More than one-third of all adults in the United States are obese, according to the CDC. This statistic translates into more than $150 billion per year spent in medical costs associated with obesity.1 Researchers continue to look for safe and effective weight-loss products, one of the latest of which is raspberry ketone. On a recent episode of his television show, Dr. Oz referred to raspberry ketone as “the number one miracle in a bottle,” while pointing out the ways that this product contributes to weight loss.2


Background


Raspberry ketone is the chemical compound found in red raspberries (Rubus idaeus) that produces the fruity aroma.3 This chemical has long been prized for flavoring in foods and beverages but has only recently been looked at for its potential health benefits. Unfortunately, the yield of raspberry ketone from the actual berry is low, making the product scarce and expensive.3 Consequently, researchers have rigorously worked to develop synthetic versions of raspberry ketone. 


Science 


Long before the Dr. Oz show, researchers were monitoring the literature for the safety and efficacy of raspberry ketone. Its very modest strength of evidence rating of “C” indicates that there was insufficient evidence to either support or discourage human use for medical reasons.

The exact metabolic action of raspberry ketone is theorized as being twofold. One action is the stimulation of the hormone adiponectin. Adiponectin is a potent enhancer of fatty acid oxidation glucose regulation, as well as an inhibitor of lipid accumulation. The second mechanism of action is thought to be the stimulation of naturally occurring norephinephrine-mediated lipolysis.4

Seeking to verify these mechanisms, researchers studied the effects of standardized raspberry ketone on cultured mammalian adipocytes. A treatment strength of 10 micrograms was used and the effect on lipolysis, fatty acid oxidation and adiponectin activity was measured at 24 and 48 hours. The concentration of extracellular glycerol was the marker for lipolysis, and at 24 hours showed a dramatic 300% increase over the untreated control mixture. Adiponectin activity was measured by Western blot analysis and, at 48 hours, showed an increase of nearly 100%.5

Another laboratory study explored the effect of raspberry ketone on adipose tissue mass in rats and mice.4 The group of rodents tested was pre-fed with a high fat diet for six to 10 weeks. The same groups were then fed the same high-fat diets with standardized raspberry ketone mixture added. At the end of treatment, each rodent was anesthetized and the liver removed and weighed.

Gross body weight was also recorded, and both weights were compared with previous identically fed rodent groups. Compared with the control group that had been fed a normal diet and to the test group of high-fat diet with no intervention, gross body weights increased by more than 20%. Rodents fed the high-fat diet with raspberry ketone added nearly equaled the results of the normal-diet group, with an increase of only 7%. Liver weights followed the same trend, with the treatment group equaling the normal-diet group.4

A second investigation using rat models studied raspberry ketone for its potential effect in preventing and treating non-alcoholic 
steatohepatitis. Control and treatment groups of rats fed either standard or high-fat diets were examined for the presence or degree of fatty infiltrate in liver cells. All treatment groups were significantly improved. It was believed that these outcomes were attributable to two specific actions of raspberry ketone in protecting hepatocytes and promoting the active inhibition of fatty infiltration.6

The only randomized, placebo-controlled, double-blind human study combined raspberry ketone with five other supplements known to enhance weight loss. A total of 45 obese adults completed an eight-week trial of exercise and controlled diet, and, in the test group, supplementation with the raspberry ketone combination.

All measurements of body weight in the test group were significantly lower at the end of the study than those of the control group.7 It is unknown how much of this effect was attributable to the raspberry ketone alone. 


 

Safety, drug interactions 


As with any plant product, allergic reactions are always possible. Because of the known smooth-muscle contractility action of red raspberry, pregnant women should not use this product. Safety for use in children and lactating women has not been proven. 


Raspberry ketone has a chemically similar structure to synephrine, a known stimulant. Individuals with heart disease or hypertension should be cautious with initial use. In vitro raspberry ketones inhibit the action of warfarin (Coumadin, Jantoven), so patients on this anticoagulant should discuss its use with a provider prior to use.



How supplied, dose, and cost


Most formulations of raspberry ketone are in capsule form. The recommended dose varies widely, but most sources suggest 600 mg with a full glass of water before breakfast and supper. Monthly costs for this dose range are from $30 to $50.


Summary 


The search for a “magic” cure for obesity continues. While the safety data for raspberry ketones is encouraging and the laboratory research promising, the results of the single human trial are probably the most realistic. Supplements may very well enhance weight loss, but for true success, they should be combined with a healthy and calorie-conscious diet plus daily exercise. 


Sherril Sego, FNP-C, DNP, is a staff clinician at the VA Hospital in Kansas City, Mo., where she practices adult medicine and women’s health. She also teaches at the nursing schools of the University of Missouri and the University of Kansas. 

References

  1. Centers for Disease Control. Adult obesity.. Available at www.cdc.gov/vitalsigns/AdultObesity.

  2. The Dr. Oz Show. Raspberry ketone. Available at www.doctoroz.com/videos/miracle-fat-burner-bottle.
  3. Beekwilder J, van der Meer IM, Sibbesen O, et al. Microbial production of natural raspberry ketone. Biotechnol J. 2007;2:
1270-1279.

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

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

  6. Morimoto C, Satoh Y, Hara M, et al. Anti-obese action of 
raspberry ketone. Life Sci. 2005;77:194-204.

  7. Lopez HL, Ziegenfuss TN, Hofheins JE, et al. Eight weeks of supplementation with a multi-ingredient weight loss product enhances body composition, reduces hip and waist girth, and increases energy levels in overweight men and women. J Int Soc Sports Nutr. 2013;10:22-27. Available at www.jissn.com/content/10/1/22.


All electronic documents accessed on June 15, 2013.