Studies demonstrating the health benefits of the Mediterranean diet are accumulating in the scientific literature. Most research has focused specifically on the benefits provided by the antioxidants contained within the diet. However, the diet may have beneficial effects not related to the effects on oxidative stress. For example, researchers1 have investigated the effects of the Mediterranean diet on calcium utilisation in young male subjects (mean age 12.9 years). The study was of a longitudinal design, and involved two study periods, where subject were first fed their normal diet for 3 days, followed by a 28 day period where a Mediterranean style diet was consumed. Measurement of the calcium content of the food, urine and faeces was determined by flame spectrometry and the difference between the two was used to assess calcium absorption and retention.
Comparisons of the normal diet with the Mediterranean diet revealed significant differences in the sources of calcium. However, total calcium intakes were not significantly different between the two. Generally, the calcium provided by meat, eggs and fish did not vary between the diets, but the contribution of cereals, whole grains, legumes, vegetables and fruit was significantly higher in the Mediterranean diet. In both diets, dairy contributed the largest proportion of calcium. When compared to the normal diet, consumption of the Mediterranean diet resulted in a 40% increase in calcium absorption, an 80% increase in calcium retention, and a 40% decrease in calcium excretion. In addition, all the vitamins and minerals measured (thiamine, riboflavin, pyridoxine, cobalamin, vitamin C, vitamin D, vitamin E, folic acid, sodium, potassium, phosphorus, magnesium and iron) increased during consumption of the Mediterranean diet.
These results suggest that the Mediterranean diet may provide health benefits because it increases the absorption and retention of calcium. Analysis of the markers of bone turnover, alkaline phosphatise and urine deoxypyridinoline, showed that this increased retention was likely due to reductions in bone turnover following consumption of the Mediterranean diet. Previous studies have shown that switching to a diet containing more fruits and vegetables, as found in the Mediterranean diet, increases intake of potassium salts which may be beneficial to bone health. Western diets which are high in protein, cause resorption of skeletal minerals, a normal metabolic response to the low pH of the blood caused by such diets. Because plant based diets contain high concentrations of potassium salts that increase the pH of the blood, this resorption of skeletal minerals is reduced and bone turnover rates decrease, allowing increases in skeletal mass.