LOS ANGELES — With up to one-third of U.S. residents reporting use of nutritional supplements marketed as aids to weight loss, health care providers must keep an open mind when discussing them with patients, according to a presenter at ObesityWeek.
“There are numerous products and ingredients that have been used for weight loss, and the popularity of various agents waxes and wanes. We have to constantly be evaluating the literature to examine evidence-based information and whether a patient should or should not consider use of these agents,” Laura Shane-McWhorter, PharmD, BCPS, BC-ADM, CDE, FASCP, FAADE, a professor in the department of pharmacology at the University of Utah College of Pharmacy, told Endocrine Today.
Providers who dismiss supplement use out of hand risk alienating their patients, Shane-McWhorter said.
Many of the most popular agents have been studied, according to Shane-McWhorter, but study designs present several issues of concern, and supplements that have been associated with statistically significant weight loss may not have shown clinically meaningful weight change.
Patients often harbor the hope that weight-loss supplements can substitute for exercise or healthy nutrition, Shane-McWhorter said. Instead, patients may experience real health problems related to the agents themselves or unlisted ingredients, such as laxatives, diuretics, prescription weight-loss drugs and thyroid hormones, besides beta-blockers included to mask cardiovascular adverse effects.
She outlined current evidence for several popular supplements.
- Uses/mechanism of action: Increases thermogenesis, stimulates fat utilization in muscle during exercise, increases endurance.
- Side effects/interactions: Increases heart rate, anxiety and irritability; large doses can induce seizures and cerebral edema. Effects are additive with other products containing caffeine. Interacts with beta-agonists and cimetidine.
- Bottom line: Studies have shown caffeine to increase exercise endurance and provide statistically significant weight loss, but the large doses available in energy drinks can have serious adverse effects.
Camellia sinensis/green tea
- Uses/mechanism of action: Contains catechins and caffeine. Increases calorie and fat metabolism, decreases lipogenesis and fat absorption and suppresses appetite.
- Side effects/interactions: Headache, dizziness, increased blood pressure, gastrointestinal discomfort. May be hepatotoxic. Contains vitamin K and interacts with warfarin. May interact with antihypertensive medications.
- Bottom line: Studies performed in Japan have shown an association with weight loss, but those outside of Japan have resulted in much less weight loss. Hepatic damage has been correlated with consuming green tea on an empty stomach and in combination products.
- Uses/mechanism of action: Decreases fatty acid synthesis and glycolysis, and increases serotonin release.
- Side effects/interactions: Headache, cough, may be hepatotoxic. Interacts with diabetes medications and perhaps with statins and selective serotonin reuptake inhibitors (SSRIs).
- Bottom line: Long-term safety and benefits are unknown due to lack of studies. Often combined with other agents.
- Uses/mechanism of action: Gut microbes allow calorie extraction from indigestible polysaccharides. Prebiotics stimulate growth of favorable microbes, and probiotics compete with unfavorable microbes in the gut.
- Side effects/interactions: Increased gastrointestinal gas, diarrhea and constipation. May contribute to antibiotic resistance. Interact with antibiotics and antifungals.
- Bottom line: What constitutes a healthy microbiome is currently unknown, as are which types of microbes are beneficial for which patients in what doses and for how long.
Use in practice
Shane-McWhorter cautions health care providers to monitor appropriately for hepatic or renal function in patients who use supplements and to be aware of possible drug interactions.
“Also, consider what may be an appropriate length of time to evaluate the use of the product,” she said. “Overall, patients must remember that there is no ‘magic pill’ and that they must still eat healthy foods and be physically active.” – by Jill Rollet
Shane-McWhorter L. Oral presentation: What’s up with all these supplements? Presented at: ObesityWeek; Nov. 2-6, 2015; Los Angeles.
Disclosure: Shane-McWhorter reports no relevant financial disclosures.