Diets with high starch, low fiber, and a high starch-to-cereal fiber ratio were associated with a higher risk of T2D. The starch-to-cereal fiber ratio of the diet may be a novel metric for assessing carbohydrate quality in relation to T2D.

Background: Healthful dietary patterns have been associated with lower risks of type 2 diabetes and coronary artery disease, but their relations with intermediate markers of cardiometabolic and endocrine health are less established. Objective: We evaluated the Dietary Approaches to Stop Hypertension (DASH), the alternate Mediterranean diet (aMED), and the Alternate Healthy Eating Index (aHEI) diet-quality scores with cardiometabolic and endocrine plasma biomarkers in US women. Design: The trial was a cross-sectional analysis of 775 healthy women in the Women's Lifestyle Validation Study that was conducted within the NHS (Nurses' Health Study) and NHS II longitudinal cohorts. Multiple linear regression models adjusted for potential confounders were used to estimate associations between quartiles of dietary pattern-adherence scores that were derived from a food-frequency questionnaire and plasma biomarker concentrations that were collected simultaneously. Results: In multivariable models in which highest and lowest quartiles of dietary pattern scores were compared, 1) DASH was significantly associated with higher concentrations of high-density lipoprotein (9%) and sex-hormone binding globulin (SHBG) (21%), and lower concentrations of leptin (28%), triglycerides (19%), and C-peptide (4%) (all P-trend # 0.04); 2) the aMED was associated with 19% higher SHBG and 16% lower triglycerides (P-trend = 0.02 and 0.003, respectively); and 3) the aHEI was associated with significantly higher concentrations of insulin (16%) and SHBG (19%) and lower concentrations of leptin (18%) (all P-trend # 0.02). Further adjustment for body mass index (BMI) attenuated these associations but remained significant for 1) DASH with leptin and triglycerides and 2) the aMED with triglycerides (all P-trend # 0.03). Conclusions: Adherence to healthful dietary patterns is associated with favorable concentrations of many cardiometabolic and endocrine biomarkers. These relations are mediated in part by BMI. Am J Clin Nutr 2017;105:432-41.

Dietary cereal fiber appears to be an important component of carbohydrate quality. The carbohydrate-to-cereal fiber ratio and the starch-to-cereal fiber ratio, but not the carbohydrate-to-fiber ratio, was associated with an increased risk for incident CHD. Future research should focus on how various measures of carbohydrate quality are associated with CHD prevention. This trial was registered at clinicaltrials.gov as NCT03214861.

Purpose Although physical activity is an established risk factor for chronic disease prevention, the specific mechanisms underlying these relationships are poorly understood. We examined the associations between total activity counts (TAC) and moderate-vigorous physical activity (MVPA) measured by accelerometer, and physical activity energy expenditure (PAEE) measured by doubly-labeled water, with plasma levels of pro-insulin, insulin, c-peptide, IGFBP-3, IGF-1, adiponectin, leptin and leptin-sR. Methods We conducted a cross-sectional analysis of 526 healthy US women in the Women’s Lifestyle Validation Study, 2010–2012. We performed multiple linear regression models adjusting for potential lifestyle and health-related confounders to assess the associations between physical activity, measured in quartiles (Q) and biomarkers. Results Participants in Q4 vs. Q1 of TAC had lower proinsulin (−20%), c-peptide (−7%), insulin (−31%) and leptin (−46%) levels, and higher adiponectin (55%), leptin-sR (25%) and IGF-1 (9.6%) levels (all P-trend≤0.05). Participants in Q4 vs Q1 of MVPA had lower proinsulin (−26%), c-peptide (−7%), insulin (−32%) and leptin (−40%) levels, and higher adiponectin (31%) and leptin-sR (22%) levels (all P-trend≤0.05). Further adjustment for body mass index attenuated these associations, but the associations with adipokines remained significant. Those in Q4 vs. Q1 of PAEE had lower leptin (−21%) and higher leptin-sR (10%) levels (all P-trend ≤0.05), after additional adjustment for body mass index. In the sensitivity analysis, the associations were similar but attenuated when physical activity was measured using the subjective physical activity questionnaire. Conclusion Our data suggests greater physical activity is modestly associated with favorable levels of cardiometabolic and endocrine biomarkers, where the strongest associations were found with accelerometer-measured physical activity. These associations may be only partially mediated through BMI, further supporting the role of physical activity in the reduction of cardiometabolic and endocrine disease risk, independent of adiposity.

A greater fiber intake and a lower starch-to-fiber intake ratio are favorably associated with adiponectin and HbA1c, but only cereal fiber intake was associated with CRP in women. Further research is warranted to understand the potential mechanism of these associations in early progression of T2D.

