Gaby
Dietary supplements sit on grocery-store shelves promising health benefits we often take at face value. But there’s no guarantee they’ll actually help. That’s why whole foods should be the primary source of the nutrients our bodies need.
Compensating for Deficiencies
Dietary supplements are meant to fill potential nutritional gaps. When used appropriately, they can support and restore bodily functions. Some studies report that regular use of certain supplements can reduce the risk of deficiency by as much as 80%. Examples include echinacea extract and omega-3 fatty acids. These bioactive substances and their combinations are usually intended to be taken with food and can sometimes be added to food products. A dietary supplement is treated as a food product rather than a drug, although the same compound can be registered as both a supplement and a medication. So who benefits from supplements, and who might find them harmful or a waste of money?
To improve diets, people can use dietary fiber, amino acids, enzymes, bioflavonoids, vitamins, and minerals. Supplements on the market include multivitamins with minerals, immunomodulators, adaptogens, and chondroprotectors. Medical professionals often question the routine use of vitamin complexes. For example, extra vitamin D and calcium can help with osteoporosis, but excessive beta-carotene raises the risk of lung cancer in smokers, and too much calcium and vitamin D increases the risk of kidney stones. Contrary to popular belief, calcium, vitamins D and C, and multivitamins have not been shown to prevent cardiovascular disease, even though many people take them for that reason.
Dietary supplements should be taken based on medical indications. A doctor may recommend supplements for adults with conditions that impair nutrient absorption, such as celiac disease. In most other cases, the best approach is to get vitamins and minerals from a balanced diet. Multi-ingredient supplements packed with active compounds should not be taken “just in case.” Balance the potential benefits and harms, and tell any new doctor about the supplements you take—interactions between supplements and prescription medications can be dangerous.
Not Everything Is Beneficial
With few exceptions, essential organic compounds cannot be synthesized by the body and must come from food. A deficiency can disrupt vital processes—slowing them down or stopping them entirely. The need for specific vitamins depends on a person’s condition and environmental factors. For example, unlike most mammals, humans cannot synthesize vitamin C and must obtain it through diet. Vegetarians need to supplement with vitamin B12 because plant-based foods don’t contain reliable sources of it. Vitamin D is produced in the skin with enough sunlight; supplements provide vitamin D but do not replace the skin’s synthesis triggered by sun exposure.
Under a doctor’s guidance, vitamin supplements may be appropriate for certain groups—older adults, newborns, pregnant people, and nursing mothers. Most people who eat a well-balanced diet do not need routine vitamin supplements. Consuming plant oils, dairy, fish, fresh vegetables, and fruits typically offers more benefits than taking a multivitamin pill. Some large studies have found that long-term use of multivitamins does not extend lifespan and may even increase risks such as heart attacks and certain cancers, including lung cancer. The need for mineral supplementation generally decreases in this order: potassium, chlorine, sodium, calcium, phosphorus, magnesium, iron, zinc, manganese, copper, iodine, chromium, molybdenum, selenium, and cobalt. Boron and silicon are generally not included in supplements.
Protein synthesis involves about 20 amino acids, and eight of those are essential and must come from the diet. Separately, essential fatty acids—omega-3 and omega-6—also cannot be made by the body and must be obtained from food. Nonessential amino acids are produced in the body from other amino acids, though the requirement for them can change with age, health, or lifestyle. Amino acids are a key part of sports nutrition. Probiotics, sold as dietary supplements, are used to help normalize gut flora and modulate the immune system. For therapeutic purposes, specific strains such as lactobacilli and bifidobacteria are prescribed. Other natural supplements—echinacea, ginseng, ginkgo biloba, St. John’s wort, lecithin, collagen, and similar products—have long histories in traditional medicine but often lack standardized production and reliable quality guarantees.
Risk of Complications
Adaptogens and natural immunomodulators can be risky because they contain hundreds of active ingredients and may be contaminated with heavy metals, toxins, or substituted components. Tests often find undeclared substances in these products. Many dietary supplements have shown signs of hepatotoxicity. For example, some weight-loss supplements contain not just diuretics and laxatives but also potent amphetamines and related compounds. A review of multiple studies published in the International Journal of Clinical Practice documents side effects and reduced therapeutic effects when dietary supplements are taken together with medications.
This is especially true for supplements containing magnesium, calcium, iron, yohimbe extract, ginkgo biloba, echinacea, St. John’s wort, and flaxseed. Cardiovascular, antiplatelet (blood-thinning), and antidiabetic medications—including warfarin, digoxin, aspirin, clopidogrel, and insulin—are among those that interact most dangerously with supplements. Side effects can involve the gastrointestinal tract, nervous system, and urogenital system. Research published in the New England Journal of Medicine estimates that roughly 23,000 emergency-room visits in the U.S. each year are tied to adverse events from dietary supplements. That’s what can happen when the balance between benefit and harm is lost.
Examples of problematic combinations include iron with green tea, melatonin with other sedative herbs, red yeast rice with niacin, St. John’s wort with antidepressants, coenzyme Q10 with antidiabetic drugs, vitamin K with blood-thinning medications, and fish oil with ginkgo biloba. To reduce risk, allow at least a two-hour gap between such supplements and medications. By contrast, some nutrients are more effective when taken together because they enhance each other’s absorption. When compatible substances interact in the stomach during a meal, they can promote mutual absorption.
Good and Bad Combinations
Some vitamins and minerals are complementary. For example, zinc helps with vitamin A absorption, while vitamins A and C and copper aid iron uptake. Magnesium supports the absorption of several B vitamins (except B1). Riboflavin (vitamin B2) can enhance zinc absorption, and vitamin B6 reduces zinc excretion. Niacin (vitamin B3) is compatible with copper and iron. Calcium helps with the absorption of vitamin B12, while vitamins B6, C, and D support calcium absorption. Vitamin C and copper act as catalysts for iron uptake. Vitamin E works well with selenium, which boosts its antioxidant effects. Vitamin K is needed for calcium to build bone tissue. Calcium also pairs with vitamins B6, B12, and D, although magnesium in the same complex can sometimes reduce those effects.
Some nutrients act as antagonists and are best taken separately; otherwise they can interfere with each other. Vitamin E and magnesium can counteract each other, and copper, iron, and zinc can compete for absorption. Folate (vitamin B9) and zinc can form an insoluble complex that is hard to absorb. Vitamin B12 can be inactivated when combined with iron, copper, or manganese. Iron and copper interfere with riboflavin (vitamin B2) absorption. Copper can reduce the activity of vitamins B5, B12, C, and E. Taking vitamins B1, B12, C, and copper in separate doses at different times can help achieve higher blood concentrations and reduce negative interactions. Aim for a 4–6 hour gap between incompatible components.
Taking vitamins B1 and B2 together may increase the risk of allergic reactions. Vitamin B1 can also be less effective when taken with B3, B6, and B12; in many supplement formulations, manufacturers arrange B vitamins with different release profiles to avoid these clashes, which makes combined B-complex supplements acceptable in many cases. Vitamins D and E can act as antagonists and are best taken separately. Avoid combining vitamins E, B12, and K when possible. Vitamins K, E, and A can hinder each other’s absorption—if you need to correct a vitamin K deficiency, take that supplement separately and leave a two-hour gap from others. Calcium antagonizes iron, zinc, sodium, and phosphorus. There are other combinations that require caution. To avoid misjudging the benefits and harms of a dietary supplement, don’t buy a product without knowing what’s inside—avoid buying a pig in a poke.
