About half of American adults and one-third of children take dietary supplements, according to the Office of Dietary Supplements. Yet many physicians remain skeptical of the category. “A vast majority of supplements are probably worthless,” said Jeffrey Linder, MD, MPH, a general internist and professor at Northwestern University’s Feinberg School of Medicine. Still, some doctors do take certain supplements themselves—though they are selective about which ones.
Vitamin D
Vitamin D supports bone health and immune function, and low levels have been linked to cancer, autoimmune diseases, and cardiovascular problems. Deficiency is common among people living at northern latitudes and those with darker skin. Few foods contain significant amounts of D, making supplementation practical for many. Nearly every one of the eight doctors who spoke for this article takes a vitamin D supplement, especially during winter.
Most physicians recommend vitamin D3 over D2, as studies show D3 is more effective at raising blood levels. Taking it with food that contains fat improves absorption, since vitamin D is fat-soluble. Sara Velayati, MD, an obesity medicine specialist at Montefiore Einstein, suggests pairing supplements with meals “the fattier and thicker the better.”
Calcium
Calcium helps build and maintain strong bones and teeth. Women approaching menopause should pay particular attention to their intake, since hormonal changes during perimenopause can accelerate bone loss. “Calcium is best sourced from your diet,” said Rachel Pessah-Pollack, MD, an endocrinologist at NYU Langone Health. “But if you’re not able to—I try to get dairy products but often come up short—a supplement is needed.” She takes a combined calcium and vitamin D tablet daily.
The type of supplement matters. Calcium carbonate requires food for proper absorption because it needs stomach acid. Calcium citrate can be taken with or without meals, making it a more flexible option for some patients.
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Magnesium
Magnesium can enhance sleep and muscle recovery, and research shows it helps prevent migraines. Raquel Zemtsov, MD, MPH, a family medicine doctor at the University of Pittsburgh, takes magnesium to stave off migraine symptoms. Several other physicians use it specifically for sleep support, including Kathleen Jordan, MD, an internal medicine physician and chief medical officer at Midi Health, and Sheeva Talebian, MD, a reproductive endocrinologist at CCRM Fertility.
Tolerance varies by form. Magnesium glycinate causes less gastrointestinal upset than oxide or citrate varieties, according to Dr. Jordan. However, magnesium oxide is the preferred type for migraine prevention. Taking magnesium with food can also help prevent stomach issues.
Omega-3s
Omega-3 fatty acids support cardiovascular health and have anti-inflammatory properties. Dr. Jordan takes krill oil, while Dr. Velayati uses fish oil selectively. “The right dose really depends on the goal, but I don’t think it’s necessary for everyone,” Dr. Velayati said. Fish oil supplements can leave a characteristic aftertaste, and finding a tolerable product may require some experimentation.
Absorption can be challenging since omega-3s are fat-soluble. Taking supplements with a fatty meal helps. Some evidence suggests krill oil may be better absorbed and cause less aftertaste than standard fish oil.
Iron
Iron deficiency is common in women due to menstrual blood loss. “Occasionally, despite trying my hardest to seek out iron-rich foods, I still develop an iron deficiency,” Dr. Zemtsov said. When that happens, she takes ferrous gluconate every other day, research shows this schedule improves absorption and reduces side effects. Dr. Jordan also takes iron, citing benefits for sleep, hair health, and energy levels.
Pairing iron supplements with vitamin C enhances absorption. Dr. Zemtsov takes her iron alongside a vitamin C supplement or iron-rich food.
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Fiber
Fiber supports digestion, helps stabilize blood sugar, and can lower LDL cholesterol. “Unless you are that rare woman who regularly gets in her 25 to 30 grams per day, extra fiber intake is beneficial for almost everyone,” Dr. Jordan said. She takes a fiber supplement on days when her diet falls short.
Increasing fiber intake suddenly can cause gas and bloating, so doctors recommend starting slowly. Higher water intake is also important since fiber requires fluid to work properly.
Choosing Supplements Wisely
Doctors stress the importance of having a specific reason for taking supplements, ideally a confirmed deficiency. “I view supplements as a way to fill a gap, not a substitute for good nutrition, sleep, exercise, and evidence-based medical care,” Dr. Velayati said.
Before starting any new supplement, patients should consult their primary care physician, especially if they take other medications. The word “natural” on a label does not guarantee safety. For those seeking reputable products, some organizations offer third-party testing services, look for certification from US Pharmacopeia or NSF International’s Certified for Sport program.
Dosage matters too. Excess calcium can increase kidney stone risk and cardiovascular issues, and too much vitamin D may cause problems through its effect on calcium absorption. Supplements work best when used to address specific gaps rather than as a routine hedge against dietary shortcomings.
