THE INFLUENCE OF DAIRY-PRODUCTS ON PLASMA URIC-ACID IN WOMEN

Elevated levels of plasma uric acid have been linked to increased risk of cardiovascular diseases and their complications. As dairy proteins have been found to decrease plasma uric acid without increasing glomerular filtration rate, a sample of postmenopausal women living in Montreal was studied to investigate the nature of this relationship. Participants (158 Roman Catholic nuns) were randomly assigned to one of two test diets for a period of four weeks: the dairy foods group (n = 81) consumed approximately 30 grams of dairy protein daily and the dairy-free diet group (n = 77) ate no dairy foods at all. Subjects completed two one-day food records, a core questionnaire and a dairy foods diet history; blood specimens were obtained, and blood pressure, height and weight were measured. Average nutrient intakes differed as a consequence of the test diets, with significantly greater intakes of protein, fat, saturated fat, monounsaturated fat, potassium and calcium (p < 0.01) in the dairy group after the study period, and lower dietary levels of protein, cholesterol, calcium and retinol (p < 0.01) in the dairy-free group. Plasma uric acid was unchanged after the dietary intervention in the dairy group, but increased by 7.8 mu mol/l (p = 0.03) in subjects on the dairy-free diet; however, diastolic blood pressure decreased in response to calcium (beta = -22.9, SE = 10.0, p = 0.02) among those whose diet included dairy foods. The study results suggest that proteins of dairy origin may play a role in stabilising or lowering plasma uric acid, and that calcium or other components found in milk products may also reduce diastolic blood pressure. While these findings have implications for dietary prevention to decrease cardiovascular risk in postmenopausal women, further investigations should examine these mechanisms in men over the age of 50 to ascertain whether a similar response would occur.