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A 53-year-old woman with a history of knee osteoarthritis, high cholesterol, type 2 diabetes, and hypertension presents with new onset of hot flashes and a question about a dietary supplement*. She is obese (body mass index [BMI] 33), does not exercise, and spends a good portion of her work day in a seated position. She eats a low-sugar diet and regularly eats packaged frozen meals for dinner because she doesn’t have time to cook regularly. Her most recent laboratory values include a low-density lipoprotein (LDL) cholesterol that is above goal at 160 mg/dL (goal <100 mg/dL), her kidney function is normal, and her hemoglobin A1c is well controlled at 6%. Her blood pressure is high at 160/100 mm Hg. Her prescription medications include simvastatin, metformin, and benazepril. She also takes over-the-counter ibuprofen for occasional knee pain and a multivitamin supplement once daily. She has heard good things about natural products and asks you if taking a garlic supplement daily could help to bring her blood pressure and cholesterol under control. She’s also very interested in St. John’s wort after a friend told her that it helped alleviate her hot flashes and could also help improve mood. How should you advise her? Are there any supplements that could increase bleeding risk if taken with ibuprofen?

The medical use of plants in their natural and unprocessed form undoubtedly began when the first intelligent animals noticed that certain food plants altered particular body functions. The World Health Organization estimates that 80% of the world’s population in developing countries currently use plants as medicines. These practices, however, are very different from the plant- and non-plant-derived dietary supplements (DS) that are available to consumers living in the United States. In the USA, the production and sale of DS is extremely profitable, growing from 27 billion dollars in 2009 to 52 billion in 2019. DS manufacturers market new formulations regularly with little regulatory oversight by the US Food and Drug Administration (FDA). This has led to much unreliable information as a result of unknown or poor-quality natural product formulations, poorly designed clinical studies that do not account for randomization errors or confounders, and—most importantly—a placebo effect that can contribute 30–50% of the observed response. Since the literature surrounding dietary supplements is evolving, reputable evidence-based resources should be used to evaluate claims and guide treatment decisions. An unbiased and regularly updated compendium of basic and clinical information regarding botanicals is Natural Medicines by Therapeutic Research Center (see Natural medicines in the references), which includes content review by an international, multidisciplinary, collaborative review committee of experts. The recommendations in this database are limited by the quality of the existing research and the quality of the DS used at the time of the research. As a result, all statements regarding positive benefits should be regarded as preliminary, and conclusions regarding safety should be considered tentative.

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