Coffee intake and risk of type 2 diabetes: the Multiethnic Cohort

Risk Factors for Type 2 Diabetes in the Multiethnic Cohort

OBJECTIVES

In this report, we investigated the association between established risk factors and type 2 diabetes (T2D) across 5 distinct ethnic groups and explored differences according to T2D definition within the Multiethnic Cohort (MEC) Study.

METHODS

Using the full MEC, with participants in Hawaii and Los Angeles (N=172,230), we applied Cox regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). All participants completed questionnaires asking about demographics, anthropometrics, lifestyle factors, and regular diet. T2D status was determined from self-reported diagnosis/medication and Medicare claims. We assessed the associations between well-established risk factors and T2D in the full cohort, after stratification by ethnic group, according to the T2D definition, and in a biorepository subset. Effect modification by ethnicity was evaluated using Wald's tests.

RESULTS

Overall, 46,500 (27%) participants had an incident T2D diagnosis after a mean follow-up of 17.1±6.9 years. All predictors were significantly associated with T2D: overweight (HR=1.74), obesity (HR=2.90), red meat intake (HR=1.15), short (HR=1.04) and long (HR=1.08) sleep duration, and smoking (HR=1.26) predicted a significantly higher T2D incidence, whereas coffee (HR=0.90) and alcohol (HR=0.78) consumption, physical activity (HR=0.89), and diet quality (HR=0.96) were associated with lower T2D incidence. The strength of these associations was similar across ethnic groups with noteworthy disparities for overweight/obesity, physical activity, alcohol intake, coffee consumption, and diet quality.

CONCLUSIONS

These findings confirm the importance of known risk factors for T2D across ethnic groups, but small differences were detected that may contribute to disparate incidence rates in some ethnic groups, especially for obesity and physical activity.

Medium Roasting and Brewing Methods Differentially Modulate Global Metabolites, Lipids, Biogenic Amines, Minerals, and Antioxidant Capacity of Hawai'i-Grown Coffee (Coffea arabica)

In the United States, besides the US territory Puerto Rico, Hawai'i is the only state that grows commercial coffee. In Hawai'i, coffee is the second most valuable agricultural commodity. Health benefits associated with moderate coffee consumption, including its antioxidant capacity, have been correlated to its bioactive components. Post-harvest techniques, coffee variety, degree of roasting, and brewing methods significantly impact the metabolites, lipids, minerals, and/or antioxidant capacity of brewed coffees. The goal of our study was to understand the impact of roasting and brewing methods on metabolites, lipids, biogenic amines, minerals, and antioxidant capacity of two Hawai'i-grown coffee (Coffea arabica) varieties, "Kona Typica" and "Yellow Catuai". Our results indicated that both roasting and coffee variety significantly modulated several metabolites, lipids, and biogenic amines of the coffee brews. Furthermore, regardless of coffee variety, the antioxidant capacity of roasted coffee brews was higher in cold brews. Similarly, total minerals were higher in "Kona Typica" cold brews followed by "Yellow Catuai" cold brews. Hawai'i-grown coffees are considered "specialty coffees" since they are grown in unique volcanic soils and tropical microclimates with unique flavors. Our studies indicate that both Hawai'i-grown coffees contain several health-promoting components. However, future studies are warranted to compare Hawai'i-grown coffees with other popular brand coffees and their health benefits in vivo.

Coffee consumption and diabetic retinopathy in adults with diabetes mellitus

We aimed to evaluate the association between the prevalence of diabetic retinopathy (DR) and coffee consumption in a Korean population. This cross-sectional study was based on data from the 2008–2011 Korean National Health and Nutrition Survey. Among 37,753 survey participants, the data of 1350 subjects with type 2 diabetes who underwent DR examination were analyzed. DR was graded using the modified Airlie House classification system. Coffee consumption data were obtained through food frequency questionnaires and categorized into four groups: almost none, < 1 cup/day, 1 cup/day, and ≥ 2 cups/day. The relationship between DR and coffee consumption was evaluated using multivariable logistic regression models adjusted for age, sex, education, occupation, income, smoking, alcohol intake, body mass index, physical activity, hypertension, dyslipidemia, diabetes duration, and glycated hemoglobin. The prevalence of DR was 20.0%. Non-proliferative DR was observed in 87.8% of all DR patients, and proliferative DR in 12.2%. The prevalence of DR and vision-threatening DR showed a significantly decreasing tendency according to daily coffee consumption (P for trend 0.025 and 0.005, respectively) after adjustment for possible confounders. This tendency was more prominent in those aged < 65 years (P for trend 0.005 and 0.003, respectively). Our findings suggest coffee consumption might be associated with DR reduction especially in Koreans with diabetes mellitus aged < 65 years.

