Prepared Foods December 12, 2005 e-newsletter

A study published in the American Journal of Clinical Nutrition found that people who drink low-fat milk may be at a lower risk of developing hypertension, a key risk factor for heart disease and stroke.

Researchers at the University of Navarra in Pamplona, Spain, in cooperation with Harvard University, analyzed the diets and risk factors of nearly 6,000 adult men and women over a 27-month period. Participants' intake ranged from 1 to 3 servings of dairy foods each day, and those who consumed low-fat options were less likely to develop hypertension. Some 92% of the low-fat dairy intake in the study was attributed to milk. There was no association found between full-fat dairy foods and hypertension risk.

The Navarra study is just one of many studies that support a possible role of low-fat milk and milk products in the prevention of hypertension. For example, the Dietary Approaches to Stop Hypertension (DASH) study found that a diet rich in low-fat milk and milk products (three servings per day) and fruits and vegetables (8-10 servings) can help lower blood pressure.

Other studies suggest that nutrients found in milk -- calcium, potassium and magnesium -- may play an important role in maintaining normal blood pressure.

Another risk factor for hypertension is poor diet. While low-fat dairy always has been recommended as part of a healthy diet, most Americans still do not get enough of it. According to the 2005 U.S. Dietary Guidelines and MyPyramid recommendations, Americans should include at least three servings of low-fat milk or milk products in their diet every day. This will ensure adequate consumption of nine essential nutrients including calcium, potassium and magnesium.

In addition, a new clinical trial, also published in the American Journal of Clinical Nutrition by researchers at Purdue University, found that women burned more fat and more calories after a meal when their diets included three to four servings of dairy daily.

"From the results of this study, we put together a rough calculation based on the increased fat burned from a meal that suggests a high-dairy diet followed over a year could potentially result in the loss of 10 pounds of fat a year," commented Dorothy Teegarden, lead investigator and professor of nutrition at Purdue University.

The purpose of this study was to investigate the mechanism by which dairy and calcium may impact body composition through the body's ability to burn fat and use calories. This study was not designed to induce weight loss. In the year-long study, researchers compared the effects of a prolonged low-dairy (one to two servings) diet to a prolonged high dairy (three to four servings) diet among 19 normal-weight women (aged 18-30 years old). The study participants' ability to burn fat and calories after a meal was measured at the beginning and end of the trial to determine the impact of increasing dairy and calcium consumption during the one-year trial. They found that women who consumed three servings of dairy each day over the course of a year burned more fat and calories from a meal compared to women who fell short of government recommendations, consuming less than three servings of dairy per day.

The subjects who consumed more dairy over the year burned more fat and calories after a meal.

Results from this study add further support to the body of research on dairy's role in weight management, providing insight into the mechanism of fat metabolism. Increased calcium decreases parathyroid hormone (PTH), and Teegarden discovered that the decreased PTH that occurs with increased dairy consumption increases fat burning. Teegarden's discovery builds on other research demonstrating the role of calcium regulating hormones as potential mediators of the relationship between an increase in dietary calcium and greater fat burning.

In addition, other studies found that overweight people on a reduced-calorie diet who consumed three servings of milk, cheese or yogurt each day lost significantly more weight and more body fat than those who just cut calories alone while consuming little or no dairy. Clinical studies also have shown that dairy foods exert a significantly greater effect on body weight and fat loss than calcium supplements -- suggesting that the mix of nutrients in dairy beyond calcium contributes to dairy's superior effect.

Sources: Cardiovascular Device Liability Week; et al.