Dr. C. Mary Schooling, professor at the CUNY Graduate School of Public Health and Health Policy, and international colleagues conducted a Mendelian randomization study to examine genetically predicted milk consumption and bone health, ischemic heart disease and type 2 diabetes. The findings were published in the European Journal of Clinical Nutrition.
[Photo: Dr. C. Mary Schooling]
Milk provides protein and micronutrients, and is recommended by some dietary guidelines, particularly for bone health. Results of meta-analysis of small randomized controlled trials suggest that milk may increase bone mineral density, but are very heterogeneous. Additionally there are no published randomized controlled trials assessing the effects of milk on major chronic diseases. Using larger genetic studies, the research team estimated the effects of milk on osteoporosis, ischemic heart disease, type 2 diabetes, adiposity, lipids and glycemic traits.
The research team used instrumental variable analysis based on a genetic variant endowing lactase persistence to obtain estimates for osteoporosis, ischemic heart disease, type 2 diabetes, adiposity, lipids, and glycaemic traits. Eye color was a negative control for ischemic heart disease, as it mirrors the distribution of lactase persistence and ischemic heart disease in Western Europe.
Genetically predicted adult milk consumption was not clearly associated with bone mineral density, ischemic heart disease, type 2 diabetes, but was associated with higher log-transformed fasting insulin and body mass index. Genetically predicted eye color was not associated with ischemic heart disease.
The research team concluded that there was a lack of association of genetically predicted milk consumption with bone health, ischemic heart disease, or type 2 diabetes. The results suggest few beneficial effects but is more consistent with milk promoting adiposity.