Coffee and type 2 diabetes risk: Is the association mediated by adiponectin, leptin, c-reactive protein or Interleukin-6? A systematic review and meta-analysis

AIM

Coffee and diabetes risk association has been demonstrated in numerous studies; however, the exact mechanism has not been clarified yet. The present meta-analysis was conducted to cover the current knowledge regarding the effect of coffee on Type 2 Diabetes (T2D), in addition to the evaluation of adiponectin, leptin, C-reactive protein (CRP) and Interleukin-6 (IL-6) levels among coffee consumers as relatively possible mediators of this effect.

METHOD

A comprehensive search of the literature was carried out using search engines up to March 2020. The effect sizes were investigated using the standardised mean difference (SMD) and odds ratios (OR) or relative risk (RR) with its 95% confidence interval (CI). A total of 69 cross-sectional and cohort studies were included and divided as follows: 31 articles for T2D risk, 15 studies for adiponectin, 6 studies for leptin, 12 studies for CRP and 5 studies for IL-6.

RESULTS

Overall, coffee consumption was inversely associated with T2D risk with an estimated pooled RR of 0.73 (95% confidence interval [0.68, 0.80] for the highest vs lowest coffee consumption categories. The combined SMD between the different coffee intake categories, showed that coffee consumption was associated with higher adiponectin levels (P = .002), and lower level of leptin (P = .04) and CRP (P = .2), with apparently no change in IL-6 levels (P = .91).

CONCLUSION

The present meta-analysis showed strong epidemiological evidence that coffee consumption is inversely associated with the risk of T2D. Also, adiponectin, leptin concentrations appeared to be potential mediators of the coffee effect on diabetes, while IL-6 levels did not.

Caffeinated Coffee Consumption and Health Outcomes in the US Population: A Dose-Response Meta-Analysis and Estimation of Disease Cases and Deaths Avoided

To explore the role of coffee on health outcomes in the United States, where coffee consumption is common, we conducted a meta-analysis of prospective studies investigating the magnitude (any compared with no consumption) and the dose-response shape (cups per day) of the associations between caffeinated coffee consumption and incidence/mortality of cardiovascular disease (CVD), as well as incidence of type 2 diabetes (T2D), hepatocellular carcinoma (HCC), endometrial cancer, melanoma, and nonmelanoma skin cancer. We selected the desirable health outcomes that have been shown to be positively associated with coffee consumption. Studies were identified by searching PubMed/Embase databases up to September 2019. Inclusion criteria included prospective studies that investigated the relation of ≥3 categories of caffeinated coffee consumption and the outcomes of interest. Twenty-six studies (42 distinct cohorts), with 93,706 cases/deaths and 3,713,932 participants, met the inclusion criteria. In any coffee consumers, there was a significant inverse association with the risk of CVD (RR = 0.90; 95% CI: 0.84, 0.96), T2D (RR = 0.90; 95% CI: 0.85, 0.96), endometrial cancer (RR = 0.85; 95% CI: 0.78, 0.92), melanoma (RR = 0.89; 95% CI: 0.80, 0.99), and nonmelanoma skin cancer (RR = 0.92; 95% CI: 0.89, 0.95). Coffee consumption was also inversely associated with HCC (RR = 0.93; 95% CI: 0.80, 1.08), without reaching statistical significance. The dose-response relation was nonlinear uniquely for CVD (P-nonlinearity = 0.01). In particular, the largest risk reduction was observed for 3-4 cups/d (∼120 mL/cup) and no reduction thereafter. For other outcomes, the risk decreased linearly over the whole coffee consumption range. Current patterns of consumption in the United States would account for a fraction of avoided cases/deaths ranging from 6% to 12% according to the outcome considered. This study confirms the beneficial health effects of caffeinated coffee consumption in the US population on the health outcomes considered, and quantifies their possible magnitude.

