Claire Springer, Patricia de Castro, Nhu Vu, Daniel Bristow

The Claim ◦ “…full-fat dairy, like whole milk, may be healthier than low-fat dairy, like skim milk.” ◦ Skim milk could increase your risk of diabetes ◦ “The science behind how the byproducts of full-fat dairy are helping to lower the risk of diabetes is still unclear. ”

Who are the authors? Rachel DickersonMozaffarian et. al.

What did they do? In this correlational study, researchers hypothesized that “Circulating fatty acid biomarkers of dairy fat are associated with lower incident of diabetes mellitus.” For baseline data, they measured the total plasma and erythrocyte fatty acid biomarkers from blood samples collected in: Nurses Health Study( ) Health Professionals follow-up Study( ) In total: 3,333 research participants Ages years 3 primary fatty acid biomarkers were tested: Pentadecanoic acid (15:0) Heptadecanoic acid (17:0) Trans-palmitoleate (t-16:ln-7) Specifically comes from dairy fat (ex: whole-fat milk)

What did they do? (cont.) ◦ Scientists controlled for: ◦ Demographics ◦ Metabolic Risk factors ◦ Lifestyle ◦ Diet ◦ BMI

Conclusions of Study ◦ “In these cohorts, plasma fatty acid biomarkers correlated more strongly with dairy fat intake than did erythrocyte biomarkers and were also more strongly inversely associate with diabetes mellitus.” ◦ “In summary, we found that plasma 15:0, 17:0, and trans-16:1n-7 were associated with a lower incidence of diabetes mellitus in 2 separate prospective cohort studies.” ◦ “Need to better understand the potential health effects of dairy fat, and the dietary and metabolic determinants of these fatty acids.”

Problems with the Study ◦ When controlled for all variables, the data was hardly conclusive ◦ ”moderate to mild increase language” ◦ ”abut half of participants were overweight or obese; 1 in 4 had hypertension or a family history of diabetes mellitus, 1;3 had hypercholerolemia ; and 1 in 12 men and 1 n 5 women were current smokers.” ◦ Genetics play a bigger role than what the study has initially surmised ◦ “…Dr Mozaffarian among coinventors, for use of trans-palmitoleic acid to prevent and treat insulin resistance, type 2 diabetes mellitus, and related conditions. The other authors report no conflicts. 3 Fatty Acid Biomarkers Pentadecanoic acid (15:0) Heptadecanoic acid (17:0) Trans -palmitoleate (t-16:ln-7) ◦ In the present analysis, t-16:1n-7 remained associated with diabetes mellitus after adjustment for the other dairy fat biomarkers, suggesting it may be particularly relevant for further investigation of its determinants and biological effects.

Problems with Media Portrayal ◦ Title of news article: Skim Milk Could Increase Your Risk of Diabetes, Study Suggests ◦ This title is suggestive of the inverse of the primary study ◦ Study does not actually claim that skim milk is bad for you or causes diabetes mellitus ◦ Study claims that there is an inverse relationship between the fatty acid biomarkers and diabetes mellitus, even though biomarkers were just pertaining to whole-fat milk ◦ Media reports that skim milk directly increases one’s risk for diabetes ◦ Article is unprofessionally written ◦ Misquoting the article: “Who had higher levels of three different byproducts of full-fat diary had an average 46 percent lower risk of developing diabetes” ◦ In reality: ◦ t-16:ln-7 with 46% lower risk ◦ 15:0 with 38% lower risk ◦ 17:0 with 32% lower risk

Problems with Media (cont.) ◦ “There is no prospective human evidence that people who eat low-fat dairy do better than people who eat whole-fat dairy.”- Dr. Dariush Mozaffarian ◦ Quote was taken out of context, and the article spins the quote to say that skim milk is bad for you ◦ There’s no evidence from primary article that says skim milk is any better for you than whole milk ◦ Published study was hard to find; did not properly cite the article ◦ Author didn’t elude to the fact that the study was not conclusive ◦ The authors stressed hesitancy toward this study We Can’t Believe the U.S. Article Claim