With more than 40% of U.S. adults reporting weight gain during the pandemic, many turned to diets or supplements for weight loss support. One supplement, raspberry ketone, is widely used as a food flavoring substance and has grown in popularity in recent years for weight loss. EN examines the scientific support and safety for this supplement.
Raspberry ketone (RK) is an aromatic compound naturally found in many foods, most notably in red raspberries and other berry fruits. Due to seasonal limitations and the expense to extract naturally occurring RK, most commercially available RK is chemically synthesized for use as a flavoring agent in processed foods and cosmetics. RK first entered the dietary supplement scene approximately a decade ago when it was featured on a national talk show for its “fat burning” potential.
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With high doses of RK, cell studies report fat burning effects such as increased fatty acid oxidation and decreased lipid accumulation. In animal studies, RK prevented increases in body weight and adipose tissues when rodents consumed a high-fat diet. While RK is marketed as a clinically proven weight-loss product, there is limited clinical data in humans to support this claim.
A 2013 study examined the effects of 2,000 milligrams (mg) of an ingredient blend containing RK on weight loss in 70 overweight adults. In this 8-week study, participants followed a calorie-restricted diet and engaged in moderate exercise. Those who consumed the supplement lost more body weight and fat mass than the placebo group.
Note: these results should be reported cautiously as the supplement in this small trial contained multiple ingredients, so any effect cannot be solely attributed to RK and over a one-third of the subjects dropped out of the study.
RK intake in adults is estimated to be 1.8-3.8 mg/day from fruits and flavoring substances compared to 100-1,400 mg in supplements. Currently, there is little research examining the safety or adverse effects of daily RK supplementation in humans at these high doses. The weight loss study mentioned above did not report any serious side effects, though additional clinical data is needed to support these findings.
Newer computer modeling data and case reports suggest a concern for adverse effects of RK on reproduction or cardiac functions. RK may stimulate the nervous system or interact with the effects of warfarin. Always talk with your doctor before starting a new diet or supplement.
(Environmental Nutrition is the award-winning independent newsletter written by nutrition experts dedicated to providing readers up-to-date, accurate information about health and nutrition in clear, concise English. For more information, visit www.environmentalnutrition.com.)