September 2012 Issue

Red Raspberry Ketone — Little Research Supports the Weight-Loss Supplement
By Clare Dyczkowski, BA, and Christin L. Seher, MS, RD, LD
Today’s Dietitian
Vol. 14 No. 9 P. 80

The weight-loss market is a multibillion-dollar industry, luring consumers with claims of fast results with minimal effort. For the estimated 108 million people currently on a diet in the United States,1 weight-loss products, with their tantalizing promises to help shed those last stubborn pounds, are hard to refuse. But new information from Marketdata Enterprises, Inc, an independent market research company tracking the weight-loss industry, reports that with the economic downturn, consumers have less discretionary income to spend on their weight-loss goals.2

This cost issue has paved the way for the introduction of the new, highly touted so-called miracle weight-loss supplement red raspberry ketone (RK), which has caught the attention of many value-conscious dieters. RK is low in cost, reportedly has no side effects, and supposedly helps the body burn fat by “[helping the] body think it’s thin,” said Mehmet Oz, MD, in a segment on The Dr. Oz Show in February.3 Oz dubbed RK the "No. 1 miracle in a bottle to burn your fat."3

But does the supplement really live up to these claims?

Why RK?
Proponents of RK as a weight-loss aid base their claims on the compound’s ability to increase circulating levels of adiponectin, a hormone secreted from adipose tissue that plays a key role in carbohydrate and fat oxidation that also may exert anti-inflammatory, antifibrotic, and antiatherogenic effects.4 In humans, low circulating levels of adiponectin are linked with an unhealthy BMI, a high percentage of body fat, elevated fasting insulin concentrations, and raised plasma triglycerides.5 Therefore, high levels of adiponectin have been indirectly associated with a decreased risk of obesity, insulin resistance, metabolic syndrome, and cardiovascular disease.5

As it appears that higher levels of adiponectin offer some protective benefit, research is now exploring the specific mechanisms that prompt the body to produce it in higher quantities. But despite early evidence indicating adiponectin can be increased through weight loss, a healthful diet, and exercise in some overweight individuals,5-7 consumers still seek a magic pill to circumvent these more difficult lifestyle changes, says Amy Goodson, MS, RD, CSSD, LD, a sports dietitian for Texas Health Ben Hogan Sports Medicine. “Most people use supplements as a quick fix when going back to the basics is the answer.”

RK’s Newfound Popularity
Since RK was introduced to the public in February, RDs report clients have taken great interest in the product. “Ever since The Dr. Oz Show featuring raspberry ketone aired a few months ago, I’ve received numerous inquiries from clients, wondering if this ‘miracle pill’ was really as impressive as it was portrayed to be on the show,” says Laura Acosta, MS, RD, LD/N, owner of LifeStyle Wellness, LLC.

Miranda Monroe, a student in the coordinated program in dietetics at Youngstown State University in Ohio, also has seen the popularity of RK. “As an employee at a health food store, I have to search for the Dr Oz picks for customers on a daily basis,” she says, noting that when the segment on RK aired, “We had about three boxes of an RK product that never sold, but after the show, we sold those three boxes within a day. Overall, the demand for [RK] where I work exceeded 400 orders within maybe two months. I’ve never seen that many customers order something before. … [They] would come in and believe that they knew the next big weight-loss secret.”

What the Evidence Says
With the public in a newfound frenzy about RK’s potential, RDs know that too-good-to-be-true supplement claims often fall short of their promises—and RK’s claims appear, at this time, to be no different. Currently, only a handful of studies have examined the efficacy of RK, and none have been conducted in humans.

Some of the earliest research investigated RK’s ability to prevent obesity, demonstrating it prevented weight gain, improved hepatic triacyglycerol, and stimulated lipolysis in adipocytes of male mice fed a high-fat diet.9 Hypothesizing that the mechanism by which RK exerted these effects was through adiponectin, Korea’s Food and Drug Administration investigated further, also using male mice.10 Researchers administered RK and monitored adiponectin and indicators of lipolysis. Data indicated that RK increased secretion of adiponectin, inhibited fat accumulation, and enhanced fatty acid oxidation, leading researchers to conclude RK holds great promise as an herbal medicine.

The latest data, released over the last year, confirm previous indicators that RK may offer some protection against obesity.11-12 While these studies are promising, no studies examining RK in humans currently exist. “What happens in a test tube or a mouse isn’t necessarily indicative of what will happen in humans,” Acosta warns.

Approach With Caution
Clients of private practitioner Lanah J. Brennan, RD, CDE, have been asking about RK in recent months. “RK is approved as safe for use as a food additive, but there are no safety studies for the higher amounts found in the supplements. For most patients, raspberry ketone isn’t harmful, but they may not provide them with the results they’re looking for,” she explains, reminding RDs to council patients about the potential effects of other additives found in RK supplements. “Bitter orange, caffeine, and hoodia are popular additives in RK supplements … and RK itself also may have stimulantlike effects,” she notes, cautioning that these properties indicate RK may not be appropriate for patients with heart disease, high blood pressure, or glaucoma.

What’s more, Brennan says, “There have been reports of a possible drug interaction with [the blood thinner] Coumadin, and with the limited safety information on the use of RK as supplements, it may be a good idea to warn patients of the potential interaction.”

Bottom Line for Dietitians
For now, many RDs are waiting for more research, skeptical of the promises made by RK proponents. “Red raspberry ketone, in my perspective, falls under the category of supplements that offer a ‘miracle effect’ on weight loss with very little to no research backing it up,” Goodson says. “The challenge in America is that people want the next best thing, the fastest answer instead of going back to the basics of energy balance: eat less, move more.”

Monroe agrees: “People shouldn’t rely solely on a pill for weight loss.” She also points out that with more permanent lifestyle changes, people often see prolonged results.

Until research provides a definitive answer, Acosta also remains leery: “At this point, while I’m not ready to dismiss the idea of red raspberry ketone possibly enhancing fat loss, I’m not jumping on the bandwagon either. When there’s a substantial body of well-designed human studies on this subject, I’ll feel better equipped to make recommendations one way or the other. For now, I'm encouraging my clients to do their own research before running out to buy any supplement and to remember that when it comes to weight loss, no product can take the place of a healthful diet and exercise.”

— Clare Dyczkowski, BA, is a recent graduate from the University of Akron Coordinated Program in Dietetics.

— Christin L. Seher, MS, RD, LD, is founder of Strategic Health Solutions, LLC, serving northeastern Ohio.


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2. 108 million Americans now on a diet, highest ever. PRWeb website. January 18, 2012. Accessed June 21, 2012.

3. Raspberry ketone: fat-burner in a bottle. The Dr. Oz Show website. Accessed June 21, 2012.

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10. Park KS. Raspberry ketone increases both lipolysis and fatty acid oxidation in 3T3-L1 adipocytes. Planta Med. 2010;76(15):1654-1658.

11. Wang L, Xianjun M, Yan Z, Wei Z. Experimental study on the mechanism of raspberry ketone on simple obesity and insulin resistance relevant to obesity. In: Proceedings 2011 International Conference on Human Health and Biochemical Engineering. Jilin, China: Systems, Man, and Cybernetics Society; 2011:58-61.

12. Wang L, Meng X, Zhang F. Raspberry ketone protects rats fed high-fat diets against nonalcoholic steatohepatitis. J Med Food. 2012;15(5):495-503.