Dietary supplements containing raspberry ketone (RK) recently experienced a massive surge in popularity following some discussion on the Dr. Oz show which suggested that it is effective for promoting weight loss. In many ways, Dr. Oz’s show probably has some level of influence on supplements that Oprah’s show had on books. I didn’t actually watch the show, but heard from a friend that it was mentioned fairly recently as the supplement of the month.
After Dr. Oz promulgated that raspberry ketone is a fat-burner in a bottle, there was an instant feeding frenzy of consumers who flocked to their local vitamin stores and the Al Gore leaving many products on back order.
What Is Raspberry Ketone?
What is raspberry ketone? Raspberry ketone has been used for years as an additive to perfumes, cosmetics, and even as a food additive to impart a fruity aroma. Yes, it is also found in raspberries. It’s been consumed for hundreds of years in raspberries.
Specifically, it’s a phenolic compound thought to have some antioxidant properties. It’s also noted to have a similar chemical structure to capsaicin and synephrine.
Of note, raspberry leaf from Rubus idaeus has a long tradition in herbal folklore with purported benefits for anything from diarrhea to use in pregnant women during delivery.
Raspberry Ketone Health Benefits
Available Research Studies on Raspberry Ketone
A quick search of PubMed shows that there are currently only 35 published research articles found in a search for the term, “Raspberry Ketone.” What’s more is that out of these 35 published articles, not one of them is a double-blind randomized controlled trial with human subjects ingesting a supplement or some oral form. In fact, there still currently isn’t a single clinical trial of any ilk listed which involves human subjects actually ingesting any form of raspberry ketone.
Out of these 35 published articles, roughly 20 are simply some type of biochemical assay. There are six studies on either melon or fruit flies. Three studies involving either rats or mice have been published while there are just 4 published in vitro studies. There is actually one published study involving humans, but it involved topical application for study promoting hair growth and skin elasticity.
Rubus idaeus Research Studies
If you think that doing a PubMed search for Rubus idaeus is a good idea, I would tend to agree with you. It’s the latin name for raspberry. With this search term, we now get 89 hits in PubMed though only 5 of these studies pertain to any type of health benefits and one of these is a duplicate from the previous search term.
Raspberry Ketone for Reversing Fatty Liver Disease and Insulin Resistance?
The most recently available research study on raspberry ketone was published by researchers in China (Wang et al, 2012). In their study, they found that it was effective for protecting against nonalcoholic steatohepatitis (NASH / fatty liver disease) in a rat model.
In this study, the rats consumed up to 2% of their body weight from raspberry ketone. The researchers suggested that it has a dual effect of liver protection and fat reduction which may be mediated by antioxidant activity, preventing degeneration of fatty liver cells, correcting dyslipidemia, reversal of leptin (like insuin, it’s an adiposity signal) and insulin resistance, and decreased liver inflammation.
Skin Whitening in the Cosmetic Industry?
I can’t say that I completely understand why there’s a market for this, but researchers in Taiwan found that topical application of either 0.2% or 2% RK was effective for skin whitening (in vitro / in vivo in mice and zebrafish, Lin et al, 2011).
Promotes Hair Growth and Skin Elasticity?
Topical application of RK was found to increase hair growth and skin elasticity in a study published by Japanese researchers (Harada et al, 2008). Topical application of .01% RK increased dermal IGF-1 (insulin-like growth factor 1) in their mouse model.
In addition, they found that topical application of .01% RK increased scalp hair growth in 5 of 10 human volunteers with alopecia in their study. Female volunteers also participated. The researchers found that topical application to the cheeks increased their skin elasticity. No observations were made as to whether or not RK promoted facial hair in the 5 women who participated in the study.
Raspberry Ketone Fat Loss
An in vitro study done by a researcher in Korea found that raspberry ketone increased the expression and secretion of adiponectin. Adiponectin is a hormone that regulates metabolism. Higher levels have been found to be inversely associated with body fat percentage. They also found that treatment with RK increased fatty acid oxidation and decreased lipid accumulation in fat cells (click here).
Anti-Obesity Action of Raspberry Ketone
One of the sentinel studies on the potential anti-obesity effects of RK was published by researchers from Japan (Morimoto et al, 2005). In a mouse model, they found a dose-response effect of RK preventing high-fat diet induced elevations in body weight and adipose tissue. Questions that initially come to mind include whether or not RK would be have similar effects without the high-fat diet and, of course, if these results will translate to human models. Dosages of RK ranged from 0.5% to up to 2% of the rodent’s body weight.
Raspberry Ketone Side Effects
Consuming raspberry itself is likely safe for most people with the exception of those who have allergies. Little is known about the safety of raspberry ketone in supplements since there’s a paucity of studies on these products in human populations. No side effects from taking these supplements have been reported to my knowledge.
Raspberry Ketone Dosage
According to Dr. Oz, the recommended dose is 100 mg per day. I’m not really sure how he or his staff arrived at this recommendation since no information is provided in his blog post.
Let’s do the math ourselves. From the latest study by Wang et al , 2012, they used dosages of 0.5, 1, and 2% of the rats body weight.
***If we did a straight conversion based on comparative mass, we would be making a big mistake and our answer would be 300 mg, 600 mg, and 1200 mg per day for a person who weighs 60 kg.
However, if we were to take a more intelligent approach to extrapolating the dosage of RK from a rat model to humans, we might consider using a generally accepted model espoused by Regan-Shaw (2008) which is based upon normalizing for differences in body surface area.
Using this formula, we’re left with 0.81, 1.62, and 3.24 mg/kg for human equivalents of the 3 dosage ranges. As such, our test subject who weights 60 kg, could consider dosages of 50 mg, 100 mg, or 200 mg per day (equivalent to 0.5, 1, and 2% of the rat dosages respectively).
Raspberry Ketone Products
I don’t personally endorse any particular RK product. However, I can offer some suggests IF you’re considering taking one.
- Pick one that actually lists the dosage of raspberry ketone (typically 100mg per pill)
- Avoid products that have “proprietary formula” with a listing of 10 random ingredients along with RK. You won’t actually know how much RK the product contains nevermind if you actually want to take the other ingredients.
- Look for products manufactured in a GMP certified facility.
- Personally, I would prefer a product manufactured in Canada or the US to one made in China etc.
- If you can find one that undergoes reputable third-party testing, then even better.
- Wang L, Meng X, Zhang F. Raspberry ketone protects rats fed high-fat diets against nonalcoholic steatohepatitis. J Med Food. 2012 May;15(5):495-503.
- 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.
- Park KS. Raspberry ketone increases both lipolysis and fatty acid oxidation in 3T3-L1 adipocytes. Planta Med. 2010 Oct;76(15):1654-8. Epub 2010 Apr 27.
- Morimoto C, Satoh Y, Hara M, Inoue S, Tsujita T, Okuda H. Anti-obese action of raspberry ketone. Life Sci. 2005 May 27;77(2):194-204. Epub 2005 Feb 25.
- Harada N, Okajima K, Narimatsu N, Kurihara H, Nakagata N. Effect of topical application of raspberry ketone on dermal production of insulin-like growth factor-I in mice and on hair growth and skin elasticity in humans. Growth Horm IGF Res. 2008 Aug;18(4):335-44. Epub 2008 Mar 5.
- Reagan-Shaw S, Nihal M, Ahmad N. Dose translation from animal to human studies revisited. FASEB J. 2008 Mar;22(3):659-61. Epub 2007 Oct 17.