Beyond nutrients: health effects of the dairy matrix
Hosted by the World Congress on Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (Paris - Palais des Congrès from April 4 to April 7), Pr Arne Astrup* will give a greater insight into the ‘food matrix’ and highlight that the effects of milk and dairy foods on health extends beyond the individual nutrients they contain.Recent scientific advances in nutrition and food sciences allow us to analyse our diet differently. Food is no longer considered simply as the sum of its components, but as a complex physical structure which influences the digestive fate of the nutrients, their metabolic effects and ultimately, their long-term effects on health.
Nutrition recommendations have historically focused on nutrients and are typically constructed to ensure the diet meets requirements for individual nutrients. Translation of nutritional requirements to dietary guidance has typically resulted in advice such as “reduce intake of cholesterol and saturated fat”. However, people consume foods not nutrients, and translation from individual nutrients to foods has proven problematic.
Recent research has shown that saturated fat (SAT) does not exert the adverse effect on cardiovascular disease (CVD) previously thought, and that the various saturated fatty acids exert very different biological effects, which are substantially modified by the food matrix. One example is cheese, which might be expected to increase CVD risk due to high content of SAT and sodium, but studies indicate the opposite, with a reduction in blood pressure, and reduced risk of CVD and particularly of stroke. The evidence for reducing sodium is also challenged, as the lowering of blood pressure achieved by reducing salt intake ismodest, even in hypertensives.
Another example is from two large observational studies from Harvard in which it was found that for each serving of milk per day was associated with a 8% lower risk of hip fracture (RR = 0.92). It is interesting that the effect could not be explained by the intake of calcium, vitamin D and protein from dairy as adjustment for these nutrients did not weaken the association. This observation supports that other nutrients, or interactions within the dairy matrix, are responsible for the effect on skeletal health.
It makes good sense to base dietary guidelines on foods, but these prove impossible to formulate at a global or even a regional level. Genetically, racially, ethically, and culturally different people, living in different geographical areas, eat different foods due to tradition and differences in availability. The nutrient content of any particular food may vary dramatically depending on the composition of the cultivars involved. Some of these differences may have consequences for nutrition guidelines for local populations, for harmonizing guidelines across countries, and for the health maintenance/disease prevention outcomes of the guidelines.
Thus the impact of the food matrix on health complicates the definition of dietary advice.
*Department Nutrition, Exercise and Sports, University of Copenhagen – Denmark.