Major scientific advances with dairy foods in nutrition and health

Apparently convincing evidence has been published over the last two decades to show that milk and dairy foods have positive effects on human health, arguably the most authoritative being a review by Dr P.J. Hulh and co-authors in 2006 in the Journal of Dairy Science, Volume 89, pages 1207-1221. The title of the review article is: Major scientific advances with dairy foods in nutrition and health. In the review evidence is presented that calcium and some nutraceuticals in dairy foods reduce the risk of osteoporosis by increasing bone acquisition during growth, by slowing age-related bone loss and by reducing osteoporotic fractures. Furthermore, dairy food consumption assists with lowering of blood pressure in patients with high and normal blood pressure; during programs of energy restriction assists with body weight and fat loss through a calcium-in-dairy mediated mechanism; calcium and vitamin D in dairy foods are positive against colon cancer; and dairy CLA has shown a wide range of anti-carcinogenic benefits in experimental models, being especially consistent in protection against breast cancer.

Despite these results the value of milk and dairy foods in human health continues to be questioned. A question that is often raised is whether it is necessary to obtain the daily calcium requirement from milk and dairy foods as some vegetables contain sufficient amounts and there are potent calcium supplements comparatively cheap on the market. In a review article published in the Journal of Dairy Science in 2011 [Volume 94, Issue 11, pages 5249-5262] Dr A. Caroli and co-authors attempted to answer the question: Is it necessary or at least preferable to obtain the daily calcium requirement from milk and dairy foods? The title of the paper is: Dairy intake and bone health: A viewpoint from the state of the art.

The authors reviewed the complexity of factors affecting bone health which makes it difficult to come to clear conclusions. The factors are genetic, physiological, nutritional and hormonal which mostly interact. Nutritionally though calcium and vitamin D are vital, but bone growth and integrity are also influenced by protein and other minerals, potassium and magnesium being prime examples. What should also be borne in mind is that although osteoporosis precipitates in the elderly, the onset of the disease may occur at a very early age with retarded bone growth and poor mineralization if the child receives inadequate amounts of critical nutrients.

Calcium supplements and foods other than milk and dairy foods containing comparatively high amounts of calcium will assist in supporting bone health, particularly if bone growth and mineralization at earlier growth phases were proper. Therefore, with particular experiments it is highly likely that no difference will be seen when sources of calcium including milk and dairy foods are compared. However, in the review of reported experiments some 80% showed an advantage to milk and dairy foods, whereas in those that did not differences were not significant. None of the experiments showed poorer results for milk and dairy foods in comparison to other foods and supplements. The authors concluded that contributing factors possibly responsible for the superior results with milk and dairy foods include high bioavailabilty of calcium and supporting minerals and particular bioactive components such as colostrum acidic proteins and milk basic proteins, for example casein phosphopeptides.

Non-dairy foods with relatively high levels of calcium include cereals, vegetables, nuts, legumes and fortified foods. Some vegetables such as spinach contain oxalates which bind with calcium and make it less absorbable. In contrast the calcium in milk and dairy foods is bioavailable and well absorbed as mentioned above, apart from calcium supplements and fortified foods they contain the most calcium per unit food and milk and dairy foods are comparatively inexpensive sources. Therefore, the overall evidence that milk and dairy foods are ideal for bone health is rather convincing.