A Natural Cure for Obesity and Insulin Resistance!? Promising Results from Animal Experiments with Bitter Melon Bioactives

In a very recent investigation, researchers from the Pennington Biomedical Research Center (Wang. 2011) found that high-fat diet fed mice gained less weight and had less compromised insulin response, if they received an (unfortunately) unspecified amount of an aquaeus extract from bitter melon:

Body weight, plasma glucose, insulin, leptin levels and HOMA-IR values were significantly lower in the BM-fed HFD group when compared to the HFD group. BM supplementation significantly increased IRS-2, IR β, PI 3K and GLUT4 protein abundance in skeletal muscle, as well as phosphorylation of IRS-1, Akt1 and Akt2 when compared with HFD (P<.05 and P<.01). BM also significantly reduced muscle lipid content in the HFD mice. BM extract greatly increased glucose uptake and enhanced insulin signaling in L6 myotubes. 

There is however two major caveat to these findings. Firstly, mice ain't a particularly good model for predictions concerning the effect of supplements that are added to a high fat diet. And secondly, even if we would see similar results in human beings, the most obvious conclusion one MUST (but obviously nobody does) draw from the results of this study is that without supplementation the low fat diet, i.e. the group of mice that consumed a diet that is appropriate to their genetic make-up, gained the least amount of weight, had the lowest leptin levels and the best insulin sensitivity.

Figure 1: Insulin levels of the mice on a low fat diet (LFD), a high fat diet (HFD) and a high fat diet supplemented with bitter melon extract (BM)

Does this tell you that you should revert to a low fat diet? No, at least not if you ain't a mouse. What it should tell you, however, is that revamping your diet, making correct food choices and eating according to what our bodies are made for is the key to health and long jeopardy - the "natural cure for obesity and insulin resistance", it's already out there. Don't even think about dietary supplements before you've got that in check...

Resveratrol Increases Lipolysis and Reduces Lipogenesis in Mature Adipocytes

If you are (as I hope) an avid reader and daily visitor of the SuppVersity, you probably remember Friday's news on the "Side Effects of Polyphenol Supplementation". I just hope you did not throw away all your supplements immediately, because eventually the question of side effects is always relative. If, for example, you are a sumo competitor and in dire need of gaining mass, no matter what. It would be an unwelcome side-effect of resveratrol supplementation not to gain or even to lose body fat...

A report (Baile. 2011), recently published in the Annals of the New York Academy of Sciences does now confirm, what supplement companies have been promising all along: the right dose of supplemental resveratrol will limit fat gain and improve lipolysis in a mouse model:

Treatment of mice with resveratrol alone was shown to improve resistance to weight gain caused by a high-fat diet. Moreover, dietary supplementation of aged ovariectomized rats with a combination of resveratrol and vitamin D, quercetin, and genistein not only decreased weight gain but also inhibited bone loss.

The human equivalent dose to that used in the cited study would be about 35mg/kg (= 2.800mg for a 80kg human being), which, unfortunately, is much more than your average resveratrol product contains. So, what does this tell you? Either you spend a fortune for minor improvements in your resistance to an unhealthy diet OR you just consume a healthy diet in the first place - I bet you will end up leaner and healthier using the second option.

Unexpected Side Effects of Flavonoid Supplementation: Do You have to Re-Evaluate the Use of EGCG, Grape Seed Extract & Co?

It is pretty exciting to see how scientists find new beneficial constituents in common foods on a daily basis. A group of these phytoprotectants is called "flavonoids". Respective extracts from grapes, green tea, etc. have been shown to exhibit various health benefits and supplement companies make a fortune selling them to health-conscious costumers. The question however remains: Did nature really intend us to consume these trace nutrients in such significant amounts?

Table 1: Potential beneficial and adverse effect of flavonoid supplements. (Egert. 2011)

Scientists from the Department of Nutrition and Food Science of the University in Bonn, Germany (Egert. 2011), have now taken a closer look at possible side-effects of a selection of these phytoprotectants. Among the possible interaction and health concerns the scientists have found were

• Flavonoid - trace element interactions - reduced the uptake of iron (and possible other trace elements)
• Flavonoid - vitamin interactions - folate, vitamin E and vitamin C absorption may be inhibited
• Flavonoid - thyroid interactions - increased risk of goiter and higher incidence of various forms of thyroid related illnesses

Last but not least, there are the effects on the cytochrome P450 pathway (hormonal interactions), possible interferences with specific medications and interactions with liver detoxification pathways (phase II enzymes in particular).

