Supplements: What's Worth Taking and What's Just Hype
Americans spend around 60 billion dollars a year on dietary supplements. A significant portion of the products have minimal evidence for the claims on the label. The supplement industry is largely unregulated in terms of efficacy claims. This does not mean supplements are useless. Some have solid evidence. The problem is separating those from the expensive placebos.
Vitamin D: Probably the Most Common Deficiency You Are Not Testing For
Between 40 and 70 percent of people in northern latitudes, people who spend most time indoors, and people with darker skin pigmentation are deficient in vitamin D. The body produces it through sun exposure on bare skin, and modern indoor lifestyles mean most people are not making enough.
Vitamin D supports calcium absorption and bone density, modulates the immune system, influences mood (deficiency is associated with depression), and plays roles in muscle function and cardiovascular health. Vitamin D3 (cholecalciferol) is significantly more effective at raising serum levels than D2. A general dose of 1,000 to 2,000 IU daily is reasonable for maintenance in people without adequate sun exposure. Confirmed deficiency needs higher doses under medical supervision.
Omega-3 Fatty Acids: Essential and Genuinely Underconsumed
Omega-3 fatty acids (EPA and DHA) cannot be produced by the body and must come from food or supplements. Primary food sources are fatty fish: salmon, mackerel, sardines, herring, and anchovies. People who do not eat fatty fish two to three times per week are likely to have suboptimal levels.
Evidence for omega-3 supplementation is strongest for cardiovascular health (reducing triglycerides), reducing inflammation, supporting brain function and mood, and eye health. DHA is critical for brain and eye development, making supplementation during pregnancy and breastfeeding well supported. Dosing: 1,000 to 2,000 mg of combined EPA and DHA per day. Check the label for the actual EPA and DHA content rather than total fish oil content. Algae-based omega-3 is available for vegans.
Magnesium: Quietly Deficient in More People Than Realize
Magnesium is involved in over 300 enzymatic reactions. Modern diets high in processed foods tend to be magnesium insufficient. Evidence supports magnesium supplementation for improving sleep quality, reducing muscle cramps, supporting blood sugar regulation, and reducing migraine frequency.
Form matters more with magnesium than most supplements. Magnesium glycinate is best absorbed and most likely to improve sleep and reduce anxiety. Magnesium oxide is cheap and poorly absorbed. Magnesium citrate is better absorbed and has a mild laxative effect. Magnesium malate is good for energy and muscle function.
Iron: Critical for Women Who Menstruate
Iron deficiency is the most common nutritional deficiency globally and disproportionately affects women of reproductive age. Symptoms include fatigue, brain fog, cold intolerance, hair shedding, pale skin, and breathlessness. Many women live with subclinical iron deficiency for years, attributing symptoms to being busy or not sleeping well.
Iron supplementation should follow a blood test confirming deficiency rather than being taken preventively, as excess iron has its own risks. Ferrous bisglycinate is the most well-tolerated form. Taking iron with vitamin C improves absorption. Taking it with calcium, coffee, or tea reduces it.
Collagen: The Evidence Is More Mixed Than the Marketing Suggests
Hydrolyzed collagen supplements have some evidence for improving skin elasticity and reducing the appearance of fine lines after 8 to 12 weeks of use. The honest caveat: collagen is a protein, digested into amino acids like any other protein. The theory that consumed collagen specifically travels to the skin is not as straightforward as marketing implies. Results vary significantly between individuals.
Biotin: Probably Not What You Think It Does
Biotin deficiency causes hair loss and nail brittleness, but actual biotin deficiency is rare. Taking high-dose biotin when you are not deficient does not produce the dramatic hair growth the packaging implies. Important practical note: high-dose biotin (5,000 mcg and above) interferes with thyroid blood tests and certain cardiac biomarker tests, producing falsely normal or abnormal results. Stop it several days before any blood tests.
How to Choose Supplements That Are Actually What They Say
Look for NSF International, USP, Informed Sport, or Informed Choice certification on the label. These organizations independently verify that the product contains what it claims, in the amounts stated, without significant contaminants. Supplements are not regulated for efficacy by the FDA before going to market, so the clinical evidence for the ingredient itself must be evaluated separately from product quality.