Volume 80, Number 3 May/June 2009
Summary
Emerging research suggests a potential protective role for dairy foods and/or dairy food nutrients (e.g., calcium, vitamin D) in metabolic syndrome and type 2 diabetes. Metabolic syndrome is generally diagnosed when three of the following five metabolic disorders are present: elevated fasting glucose, low high density lipoprotein (HDL) cholesterol, high triglyceride levels, abdominal obesity, and hypertension. Persons with metabolic syndrome are at risk for type 2 diabetes and cardiovascular disease. Metabolic syndrome is reported to affect more than one-third of U.S. adults and this syndrome is being diagnosed more frequently among children and adolescents.
Although genetic and environmental factors influence the development of metabolic syndrome and type 2 diabetes, the focus is on lifestyle choices, including diet, to help prevent these diseases. Because overweight/obesity increases the risk of metabolic syndrome and type 2 diabetes, achieving and maintaining a healthy body weight is recommended. Increasing physical activity and consuming a diet consistent with the 2005 Dietary Guidelines for Americans are also encouraged. Recently, scientists have begun to explore the possible beneficial role of dairy foods and/or dairy food nutrients in metabolic syndrome and type 2 diabetes.
Findings from epidemiological studies demonstrate a relatively consistent inverse association between consumption of dairy foods and metabolic syndrome in various populations. When data from several cross-sectional studies were combined, researchers reported that the prevalence of metabolic syndrome was 29% lower among adults who consumed three to four servings of dairy foods a day compared to those who consumed 0.9 to 1.7 dairy servings/day. Prospective studies in large populations of adults also support an inverse association between dairy food consumption and metabolic syndrome.
Although few clinical studies have examined the relationship between dairy foods and metabolic syndrome, intervention trials have shown a beneficial effect of dairy foods on components of the metabolic syndrome such as hypertension and obesity/adiposity. Also, studies demonstrate that several dairy food nutrients are inversely associated with metabolic syndrome and that they favorably affect its components.
The relationship between dairy foods and type 2 diabetes has been examined primarily by epidemiological studies. Based on a meta-analysis of prospective studies, researchers reported that the incidence of type 2 diabetes was 14% lower for adults consuming three to five servings of dairy foods a day compared to those consuming less than 1.5 dairy food servings a day. Dairy food nutrients such as calcium, vitamin D, and magnesium may contribute to dairy foods’ potential protective effect against type 2 diabetes.
Additional studies, particularly randomized controlled trials, are needed to substantiate the beneficial role of dairy foods and dairy food nutrients such as calcium and vitamin D in the prevention and management of metabolic syndrome and type 2 diabetes. However, findings to date are promising and provide another reason to consume three cups of low-fat or fat-free milk or equivalent milk products (cheese, yogurt) a day as part of a healthful diet recommended by the 2005 Dietary Guidelines for Americans.
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