplements is associated with adverse outcomes.

Multiple meta-analysis studies demonstrate that calcium supplementation does not reliably decrease the occurrence of fractures, especially in well-designed randomized controlled trials. Additionally, multiple studies indicate a statistically significant association between calcium supplementation and an increased risk of heart attacks. A particular study demonstrated an approximately 90% increase in the risk of heart attacks among users of calcium supplements who had inadequate vitamin D levels.

The probable explanation for these associations is that supplements may lead to spikes in blood calcium levels, which may contribute to the buildup of calcium in artery walls. In contrast, calcium obtained from food sources appears to have no similar association with cardiovascular risks. Furthermore, there is evidence suggesting that calcium obtained from food sources may be protective.

Therefore, aim to obtain your daily requirements of calcium from food sources (e.g., milk, leafy green vegetables, and fortified plant milks) instead of supplements unless your healthcare professional advises you otherwise.

Iron

Iron is vital for delivering oxygen to tissues and for providing energy. However, supplementation is risky for individuals who do not have an iron deficiency. Over-supplementing with iron may interfere with zinc absorption, disrupt gastrointestinal processes, and may cause damage to organs.

For the majority of healthy adults, obtaining adequate amounts of iron through their diets is sufficient, through foods such as red meats, beans, and leafy green vegetables, and not through supplements.

However, there are exceptions. For example, during pregnancy; for women experiencing heavy menstrual bleeding; or for individuals diagnosed with an iron deficiency, supplementation may be warranted. However, it is recommended that these instances be monitored by a healthcare professional.

Vitamin E

As antioxidants, vitamin E supplements were aggressively marketed as anti-aging agents and to promote cardiovascular health. Unfortunately, the evidence does not support these claims.

Large-scale studies demonstrate that supplementation with vitamin E increases the likelihood of mortality. Some studies also show an increased risk of prostate cancer in some groups.

A Cochrane review of over 400,000 participants demonstrated no benefit from vitamin E supplementation and potential harm. Vitamin E deficiency is extremely rare because of the abundance of the nutrient in food sources such as nuts, seeds, oils, and green vegetables.

Take away message: Do not consume vitamin E supplements unless specifically ordered by a physician.

Vitamin A

Another fat-soluble vitamin, vitamin A is critical for vision and immune system function. However, excessive intake from supplements has been associated with liver damage, weakened bones, and congenital malformations.

Similar to vitamin E, vitamin A is readily available in foods such as carrots, sweet potatoes, and leafy green vegetables. Therefore, the vast majority of people receive adequate amounts of vitamin A from their diets.

Resveratrol

Once touted as an anti-aging "miracle" supplement due to early laboratory findings related to longevity, subsequent human studies failed to validate these claims. Resveratrol does not appear to stimulate the key longevity pathways researchers initially thought it would stimulate.

In fact, some studies suggest that resveratrol may actually diminish the benefits of physical activity and decrease testosterone levels. There is no credible evidence to support the claim that resveratrol improves lifespan or promotes optimal metabolic health.

The Better Alternative

Nutrition is complex and more is not necessarily better when considering the use of dietary supplements. Although certain individuals may derive benefit from specific supplements, the majority of people will be better served by receiving their required nutrients from whole foods, not supplements.

To evaluate whether you need to supplement or address bone health concerns, consult a healthcare professional to discuss testing and assess your needs. To explore more about the evaluation of supplements and other science-backed ways to improve sleep, energy, metabolism and longevity, you may want to read the article on berberine benefits, risks, and best uses.

Research Sources

Filed in: Supplements

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