Prospective study of a diabetes risk reduction diet and the risk of breast cancer

BACKGROUND

Hyperinsulinemia and higher insulin-like growth factors may increase breast cancer risk. We evaluated a diabetes risk reduction diet (DRRD) and breast cancer risk.

OBJECTIVES

We prospectively evaluated the association between adherence to a DRRD and the incidence of breast cancer.

METHODS

We followed 88,739 women from the Nurses' Health Study (NHS; 1980-2016) and 93,915 women from the NHSII (1991-2017). Incident breast cancer cases (n = 11,943) were confirmed with medical records, and subtypes were determined by tissue microarray data and pathology reports. Information on diet and breast cancer risk factors was repeatedly ascertained in follow-up questionnaires. A DRRD score was derived with 9 factors: lower glycemic index of diet; lower intakes of trans fat, sugar-sweetened beverages/fruit juices, and red/processed meat; higher intakes of cereal fiber, coffee, nuts, and whole fruits; and a higher ratio of polyunsaturated to saturated fat (score range: 9-45). Multivariable-adjusted hazard ratios (MVHRs) and 95% CIs were calculated with Cox proportional hazards models.

RESULTS

Being in the highest compared with the lowest DRRD adherence quintile was associated with a modestly lower breast cancer risk (MVHRQ5vsQ1: 0.89; 95% CI: 0.84, 0.95; P-trend = 0.0002); this was attenuated after adjusting for weight change since age 18 y (MVHRQ5vsQ1: 0.92; 95% CI: 0.87, 0.98; P-trend = 0.01). The inverse association was strongest among women with current BMI < 25 kg/m2 (MVHRQ5vsQ1: 0.89; 95% CI: 0.81, 0.98; P-trend = 0.004; P-interaction = 0.04). Among tumor molecular subtypes, the strongest inverse association was observed with basal-type tumors (MVHRQ5vsQ1: 0.67; 95% CI: 0.45, 1.01; P-trend = 0.04).

CONCLUSIONS

Greater DRRD-adherence was associated with lower breast cancer risk, likely mediated by less weight gain with a DRRD; however, independently of weight change, DRRD-adherence was modestly associated with lower breast cancer risk, particularly among lean women.

Inter-Individual Variation in Cancer and Cardiometabolic Health Outcomes in Response to Coffee Consumption: A Critical Review

SCOPE

Coffee is associated with a lower risk of cancer, cardiovascular disease, and type 2 diabetes at the population level. However, individual susceptibility to the effects of coffee consumption will cause heterogeneity in health responses between individuals. In this critical review determinants of inter-individual variability in cancer and cardiometabolic health outcomes in response to coffee and caffeine consumption are systematically evaluated.

METHODS AND RESULTS

Embase and MEDLINE are searched for observational studies and clinical trials that examined variation in the response to coffee consumption. A total of 74 studies meet the inclusion criteria, which report variation in cancer (n = 24) and cardiometabolic health (n = 50) outcomes. The qualitative analysis shows that sex, BMI, smoking, alcohol intake, menopausal status, and genetic polymorphisms are probable or possible determinants of inter-individual variability in cancer and cardiometabolic health outcomes in response to coffee and caffeine consumption, albeit the majority of studies have insufficient statistical power to detect significant interaction between these factors and coffee consumption.

CONCLUSION

Several genetic and non-genetic determinants of inter-individual variability in the responses to coffee and caffeine consumption are identified, indicating that some of the health benefits of coffee may only occur in a subgroup of subjects.

Caffeine Consumption through Coffee: Content in the Beverage, Metabolism, Health Benefits and Risks

Caffeine (1,3,7-trimethylxanthine) is the most consumed psychoactive substance in the world, acting by means of antagonism to adenosine receptors, mainly A1 and A2A. Coffee is the main natural source of the alkaloid which is quite soluble and well extracted during the brew’s preparation. After consumption, caffeine is almost completely absorbed and extensively metabolized in the liver by phase I (cytochrome P450) enzymes, mainly CYP1A2, which appears to be polymorphically distributed in human populations. Paraxanthine is the major caffeine metabolite in plasma, while methylated xanthines and methyluric acids are the main metabolites excreted in urine. In addition to stimulating the central nervous system, caffeine exerts positive effects in the body, often in association with other substances, contributing to prevention of several chronic diseases. The potential adverse effects of caffeine have also been extensively studied in animal species and in humans. These aspects will be approached in the present review.

