Dietary linoleic acid and risk of coronary heart disease: a systematic review and meta-analysis of prospective cohort studies

BACKGROUND

Previous studies on intake of linoleic acid (LA), the predominant n-6 fatty acid, and coronary heart disease (CHD) risk have generated inconsistent results. We performed a systematic review and meta-analysis of prospective cohort studies to summarize the evidence regarding the relation of dietary LA intake and CHD risk.

METHODS AND RESULTS

We searched MEDLINE and EMBASE databases through June 2013 for prospective cohort studies that reported the association between dietary LA and CHD events. In addition, we used unpublished data from cohort studies in a previous pooling project. We pooled the multivariate-adjusted relative risk (RR) to compare the highest with the lowest categories of LA intake using fixed-effect meta-analysis. We identified 13 published and unpublished cohort studies with a total of 310 602 individuals and 12 479 total CHD events, including 5882 CHD deaths. When the highest category was compared with the lowest category, dietary LA was associated with a 15% lower risk of CHD events (pooled RR, 0.85; 95% confidence intervals, 0.78-0.92; I(2)=35.5%) and a 21% lower risk of CHD deaths (pooled RR, 0.79; 95% confidence intervals, 0.71-0.89; I(2)=0.0%). A 5% of energy increment in LA intake replacing energy from saturated fat intake was associated with a 9% lower risk of CHD events (RR, 0.91; 95% confidence intervals, 0.87-0.96) and a 13% lower risk of CHD deaths (RR, 0.87; 95% confidence intervals, 0.82-0.94).

CONCLUSIONS

In prospective observational studies, dietary LA intake is inversely associated with CHD risk in a dose-response manner. These data provide support for current recommendations to replace saturated fat with polyunsaturated fat for primary prevention of CHD.

Genome-wide association study of selenium concentrations

Selenium (Se) is an essential trace element in human nutrition, but its role in certain health conditions, particularly among Se sufficient populations, is controversial. A genome-wide association study (GWAS) of blood Se concentrations previously identified a locus at 5q14 near BHMT. We performed a GW meta-analysis of toenail Se concentrations, which reflect a longer duration of exposure than blood Se concentrations, including 4162 European descendants from four US cohorts. Toenail Se was measured using neutron activation analysis. We identified a GW-significant locus at 5q14 (P < 1 × 10(-16)), the same locus identified in the published GWAS of blood Se based on independent cohorts. The lead single-nucleotide polymorphism (SNP) explained ∼1% of the variance in toenail Se concentrations. Using GW-summary statistics from both toenail and blood Se, we observed statistical evidence of polygenic overlap (P < 0.001) and meta-analysis of results from studies of either trait (n = 9639) yielded a second GW-significant locus at 21q22.3, harboring CBS (P < 4 × 10(-8)). Proteins encoded by genes at 5q14 and 21q22.3 function in homocysteine (Hcy) metabolism, and index SNPs for each have previously been associated with betaine and Hcy levels in GWAS. Our findings show evidence of a genetic link between Se and Hcy pathways, both involved in cardiometabolic disease.

Parent-of-origin-specific allelic associations among 106 genomic loci for age at menarche

Age at menarche is a marker of timing of puberty in females. It varies widely between individuals, is a heritable trait and is associated with risks for obesity, type 2 diabetes, cardiovascular disease, breast cancer and all-cause mortality. Studies of rare human disorders of puberty and animal models point to a complex hypothalamic-pituitary-hormonal regulation, but the mechanisms that determine pubertal timing and underlie its links to disease risk remain unclear. Here, using genome-wide and custom-genotyping arrays in up to 182,416 women of European descent from 57 studies, we found robust evidence (P < 5 × 10(-8)) for 123 signals at 106 genomic loci associated with age at menarche. Many loci were associated with other pubertal traits in both sexes, and there was substantial overlap with genes implicated in body mass index and various diseases, including rare disorders of puberty. Menarche signals were enriched in imprinted regions, with three loci (DLK1-WDR25, MKRN3-MAGEL2 and KCNK9) demonstrating parent-of-origin-specific associations concordant with known parental expression patterns. Pathway analyses implicated nuclear hormone receptors, particularly retinoic acid and γ-aminobutyric acid-B2 receptor signalling, among novel mechanisms that regulate pubertal timing in humans. Our findings suggest a genetic architecture involving at least hundreds of common variants in the coordinated timing of the pubertal transition.

