‘ditch the dairy’ references

Connelly MA, Wolak-Dinsmore J, Dullaart RPF

Conclusion:Insulin resistance was associated with BCAA. This association remained after adjusting for age, sex, T2DM, BMI, as well as leptin and adiponectin. It is unlikely that the relationship of insulin resistance with BCAA is to a major extent attributable to effects of leptin and adiponecti.

Background:
Branched chain amino acids (BCAA) may be involved in the pathogenesis of insulin resistance and are associated with type 2 diabetes mellitus (T2DM) development. Adipokines such as leptin and adiponectin influence insulin resistance and reflect adipocyte dysfunction. We examined the extent to which the association of BCAA with insulin resistance is attributable to altered leptin and adiponectin levels in individuals with varying degrees of glucose tolerance.

Methods:
BCAA were measured by nuclear magnetic resonance, whereas leptin and adiponectin were measured by immunoassay, in subjects with normal fasting glucose (n = 30), impaired fasting glucose (n = 25), and T2DM (n = 15). Insulin resistance was estimated by homeostasis model assessment (HOMAir).

Results:
BCAA were higher in men than in women (P < 0.001) and tended to be higher in T2DM subjects (P = 0.10) compared to subjects with normal or impaired fasting glucose. In univariate regression analysis, BCAA were correlated with HOMAir (r = 0.46; P < 0.001) and inversely with adiponectin (r = -0.53; P < 0.001) but not with leptin (r = -0.08; P > 0.05). Multivariable linear regression analysis, adjusting for age, sex, T2DM, and body mass index (BMI), demonstrated that BCAA were positively associated with HOMAir (β = 0.242, P = 0.023). When BCAA, leptin, and adiponectin were included together, the positive relationship of HOMAir with BCAA (β = 0.275, P = 0.012) remained significant.

Kirsty M Turner, Jennifer B Keogh, and Peter M Clifton

Conclusion: In contrast to some epidemiologic findings, these results suggest that high consumption of dairy reduces insulin sensitivity compared with a diet high in lean red meat in overweight and obese subjects, some of whom had glucose intolerance.

Background: Epidemiologic studies have linked high consumption of red and processed meat with risk of developing type 2 diabetes, whereas high dairy consumption has been associated with decreased risk, but interventions have been limited.

Objective: We compared the effects on insulin sensitivity of consuming a diet high in lean red meat with minimal dairy, a diet high in dairy primarily low fat (from milk, yogurt, or custard) with no red meat, and a control diet that contained neither red meat nor dairy.

Design: A randomized crossover study was undertaken with 47 overweight and obese men and women divided into 2 groups as follows: those with normal glucose tolerance and those with impaired fasting glucose or impaired glucose tolerance. Participants followed the 3 weight-stable dietary interventions for 4 wk with glucose, insulin, and C-peptide measured by using oral-glucose-tolerance tests at the end of each diet.

Results: Fasting insulin was significantly higher after the dairy diet than after the red meat diet (P < 0.01) with no change in fasting glucose resulting in a decrease in insulin sensitivity after the high-dairy diet (P < 0.05) as assessed by homeostasis model assessment of insulin resistance (HOMA-IR). A significant interaction between diet and sex was observed such that, in women alone, HOMA-IR was significantly lower after the red meat diet compared with dairy diet (1.33 ± 0.8 compared with 1.71 ± 0.8, respectively; P < 0.01). Insulin sensitivity calculated by using the Matsuda method was 14.7% lower in women after the dairy diet compared with red meat diet (P < 0.01) with no difference between diets in men. C-peptide was not different between diets.

Tucker LA1, Erickson A1, LeCheminant JD1, Bailey BW1.
College of Life Sciences, Brigham Young University, Provo, UT 84602, USA.
J Diabetes Res. 2015;2015:206959. doi: 10.1155/2015/206959. Epub 2015 Jan 29.
Conclusion:
High dairy intake is a significant predictor of insulin resistance in middle-aged, nondiabetic women.
Abstract
The relationship between dairy consumption and insulin resistance was ascertained in 272 middle-aged, nondiabetic women using a cross-sectional design. Participants kept 7-day, weighed food records to report their diets, including dairy intake. Insulin resistance was assessed using the homeostatic model assessment (HOMA). The Bod Pod was used to measure body fat percentage, and accelerometry for 7 days was used to objectively index physical activity. Regression analysis was used to determine the extent to which mean HOMA levels differed across low, moderate, and high dairy intake categories. Results showed that women in the highest quartile of dairy consumption had significantly greater log-transformed HOMA values (0.41 ± 0.53) than those in the middle-two quartiles (0.22 ± 0.55) or the lowest quartile (0.19 ± 0.58) (F = 6.90, P = 0.0091). The association remained significant after controlling for each potential confounder individually and all covariates simultaneously. Adjusting for differences in energy intake weakened the relationship most, but the association remained significant. Of the 11 potential confounders, only protein intake differed significantly across the dairy categories, with those consuming high dairy also consuming more total protein than their counterparts. Apparently, high dairy intake is a significant predictor of insulin resistance in middle-aged, nondiabetic women.

Milk intake and risk of mortality and fractures in women and men: cohort studies.
Michaëlsson K, Wolk A, Langenskiöld S, Basu S, Warensjö Lemming E, Melhus H, Byberg L.
Conclusion: High milk intake was associated with higher mortality in one cohort of women and in another cohort of men, and with higher fracture incidence in women. Given the observational study designs with the inherent possibility of residual confounding and reverse causation phenomena, a cautious interpretation of the results is recommended.