Ambika Satija

Long-Term Coffee Consumption and Risk of Cardiovascular Disease A Systematic Review and a Dose–Response Meta-Analysis of Prospective Cohort Studies

Background— Considerable controversy exists on the association between coffee consumption and cardiovascular disease (CVD) risk. A meta-analysis was performed to assess the dose–response relationship of long-term coffee consumption with CVD risk. Methods and Results— PubMed and EMBASE were searched for prospective cohort studies of the relationship between coffee consumption and CVD risk, which included coronary heart disease, stroke, heart failure, and CVD mortality. Thirty-six studies were included with 1 279 804 participants and 36 352 CVD cases. A nonlinear relationship of coffee consumption with CVD risk was identified (P for heterogeneity=0.09, P for trend <0.001, P for nonlinearity <0.001). Compared with the lowest category of coffee consumption (median, 0 cups per day), the relative risk of CVD was 0.95 (95% confidence interval, 0.87–1.03) for the highest category (median, 5 cups per day) category, 0.85 (95% confidence interval, 0.80–0.90) for the second highest category (median, 3.5 cups per day), and 0.89 (95% confidence interval, 0.84–0.94) for the third highest category (median, 1.5 cups per day). Looking at separate outcomes, coffee consumption was nonlinearly associated with both coronary heart disease (P for heterogeneity=0.001, P for trend <0.001, P for nonlinearity <0.001) and stroke (P for heterogeneity=0.07, P for trend <0.001, P for nonlinearity <0.001; P for trend differences >0.05) risks. Conclusions— A nonlinear association between coffee consumption and CVD risk was observed in this meta-analysis. Moderate coffee consumption was inversely significantly associated with CVD risk, with the lowest CVD risk at 3 to 5 cups per day, and heavy coffee consumption was not associated with elevated CVD risk.

Understanding Nutritional Epidemiology and Its Role in Policy

Nutritional epidemiology has recently been criticized on several fronts, including the inability to measure diet accurately, and for its reliance on observational studies to address etiologic questions. In addition, several recent meta-analyses with serious methodologic flaws have arrived at erroneous or misleading conclusions, reigniting controversy over formerly settled debates. All of this has raised questions regarding the ability of nutritional epidemiologic studies to inform policy. These criticisms, to a large degree, stem from a misunderstanding of the methodologic issues of the field and the inappropriate use of the drug trial paradigm in nutrition research. The exposure of interest in nutritional epidemiology is human diet, which is a complex system of interacting components that cumulatively affect health. Consequently, nutritional epidemiology constantly faces a unique set of challenges and continually develops specific methodologies to address these. Misunderstanding these issues can lead to the nonconstructive and sometimes naive criticisms we see today. This article aims to clarify common misunderstandings of nutritional epidemiology, address challenges to the field, and discuss the utility of nutritional science in guiding policy by focusing on 5 broad questions commonly asked of the field.

Cardiovascular Benefits of Dietary Fiber

The relationship between dietary fiber and risk of cardiovascular disease (CVD) has been extensively studied. There is considerable epidemiological evidence indicating an inverse association between dietary fiber intake and CVD risk. The association has been found to be stronger for cereal fiber than for fruit or vegetable fiber, and several studies have also found increased whole grain consumption to be associated with CVD risk reduction. In light of this evidence, recent US dietary guidelines have endorsed increased consumption of fiber rich whole grains. Regular consumption of dietary fiber, particularly fiber from cereal sources, may improve CVD health through multiple mechanisms including lipid reduction, body weight regulation, improved glucose metabolism, blood pressure control, and reduction of chronic inflammation. Future research should focus on various food sources of fiber, including different types of whole grains, legumes, fruits, vegetables, and nuts, as well as resistant starch in relation to CVD risk and weight control; explore the biological mechanisms underlying the cardioprotective effect of fiber-rich diets; and study different ethnic groups and populations with varying sources of dietary fiber.

Association of Coffee Consumption With Total and Cause-Specific Mortality in 3 Large Prospective Cohorts.

