“If you want to burn fat all over your body, try this raspberry ketone supplement. Learn how it works to burn fat, helping you break through a weight-loss plateau. Raspberry ketone … is a safe and healthy supplement with no side effects.” Dr. Oz’s website
Pretty bold claim. We’re wondering how you can claim that it is “safe and healthy with no side effects” when there are NO published studies in actual humans! Doesn’t sound terribly evidence-based, does it? So, if there are no studies looking at efficacy in humans, what IS the evidence for this supplement and why is it flying off the shelves everywhere?
Raspberry ketone, also known as red raspberry or Rubus idaeus, is a naturally occurring substance that gives the characteristic smell to ripe raspberries, and has antioxidant properties (1). Note: it has nothing to do with the ketone bodies produced as a by-product of energy production from fatty acid breakdown when glucose is not available (such as during diabetic ketoacidosis, fasting and on ultra-low carb diets like The Dukan Diet).
As usual, the supplement also contains a veritable laundry list of other ingredients, including African mango, acai, green tea and caffeine, none of which (aside from green tea) have any reasonable evidence to support possible links to weight loss.
What evidence supports the claim that raspberry ketone is a miraculous fat-burner? Not a whole lot. A 2005 study (2) from Japan found that mice fed a high-fat diet (40% beef tallow – yum!) for 10 weeks along with raspberry ketone showed improvements in adiposity and fatty liver markers. The abstract reports that raspberry ketone increased “norepinephrine-induced lipolysis” (basically fat burning), but this was only when raspberry ketone was applied to cells in a petri dish, and was not tested when given to live animals.
In an attempt to determine why raspberry ketone had the above effects in mice, a subsequent Korean study published in 2010 (3) studied IN VITRO (i.e., petri dishes) application of raspberry ketone. When applied as a solution to fat cells, raspberry ketone increased fat burning (lipolysis) and reduced fat accumulation; expression and secretion of adiponectin also increased. Adiponectin is a hormone secreted by fat cells that is involved in glucose metabolism and fat breakdown. While higher circulating adiponectin levels have been linked to reduced risk of obesity and diabetes (4), just because secretion in cell cultures increased, this does not necessarily translate to higher circulating levels in humans.
So, this is what the supplement “evidence” is based on – one study in cells, another in mice. Not terribly convincing. Begs the question: if this is such a “miracle” supplement, why is it not being studied more? Well, red raspberry / raspberry ketone antioxidant capacity and proposed anti-inflammatory properties have been studied, but again only in cell culture and animal models, not people.
Interestingly, the raspberry ketone given to mice in the Japanese study (2) made up 1 – 2% of total calories; for a person consuming 2,000 calories, this would work out to 4 – 8 g of raspberry ketone per day (based on ketones providing ~ 5 kcal/g)! That’s an awful lot more than the 100 mg capsules taken twice daily as advised by the supplement company. Not that we are endorsing taking more: if the company is basing efficacy on two studies, you would think the dosage would have something to do with the research though!
No Baloney’s advice. Save your money and avoid being swept up in the hype! File this one under the here-today-gone-tomorrow never-ending line of Magic Bullet weight loss supplements. Remember, a manufacturer does not have to PROVE any effectiveness before marketing a supplement, so it’s buyer beware.
- Beekwilder J, Hall RD, de Vos CH. Identification and dietary relevance of antioxidants from raspberry.Biofactors 2005; 23:197-205.
Morimoto C, Satoh Y, Hara M, Inoue S, Tsujita T, Okuda H. Anti-obese action of raspberry ketone. Life Sci 2005; 77:194-204.
Park KS. Raspberry ketone increases both lipolysis and fatty acid oxidation in 3T3-L1 adipocytes. Planta Med 2010; 76:1654-8.
Li S, Shin HJ, Ding EL, van Dam RM. Adiponectin levels and risk of type 2 diabetes: a systematic review and meta-analysis. J Amer Med Assoc 2009; 302:179-88.