Food Addiction and Opioid Peptides

It has been suggested that overeating is related to auto-addiction to endogenous opioid peptides. 8 That possibility is supported by the observation that administration of naloxone (an opioid antagonist) prevented stress-induced eating in rats9 and abolished overeating in genetically obese mice.10 In addition, administration of naloxone decreased ad libitum food intake in obese human volunteers. 11

An interaction with the opioid system might explain, above and beyond the purported allergy/addiction syndrome, why so many patients crave wheat or dairy products. Hydrolysis of wheat gluten and alpha-casein (a milk protein) by pepsin has been reported to yield peptides that have opioid activity.12 Since peptides can be absorbed intact into the bloodstream,13 these molecules have the potential to interact with the endogenous opioid system.

Depending on the efficiency with which a person's digestive enzymes breaks down peptides into individual amino acids, and depending on the sensitivity of their endogenous opioid system to exogenous opioid peptides, different people may be more or less susceptible to becoming addicted to wheat or dairy products.

Addiction to refined sugar may also be mediated in part by the opioid system. In rats fed a 10% sucrose solution for 21 days or a 25% glucose solution for 8 days in addition to their usual chow, administration of naloxone caused biochemical imbalances in the brain that resembled the effects of morphine withdrawal. Naloxone did not produce these effects in rats fed chow alone.14

The recognition that the opioid system may contribute to addictive eating does not lead to any particular medical strategy for managing obesity, other than maintaining awareness that wheat, dairy products, and refined sugar may be common triggers for addictive eating. However, patients may benefit psychologically from the knowledge that their "lack of willpower" could have a physical basis. Such knowledge often makes it easier for patients to endure withdrawal symptoms, and to resume healthful eating after periodic lapses.

8. Kather H, Simon B. Opioid peptides and obesity. Lancet 1979;2:905.
9. Morley JE, Levine AS. Stress-induced eating is mediated through endogenous opiates. Science 1980;209:1259-1261.
10. Margules DL, Moisset B, Lewis MJ, et al. Beta-endorphin is associated with overeating in genetically obese mice (ob/ob) and rats (fa/fa). Science 1978;202:988-991.
11. Wolkowitz OM, Doran AR, Cohen MR, et al. Effect of naloxone on food consumption in obesity. N Engl J Med 1985;313:327.
12. Zioudrou C, Streaty RA, Klee WA. Opioid peptides derived from food proteins. The exorphins. J Biol Chem 1979;254:2446-2449.
13. Walker WA, Isselbacher KJ. Uptake and transport of macro-molecules by the intestine. Possible role in clinical disorders. Gastroenterology 1974;67:531-550.
14. Colantuoni C, Rada P, McCarthy J, et al. Evidence that intermittent, excessive sugar intake causes endogenous opioid dependence. Obes Res 2002;10:478-488.

http://www.holisticprimarycare.net/topics/topics-h-n/nutrition-a-lifestyle/1052-nutritional-medicine-a-textbook-by-alan-r-gaby-md

http://www.depsyl.com/

http://back2basicnutrition.com/

http://bionutritionalresearch.olhblogspace.com/