Along with building bones,
milk offers many benefits
Last week, a study published in JAMA, the prestigious Journal of the American Medical Association, reported that overweight young adults who consumed the most milk and milk products during a 10-year study had a lower incidence of insulin-resistance syndrome. Since the syndrome is associated with the development of non-insulin dependent diabetes and cardiovascular disease, this was big news. A CNN medical correspondent commented, "These results surprised the heck out of me."
Question: Are the beneficial properties of milk really so surprising?
Answer: Not if you have been following the scientific literature on this topic. Dating back to at least 1987, a steady series of scientific papers has reported a positive relationship between higher levels of calcium or milk in the diet and better insulin function and decreased obesity.
The tendency is to think of dairy foods and calcium as important only for healthy bones. But beneficial effects include reduced blood pressure and a decreased risk of cardiovascular disease and colon cancer.
Q: Then why are people so surprised?
A: Certainly, a lack of awareness of the extensive research is part of the reason. Also, recommendations to reduce consumption of higher-fat milk products may have led many to think of milk as a "bad food."
Various groups opposed to milk production for philosophical reasons continue to distort facts about the health benefits. Strongly biased interpretations of scientific studies often present an aura of authority, encouraging people to completely avoid dairy foods.
Less biased perspectives find milk products to be a reasonable part of a varied diet based primarily on fruits, vegetables, grains, and beans, along with smaller amounts of foods such as nuts, fish, poultry and meat.
Excessive intake from any single group of foods, including milk, can imbalance an otherwise healthy diet.
Q: What is the relationship between dairy products and obesity?
A: A number of studies have reported that adding milk products to a low-calcium diet enhances the loss of body fat.
One study was conducted on obese African American men to see if adding 2 cups of yogurt to their daily diet would help to decrease high blood pressure. It did. But something else happened: Unrelated to any obvious change in calorie intake, after 12 months, the average participant lost about 11 pounds.
Another study found that overweight adults consuming a 1,300-calorie diet for 16 weeks lost 12 pounds more than a group eating 800 calories. The 800-calorie diet only had about 500 mg of calcium, but the 1,300 calorie diet had more than 1,500 mg.
To determine how milk or calcium might have this effect, Dr. Michael B. Zemel, at the University of Tennessee Knoxville, has identified a fairly complex sequence of metabolic events that show how increased calcium intake, especially from dairy foods, causes fat cells to make and store less fat and to release more fat.
These positive aspects of milk and milk products are not well-publicized. This may change with studies showing up in major journals like JAMA.
And no, we don't get funding from the dairy industry.
Alan Titchenal, Ph.D., C.N.S., is a sports nutritionist in the
Department of Human Nutrition, Food and Animal Science,
University of Hawaii-Manoa.
Joannie Dobbs, Ph.D., C.N.S., is a food and nutrition consultant
and owner of Exploring New Concepts, a nutritional consulting firm.
She is also responsible for the nutritional analyses
indicated by an asterisk in this section.