All this does not mean, that you should generally shy away from these nutrients. It shall only remind you of the fact that isolated in-vitro studies on certain beneficial effects of certain plant / fruit / legume extracts may not be enough to decide whether its worth risking unwanted side effects of inadequately researched "wonder supplements". Maybe, trying to get a diversified menu of flavonoids from a healthy and varied diet (yes, I am thinking of those of you who live on chicken breasts and broccoli), would be a viable alternative!?

B-Vitamins & Diabetes: Protective or Causative?

In a very interesting study, scientists from China and Japan (Zhou. 2010) found that "long-term exposure to high level of the B vitamins may be involved in the increased prevalence of obesity and diabetes in the US in the past 50 years". At first this appears to be counterintuitive, since we have been told over and over that B-Vitamins are not only good for our health, but that we could not even "overdose" them. While the latter has been questioned for years and certainly is not the case for e.g. B6 and niacin, even the former seems questionable, if you read the results from the above mentioned study:

The prevalences of diabetes and adult obesity were highly correlated with per capita consumption of niacin, thiamin and riboflavin with a 26- and 10-year lag, respectively (R2 = 0.952, 0.917 and 0.83 for diabetes, respectively, and R2  = 0.964, 0.975 and 0.935 for obesity, respectively). [...] The relationships between the diabetes or obesity prevalence and per capita niacin consumption were´similar both in different age groups and in male and female populations. The prevalence of adult obesity and diabetes was highly correlated with the grain contribution to niacin (R2 = 0.925 and  0.901, respectively), with a 10- and 26-year lag, respectively.

These results (especially those referring to the detrimental effect of niacin) confirm test-tube studies conducted by a group of scientists from South Korea earlier this year (Choi. 2010), who found that

NA [nicotinic acid] alters gene expression in insulin-sensitive tissues by various mechanisms. Some of the NA-induced changes in gene expression are discussed as potential mechanisms underlying wanted and unwanted effects of NA treatment.

Just anecdotal: My personal perspective on B-vitamins has changed since my overall energy and well being, as well as my physique have largely improved after stopping to take those B-vitamin (over-)loaden mulit-vitamin preparations like Now ADAM, CL Orange Triad, Animal Pak, ON Opti-Men etc. But remember: it is mere speculation that this could in fact be related to their high B-vitamin contents - could be any other constituent, as well.

Vitamin D & Insulin: A Question of Race?

Could it be that vitamin D intake is more important for people with an African American (AA) background than for their European American (EA) neighbors? This is exactly, what a study that was recently published in Nutrition&Metabolism (Alvarez. 2010) seems to suggest.

In 115 African American (AA) and 137 European American (EA) healthy, premenopausal women the scientists  determined with 4-day food records and assessed the individual insulin sensitivity indexes (SI), as well as the Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) values. The results are quite unequivocal:

Vitamin D intake was positively associated with SI (standardized β = 0.18, P = 0.05) and inversely associated with HOMA-IR (standardized β = -0.26, P = 0.007) in AA, and the relationships were independent of age, total body fat, energy intake, and % kcal from fat. Vitamin D intake was not significantly associated with indices of insulin sensitivity/resistance in EA (standardized β = 0.03, P = 0.74 and standardized β = 0.02, P = 0.85 for SI
and HOMA-IR, respectively). Similar to vitamin D, dietary calcium was associated with SI
and HOMA-IR among AA but not EA.

While the scientists refrain from premature speculation about the underlying reasons of the observed discrepancy, they highlight the importance of both, adequate vitamin D, as well as dietary calcium consumption for premenopausal women of African American descent. What I consider noteworthy is the fact that the mean vitamin D intake of both groups was way beyond even the currently suggested 400IU (most experts already suggest 1.000-2.000 IU per day). With a mean vitamin D intake of 111.5IU and 133.7IU per day. All subjects carry the risk of being "vitamin D deficient" and this is where increased intake may produce significant positive effects on various health marker (cf. More on Vitamin D).