Duration of obesity and overweight and risk of type 2 diabetes among US women

OBJECTIVE

The purpose of this study was to examine the association between duration of adiposity and risk of type 2 diabetes (T2D) in US women.

METHODS

Nearly 61,821 participants were prospectively followed from the Nurses' Health Study (1984-2008) and 63,653 participants from Nurses' Health Study II (1991-2011). Participants were considered overweight (BMI 25-30 kg m(-2) ) or obese (BMI ≥ 30 kg m(-2) ) if their BMI was above the cutoffs for two successive assessments. The time-dependent Cox proportional hazard models were used to assess associations between excess weight duration and T2D risk.

RESULTS

In pooled multivariable analyses of the two cohorts, each two extra years of being overweight was associated with 9% (RR = 1.09, 95% CI 1.08-1.09) increased risk of developing T2D. For each 2-year increment in obesity duration, the risk of T2D was increased by 14% (RR = 1.14, 95% CI 1.14-1.15). Adjustment for current BMI greatly attenuated the association for obesity duration (RR = 1.02, 95% CI 1.01-1.03), although the attenuation was less for overweight duration (RR = 1.04, 95% CI 1.04-1.05).

CONCLUSIONS

Both overweight and obesity duration were associated with a significantly higher risk of T2D, and these associations were mainly explained by current BMI, especially for obesity duration.

Trends in dietary quality among adults in the United States, 1999 through 2010

IMPORTANCE

Many changes in the economy, policies related to nutrition, and food processing have occurred within the United States since 2000, and the net effect on dietary quality is not clear. These changes may have affected various socioeconomic groups differentially.

OBJECTIVE

To investigate trends in dietary quality from 1999 to 2010 in the US adult population and within socioeconomic subgroups.

DESIGN, SETTING, AND PARTICIPANTS

Nationally representative sample of 29 124 adults aged 20 to 85 years from the US 1999 to 2010 National Health and Nutrition Examination Survey.

MAIN OUTCOMES AND MEASURES

The Alternate Healthy Eating Index 2010 (AHEI-2010), an 11-dimension score (range, 0-10 for each component score and 0-110 for the total score), was used to measure dietary quality. A higher AHEI-2010 score indicated a more healthful diet.

RESULTS

The energy-adjusted mean of the AHEI-2010 increased from 39.9 in 1999 to 2000 to 46.8 in 2009 to 2010 (linear trend P < .001). Reduction in trans fat intake accounted for more than half of this improvement. The AHEI-2010 component score increased by 0.9 points for sugar-sweetened beverages and fruit juice (reflecting decreased consumption), 0.7 points for whole fruit, 0.5 points for whole grains, 0.5 points for polyunsaturated fatty acids, and 0.4 points for nuts and legumes over the 12-year period (all linear trend P < .001). Family income and education level were positively associated with total AHEI-2010, and the gap between low and high socioeconomic status widened over time, from 3.9 points in 1999 to 2000 to 7.8 points in 2009 to 2010 (interaction P = .01).

CONCLUSIONS AND RELEVANCE

Although a steady improvement in AHEI-2010 was observed across the 12-year period, the overall dietary quality remains poor. Better dietary quality was associated with higher socioeconomic status, and the gap widened with time. Future efforts to improve nutrition should address these disparities.

Adherence to healthy lifestyle and risk of gestational diabetes mellitus: prospective cohort study

OBJECTIVE

To quantify the association between a combination of healthy lifestyle factors before pregnancy (healthy body weight, healthy diet, regular exercise, and not smoking) and the risk of gestational diabetes.

DESIGN

Prospective cohort study.

SETTING

Nurses' Health Study II, United States.

PARTICIPANTS

20,136 singleton live births in 14,437 women without chronic disease.