Coffee consumption is positively related to insulin secretion in the Shanghai High-Risk Diabetic Screen (SHiDS) Study

Background

It has been proved that coffee consumption was associated with a lower risk of type 2 diabetes mellitus. But the benefit effect of coffee on hyperglycemia in Chinese population was largely unknown. Besides, the relationship of coffee intake and diabetic pathogenesis was still unclear.

Methods

The study population was selected from the Shanghai High-Risk Diabetic Screen (SHiDS) project. A total of 1328 individuals over 18 years of age who have the information of coffee intake were enrolled in the study from 2012 to 2016. Each participant finished a five-point 75 g oral glucose tolerance test and finished a standard questionnaire. Insulin resistance was evaluated by HOMA-IR and insulin secretion was evaluated by HOMA-β, Stumvoll first phase and second phase indexes.

Results

Coffee consumption group had lower plasma glucose levels at 2-h and 3-h and higher insulin levels at fasting, 30-min and 1-h during OGTT after adjustment with age, fat%, BMI, waist, tea intake, smoking habit, alcohol intake, diabetes family history and educational status (P for PG2h = 0.002; P for PG3h = 0.010; P for FIN = 0.010; P for IN30min = 0.001; P for IN1h = 0.002). Both HOMA-β and Stumvoll formula indexes were positively related to coffee consumption (P for HOMA-β = 0.033; P for Stumvoll first phase = 0.003; P for Stumvoll second phase = 0.001). Logistic regression analysis further confirmed that coffee intake was independently associated with higher levels of HOMA-β and Stumvoll insulin secretion indexes [OR (95% CI) for HOMA-β = 2.270 (1.456–3.538); OR (95% CI) for Stumvoll first phase = 2.071 (1.352–3.173); OR (95% CI) for Stumvoll second phase = 1.914 (1.260–2.906)].

Conclusions

Coffee intake is independently and positively related to pancreatic beta cell function in a large high-risk diabetic Chinese population.

Lack of Association of Coffee Consumption with the Prevalence of Self-Reported Type 2 Diabetes Mellitus in a Mexican Population: A Cross-Sectional Study

It is estimated that almost 366 million people are currently suffering from diabetes mellitus worldwide. However, it has been suggested that coffee consumption has a protective effect against the development of type 2 diabetes mellitus. This association has been observed in many regions around the world. Today, there are no reports in Mexico regarding this association. Therefore, the aim of this study was to assess the association between coffee intake and self-reported type 2 diabetes mellitus in the southeastern part of Mexico. This study included 1277 residents of Comalcalco, a municipality of Tabasco State, Mexico. We calculated the prevalence for diabetes and performed multivariate analysis using multiple logistic regressions to evaluate the combined association with type 2 diabetes mellitus. The prevalence of the diabetes was 12.52% (95% CI: 10.67⁻14.38). The majority of people surveyed (77.29%; 95% CI: 74.95⁻79.60) indicated they were coffee drinkers. The results of multivariate analysis showed a non-significant relationship between the number of cups of coffee drank and type 2 diabetes mellitus. The adjusted odds ratio gave the following values: 1.20, (95% CI: 0.59⁻2.41) for non-daily consumption; 1.66 (0.82⁻3.34), for 1 cup of coffee peer day, and 1.49 (0.78⁻2.86) for 2⁻3 cups. Subsequently, an adjustment was made for age, gender, marital status, education, alcohol consumption, and cigarette smoking. In our population, we did not observe an association between coffee intake and its protective relationship with self-reported type 2 diabetes mellitus.

Intake of cocoa products and risk of type-2 diabetes: the multiethnic cohort

BACKGROUND/OBJECTIVES

As cocoa products may be protective against chronic disease due to their polyphenol content, the current study determined the association of chocolate consumption and flavanol intake with type-2 diabetes (T2D) incidence in the Multiethnic Cohort (MEC) Study.

