1.
Relationship between dietary carbohydrates intake and circulating sex hormone-binding globulin levels in postmenopausal women.
Huang, M, Liu, J, Lin, X, Goto, A, Song, Y, Tinker, LF, Chan, KK, Liu, S
Journal of diabetes. 2018;(6):467-477
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Abstract
BACKGROUND Low circulating levels of sex hormone-binding globulin (SHBG) have been shown to be a direct and strong risk factor for type 2 diabetes, cardiovascular diseases, and hormone-dependent cancers, although the relationship between various aspects of dietary carbohydrates and SHBG levels remains unexplored in population studies. METHODS Among postmenopausal women with available SHBG measurements at baseline (n = 11 159) in the Women's Health Initiative, a comprehensive assessment was conducted of total dietary carbohydrates, glycemic load (GL), glycemic index (GI), fiber, sugar, and various carbohydrate-abundant foods in relation to circulating SHBG levels using multiple linear regressions adjusting for potential covariates. Linear trend was tested across quartiles of dietary variables. Benjamini and Hochberg's procedure was used to calculate the false discovery rate for multiple comparisons. RESULTS Higher dietary GL and GI (both based on total and available carbohydrates) and a higher intake of sugar and sugar-sweetened beverages were associated with lower circulating SHBG concentrations (all P trend < 0.05; Q -values = 0.04,0.01, 0.07, 0.10, 0.01, and <0.0001, respectively). In contrast, women with a greater intake of dietary fiber tended to have elevated SHBG levels (P trend = 0.01, Q -value = 0.04). There was no significant association between total carbohydrates or other carbohydrate-abundant foods and SHBG concentrations. CONCLUSIONS The findings suggest that low GL or GI diets with low sugar and high fiber content may be associated with higher serum SHBG concentrations among postmenopausal women. Future studies investigating whether lower GL or GI diets increase SHBG concentrations are warranted.
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Dietary glycemic load and atherothrombotic risk.
Liu, S, Willett, WC
Current atherosclerosis reports. 2002;(6):454-61
Abstract
Hyperglycemia and hyperinsulinemia are central features of the metabolic syndrome and type 2 diabetes mellitus, which contribute to the pathogenesis of coronary heart disease (CHD). Recent data indicate that increased dietary glycemic load (GL) due to replacing fats with carbohydrates or increasing intake of rapidly absorbed carbohydrates (ie, high glycemic index) can create a self-perpetuating insulin resistance state and predicts greater CHD risk. In this paper, we discuss the historic development of the GI and GL concepts and summarize metabolic experiments and epidemiologic observations relating to clinical utilities of these measures. On balance, increased consumption of low-GI foods leads to improvements in glycemia and dyslipidemia in metabolic studies, and a low-GL diet has been associated with lower risk of type 2 diabetes and CHD in prospective cohort studies. We conclude that decreasing dietary GL by reducing the intake of high-glycemic beverages and replacing refined grain products and potatoes with minimally processed plant-based foods such as whole grains, fruits, and vegetables may reduce CHD incidence in sedentary individuals and populations with a high prevalence of overweight. Because of advances in food-processing technologies and changes in ingredients in our food supply, the composition and physiologic effects of foods are likely to change over time. Future efforts should continue to quantify and monitor the metabolic impacts of different foods, and such information should be routinely incorporated into long-term prospective studies to allow for the assessment of the interactive effects of diets and other metabolic determinants on chronic disease risk.
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Intake of refined carbohydrates and whole grain foods in relation to risk of type 2 diabetes mellitus and coronary heart disease.
Liu, S
Journal of the American College of Nutrition. 2002;(4):298-306
Abstract
Recent survey data indicate that more than 50% of all adult Americans are overweight or obese. In parallel with this epidemic of weight gain in the general population, the incidence rate of type 2 diabetes mellitus (DM) is rapidly rising. Although their precise contributions are unclear, dietary factors are thought to affect body weight and the development of insulin resistance. Recent epidemiological data indicate that diets rich in high-fiber whole grains are associated with lower risk of coronary heart disease (CHD) and type 2 DM. These data are consistent with results from recent metabolic experiments, suggesting favorable lipid profiles and glycemic control associated with higher intake of whole grains, but not with refined grains. It seems prudent, therefore, to distinguish whole-grain rather than refined-grain cereal products for the prevention of chronic diseases.
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Dietary carbohydrates, physical inactivity, obesity, and the 'metabolic syndrome' as predictors of coronary heart disease.
Liu, S, Manson, JE
Current opinion in lipidology. 2001;(4):395-404
Abstract
Several decades of epidemiological and clinical research have identified physical inactivity, excessive calorie consumption, and excess weight as common risk factors for both type 2 diabetes mellitus and coronary heart disease. This trio forms the environmental substrate for a now well-recognized metabolic phenotype called the insulin resistance syndrome. Recent data suggest that a high intake of rapidly absorbed carbohydrates, which is characterized by a high glycemic load (a measure of carbohydrate quality and quantity), may increase the risk of coronary heart disease by aggravating glucose intolerance and dyslipidemia. These data also suggest that individuals who are obese and insulin resistant are particularly prone to the adverse effects of a high dietary glycemic load. In addition, data continue to accumulate suggesting the important beneficial effects of physical activity, even at moderate levels, and weight reduction on improving insulin sensitivity and reducing the risk of coronary heart disease. Future metabolic studies should continue to quantify the physiological impact of different foods on serum glucose and insulin, and such information should routinely be incorporated into large-scale and long-term prospective studies, in which the possible interaction effects between diet and other metabolic determinants such as physical activity and obesity can be examined. Until more definitive data are available, replacing refined grain products and potatoes with minimally processed plant-based foods such as whole grains, fruits, and vegetables, and reducing the intake of high glycemic load beverages may offer a simple strategy for reducing the incidence of coronary heart disease.