MAIN OUTCOME MEASURE

Self reported incident gestational diabetes diagnosed by a physician, validated by medical records in a previous study.

RESULTS

Incident first time gestational diabetes was reported in 823 pregnancies. Each lifestyle factor measured was independently and significantly associated with risk of gestational diabetes. The combination of three low risk factors (non-smoker, ≥ 150 minutes a week of moderate to vigorous physical activity, and healthy eating (top two fifths of Alternate Healthy Eating Index-2010 adherence score)) was associated with a 41% lower risk of gestational diabetes compared with all other pregnancies (relative risk 0.59, 95% confidence interval 0.48 to 0.71). Addition of body mass index (BMI) <25 before pregnancy (giving a combination of four low risk factors) was associated with a 52% lower risk of gestational diabetes compared with all other pregnancies (relative risk 0.48, 0.38 to 0.61). Compared with pregnancies in women who did not meet any of the low risk lifestyle factors, those meeting all four criteria had an 83% lower risk of gestational diabetes (relative risk 0.17, 0.12 to 0.25). The population attributable risk percentage of the four risk factors in combination (smoking, inactivity, overweight, and poor diet) was 47.5% (95% confidence interval 35.6% to 56.6%). A similar population attributable risk percentage (49.2%) was observed when the distributions of the four low risk factors from the US National Health and Nutrition Examination Survey (2007-10) data were applied to the calculation.

CONCLUSIONS

Adherence to a low risk lifestyle before pregnancy is associated with a low risk of gestational diabetes and could be an effective strategy for the prevention of gestational diabetes.

Low carbohydrate diet from plant or animal sources and mortality among myocardial infarction survivors

BACKGROUND

The healthiest dietary pattern for myocardial infarction (MI) survivors is not known. Specific long-term benefits of a low-carbohydrate diet (LCD) are unknown, whether from animal or vegetable sources. There is a need to examine the associations between post-MI adherence to an LCD and all-cause and cardiovascular mortality.

METHODS AND RESULTS

We included 2258 women from the Nurses' Health Study and 1840 men from the Health Professional Follow-Up Study who had survived a first MI during follow-up and provided a pre-MI and at least 1 post-MI food frequency questionnaire. Adherence to an LCD high in animal sources of protein and fat was associated with higher all-cause and cardiovascular mortality (hazard ratios of 1.33 [95% CI: 1.06 to 1.65] for all-cause mortality and 1.51 [95% CI: 1.09 to 2.07] for cardiovascular mortality comparing extreme quintiles). An increase in adherence to an animal-based LCD prospectively assessed from the pre- to post-MI period was associated with higher all-cause mortality and cardiovascular mortality (hazard ratios of 1.30 [95% CI: 1.03 to 1.65] for all-cause mortality and 1.53 [95% CI: 1.10 to 2.13] for cardiovascular mortality comparing extreme quintiles). An increase in adherence to a plant-based LCD was not associated with lower all-cause or cardiovascular mortality.

CONCLUSIONS

Greater adherence to an LCD high in animal sources of fat and protein was associated with higher all-cause and cardiovascular mortality post-MI. We did not find a health benefit from greater adherence to an LCD overall after MI.

Prevalence and correlates of diabetic peripheral neuropathy in a Saudi Arabic population: a cross-sectional study