SUBJECTS/METHODS

The analysis included 151,691 participants of Native Hawaiian, Japanese American, Latino, African American, and white ancestry with 8487 incident T2D cases after 7.8 ± 3.5 years of follow-up. T2D status was based on three self-reports and confirmed by at least one of three administrative data sources. Dietary intake was assessed using a validated quantitative food frequency questionnaire, and flavanols from cocoa products were estimated from self-reported consumption of chocolate candy and drinks. Cox hazard regression, adjusted for potential confounders was applied to estimate hazard ratios (HR) and 95% confidence intervals (CI).

RESULTS

For chocolate candy, both the highest vs. lowest (≥10 vs. <1 g/day) consumption (HR = 0.90; 95% CI, 0.83-0.97; p_trend = 0.01) and the frequency (≥4/week vs. <1/month) of intake (HR = 0.81; 95% CI, 0.72-0.91; p_trend = 0.0002) were inversely associated with T2D. The estimated flavanol intake from cocoa products (≥3 vs. <1 mg/day) also showed an inverse association with T2D risk (HR = 0.93; 95% CI, 0.88-0.99; p_trend = 0.02). Significant interaction terms indicated that the inverse relation was limited to Japanese Americans, normal-weight individuals, and to those without comorbidities.

CONCLUSIONS

The current study confirms previous reports that participants with high intake of chocolate products and cocoa-derived flavanols experience a reduced risk of developing T2D even after controlling for sugar intake, diet quality, and other aspects of the diet.

Sleep duration and incidence of type 2 diabetes: the Multiethnic Cohort

OBJECTIVES

As an emerging risk factor for the rising incidence of type 2 diabetes, we examined sleep duration in relation to type 2 diabetes and several biomarkers.

DESIGN

Prospective cohort recruited 1993-1996.

SETTING

The Multiethnic Cohort in Hawaii and California.

PARTICIPANTS

A cohort of 151,691 White, African American, Japanese American, Native Hawaiian, and Latino participants; 9695 cohort members had biomarker measurements.

MEASUREMENTS

Sleep duration was self-reported at cohort entry. Diabetes status was obtained from 3 questionnaires and confirmed by 3 administrative data sources. Biomarkers were measured by standard assays 9.6±2.1 years after cohort entry. We estimated diabetes risk as a time-varying outcome using Cox regression adjusted for body mass index assessed at 3 time points and other known confounders and computed adjusted means of biomarkers by sleep hours.

RESULTS

During 7.9±3.5 years of follow-up, 8487 new diabetes cases were diagnosed. Long sleep duration (≥9 hours), as compared with 7-8 hours, was significantly associated with higher incidence (hazard ratio, 1.12; 95% confidence interval 1.04-1.21), but the 4% elevated incidence for short sleep duration (≤6 hours) did not reach significance (95% confidence interval 0.99-1.09). After stratification, the associations appeared stronger in Japanese American than other ethnic groups and in participants without comorbidity. Hours of sleep were positively associated with C-reactive protein and triglycerides and inversely related to high-density lipoprotein cholesterol and adiponectin but not with leptin levels and homeostatic model assessment of insulin resistance.

CONCLUSION

In this multiethnic population, the 12% higher diabetes risk for long sleep hours may be mediated through inflammation, a poor lipid profile, and lower adiponectin levels.

Systematic Review and Meta-analysis of the Effects of Caffeine in Fatigued Shift Workers: Implications for Emergency Medical Services Personnel

BACKGROUND

Emergency Medical Services (EMS) workers may experience fatigue as a consequence of shift work. We reviewed the literature to determine the impact of caffeine as a countermeasure to fatigue in EMS personnel and related shift workers.

METHODS

We employed the GRADE methodology to perform a systematic literature review and search multiple databases for research that examined the impact of caffeine on outcomes of interest, such as patient and EMS personnel safety. For selected outcomes, we performed a meta-analysis of pooled data and reported the pooled effect in the form of a Standardized Mean Difference (SMD) with corresponding 95% confidence intervals.

