Warding Off Holiday Weight Gain 2.0: The Anti-Diabesity Effect of Coffee Goes Beyond its Caffeine Content.

Image 1: If they are not laden with pesticides and anti-fungals, the small brown beans from the coffee pant can easily compete with green, black oolong and pu-erh teas, when it comes to countering the unwanted side-effects of the "holiday diet"

Back in the days, both, tea and coffee were luxury goods and people felt privileged if they could have any of them. Today, they have become another of the endless commodities of our convenience society, where coffee, the former drink of the kings (and popes), has gotten a bad rep lately as being the underlying cause of the "adrenal burnout" that has befallen 90% of the visitors of pertinent Internet bulletin boards. I was thusly not surprised that SuppVersity student Fat Free commented yesterday's blogpost on the anti-obesity effects of tea rather sheepishly. As if his wish for "a coffee" on the list of the anti-holiday-weight-gain items was some atrocious act in the sense that "a coffee" could never be as healthy as a hip green tea. I mean wasn't it bad enough that the "holy" green tea was outperformed by its primitive black brother?

Well, guess what, dear green tea connoisseurs, it may well be that (organic) coffee beans are in no way inferior to the unquestionably healthy, yet recently slightly over-hyped unoxidized camellia sinensis leaves. At least this is what a soon to be published study by Yuji Matsuda and his colleagues from the Nagoja University in Japan would suggest (Matsuda. 2011).

Tea or coffee during the holiday season - only a matter taste?

Matsuda et al. put a group of 8-week old mice on a pro-diabetic high-fat diet (this is the type of "high fat diet" that is high both in fat and in carbs and thusly is a perfect image of what 75% of the people are "eating" in the holiday season ;-). In the course of the 17-week study period the mice received either regular drinking water, or 2.5x diluted coffee, or water that was laced with 200mg of caffeine per liter (with a water intake of 13-14g/100g BW this would translate to a daily dose of 2.8mg/100mg and a human equivalent of 2.3mg/kg, or 182mg of caffeine per day for an 80kg human being). The intention was to investigate whether the results of epidemiological studies by van Dam (2002; 2005), Huxley (2009) and Goto (2011), which suggest that regular coffee consumption is associated with a profoundly reduced risk of developing metabolic syndrome or type II diabetes, could be replicated in a laboratory setting.

Figure 1: Body weight at the beginning and end of the study period in the control group and the mice receiving 2.5x dilluted coffee or 200mg/L caffeine in their drinking water; food intake in g per 100g of  body weight (data adapted from Matsuda. 2011).

If you look at the weight changes of the animals in figure 1, it becomes evident that despite a (non significantly) greater food intake esp. in the "real coffee" group, the mice on the coffee or caffeine supplemented high-fat diets gained approx. 8% less body weight than their water guzzling peers.

Figure 2: Fat weight in mice after 17 weeks on high fat diet with either water, 2.5x diluted coffee or water + 200mg caffeine per L (data adapted from Matsuda. 2011).

Now while the intrinsically flawed concept of a "body mass index" that is still propagated by mainstream media would suggest that there is something like an "ideal body weight", the numbers on your scale, alone, have no predictive value in terms of future health risk. The reductions in visceral (epididymal fat) and subcatenous fat accumulation in the mice of the coffee and caffeine arm is thusly a considerably more important finding of this study than the slightly reduced weight gain. After all, the amount of visceral (=inter-organ) fat you are carrying around is one of the few relatively reliable indicators of whether you are going to see your grand-children graduate, or not.

Time and again: Whole foods, or drinks, outperform extracts

If you take a closer look you will notice that despite a general tendency towards lower body fat levels in the coffee and caffeine group, the "whole food", or I should say, "whole beverage" has a much more pronounced effect on the "bad" visceral (epididymal) fat depots. So, just in case you still like your pills, caps and powders: This is only the latest in a long line of foods (this is the stuff that is not sold in caps or powder form) with verified health benefits, where one isolated compound, of which we believe that it is the "active ingredient" turns less potent than the whole food - so, could it possibly be that Nature knows best?

Figure 3: Reductions in inflammatory cytokine (MCP-1, TNF-alpha, IL-6) and adipokine expression in the epididymal fat pads of mice receiving 2.5x diluted coffee or water laced with 200mg/L caffeine in addition to their high fat diet (data calculated based on Matsuda. 2011).

The "whole foods" vs. "extract" difference is also evident in the differential effects coffee and caffeine had the expression of the inflammatory cytokines MCP-1, TNF-Alpha and IL-6 and the adipokines adiponectin and leptin. With a more pronounced expression of the latter (leptin) and an almost identical expression of the former (adiponectin) indicating an improved visceral fat metabolism in the epididymal fat pads of the "coffee-drinking" mice.

Figure 4: Insulin response (area under the curve in mg * min / dl) during glucose tolerance at different time-points during the 17-week study period (data calculated based on Matsuda. 2011).

As the areas under the insulin response curve in the glucose tolerance test go to show. Coffee (=whole food!) consumption does also reduce the transient caffeine induced decrease in insulin sensitivity that has been touted as one of the reasons why coffee would be "bad" for you. As the data from the study goes to show, this effect is only temporary, even for plain caffeine and should not be an issue for the habitual coffee drinker. Moreover, the long term benefits totally outweigh any short term increases in fasting blood glucose (approx. +8% in the first weeks of the study) - or, getting back to the initial research hypothesis: Coffee consumption is a possible way to reduce the risk of developing type II diabetes (at least  for mice ;-)

Coffee or tea? The choice is up to thee!

Since a direct comparison of the data from yesterday's tea study on teas would not be valid, anyways, and because I do not want to disturb the pre-Chrismas harmony and provoke a war between coffee and tea drinkers in the comment area of this blogpost, I would just advice everyone to just decline the soda your relatives may be offering you over the holidays and stick to either tea or coffee... whatever you like better - and by the way, dehydration is neither an issue for the habitual tea nor the habitual coffee drinker (Grandjean. 2000)!