The impact of diets rich in low-fat or\ full-fat dairy on glucose tolerance and its determinants: a randomized controlled trial

Abstract

Background Dairy foods, particularly yogurt, and plasma biomarkers of dairy fat intake are consistently inversely associated with incident type 2 diabetes. Yet, few trials assessing the impact of dairy on glucose homeostasis include fermented or full-fat dairy foods. Objectives We aimed to compare the effects of diets rich in low-fat or full-fat milk, yogurt, and cheese on glucose tolerance and its determinants, with those of a limited dairy diet. Methods In this parallel-design randomized controlled trial, 72 participants with metabolic syndrome completed a 4-wk wash-in period, limiting dairy intake to ≤3 servings/wk of nonfat milk. Participants were then randomly assigned to either continue the limited dairy diet, or switch to a diet containing 3.3 servings/d of either low-fat or full-fat dairy for 12 wk. Outcome measures included glucose tolerance (area under the curve glucose during an oral-glucose-tolerance test), insulin sensitivity, pancreatic β-cell function, systemic inflammation, liver-fat content, and body weight and composition. Results In the per-protocol analysis (n = 67), we observed no intervention effect on glucose tolerance (P = 0.340). Both the low-fat and full-fat dairy diets decreased the Matsuda insulin sensitivity index (ISI) (means ± SDs −0.47 ± 1.07 and −0.25 ± 0.91, respectively) and as compared with the limited dairy group (0.00 ± 0.92) (P = 0.012 overall). Body weight also changed differentially (P = 0.006 overall), increasing on full-fat dairy (+1.0 kg; −0.2, 1.8 kg) compared with the limited dairy diet (−0.4 kg; −2.5, 0.7 kg), whereas the low-fat dairy diet (+0.3 kg; −1.1, 1.9 kg) was not significantly different from the other interventions. Intervention effects on the Matsuda ISI remained after adjusting for changes in adiposity. No intervention effects were detected for liver fat content or systemic inflammation. Findings in intent-to-treat analyses (n = 72) were consistent. Conclusions Contrary to our hypothesis, neither dairy diet improved glucose tolerance in individuals with metabolic syndrome. Both dairy diets decreased insulin sensitivity through mechanisms largely unrelated to changes in key determinants of insulin sensitivity. This trial was registered at clinicaltrials.gov as NCT02663544.

Exploring the Links between Diet and Inflammation: Dairy Foods as Case Studies

“…Last, Schmidt et al ( 51 ) randomly assigned 67 men and women with the metabolic syndrome to follow 1 of 3 intervention diets: 3.3 servings per day of low-fat and fat-free dairy, 3.3 servings of whole-fat dairy, or limited dairy. No differential effect of the 3 intervention diets was seen for hs-CRP, IL-6, or total adiponectin in fasting plasma.…”

Whole-fat dairy products do not adversely affect adiposity or cardiometabolic risk factors in children in the Milky Way Study: a double-blind randomized controlled pilot study

“…However, we noted a trend toward a lower BMI percentile in the whole-fat relative to the reduced-fat group ( P = 0.054), which matches emerging observational evidence ( 41 , 81 ) questioning the recommendation to provide reduced-fat dairy to healthy children. In adults, whole-fat compared with reduced-fat dairy has been associated with neutral or beneficial effects on body composition in intervention studies ( 84–86 ), and in a systematic review ( 37 ) and a meta-analysis ( 2 ) of observational studies, although some interventions have found adverse effects on body weight where energy intake is ad libitum ( 87 , 88 ).…”

“…This finding matches that from the child cluster intervention to reduce dairy fat or screen time ( 65 ). However, adults with MetS ( n = 72) supplied with 3.3 servings of whole- or reduced-fat dairy per day increased their dietary energy compared with limited dairy consumption ( P < 0.001), suggesting relative failure to balance ad libitum energy intake ( 87 ). Whereas young children generally do eat according to their energy needs, environmental and social factors can affect intake in older children ( 95 ).…”

Dairy Consumption and 3-Year Risk of Type 2 Diabetes after Myocardial Infarction: A Prospective Analysis in the Alpha Omega Cohort

“…Also, results from meta-analyses need to be interpreted with caution, since not all individual prospective cohort studies showed an inverse association between yogurt consumption and T2D risk, and results from meta-analyses were found in the context of significant heterogeneity. Furthermore, to date, the potential benefit of yogurt against T2D is largely supported by observational evidence [33][34][35][36].…”