Part 2 of my critical examination of the scientific evidence behind the ‘miracles’ that Dr. Oz promotes. Don’t miss Part 1! Today I will examine Raspberry Ketones and Green Bean Coffee Extract.
Dr. Oz Recommendations:
Dr. Oz claims this supplement is a ‘miracle in a bottle to burn fat’. Raspberry ketone is the primary aroma compound of red raspberries. This compound regulates adiponectin, a protein used by the body to regulate metabolism. Raspberry ketone causes the fat within your cells to get broken up more effectively, helping your body burn fat faster. The recommended dose is 100mg per day.
Caution: Although it’s marketed as a natural compound, much of the raspberry ketone products on the market are made synthetically. Raspberry ketone occurs naturally in only very small amounts, so companies produce it in a lab.
Let’s look at the research:
- The majority of the research has been based on mice or conducted in test tubes (Parks, 2010; Wang, Xianjun, Yan & Wei, 2011;Wang, Meng &Zhang, 2012). There has been one human study to date
- It should be noted that in the mice studies, the animals were fed high doses of raspberry ketone – about 2 per cent of their body weight. That would translate to far more than a human would be likely to consume on a daily basis for a prolonged period.
- The human study (Lopez, 2013) was only 2 months in length and it used a ‘multi-ingredient’ weight loss product containing raspberry ketone, caffeine, capsaicin, garlic, ginger and Citrus aurantium, in addition to a calorie restricted diet and exercise training. Although there was a very small changes in body weight in the supplemental group, no biochemical changes or body fat changes were found in the supplemental group. The big problem with this study: how can we conclude the results were due to Raspberry Ketones??
It should also be noted that raspberry ketone appears to act on the body by driving stress hormones, which is not a good thing. Raspberry ketones are structually similar to the stimulant synephrine, which can lead to problems such as increased heart rate. In the U.S, there have been reports of heart palpations from people consuming raspberry ketones.
Bottom Line: The research thus far is not strong enough to demonstrate raspberry ketones have a beneficial effect on human health and weight loss. Safety concerns should also be noted. More human trials are needed before I would consider recommending raspberry ketones for weight loss.
Green Bean Coffee Extract
Dr. Oz Recommendations:
Green coffee beans are simply beans that haven’t been roasted. Green coffee beans contain chlorogenic acids, which in vitro studies have shown, can alter glucose uptake after meals. This is why Dr. Oz claims it to be ‘the miracle fat burner!” When coffee beans are roasted, most of the chlorogenic acid is lost. Dr. Oz recommends 800 mg of Pure Green Coffee Bean Extract twice per day.
What makes chlorogenic acid effective for weight loss and weight management remains unclear. The current hypothesis suggests that the alteration of intestinal glucose uptake (likely via the inhibition of hepatic glucose-6-phosphatase) affects glucose absorption and can decrease caloric input from carbohydrate consumption.
Let’s look at the research:
- A 2011 meta-analysis looked at 3 studies that revealed a decrease of almost 5 lbs in body weight for individuals who received green coffee bean extract compared with placebo (a moderate effect). The study authors, however, remained cautious regarding the extract’s potential as a weight-loss supplement, noting major methodological limitations (short duration, small sample size and heterogeneous) in the clinical trials done to date
- Since the meta-analysis published in 2011, additional studies have reported success with green coffee bean extract as a weight-loss aid.
However, this results should not be taken a face value, as they require some critical analysis. For example, for the study published in the journal Diabetes, Metabolic Syndrome and Obesity – it should be noted that study participants also lost weight during the placebo phase of the trial, which suggests green coffee bean extract was not responsible for their weight loss. Participants may have felt encouraged to slim down because their weight and diet were monitored as part of the study. It should also be noted that one of the clinical trials was associated (at least loosely) with a pharmaceutical company that markets the extract as a weight-loss product.
Although it would seem that studies reveal that there is potential for green bean coffee extract to work as a weight-loss aid, the evidence is weak and minimal. Clinical studies continue to be tied to industry funding as well as include small sample sizes, short duration exposure, and varying types and dosages of the extract. The current evidence regarding its safety or efficacy isn’t strong enough to recommend its use as a weight-loss aid.
Before conclude, I wanted to point out the profits that the nutraceutical industry is reaping from these promoted products. At the end of 2014, the nutraceutical industry is projected to bring in more than $350 billion, in part because of the sale of products such as green coffee bean extract. It should also be noted that dietary supplements and weight-loss aids aren’t subject to the same rigorous standards as prescription drugs.
Why would we choose to spend such big dollars on a supplement with minimal promising research behind it, as a way to slim the waistline and maintain metabolic health? Have we completely ruled out working on changing dietary behavior or physical activity?
“Usually when studies break the physical laws of the universe, there’s usually something wrong with the study itself.”
-Dr. Yoni Freedhoff, medical director of Ottawa’s Bariatric Medical Institute