The purpose of this cross-sectional study was to investigate the prevalence and correlates of diabetic peripheral neuropathy (DPN) in a Saudi population. The study population consisted of 552 diabetic participants with an average age of 53.4 years. Among this population, 62.7% were male and 94.9% had type 2 diabetes. The average body mass index was 31.1 kg/m². DPN was diagnosed based on a combination of reduced vibration perception measured by neurothesiometer and/or reduced light touch perception evaluated by the 10-g Semmes-Weinstein monofilament, as well as neurological symptoms. Information on socio-demographic variables, smoking status, duration of diabetes, and medications was obtained through interviews by physicians. Body weight, height, waist circumference, blood pressure and clinical markers were assessed following standard procedures. The prevalence of DPN in this population was 19.9% (95% CI, 16.7%-23.5%). In the multivariable analyses, longer duration of diabetes [odds ratio (OR) for every 5-year increase, 2.49, 95% CI, 1.75-3.53], abdominal obesity (OR, 2.53, 95% CI, 1.41-4.55), and higher levels of fasting blood glucose (OR for every 1 mmol/L increase, 1.05, 95% CI, 0.99-1.12), creatinine (OR for every 10 µmol/L increase, 1.07, 95% CI, 0.99-1.14) and white blood cell count (OR for every 10⁶/L increase, 1.08, 95% CI, 1.01-1.16) were associated with higher odds of DPN, while oral hypoglycemic medication use was associated with a lower odds of DPN (OR, 0.47, 95% CI, 0.26-0.85). In this large Saudi population, several correlates for DPN, in addition to glycemic control and diabetes duration, were identified, including abdominal obesity, creatinine and white blood cell count.

Changes in BMI before and during economic development and subsequent risk of cardiovascular disease and total mortality: a 35-year follow-up study in China

OBJECTIVE

It is unclear whether changes in BMI during rapid economic development influence subsequent mortality.

RESEARCH DESIGN AND METHODS

We analyzed whether BMI in 1976 and 1994 and changes in BMI during 1976-1994 predict cardiovascular disease (CVD) and all-cause mortality in a 35-year follow-up cohort of 1,696 Chinese (1,124 men and 572 women, aged 35-65 years) in Xi'an, China. Participants were categorized as underweight (<18.5 kg/m(2)), normal weight (18.5-24.9 kg/m(2)), and overweight (≥25.0 kg/m(2)).

RESULTS

During 51,611 person-years of follow-up, we identified 655 deaths from all causes and 234 from CVD. From 1976 to 1994, the prevalence of overweight rose from 9.2 to 27.8%. With each unit increment in 1976 BMI, multivariate hazard ratios (HRs) (95% CI) were 0.78 (0.72-0.84) for CVD and 0.91 (0.87-0.95) for all-cause mortality. In contrast, corresponding HRs were 1.14 (1.08-1.19) and 1.05 (1.01-1.08) in 1994 BMI. The HRs for each unit increment in BMI change from 1976 to 1994 were 1.35 (1.25-1.41) for CVD and 1.09 (1.05-1.13) for all-cause mortality. Compared with participants with stable normal weight in 1976 and 1994, HRs of all-cause mortality for those who had normal weight in 1976 but became overweight in 1994 and for those who were persistently overweight during 1976-1994 were 1.42 (1.12-1.80) and 1.80 (1.04-3.14), respectively.

CONCLUSIONS

Gaining weight with increased BMI at middle age in Chinese during economic development was associated with elevated risks of all-cause and CVD mortality. Higher BMI measured before economic development was associated with lower mortality risk, whereas BMI measured afterward was associated with increased mortality.

Sugar-sweetened soda consumption and risk of developing rheumatoid arthritis in women

BACKGROUND

Sugar-sweetened soda consumption is consistently associated with an increased risk of several chronic inflammatory diseases such as type 2 diabetes and cardiovascular diseases. Whether it plays a role in the development of rheumatoid arthritis (RA), a common autoimmune inflammatory disease, remains unclear.

OBJECTIVE

The aim was to evaluate the association between sugar-sweetened soda consumption and risk of RA in US women.

DESIGN

We prospectively followed 79,570 women from the Nurses' Health Study (NHS; 1980-2008) and 107,330 women from the NHS II (1991-2009). Information on sugar-sweetened soda consumption (including regular cola, caffeine-free cola, and other sugar-sweetened carbonated soda) was obtained from a validated food-frequency questionnaire at baseline and approximately every 4 y during follow-up. Incident RA cases were validated by medical record review. Time-varying Cox proportional hazards regression models were used to calculate HRs after adjustment for confounders. Results from both cohorts were pooled by an inverse-variance-weighted, fixed-effects model.