RESULTS

There are no studies that investigate caffeine use and its effects on EMS workers or on patient safety. Four of 8 studies in shift workers showed that caffeine improved psychomotor vigilance, which is important for performance. Caffeine decreased the number of lapses on a standardized test of performance [SMD = 0.75 (95% CI: 0.30 to 1.19), p = 0.001], and lessened the slowing of reaction time at the end of shifts [SMD = 0.52 (95% CI: 0.19 to 0.85); p = 0.002]. Finally, 2 studies reported that caffeine reduced sleep quality and sleep duration.

CONCLUSIONS

Although the quality of evidence was judged to be low to moderate, when taken together, these studies demonstrate that caffeine can improve psychomotor performance and vigilance. However, caffeine negatively affects sleep quality and sleep duration. More systematic, randomized studies need to be conducted in EMS workers in order to address the critical outcomes of health and safety of EMS personnel and patients. The risk/benefit ratio of chronic caffeine use in shift workers is currently unknown.

Ethnic admixture affects diabetes risk in native Hawaiians: the Multiethnic Cohort

BACKGROUND/OBJECTIVES

Obesity and diabetes rates are high in Native Hawaiians (NHs) who commonly have mixed ancestries. People of Asian ancestry experience a high risk of type 2 diabetes despite the relatively low body weight. We evaluated the impact of ethnic admixture on diabetes risk among NHs in the Multiethnic Cohort (MEC).

SUBJECTS/METHODS

On the basis of self-reports, 11 521 eligible men and women were categorized into NH/white, NH/other, NH alone, NH/Asian and the most common three ancestry admixture, NH/Chinese/white. Cox proportional hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated with the NH/white category as the reference group; covariates included known confounders-that is, body mass index (BMI), dietary and other lifestyle factors.

RESULTS

The NH alone category had the highest proportion of overweight and obese individuals and the NH/Asian category the lowest proportion. During 12 years of follow-up after cohort entry at 56 years, 2072 incident cases were ascertained through questionnaires and health plan linkages. All NH categories had higher HRs than the NH/white category before and after adjustment for BMI. In the fully adjusted models, the NH/Asian category showed the highest risk (HR=1.45; 95% CI: 1.27-1.65), followed by NH/other (HR=1.20; 95% CI: 1.03-1.39), NH/Chinese/white (HR=1.19; 95% CI: 1.04-1.37) and NH alone (HR=1.19; 95% CI: 1.03-1.37). The elevated risk by Asian admixture was more pronounced in normal weight than overweight/obese individuals.

CONCLUSIONS

These findings indicate that Asian admixture in NHs is associated with a higher risk for type 2 diabetes independent of known risk factors and suggest a role for ethnicity-related genetic factors in the development of this disease.

Are campus food environments healthy? A novel perspective for qualitatively evaluating the nutritional quality of food sold at foodservice facilities at a Brazilian university

Aims:

The purpose of this novel study was to evaluate the food environment at a Brazilian university, encompassing 6 restaurants and 13 snack bars. The investigation uniquely analyses the food environment (barriers, facilitators, type of foods and prices). This was a food-based analysis of the nutritional quality of the products sold on campus.

Methods:

A cross-sectional descriptive design was used, applying the classic Nutrition Environment Measures Survey–Restaurants (NEMS-R) adapted for Brazil and an original methodology to evaluate and classify qualitatively the nutritional quality and characteristics of the food. A census of all campus food environments was applied.

Results:

The main results show most food and beverage products were made with processed ingredients and had a lower nutritional quality and price when compared with similar products made on premises, that is, processed iced tea compared with fresh tea ( p < .001), fried refined flour salgados compared with baked wholegrain flour salgados ( p < .001) and refined flour biscuits compared with those made with whole grains ( p = .028). Only 16% of the outlets provided food ingredients or nutritional information of products available.

Conclusion:

The overall options for healthy food choices and good nutritional quality on campus were mostly limited by the availability and higher prices of products. These findings could be used to develop new policy perspectives for the offering of healthy food items and to facilitate better food choices among students in a healthier food environment.