Background— The association between consumption of caffeinated and decaffeinated coffee and risk of mortality remains inconclusive. Methods and Results— We examined the associations of consumption of total, caffeinated, and decaffeinated coffee with risk of subsequent total and cause-specific mortality among 74 890 women in the Nurses’ Health Study (NHS), 93 054 women in the Nurses’ Health Study II, and 40 557 men in the Health Professionals Follow-up Study. Coffee consumption was assessed at baseline using a semiquantitative food frequency questionnaire. During 4 690 072 person-years of follow-up, 19 524 women and 12 432 men died. Consumption of total, caffeinated, and decaffeinated coffee were nonlinearly associated with mortality. Compared with nondrinkers, coffee consumption of 1 to 5 cups per day was associated with lower risk of mortality, whereas coffee consumption of more than 5 cups per day was not associated with risk of mortality. However, when restricting to never smokers compared with nondrinkers, the hazard ratios (and 95% confidence intervals) of mortality were 0.94 (0.89–0.99) for 1.0 or less cup per day, 0.92 (0.87–0.97) for 1.1 to 3.0 cups per day, 0.85 (0.79–0.92) for 3.1 to 5.0 cup per day, and 0.88 (0.78–0.99) for more than 5.0 cup per day (P value for nonlinearity = 0.32; P value for trend < 0.001). Significant inverse associations were observed for caffeinated (P value for trend < 0.001) and decaffeinated coffee (P value for trend = 0.022). Significant inverse associations were observed between coffee consumption and deaths attributed to cardiovascular disease, neurologic diseases, and suicide. No significant association between coffee consumption and total cancer mortality was found. Conclusions— Higher consumption of total coffee, caffeinated coffee, and decaffeinated coffee was associated with lower risk of total mortality.

Plant-Based Dietary Patterns and Incidence of Type 2 Diabetes in US Men and Women: Results from Three Prospective Cohort Studies

Background Plant-based diets have been recommended to reduce the risk of type 2 diabetes (T2D). However, not all plant foods are necessarily beneficial. We examined the association of an overall plant-based diet and hypothesized healthful and unhealthful versions of a plant-based diet with T2D incidence in three prospective cohort studies in the US. Methods and Findings We included 69,949 women from the Nurses’ Health Study (1984–2012), 90,239 women from the Nurses’ Health Study 2 (1991–2011), and 40,539 men from the Health Professionals Follow-Up Study (1986–2010), free of chronic diseases at baseline. Dietary data were collected every 2–4 y using a semi-quantitative food frequency questionnaire. Using these data, we created an overall plant-based diet index (PDI), where plant foods received positive scores, while animal foods (animal fats, dairy, eggs, fish/seafood, poultry/red meat, miscellaneous animal-based foods) received reverse scores. We also created a healthful plant-based diet index (hPDI), where healthy plant foods (whole grains, fruits, vegetables, nuts, legumes, vegetable oils, tea/coffee) received positive scores, while less healthy plant foods (fruit juices, sweetened beverages, refined grains, potatoes, sweets/desserts) and animal foods received reverse scores. Lastly, we created an unhealthful plant-based diet index (uPDI) by assigning positive scores to less healthy plant foods and reverse scores to healthy plant foods and animal foods. We documented 16,162 incident T2D cases during 4,102,369 person-years of follow-up. In pooled multivariable-adjusted analysis, both PDI and hPDI were inversely associated with T2D (PDI: hazard ratio [HR] for extreme deciles 0.51, 95% CI 0.47–0.55, p trend < 0.001; hPDI: HR for extreme deciles 0.55, 95% CI 0.51–0.59, p trend < 0.001). The association of T2D with PDI was considerably attenuated when we additionally adjusted for body mass index (BMI) categories (HR 0.80, 95% CI 0.74–0.87, p trend < 0.001), while that with hPDI remained largely unchanged (HR 0.66, 95% CI 0.61–0.72, p trend < 0.001). uPDI was positively associated with T2D even after BMI adjustment (HR for extreme deciles 1.16, 95% CI 1.08–1.25, p trend < 0.001). Limitations of the study include self-reported diet assessment, with the possibility of measurement error, and the potential for residual or unmeasured confounding given the observational nature of the study design. Conclusions Our study suggests that plant-based diets, especially when rich in high-quality plant foods, are associated with substantially lower risk of developing T2D. This supports current recommendations to shift to diets rich in healthy plant foods, with lower intake of less healthy plant and animal foods.