RESULTS

During 3,381,268 person-years of follow-up, 857 incident cases of RA were documented in the 2 cohorts. In the multivariable pooled analyses, we found that women who consumed ≥1 serving of sugar-sweetened soda/d had a 63% (HR: 1.63; 95% CI: 1.15, 2.30; P-trend = 0.004) increased risk of developing seropositive RA compared with those who consumed no sugar-sweetened soda or who consumed <1 serving/mo. When we restricted analyses to those with later RA onset (after age 55 y) in the NHS, the association appeared to be stronger (HR: 2.64; 95% CI: 1.56, 4.46; P-trend < 0.0001). No significant association was found for sugar-sweetened soda and seronegative RA. Diet soda consumption was not significantly associated with risk of RA in the 2 cohorts.

CONCLUSION

Regular consumption of sugar-sweetened soda, but not diet soda, is associated with increased risk of seropositive RA in women, independent of other dietary and lifestyle factors.

Lipopolysaccharide binding protein, obesity status and incidence of metabolic syndrome: a prospective study among middle-aged and older Chinese

AIMS/HYPOTHESIS

Although microbiota-derived endotoxaemia has previously been shown to induce metabolic disorders, data from population-based longitudinal studies are scarce. This study therefore investigated the associations between lipopolysaccharide binding protein (LBP) levels and 6 year incident metabolic syndrome (MetS), as well as the potentially modifying effects of obesity status in middle-aged and older Chinese men and women.

METHODS

A total of 2,529 men and women aged 50-70 years from Beijing and Shanghai, China, were followed for 6 years. Those free of MetS at baseline (1,312) were included in the analyses for the risk of developing MetS. Baseline plasma LBP was measured using an ELISA kit.

RESULTS

During the 6 year follow-up, 449 (34.2%) participants developed MetS. Baseline LBP was significantly associated with BMI, waist circumference, blood lipid profile and C-reactive protein (CRP) both at baseline and during follow-up (all p < 0.05). The RR for incident MetS comparing extreme quartiles of LBP was 1.28 (95% CI 1.04, 1.58), after multivariate adjustment including BMI and CRP. In stratified analysis, LBP was positively associated with incident MetS only in normal-weight participants (RR, comparing extreme tertiles, 1.59; 95% CI 1.18, 2.15; p(trend)= 0.002), but not in their overweight/obese counterparts (RR, comparing extreme tertiles, 0.99; 95% CI 0.80, 1.22; p(trend) = 0.880). A significant interaction was observed between LBP and obesity status (p(interaction) = 0.013).

CONCLUSIONS/INTERPRETATION

Our study suggested that elevated plasma LBP was associated with an increased risk of developing MetS among middle-aged and older Chinese, especially in normal-weight individuals.

Inverse association of plasma vanadium levels with newly diagnosed type 2 diabetes in a Chinese population

Vanadium compounds have been proposed to have beneficial effects on the pathogenesis and complications of type 2 diabetes. Our objective was to evaluate the association between plasma vanadium levels and type 2 diabetes. We performed a case-control study involving 1,598 Chinese subjects with or without newly diagnosed type 2 diabetes (December 2004-December 2007). Cases and controls were frequency-matched by age and sex. Plasma vanadium concentrations were measured and compared between groups. Analyses showed that plasma vanadium concentrations were significantly lower in cases with newly diagnosed type 2 diabetes than in controls (P = 0.001). Mean plasma vanadium levels in participants with and without diabetes were 1.0 μg/L and 1.2 μg/L, respectively. Participants in the highest quartile of plasma vanadium concentration had a notably lower risk of newly diagnosed type 2 diabetes (odds ratio = 0.26, 95% confidence interval: 0.19, 0.35; P < 0.001), compared with persons in the lowest quartile. The trend remained significant after adjustment for known risk factors and in further stratification analyses. Our results suggested that plasma vanadium concentrations were inversely associated with newly diagnosed type 2 diabetes in this Chinese population.