Whole food approach for type 2 diabetes prevention

Diet is intimately associated with the risk of type 2 diabetes (T2D). Recently, attention has focused on the contributions of individual nutrients, food groups and eating patterns to the outcome of T2D. High consumption of coffee, whole grains, fruits and vegetables, and nuts are each independently associated with the reduced risk of T2D in high risk, glucose intolerant individuals. Experimental and clinical trials have given insight to the diverse mechanisms that may be responsible for the observed protective effects of certain foods on T2D, including nutrients, phytochemicals and dietary fiber, weight control, enhanced satiety and improvement in glucose tolerance and insulin sensitivity in diabetic patients. Elevated consumption of refined grains and sugar-sweetened beverages has shown to significantly elevate the risk of incident T2D. An overall healthy diet primarily comprising whole plant-based foods, together with regular physical activity and weight manage, could significantly reduce the risk of T2D. The present review consolidates current research and delineates major food groups shown to significantly influence risk of T2D. Documenting and quantifying the effects of diet on the outcome of T2D are of great scientific and public health importance as there is urgent need to implement dietary strategies to prevent and manage the outcome of T2D.

Intakes of caffeine, coffee and tea and risk of amyotrophic lateral sclerosis: Results from five cohort studies

Caffeine is thought to be neuroprotective by antagonizing the adenosine A2A receptors in the brain and thereby protecting motor neurons from excitotoxicity. We examined the association between consumption of caffeine, coffee and tea and risk of amyotrophic lateral sclerosis (ALS). Longitudinal analyses based on over 1,010,000 males and females in five large cohort studies (the Nurses' Health Study, the Health Professionals Follow-up Study, the Cancer Prevention Study II Nutrition Cohort, the Multiethnic Cohort Study, and the National Institutes of Health-AARP Diet and Health Study). Cohort-specific multivariable-adjusted risk ratios (RR) and 95% confidence intervals (CI) estimates of ALS incidence or death were estimated by Cox proportional hazards regression and pooled using random-effects models. Results showed that a total of 1279 cases of ALS were documented during a mean of 18 years of follow-up. Caffeine intake was not associated with ALS risk; the pooled multivariable-adjusted RR comparing the highest to the lowest quintile of intake was 0.96 (95% CI 0.81-1.16). Similarly, neither coffee nor tea was associated with ALS risk. In conclusion, the results of this large study do not support associations of caffeine or caffeinated beverages with ALS risk.

A priori-defined diet quality indexes and risk of type 2 diabetes: the Multiethnic Cohort

AIMS/HYPOTHESIS

Dietary patterns have been associated with the incidence of type 2 diabetes, but little is known about the impact of ethnicity on this relationship. This study evaluated the association between four a priori dietary quality indexes and risk of type 2 diabetes among white individuals, Japanese-Americans and Native Hawaiians in the Hawaii component of the Multiethnic Cohort.

METHODS

After excluding participants with prevalent diabetes and missing values, the analysis included 89,185 participants (11,217 cases of type 2 diabetes). Dietary intake was assessed at baseline with a quantitative food frequency questionnaire designed for use in the relevant ethnic populations. Sex- and ethnicity-specific HRs were calculated for the Healthy Eating Index-2010 (HEI-2010), the Alternative HEI-2010 (AHEI-2010), the Alternate Mediterranean Diet Score (aMED) and the Dietary Approaches to Stop Hypertension (DASH).

RESULTS

We observed significant inverse associations between higher DASH index scores and risk of type 2 diabetes in white men and women, as well as in Japanese-American women and Native Hawaiian men, with respective risk reductions of 37%, 31%, 19% and 21% (in the highest compared with the lowest index category). A higher adherence to the AHEI-2010 and aMED diet was related to a 13-28% lower risk of type 2 diabetes in white participants but not in other ethnic groups. No significant associations with risk of type 2 diabetes were observed for the HEI-2010 index.

CONCLUSIONS/INTERPRETATION

The small ethnic differences in risk of type 2 diabetes associated with scores of a priori-defined dietary patterns may be due to a different consumption pattern of food components and the fact that the original indexes were not based on diets typical for Asians and Pacific Islanders.

