The self-proclaimed weight loss “experts” are at it again touting the latest fashionable supplement du jour. Raspberry ketones (RK) derived – not so surprisingly – from raspberries purportedly help you lose that extra fat once and for all. Suppliers can’t keep up with the demand since television health evangelist Dr. Oz and supplement-spruiking side-kick Lisa Lynn gave the product the green light to millions of viewers earlier this year.
Sounds like a simple solution to a complex problem, but is it really that easy? Are raspberry ketones really a “miracle in a bottle” or are such claims treading on thin ice? In this article, I explore the other side of the marketing hype and dig deep into the science and facts surrounding raspberry ketones.
What are raspberry ketones?
Raspberry ketone, also known as rheosmin is a natural phenolic compound most active in mature red raspberries (rubus idaeus) responsible for their distinctive aroma. It is also an additive used in perfumes, shampoos, cosmetics and the food industry, plus we’ve been consuming it in REAL raspberries for hundreds of years.
Raspberry ketones are produced naturally in the raspberry fruit via a process called biosynthesis. The natural quantity of RK found in raspberries is very low. However, advances in food technology have enabled the compound to be produced synthetically thus making it more commercially abundant.
How do raspberry ketones work and what are the claims?
Respected cardiothoracic surgeon and professor, Dr. Mehmet Oz first made it big on the Oprah Winfrey show but has since swapped his scrubs for a shiny suit and now saturates his popular TV show with fad diets, gimmicks, and supplements “guaranteed” to be your next weight loss solution. No surprise then that raspberry ketones were given a grandiose reception on a recent show. Dr. Oz unraveled the wonder of Raspberry Ketones with guest and personal trainer Lisa Lynn.
Who is Lisa Lynn anyway?
Before we go on, who is Lisa Lynn anyway and is she qualified to speak on nutrition? Her website lists certifications through the International Sports and Sciences Association (ISSA), but there is no mention of any university degrees or coursework in the nutritional sciences (i.e., nutritional biochemistry, physiology, etc). Moreover, there appears to be a conflict of interest because her “recommendations” for raspberry ketones on Dr. Oz’s show appear to serve her website supplement sales agenda.
A colleague of mine, Joe Cannon, MS, CSCS has also authored a raspberry ketones article and provides more information on Lisa Lynn.
Dr Oz and nutrition advice: “Trust me, I’m a doctor”
It is noteworthy to point out that when a doctor discredits a popular diet or supplement, the main criticism leveled at the dissenter is that doctors receive minimal university nutrition training. However, if a doctor says a supplement is the latest greatest, then people immediately run out to the shops and sweep the product off the shelves. While Dr. Oz is clearly an intelligent person, he should have done his homework on raspberry ketones before lending his increasingly-dwindling reputation to this product.
CLAIM: Raspberry ketones promote weight loss through their fat-burning properties
Raspberry ketones appear to have a similar chemical structure to capsaicin and synephrine which may have a mild fat-mobilizing effect. This potential weight-loss link prompted the current research which is now being used as “support” for the over-the-top marketing claims for RK. Unfortunately, this is a common theme in the supplement world with previous substances like pyruvate, caralluma fimbriata, and liproxenol being sold with less than adequate scientific evidence.
CLAIM: Raspberry ketones stimulate the release of adiponectin from fat cells
Adiponectin is a hormone exclusively released by fat cells in adipose tissue and plays an important role in glucose regulation and fat metabolism. It has anti-inflammatory benefits and reduced adiponectin levels are associated with obesity, diabetes, and increased cardiovascular risk. (More on the role of adiponectin in human disease here).
While it is true that adiponectin has the above protective properties, there is insufficient scientific evidence that raspberry ketones exert a favorable effect on this hormone. More on this below.
CLAIM: “Raspberry ketone can help in your weight loss efforts, especially when paired with regular exercise and a well-balanced diet of healthy and whole foods.” (doctoroz.com)
As of this writing, there is no objective scientific evidence that raspberry ketones contribute to weight loss in humans (see below).
The second half of this claim is probably the best advice you could receive. It is more likely that any associated weight loss would stem from the inclusion of a balanced diet and regular exercise, particularly if you are increasing your energy expenditure above and beyond what you were previously doing. Unfortunately, most people miss the fine print and end up attributing their hard work and results to raspberry ketones alone – the effects of which are yet to be determined in humans.
Raspberry ketones research
When Dr. Oz asked Lisa Lynn “How did you find it and why do you think it’s so valuable?” she replied, “research, research, research!” That might be enough to make most viewers to switch off their boloney detectors, but to which research is she referring? As I start to uncover the missing pieces to the puzzle, it is absolutely clear that MORE research needs to be done.
What “they” don’t want you to know about raspberry ketones
As of this writing, there is no evidence that raspberry ketones effectively reduce body fat and improve fat metabolism in human beings. No studies have been conducted involving humans ingesting an oral form of raspberry ketone. We have no information about the short or long-term effects of using raspberry ketones as a dietary supplement, which involves much higher dosages than that used in other industrial applications.
What? Only two raspberry ketone studies?