FTO genetic variants, dietary intake and body mass index: insights from 177,330 individuals

FTO is the strongest known genetic susceptibility locus for obesity. Experimental studies in animals suggest the potential roles of FTO in regulating food intake. The interactive relation among FTO variants, dietary intake and body mass index (BMI) is complex and results from previous often small-scale studies in humans are highly inconsistent. We performed large-scale analyses based on data from 177,330 adults (154 439 Whites, 5776 African Americans and 17 115 Asians) from 40 studies to examine: (i) the association between the FTO-rs9939609 variant (or a proxy single-nucleotide polymorphism) and total energy and macronutrient intake and (ii) the interaction between the FTO variant and dietary intake on BMI. The minor allele (A-allele) of the FTO-rs9939609 variant was associated with higher BMI in Whites (effect per allele = 0.34 [0.31, 0.37] kg/m(2), P = 1.9 × 10(-105)), and all participants (0.30 [0.30, 0.35] kg/m(2), P = 3.6 × 10(-107)). The BMI-increasing allele of the FTO variant showed a significant association with higher dietary protein intake (effect per allele = 0.08 [0.06, 0.10] %, P = 2.4 × 10(-16)), and relative weak associations with lower total energy intake (-6.4 [-10.1, -2.6] kcal/day, P = 0.001) and lower dietary carbohydrate intake (-0.07 [-0.11, -0.02] %, P = 0.004). The associations with protein (P = 7.5 × 10(-9)) and total energy (P = 0.002) were attenuated but remained significant after adjustment for BMI. We did not find significant interactions between the FTO variant and dietary intake of total energy, protein, carbohydrate or fat on BMI. Our findings suggest a positive association between the BMI-increasing allele of FTO variant and higher dietary protein intake and offer insight into potential link between FTO, dietary protein intake and adiposity.

Changes in body weight and health-related quality of life: 2 cohorts of US women

Studies have shown that body weight is a determinant of health-related quality of life (HRQoL). However, few studies have examined long-term weight change with changes in HRQoL. We followed 52,682 women aged 46-71 years in the Nurses' Health Study (in 1992-2000) and 52,587 women aged 29-46 years in the Nurses' Health Study II (in 1993-2001). Body weight was self-reported, HRQoL was measured by the Medical Outcomes Study's 36-Item Short Form Health Survey, and both were updated every 4 years. The relationship between changes in weight and HRQoL scores was evaluated at 4-year intervals by using a generalized linear regression model with multivariate adjustment for baseline age, ethnicity, menopausal status, and changes in comorbidities and lifestyle factors. Weight gain of 15 lbs (1 lb = 0.45 kg) or more over a 4-year period was associated with 2.05-point lower (95% confidence interval: 2.14, 1.95) physical component scores, whereas weight loss of 15 lbs or more was associated with 0.89-point higher (95% confidence interval: 0.75, 1.03) physical component scores. Inverse associations were also found between weight change and physical function, role limitations due to physical problems, bodily pain, general health, and vitality. However, the relations of weight change with mental component scores, social functioning, mental health, and role limitations due to emotional problems were small.

Circulating IGF-axis protein levels and their relation with levels of plasma adipocytokines and macronutrient consumption in women

OBJECTIVE

Circulating free insulin-like growth factor (IGF)-I and its binding proteins, most notably, IGFBP-1 and IGFBP-2, have been prospectively associated with incident type 2 diabetes in women. However, little is known regarding the factors that may influence these IGF-axis protein levels. The aim is to study the relation of IGF-axis protein levels with adipcytokines, macronutrient consumption, and other factors related to diabetes.

DESIGN

Fasting plasma from 558 controls enrolled in a nested case-control study within the Nurses' Health Study of incident type 2 diabetes in women was tested for: IGF-axis proteins (free and total IGF-I, IGFBP-1, IGFBP-2, IGFBP-3), adipocytokines (leptin, adiponectin, resistin), soluble leptin receptor (sOB-R), inflammatory factors (IL-18 and C-reactive protein (CRP)), insulin, and glycated hemoglobin (HbA1C).

