Remember Whole Milk?
Compared to watery skim milk, whole milk has a rich taste; so good it almost made you feel guilty. And why not? For years we’ve been told to avoid full fat dairy and our government, always looking out for us, provides only skim milk in school lunch programs. Interesting but not surprising, they yet allow chocolate skim milk with added sugars.
In prospective studies, relationship of self-reported consumption of dairy foods with risk of diabetes mellitus is inconsistent. Few studies have assessed dairy fat, using circulating biomarkers, and incident diabetes. We tested hypothesis that circulating fatty acid biomarkers of dairy fat, 15:0, 17:0, and t-16:1n-7, are associated with lower incident diabetes.
Methods & Results:
Among 3,333 adults aged 30-75 years and free of prevalent diabetes at baseline, total plasma and erythrocyte fatty acids were measured in blood collected in 1989-90 (Nurses’ Health Study) and 1993-94 (Health Professionals Follow-Up Study). Incident diabetes through 2010 was confirmed by validated supplementary questionnaire based on symptoms, diagnostic tests, and medications.
Risk was assessed using Cox proportional hazards, with cohort findings combined by meta-analysis. During mean follow up, 277 new cases of diabetes were diagnosed. In pooled multivariate analyses adjusting for demographics, metabolic risk-factors, lifestyle, diet, and other circulating fatty acids, individuals with higher plasma had a 44% lower risk of diabetes.
In two prospective cohorts, higher plasma dairy fatty acid concentrations were associated with lower incident diabetes. Our findings highlight need to better understand potential health effects of dairy fat; and dietary and metabolic determinants of these fatty acids.