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.
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.
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).
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.
High dairy intake is a significant predictor of insulin resistance in middle-aged, nondiabetic women.
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.
Milk and mortality
Genetic studies could help us interpret a biologically plausible but preliminary association
C Mary Schooling
City University of New York School of Public Health and Hunter College, New York, NY 10035, USA
BMJ 2014;349:g6205 doi: 10.1136/bmj.g6205 (Published 27 October 2014)
High intakes of milk, but not meat, increase s-insulin and insulin resistance in 8-year-old boys
Conclusion:A short-term high milk protein intake increased insulin secretion and resistance – fasting insulin levels doubled after 7 days in the milk protein group, whereas there was no change in the levels of insulin in the meat protein group.
Hoppe C, Mølgaard C, Vaag A, Barkholt V, Michaelsen KF.
The Royal Veterinary and Agricultural University, Denmark
Case-control study of risk factors for hip fractures in the elderly
Conclusion:Consumption of dairy products, particularly at age 20 years, was associated with an increased risk of hip fracture in old age. Some of the results of this study were unanticipated and may be due to chance or bias. If confirmed by other studies, these results would challenge some of the current approaches to hip fracture prevention.
Cumming RG, Klineberg RJ.
Department of Public Health, University of Sydney, NSW, Australia.
Am J Epidemiol. 1994 Mar 1;139(5):493-503.
Milk, dietary calcium, and bone fractures in women: a 12-year prospective study
Conclusion:This study from Harvard on 77,761 women looked into whether higher intakes of milk and other calcium-rich foods during adult years reduced the risk of osteoporotic fractures later in life – their data showed that a higher consumption of milk or other food sources of calcium by adult women did not protect against future hip or forearm fractures.
Feskanich D, Willett WC, Stampfer MJ, Colditz GA.
Am J Public Health. 1997 Jun;87(6):992-7.
Calcium, vitamin D, milk consumption, and hip fractures: a prospective study among postmenopausal women
Conclusion:This 18-year analysis of the dietary and nutritional supplement habits of 72,337 post menopausal women showed that neither milk nor a high-calcium diet reduced the risk of osteoporotic hip fractures, whereas an adequate intake of vitamin D was associated with a lower risk of fractures.
Feskanich D, Willett WC, Colditz GA.
Harvard Medical School
Am J Clin Nutr. 2003 Feb;77(2):504-11.
Circulating branched-chain amino acid concentrations are associated with obesity and future insulin resistance in children and adolescents
Elevations in the concentrations of circulating BCAAs are significantly associated with obesity in children and adolescents, and may independently predict future insulin resistance.
McCormack SE, Shaham O, McCarthy MA, Deik AA, Wang TJ, Gerszten RE, Clish CB, Mootha VK, Grinspoon SK, Fleischman A.
Massachusetts General Hospital and Harvard Medical School
Skim milk, whey, and casein increase body weight and whey and casein increase the plasma C-peptide concentration in overweight adolescents
In adults, dietary protein seems to induce weight loss and dairy proteins may be insulinotropic. However, the effect of milk proteins in adolescents is unclear.
Conclusion:Our data suggest that high intakes of skim milk, whey, and casein increase BAZs (BMI-for-age Z-scores) in overweight adolescents and that whey and casein increase insulin secretion. Whether the effect on body weight is primary or secondary to the increased insulin secretion remains to be elucidated.
Arnberg K, Mølgaard C, Michaelsen KF, Jensen SM, Trolle E, Larnkjær A.
Should dairy be recommended as part of a healthy vegetarian diet? Counterpoint.
Conclusion:Osteoporotic bone fracture rates are highest in countries that consume the most dairy, calcium, and animal protein. Most studies of fracture risk provide little or no evidence that milk or other dairy products benefit bone. Accumulating evidence shows that consuming milk or dairy products may contribute to the risk of prostate and ovarian cancers, autoimmune diseases, and some childhood ailments. Bones are better served by attending to calcium balance and focusing efforts on increasing fruit and vegetable intakes, limiting animal protein, exercising regularly, getting adequate sunshine or supplemental vitamin D, and getting approximately 500 mg Ca/d from plant sources.
University of North Carolina
Metabolic effects of milk protein intake strongly depend on pre-existing metabolic and exercise status
Conclusion:Milk protein intake has recently been suggested to improve metabolic health. This Perspective provides evidence that metabolic effects of milk protein intake have to be regarded in the context of the individual’s pre-existing metabolic and exercise status. Milk proteins provide abundant branched-chain amino acids (BCAAs) and glutamine. Plasma BCAAs and glutamine are increased in obesity and insulin resistance, but decrease after gastric bypass surgery resulting in weight loss and improved insulin sensitivity. Milk protein consumption results in postprandial hyperinsulinemia in obese subjects, increases body weight of overweight adolescents and may thus deteriorate pre-existing metabolic disturbances of obese, insulin resistant individuals.
Melnik BC, Schmitz G, John S, Carrera-Bastos P, Lindeberg S, Cordain L.
How sound is the science behind the dietary recommendations for
Connie M Weaver
Am J Clin Nutr May 2014 99: 1217S-1222S; First published online March 19, 2014. doi:10.3945/ajcn.113.073007