Milk minerals and the metabolic syndrome

The prevalence of the metabolic syndrome or single components of it has dramatically risen across continents in the recent past and shows a tendency to increase in the future. The increase of these metabolic disorders was accompanied by dramatic changes in people's lifestyles, mainly less physical activity and a change in dietary habits. The consumption of fast food, convenience food and soft drinks increased, while a decline in the consumption of milk and milk products occurred. Most epidemiological studies have demonstrated a negative association between calcium and dairy consumption, and the prevalence of components of the metabolic syndrome. Diets rich in calcium or dairy products facilitated weight loss and fat loss in obese subjects or rodents and reduced weight and the regaining of fat in rodents during re-feeding after dieting. A more pronounced effect was seen if calcium was derived from dairy products. From animal and cell culture experiments a mechanism was proposed that is based mainly on dietary calcium-stimulated reduction of circulating calcitriol levels, which consequently results in a lower influx of calcium into adipocytes, leading to a metabolic state that favors catabolic over anabolic pathways. Moreover, the direct effect of calcitriol on autocrine cortisol synthesis may contribute to the weight-regulating effect of calcium. Overall, human and animal experiments have shown that dietary calcium has a slight but significantly beneficial effect on blood pressure. This was more pronounced if the calcium intake was based on milk products, which may be due to the high magnesium and potassium, and low sodium content, and to angiotensin converting enzyme-inhibiting peptides in milk products. The threshold for the minimum calcium requirement with respect to weight regulation is considered to be 800–1000 mg per day. More controlled intervention studies are needed to confirm the findings and support this hypothesis. The diversity of results indicates a complex rather than a simplistic model.