Raspberry Ketones: Hype or Hope as a Weight Loss Supplement

September 10, 2012 By

For those involved in the natural health products (NHP) industry there is a new compound of interest known as raspberry ketones, that is gathering a great deal of attention as a weight loss supplement. When a Google search with the search terms “raspberry ketones” is conducted, the first link to appear is “Raspberry Ketone: Fat-Burner in a Bottle | The Dr. Oz Show”. Yes – the Dr. Oz episode explains why we have received several inquiries at dicentra regarding the possibility of obtaining product licenses for NHPs containing raspberry ketones.

But what are raspberry ketones? Raspberry ketone (RK) is 4-(4-hydroxyphenyl) butan-2-one1, derived from raspberries as well as Rheum officinale, a traditional Chinese medicinal plant. Raspberry ketone was given a generally regarded as safe (GRAS) status in 1965 by the Federal Emergency Management Agency (FEMA) and is used in perfumery, cosmetics, and as a flavouring agent2. It may be included as a non-medicinal ingredient for use in Canadian NHPs for the purpose of “Flavour Enhancer”3.

The reality is that RK is not gaining fame for its use in the cosmetics, perfume, and food industry or for its use in NHPs as a flavor enhancer. RK is currently a topic of interest because it is marketed for weight loss in humans for its ability to stimulate the metabolism of white adipose tissue via an increase in lipolysis (fat breakdown) and thermogenesis (heat generation) in brown adipose tissue, while inhibiting the absorption of dietary fat in the intestines3.

The 2005 Morimoto study was conducted on mice fed a high-fat diet and was shown to decrease and prevent diet-induced elevations in body weight and fat around the organs – which is exactly the kind of fat that you do not want. RK has also demonstrated an increase in the breakdown of fat cells1. For good reason, the Morimoto study pulls huge weight in the industry due to the epidemic of obesity in the Western world and the marketability of anti-obesity agents. However, it is not scientifically sound to extrapolate the conditions and results of animal data to conclusions in humans, and this is completely reasonable to any balanced, unbiased evaluation. Why? One of the greatest disasters in drug safety evaluation comes to mind: the story of thalidomide. Thalidomide was deemed to be safe in rodent testing, but led to approximately 5000-12,000 birth deformities and an unknown number of abortions in humans in 46 countries in the 1960’s4. This is not to say that RKs are extremely dangerous or teratogenic, it merely drives home the point: it is not possible to extrapolate pre-clinical evidence to human subjects.

So, given the popularity of this ingredient it is very surprising that there is a complete dearth of corroborative studies or clinical trials in humans. In fact, a search of ClinicalTrials.gov with the search terms “raspberry ketone” or “raspberry ketones” provides zero results. That’s right – there is not one clinical trial available in the public domain.

This absolute lack of human clinical data is why it is very difficult to get an NHP license in Canada for products that contain RK as a medicinal ingredient. The preclinical (animal) data are encouraging, and the effects observed in mice may possibly be confirmed in humans in future studies. However, as long as there are no RK human clinical trials completed, Health Canada will not be able to approve the safety, let alone the efficacy, of RK for any medicinal use.

Due to the potential benefit to consumers and manufacturers, hopefully there will be some high quality clinical trials in humans in the near future that will conclusively prove that RK is effective in the treatment of obesity. Until then, you won’t see too many Canadian NHP licenses including 4-(4-hydroxyphenyl) butan-2-one (RK) in the list of medicinal ingredients.



  1. Morimoto C, Satoh Y, Hara M, Inoue S, Tsujita T, Okuda H. Anti-obese action of raspberry ketone. J Life Sci. 2005;77(2):194-204.
  2. Lin CH, Ding HY, Kuo SY, Chin LW, Wu JY, Chang TS. Evaluation of in Vitro and in Vivo Depigmenting Activity of Raspberry Ketone from Rheum officinale. Int J Mol Sci. 2011;12(8):4819-35. Epub 2011 Jul 28.
  3. NHPD Ingredient Database: Raspberry ketone. Modified August 27, 2012. Available: http://webprod.hc-sc.gc.ca/nhpid-bdipsn/ingredReq.do?id=1767&lang=eng. Accessed: August 29, 2012.
  4. Teo SK, Evans MG, Brockman MJ, Ehrhart J, Morgan JM, Stirling DI, Thomas SD. Safety profile of thalidomide after 53 weeks of oral administration in beagle dogs. Toxicol Sci. 2001 Jan;59(1):160-8.

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