Objectives Carbohydrate intake has been reported to be associated with higher type 2 diabetes (T2D) risk, but high and low quality of carbohydrate may have different effects. Furthermore, these effects may differ depending on overall macronutrient composition. We aimed to examine associations of isocalorically substituting high quality carbohydrates (HQC) and low quality carbohydrates (LQC) with other macronutrients on T2D risk. Methods We included 69,949 women from the Nurses’ Health Study, 90,239 women from the Nurses’ Health Study 2, and 40,539 men from the Health Professionals Follow-up Study. Dietary data were collected every 2–4 years using a semi-quantitative food frequency questionnaire, from which dietary intake of LQC and HQC were calculated. LQC was defined as the percentage of energy (E%) from carbohydrates from refined grains, sugary foods, and potatoes, and HQC as E% from carbohydrate from whole grains. Hazard ratios were estimated using Cox proportional hazard regression analyses with time-varying covariates. Results During 4389,996 years of follow-up, we documented 11,872 T2D cases. In pooled multivariable-adjusted analyses, substituting 5E% from saturated fat with 5E% from LQC was associated with a higher T2D (HR[95% CI] = 1.05[1.00–1.09]) while substitution with HQC was associated with a lower T2D risk (HR[95% CI] = 0.93[0.87–0.99]). Isocaloric substitution of other macronutrients with LQC was not associated with T2D risk. On the other hand, isocaloric substitution of HQC was associated with lower T2D risk when the replacement nutrient was monounsaturated fat (HR[95% CI] = 0.88[0.83–0.94]), polyunsaturated fat (HR[95% CI] = 0.92[0.86–0.98]), trans fat (HR[95% CI] = 0.90[0.85–0.97]), animal protein (HR[95% CI] = 0.88[0.83–0.93]), and vegetable protein (HR[95% CI] = 0.90[0.84–0.96]). Conclusions Our study suggests that higher intake of HQC, especially from whole grains, is associated with a lower T2D risk, irrespective of the macronutrient it replaces. In contrast, a higher intake of LQC is associated with a higher risk of type 2 diabetes, but only when it replaces saturated fat. Our findings highlight the importance of making a distinction between carbohydrate from high and low quality sources and taking into account different substitutions when examining macronutrients. Funding Sources National Institutes of Health.

Background: Carbohydrate quality may be an important determinant of type 2 diabetes (T2D), however, the relationships between various carbohydrate quality metrics and T2D risk have not been systematically investigated. Objective: To prospectively examine the association between carbohydrate, starch, fiber, and different combinations of these nutrients in relation to the risk of T2D in US women. Methods: We prospectively collected information on diet and lifestyle behaviors among 70,041 women from the Nurses Health Study every 2-4 years, after baseline in 1984. These participants were free of diagnosed cardiovascular disease, cancer, or diabetes at baseline. We used Cox proportional hazards regression models to assess the association between dietary factors of interest and incidence of T2D. Results: With 24 years of follow-up we ascertained 6,934 incident cases of T2D during 1,484, 213 person years of follow-up. After adjusting for age, lifestyle and dietary variables, total carbohydrate intake was not associated with T2D (RR=0.98, 95% CI: 0.89 - 1.08, p for trend=0.84), while starch was positively associated with T2D (RR=1.23, 95%CI: 1.12 - 1.35), p for trend <0.0001), comparing the highest to lowest quintile. Total fiber (RR= 0.80, 95%CI: 0.72 - 0.89, p for trend < 0.0001), cereal fiber (RR= 0.71, 95%CI: 0.65 - 0.78, p for trend < 0.0001) and fruit fiber (RR= 0.80, 95%CI: 0.73 - 0.88, p for trend < 0.0001) were all inversely associated with T2D, comparing extreme quintiles. . There was a borderline significant positive association between the ratio of carbohydrate to total fiber intake and risk of T2D (RR= 1.09, 95%CI: 1.00 - 1.20, p for trend = 0.039), and stronger positive associations between the ratios of carbohydrate to cereal fiber (RR= 1.28, 95%CI: 1.17 - 1.39, p for trend < 0.0001), starch to total fiber (RR= 1.12, 95%CI: 1.02 - 1.23, p for trend = 0.030) and starch to cereal fiber (RR= 1.39, 95%CI: 1.27 - 1.53, p for trend < 0.0001) with T2D, comparing extreme quintiles.. Conclusion: Diets with high starch, low fiber and high starch to cereal fiber ratio were associated with increased risk of T2D. Using the starch to cereal fiber ratio of the overall diet is a potentially useful way of assessing carbohydrate quality in relation to T2D.

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