The evidence is limited to only two preliminary studies involving mice, test tubes and cell cultures:
A 2005 Japanese study investigated the effects of raspberry ketones on obese male mice fed a high fat diet. They wanted to see if: 1) raspberry ketones could prevent obesity; and 2) reduce overall body fat and fat stores around the organs (called visceral fat). The experimental and placebo groups each contained only six (6) mice. The PREVENTION Groups were either fed a normal laboratory diet, a high fat diet (approx. 40% of total calories), or a high fat diet plus raspberry ketone (0.5% – 2%) for 10 weeks. The WEIGHT LOSS groups were fed the same high fat diet for 6 weeks and then high fat plus raspberry ketone (1%) for 5 weeks.
Results from this study demonstrated that the addition of raspberry ketone helped reduce body weight and liver fat stores. A secondary response was that the combination of raspberry ketones with the action of norepinephrine proved better at drawing fat from cells than norepinephrine alone.
To the untrained observer, these results might seemingly warrant a victory lap, but they must be interpreted and put into context for them to be meaningful in a practical sense.
- This is a rodent study. These effects have not been tested or observed in human beings.
- The study used male mice only. It is not known if there is a gender effect, as this was not tested in female mice.
- There were only 6 mice in each group (experimental and placebo). Such a low number may detract from the strength of the statistical calculations. It is necessary to see human studies with a large number of subjects. This would increase the statistical integrity of the study and make it more relevant to dieters.
- These studies were carried out in controlled conditions using rodents. However, if implemented in free-living humans, there is much more opportunity for variations in diet, activity, and overall adherence to the study protocol which would affect the results. Thus, human studies are much more cumbersome (though they must still be conducted).
- Because only two small studies have been conducted, there is no evidence supporting the long-term use of raspberry ketones in humans nor on the effects of different calorie intakes.
This 2010 Korean study investigated the possible mechanism for the anti-obesity action of raspberry ketones. It demonstrated that by stimulating lipolysis, fatty acid oxidation, and adiponectin secretion, raspberry ketones suppress fat accumulation and improve fat metabolism. So the effects of raspberry ketones on these processes were determined but the underlying mechanisms were not confirmed. Unfortunately this study was only conducted in controlled conditions in test tubes and with cell cultures. We may see a different response in humans considering the numerous other factors affecting our accumulation of body fat and taking into account individual differences (Park, K.S., 2010).
An Australian study looked at how adiponectin levels can be affected by exercise in humans. It concluded that after short-term, moderate intensity exercise adiponectin levels increased by 260%. These changes were apparent after 1 week of 2-3 short bouts of exercise (Kriketos, A.D. et al, 2004).
So for no cost at all, you can get a more effective response just by exercising at the right intensity and duration.
How much do raspberry ketone supplements cost?
Wholesale raspberry ketones are widely available through Asian manufacturers.
- Pure Laboratory Raspberry Ketone (Hazardous): Approximately $5000/kg
- Synthetic Raspberry Ketone Powder: Approximately $10-$50/kg
- Raspberry Ketone Capsules: Wholesale can be as little as $2.50 for one bottle
Raspberry ketone supplements in Australia
Raspberry ketone supplements have made their way down under and can be purchased for around $50.
The mark ups are huge and you can see why they are so commercially attractive.
The last word on raspberry ketones
Unfortunately raspberry ketones are not the amazing miracle supplement they’re claimed to be. The extrapolated evidence is only speculation and the exact mechanisms for raspberry ketone weight loss are not completely understood and, as of this writing, there is limited independent science to substantiate marketing claims.
The obesity epidemic didn’t happen because of a worldwide raspberry ketone shortage so direct your time, money and energy towards a nutritious diet (low in processed foods) and improving unproductive habits. Support this with evidenced-based exercise and you’re on the right track!
The age-old adage of eat a healthy, low-calorie, nutrient rich diet and get regular exercise still holds true. There is nothing wrong with taking a dietary supplement, but make sure there is a reasonable body of scientific evidence to support the often overblown marketing claims.
For more specific information, consult a university-trained dietitian or clinical exercise physiologist for reliable information on diet and exercise.
- Morimoto C, Satoh Y, Hara M, Inoue S, Tsujita T, & Okuda H. (2005). Anti-obese action of raspberry ketone. Life Sciences. 77(2), 194-204. http://www.ncbi.nlm.nih.gov/pubmed/15862604
- Park KS. (2010). Raspberry ketone increases both lipolysis and fatty acid oxidation in 3T3-L1 adipocytes. Planta Medica. 76(15), 1654-8. http://www.ncbi.nlm.nih.gov/pubmed?term=red%20raspberry%20adiponectin
- Beekwilder J, van der Meer IM, Sibbesen O, Broekgaarden M, Qvist I, Mikkelsen JD, & Hall RD. (2007). Microbial production of natural raspberry ketone. Biotechnology Journal. 2(10), 1270-9. http://www.ncbi.nlm.nih.gov/pubmed/17722151
- Kriketos AD, Gan SK, Poynten AM, Furler SM, Chisolm DJ, and Campbell LV(2004). Exercise Increases adiponectin levels and insulin sensitivity in humans. Diabetes Care. 27, 629-630.https://www.ncbi.nlm.nih.gov/pubmed/14747265