Over 60% of U.S. adults take dietary supplements beyond vitamins and minerals. These include herbs, mushrooms, amino acids, and plant-based compounds promoted for sleep, mood, cognition, blood sugar, and cardiovascular health. While some have solid scientific evidence, approaching health claims cautiously, especially those from those without appropriate credentials is warranted.

Supplements with Strong Clinical Support

Melatonin is a hormone from the pineal gland, a small brain structure that helps regulate the body’s sleep/wake cycle. Melatonin levels rise in response to darkness. Synthetic melatonin supplements (0.5–5 mg) can improve sleep quality. Melatonin also occurs in tart cherries and especially pistachios. Though generally safe, long-term use may disrupt hormonal cycles.

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Ashwagandha, a traditional herb from Ayurvedic medicine, has been shown to lower cortisol, reduce stress and anxiety, and improve sleep and mood when taken at 300–600 mg/day (about ⅛ to ¼ teaspoon of root extract). It is generally well tolerated but may interact with thyroid drugs and immunosuppressants.

Turmeric, particularly its active compound curcumin, is known for anti-inflammatory effects. Derived from the Curcuma longa root, curcumin is poorly absorbed unless paired with piperine, a black pepper compound that boosts absorption up to 2000%. At 500–1000 mg/day (about ¼–½ teaspoon), curcumin may reduce inflammation in arthritis and metabolic syndrome. It may increase bleeding risk when taken with blood thinners. Turmeric is about 5% curcumin.

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Berberine, a yellow alkaloid found in plants like barberry and goldenseal, improves blood sugar control and lowers LDL cholesterol, with effects comparable to the diabetes drug metformin. A typical dose is 500 mg, taken 2–3 times daily with meals. Berberine interferes with cytochrome P450 enzymes, especially CYP3A4 in the liver and intestines that normally break down many medications. Berberine also inhibits P-glycoprotein, a transporter that removes drugs from cells potentially increasing blood drug concentrations to harmful levels.

Garlic, particularly aged extract, can moderately reduce blood pressure and cholesterol. Doses of 600–1200 mg/day are effective. However, garlic may increase bleeding when combined with aspirin or warfarin.

St. John’s Wort has been used to treat mild to moderate depression, has shown results comparable to some antidepressants. However, opposite of berberine, it strongly induces the CYP3A4 enzyme, accelerating the breakdown of many medications, including birth control, SSRIs, and blood thinners.

L-theanine, an amino acid in green tea, promotes calm without sedation and may improve focus. Doses range from 100–200 mg (equal to 10–20 cups of tea) and are generally well tolerated with minimal side effects or drug interactions.

Lion’s Mane (Hericium erinaceus), a medicinal mushroom, contains compounds that may stimulate nerve growth factor (NGF), supporting brain function. One placebo-controlled study showed cognitive improvement in older adults with mild impairment. Common doses range from 500–1000 mg/day. It appears safe, with occasional reports of mild gastrointestinal upset.

Bergamot, a citrus fruit native to southern Italy, can reduce LDL and triglycerides while modestly increasing HDL. Doses of 500–1000 mg/day may intensify the effect of statins and inhibit CYP3A4, raising blood drug levels, for those on medications.

Conclusion

Many natural supplements show promise as complements or even alternatives to conventional medicine. However, consulting with a healthcare provider, including a registered dietitian, is crucial before adding any to a daily routine. While some may offer real benefit, others may be inadequate or even interfere with prescription drugs amplifying or nullifying their effect.

About the Author

Patrick Traynor, PhD, MPH, RD, CPT is a registered dietitian and founder of MNT Scientific, LLC, an insurance-based nutrition practice serving South Lake Tahoe and Sacramento, CA; Minden, NV; and Ashland, OR. Virtual appointments are also available via telehealth. To request a consultation, visit MNTScientific.com. For inquiries, email patricktraynor@patricktraynor.com.