[Xanthine oxidase in homogenized cow's milk and Oster's hypothesis: a review]

Oster has postulated that the enzyme xanthine oxidase in homogenized cow's milk is the cause of myocardial infarction and angina pectoris. This enzyme may be absorbed by ingestion, especially of the small particles of the fat globules, and then carried by lymph streams to the arterial vascular system, where it is deposited into the myocardium. Then it destroys the aldehydes liberated from the cell membrane-based plasmalogens. This results in the intimal damage to the cell membranes of the arterial intima and the myocardium and ultimately in the development of typical atherosclerotic lesions in the arteries. The presented review is a critical approach to this hypothesis. The following factors are discussed: - the influence of conditions prevailing in the intestine and the stomach on the activity of the xanthine oxidase in milk, - the possibility of this enzyme being absorbed in the intestine, - the formation of antibodies against absorbed xanthine oxidase and - the behaviour of xanthine oxidase administered intravenously. Compared with present knowledge, this theory gives little evidence only.