Circulating irisin levels are not affected by coffee intake: a randomized controlled trial

Irisin, secreted by skeletal muscle and possibly fat, is hypothesized to play an important role in modulating energy expenditure, obesity and metabolism. Coffee consumption also increases energy expenditure and leads to positive metabolic effects, but whether these effects are mediated by irisin remains unknown. The objective of this study was to determine the association between baseline irisin levels and the metabolic profile in humans and to investigate whether consumption of caffeinated coffee alters irisin levels. To this end, a secondary analysis was performed investigating irisin levels at baseline and after eight weeks in 32 healthy, overweight coffee drinkers who were randomized to consumption of 5 cups per day of instant caffeinated coffee, decaffeinated coffee, or water. Spearman correlation and analysis of covariance analyses were performed to identify possible associations. Irisin levels were positively correlated with waist circumference (r = 0.41, p = 0.02), fat mass (r = 0.44, p = 0.01) and CRP (r = 0.47, p = 0.007). Though there was a trend towards increased levels of irisin over time in the caffeinated coffee group (+1.8%) when compared to the placebo group (−4%) this did not reach statistical significance (p = 0.75 for the trend). This first randomized trial failed to reveal any effects of coffee consumption on irisin levels, but a larger trial, appropriately sized on the basis of data provided by this study, is needed to conclusively investigate such a relationship.

Caffeinated and decaffeinated coffee consumption and risk of type 2 diabetes: a systematic review and a dose-response meta-analysis

OBJECTIVE

Previous meta-analyses identified an inverse association of coffee consumption with the risk of type 2 diabetes. However, an updated meta-analysis is needed because new studies comparing the trends of association for caffeinated and decaffeinated coffee have since been published.

RESEARCH DESIGN AND METHODS

PubMed and Embase were searched for cohort or nested case-control studies that assessed the relationship of coffee consumption and risk of type 2 diabetes from 1966 to February 2013. A restricted cubic spline random-effects model was used.

RESULTS

Twenty-eight prospective studies were included in the analysis, with 1,109,272 study participants and 45,335 cases of type 2 diabetes. The follow-up duration ranged from 10 months to 20 years. Compared with no or rare coffee consumption, the relative risk (RR; 95% CI) for diabetes was 0.92 (0.90-0.94), 0.85 (0.82-0.88), 0.79 (0.75-0.83), 0.75 (0.71-0.80), 0.71 (0.65-0.76), and 0.67 (0.61-0.74) for 1-6 cups/day, respectively. The RR of diabetes for a 1 cup/day increase was 0.91 (0.89-0.94) for caffeinated coffee consumption and 0.94 (0.91-0.98) for decaffeinated coffee consumption (P for difference = 0.17).

CONCLUSIONS

Coffee consumption was inversely associated with the risk of type 2 diabetes in a dose-response manner. Both caffeinated and decaffeinated coffee was associated with reduced diabetes risk.

Coffee and caffeine intake and incidence of type 2 diabetes mellitus: a meta-analysis of prospective studies

PURPOSE

Coffee and caffeine have been linked to type 2 diabetes mellitus (T2DM). A dose-response meta-analysis of prospective studies was conducted to assess the association between coffee and caffeine intake and T2DM incidence.

METHODS

Pertinent studies were identified by a search of PubMed and EMBASE. The fixed- or random-effect pooled measure was selected based on between-study heterogeneity. Dose-response relationship was assessed by restricted cubic spline.

RESULTS

Compared with the lowest level, the pooled relative risk (95 % CI) of T2DM was 0.71 (0.67-0.76) for the highest level of coffee intake (26 articles involving 50,595 T2DM cases and 1,096,647 participants), 0.79 (0.69-0.91) for the highest level of decaffeinated coffee intake (10 articles involving 29,165 T2DM cases and 491,485 participants) and 0.70 (0.65-0.75) for the highest level of caffeine intake (6 articles involving 9,302 T2DM cases and 321,960 participants). The association of coffee, decaffeinated coffee and caffeine intake with T2DM incidence was stronger for women than that for men. A stronger association of coffee intake with T2DM incidence was found for non-smokers and subjects with body mass index <25 kg/m(2). Dose-response analysis suggested that incidence of T2DM decreased by 12 % [0.88 (0.86-0.90)] for every 2 cups/day increment in coffee intake, 11 % [0.89 (0.82-0.98)] for every 2 cups/day increment in decaffeinated coffee intake and 14 % [0.86 (0.82-0.91)] for every 200 mg/day increment in caffeine intake.

CONCLUSIONS

Coffee and caffeine intake might significantly reduce the incidence of T2DM.