Homogenized bovine milk xanthine oxidase: a critique of the hypothesis relating to plasmalogen depletion and cardiovascular disease
A hypothesis has repeatedly been promoted that xanthine oxidase from homogenized bovine milk is absorbed intact, damaging cardiovascular tissue by depleting plasmalogens and initiating atherosclerotic changes that culminate in heart disease. In the light of recent experimental evidence, the present paper examines the validity of this hypothesis and associated claims. The evidence leads to the conclusion that 1) absorption of dietary xanthine oxidase has not been demonstrated: 2) a relationship between intakes of homogenized milk and levels of serum xanthine oxidase activity have not been established; 3) a direct role for xanthine oxidase in plasmalogen depletion has not been established: 4) neither liposome formation during homogenization of milk nor absorption of intact liposomes from the gastrointestinal tract has been demonstrated: and 5) data are lacking to support the claim that large doses of folic acid inhibit xanthine oxidase in vivo and/or are therapeutic in heart disease. Experimental evidence has failed to substantiate, and in many cases has refuted, the xanthine oxidase/plasmalogen depletion hypothesis.
American Journal of Clinical Nutrition, Vol. 38, August 1983, 327-332.