One of the great controversies in nutrition is the role of coffee and human health. On the one hand, coffee is the primary source of polyphenols in the American diet because of the lack of consumption of fruits and vegetables. On the other hand, coffee is rich in caffeine, an alkaloid that acts as a stimulant on the central nervous system and is known to be an addictive agent (1). In fact, Roland Griffiths, professor of Behavioral Biology at the John Hopkins School of Medicine (and my old college roommate), says, “Caffeine is the world’s most widely used mood-altering drug.” So the question remains is caffeine good for you?
No one knows for sure, but one interesting point has been made that it appears the more coffee you drink, the lower your risk for developing diabetes (2). In fact, if you drink more than four cups of coffee per day, you decrease your risk of diabetes by 50 percent. This new research demonstrates that coffee increases the levels of sex hormone-binding globlin (SHBG) in the blood. As I pointed out in my book “The Anti-Aging Zone,” SHBG plays an important role in sequestering the levels of estrogen and testosterone in the blood so that levels of these unbound sex hormones that can interact with their receptors are tightly regulated (3). Usually as insulin resistance increases, the levels of SHBG decrease in the blood (4). This can lead to an over-stimulation of the receptors by the unbound sex hormones resulting in increased risk for breast and prostate cancer development.
What in the coffee actually causes the increase in SHBG is unknown, but what is known is that once you decaffeinate the coffee, all its benefits on the elevation of SHBG levels and any reduction in risk for diabetes disappear.
It is highly unlikely that caffeine by itself is beneficial for reducing type 2 diabetes, since there were no benefits related to drinking tea or to total daily caffeine intake (2). Perhaps some other compound that was also extracted with the caffeine may play a role in the reduction of type 2 diabetes.
So what really happens when you decaffeinate coffee? First, you soak the beans in water to remove the caffeine and flavors as well as the polyphenols. Then you treat the water with organic solvents (methylene chloride or ethyl acetate) to remove the caffeine (as well as many of the polyphenols and much of the flavor). Then (assuming you have removed all of the organic solvent), you add back the treated water extract to the beans to hopefully reabsorb some of the flavors back into them. Obviously, not all the flavors or polyphenols return since the resulting taste is far less robust than the original coffee bean.
So it seems to me that exploring what else has been extracted in addition to the caffeine may lead to new dietary treatments for diabetes. Whether that will be done is highly unlikely. Instead of waiting for such experiments, you might as well follow the best treatment for preventing diabetes, which is following the anti inflammatory diet for a lifetime. That is how you control cellular inflammation, which is the driving force for development of type 2 diabetes (5,6).
- Juliano LM and Griffiths RR. “A critical review of caffeine withdrawal: empirical validation of symptoms and signs, incidence, severity, and associated features.” Psychopharmacology 176: 1-29 (2004).
- Goto A, Song Y, Chen BH, Manson JE, Buring JE, and Liu S. “Coffee and caffeine consumption in relation to sex hormone-binding globulin and risk of type 2 diabetes in postmenopausal women.” Diabetes 60: 269-275 (2011).
- Sears B. “The Anti-Aging Zone.” Regan Books. New York, NY (1999).
- Akin F, Bastemir M, and Alkis E. “Effect of insulin sensitivity on SHBG levels in premenopausal versus postmenopausal obese women.” Adv Ther 24: 1210-1220 (2007).
- Sears B. “Anti-inflammatory diets for obesity and diabetes.” J Coll Amer Nutr 28: 482S-491S (2009).
- Sears B. “The Anti-Inflammation Zone.” Regan Books. New York, NY (2005).