Foods, Nutrients, and Dietary Patterns: Interconnections and Implications for Dietary Guidelines

Dietary guidelines provide evidence-based statements on food choices to meet nutritional requirements and reduce the risk of prevailing chronic disease. They involve a substantial amount of research translation, and their implementation has important health consequences. Foods, however, are complex combinations of nutrients and other compounds that act synergistically within the food and across food combinations. In addition, the evidence base underpinning dietary guidelines accesses research that reflects different study designs, with inherent strengths and limitations. We propose a systematic approach for the review of evidence that begins with research on dietary patterns. This research will identify the combinations of foods that best protect, or appear deleterious to, health. Next, we suggest that evidence be sought from research that focuses on the effects of individual foods. Finally, nutrient-based research should be considered to explain the mechanisms by which these foods and dietary patterns exert their effects, take into account the effects of ingredients added to the food supply, and enable assessments of dietary sufficiency. The consideration of individual nutrients and food components (e.g., upper limits for saturated fat, added sugar, and sodium) provides important benchmarks for evaluating overall diet quality. The concepts of core and discretionary foods (nutrient-rich and nutrient-poor foods, respectively) enable distinctions between foods, and this has implications for the relation between food policy and food manufacturing. In summary, evidence supporting healthy dietary patterns provides the foundation for the development of dietary guidelines. Further reference to individual foods and nutrients follows from the foundation of healthy dietary patterns.

Curbing the Diabetes Pandemic: The Need for Global Policy Solutions.

disease of the affluent, with lower socioeconomic groups being disproportionately affected in high-income countries and with 77% of the world’s diabetic population living in low- and middle-income countries. It is also no longer predominantly a disease of older persons, with almost half of the people with diabetes in the 40- to 59-year age range. Low- and middle-income countries face the added challenge of dealing with a dual burden of disease, as they are seeing an increase in obesity and diabetes levels, while still grappling with undernutrition and infectious diseases. 3 In 2013, diabetes was associated with US

Fruit and Vegetable Consumption and the Incidence of Hypertension in Three Prospective Cohort Studies

548 billion in health care expenditures globally. 1 This figure is

Type 2 diabetes and risk of cancer

Increased fruit and vegetable intake lowers blood pressure in short-term interventional studies. However, data on the association of long-term intake of fruits and vegetables with hypertension risk are scarce. We prospectively examined the independent association of whole fruit (excluding juices) and vegetable intake, as well as the change in consumption of whole fruits and vegetables, with incident hypertension in 3 large longitudinal cohort studies: Nurses’ Health Study (n=62 175), Nurses’ Health Study II (n=88 475), and Health Professionals Follow-up Study (n=36 803). We calculated hazard ratios and 95% confidence intervals for fruit and vegetable consumption while controlling for hypertension risk factors. Compared with participants whose consumption was ⩽4 servings/week, the pooled hazard ratios among those whose intake was ≥4 servings/day were 0.92(0.87–0.97) for total whole fruit intake and 0.95(0.86–1.04) for total vegetable intake. Similarly, compared with participants who did not increase their fruit or vegetable consumption, the pooled hazard ratios for those whose intake increased by ≥7 servings/week were 0.94(0.90–0.97) for total whole fruit intake and 0.98(0.94–1.01) for total vegetable. Analyses of individual fruits and vegetables yielded different results. Consumption levels of ≥4 servings/week (as opposed to <1 serving/month) of broccoli, carrots, tofu or soybeans, raisins, and apples was associated with lower hypertension risk. In conclusion, our results suggest that greater long-term intake and increased consumption of whole fruits may reduce the risk of developing hypertension.

Long-term intake of animal flesh and risk of developing hypertension in three prospective cohort studies.

Strong evidence points to an association between diabetes and several major cancers