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Carbohydrate quality and quantity and risk of type 2 diabetes in US women.
AlEssa, HB, Bhupathiraju, SN, Malik, VS, Wedick, NM, Campos, H, Rosner, B, Willett, WC, Hu, FB
The American journal of clinical nutrition. 2015;(6):1543-53
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Abstract
BACKGROUND Carbohydrate quality may be an important determinant of type 2 diabetes (T2D); however, relations between various carbohydrate quality metrics and T2D risk have not been systematically investigated. OBJECTIVE The purpose of this study was to prospectively examine the association between carbohydrates, starch, fibers, and different combinations of these nutrients and risk of T2D in women. DESIGN We prospectively followed 70,025 women free of cardiovascular disease, cancer, and diabetes at baseline from the Nurses' Health Study (1984-2008). Diet information was collected with the use of a validated questionnaire every 4 y. Cox regression was used to evaluate associations with incident T2D. RESULTS During 1,484,213 person-years of follow-up, we ascertained 6934 incident T2D cases. In multivariable analyses, when extreme quintiles were compared, higher carbohydrate intake was not associated with T2D (RR = 0.98; 95% CI: 0.89, 1.08; P-trend = 0.84), whereas starch was associated with a higher risk (RR = 1.23; 95% CI: 1.12, 1.35; P-trend <0.0001). Total fiber (RR = 0.80; 95% CI: 0.72, 0.89; P-trend < 0.0001), cereal fiber (RR = 0.71, 95% CI: 0.65, 0.78; P-trend < 0.0001), and fruit fiber (RR = 0.79; 95% CI: 0.72, 0.85; P-trend < 0.0001) were associated with a lower T2D risk. The ratio of carbohydrate to total fiber intake was marginally associated with a higher risk of T2D (RR = 1.09; 95% CI: 1.00, 1.20; P-trend = 0.04). On the other hand, we found positive associations between the ratios of carbohydrate to cereal fiber (RR = 1.28; 95% CI: 1.17, 1.39; P-trend < 0.0001), starch to total fiber (RR = 1.12; 95% CI: 1.02, 1.23; P-trend = 0.03), and starch to cereal fiber (RR = 1.39; 95% CI: 1.27, 1.53; P-trend < 0.0001) and T2D. CONCLUSIONS 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.
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A prospective study of dietary fiber intake and risk of cardiovascular disease among women.
Liu, S, Buring, JE, Sesso, HD, Rimm, EB, Willett, WC, Manson, JE
Journal of the American College of Cardiology. 2002;(1):49-56
Abstract
OBJECTIVES This study was designed to examine the hypothesis that higher intake of dietary fiber is inversely related to the risk of cardiovascular disease (CVD) and myocardial infarction (MI) in a large prospective cohort of women. BACKGROUND Although dietary fiber has been suggested to reduce the risk of coronary disease, few prospective studies have examined the association between the types and amounts of dietary fiber and CVD risk, particularly among women. METHODS In 1993, we used a semi-quantitative food frequency questionnaire to assess dietary fiber intake among 39,876 female health professionals with no previous history of CVD or cancer. Women were subsequently followed for an average of six years for incidence of nonfatal MI, stroke, percutaneous transluminal coronary angioplasty, coronary artery bypass graft or death due to CVD confirmed by medical records or death certificates. RESULTS During 230,006 person-years of follow-up, 570 incident cases of CVD were documented, including 177 MIs. After adjustment for age and randomized treatment status, a significant inverse association was observed between dietary fiber intake and CVD risk. Comparing the highest quintile of fiber intake (median: 26.3 g/day) with the lowest quintile (median: 12.5 g/day), the relative risks (RR) were 0.65 (95% confidence interval [CI]: 0.51, 0.84) for total CVD and 0.46 (95% CI: 0.30, 0.72) for MI. Additional adjustment for CVD risk factors reduced the RRs to 0.79 (95% CI: 0.58, 1.09) for total CVD and 0.68 (95% CI: 0.36, 1.22) for MI. The inverse trends across categories generally remained, although they were no longer statistically significant. Inverse relations were observed between both soluble and insoluble fiber and risk of CVD and MI, and among those who had never smoked and those with body mass index <25. CONCLUSIONS A higher intake of dietary fiber was associated with a lower risk of CVD and MI, although the association was not statistically significant after further adjusting for multiple confounding factors. Nevertheless, these prospective data generally support current dietary recommendations to increase the consumption of fiber-rich whole grains and fruits and vegetables as a primary preventive measure against CVD.