RESULTS

In multivariate models, each 1% increase in sOB-R (mean 34.9ng/mL, standard deviation (SD) ±11.3) was associated with -0.20% total IGF-I (P=0.0003) and -0.42% free IGF-I (P=0.002), as well as 0.73% higher IGFBP-1 (P<0.0001) and 0.27% IGFBP-2 (P=0.003). For example, a one SD change from the mean sOB-R level was associated with 11% lower free IGF-I. Insulin levels (mean 6.8μU/mL±5.3) were inversely and adiponectin (mean 18.3μg/mL±7.4) positively associated with IGFBP-1 and IGFBP-2 (all P<0.01). Consumption of dairy protein, monounsaturated fats, and saturated fats, was also correlated with IGF-axis protein levels (all P<0.05).

CONCLUSIONS

Several molecular factors and macronutrients were independently associated with plasma IGF-axis protein levels. Which of these, if any, reflect biologic relationships that can be intervened upon to influence IGF-axis protein concentrations warrants further investigation.

Instant noodle intake and dietary patterns are associated with distinct cardiometabolic risk factors in Korea

The consumption of instant noodles is relatively high in Asian populations. It is unclear whether a higher intake of instant noodles is associated with cardiometabolic risk independent of overall dietary patterns. We therefore investigated the association using the Korean National Health and Nutrition Examination Survey IV 2007-2009, a nationally representative cross-sectional survey of the Korean population with a clustered, multistage, stratified, and rolling sampling design. A total of 10,711 adults (54.5% women) 19-64 y of age were analyzed, with adjustment for sampling design complexity. Diet was assessed by using a 63-item food-frequency questionnaire. We identified 2 major dietary patterns with the use of principal components analysis: the "traditional dietary pattern" (TP), rich in rice, fish, vegetables, fruit, and potatoes, and the "meat and fast-food pattern" (MP), with less rice intake but rich in meat, soda, fried food, and fast food including instant noodles. The highest MP quintile was associated with increased prevalence of abdominal obesity (OR: 1.41; 95% CI: 1.05, 1.90), LDL cholesterol ≥130 mg/dL (1.3 g/L) (OR: 1.57, 95% CI 1.26, 1.95), decreased prevalence of low HDL cholesterol (OR: 0.65; 95% CI: 0.53, 0.80), and high triglycerides [≥150 mg/dL (1.5 g/L); OR: 0.73; 95% CI: 0.57, 0.93]. The highest quintile for the TP was associated with decreased prevalence of elevated blood pressure (OR: 0.73; 95% CI: 0.59, 0.90) and marginally lower trends for abdominal obesity (OR: 0.76; 95% CI: 0.58, 0.98; P-trend = 0.06), but neither of the dietary patterns was associated with prevalence of metabolic syndrome. The consumption of instant noodles ≥2 times/wk was associated with a higher prevalence of metabolic syndrome (OR: 1.68; 95% CI: 1.10, 2.55) in women but not in men (OR: 0.93; 95% CI: 0.58, 1.49; P-interaction = 0.04). The 2 major dietary patterns were associated with distinct cardiometabolic risk factors. The consumption of instant noodles was associated with increased prevalence of metabolic syndrome in women, independent of major dietary patterns.

Fried-food consumption and risk of type 2 diabetes and coronary artery disease: a prospective study in 2 cohorts of US women and men

BACKGROUND

Through the processes of oxidation, polymerization, and hydrogenation, the cooking method of frying modifies both foods and their frying medium. However, it remains unknown whether the frequent consumption of fried foods is related to long-term cardiometabolic health.

OBJECTIVE

We examined fried-food consumption and risk of developing incident type 2 diabetes (T2D) or coronary artery disease (CAD).

DESIGN

Fried-food consumption was assessed by using a questionnaire in 70,842 women from the Nurses' Health Study (1984-2010) and 40,789 men from the Health Professionals Follow-Up Study (1986-2010) who were free of diabetes, cardiovascular disease, and cancer at baseline. Time-dependent Cox proportional hazards models were used to estimate RRs and 95% CIs for T2D and CAD adjusted for demographic, diet, lifestyle, and other cardiometabolic risk factors. Results were pooled by using an inverse variance-weighted random-effects meta-analysis.

RESULTS

We documented 10,323 incident T2D cases and 5778 incident CAD cases. Multivariate-adjusted RRs (95% CIs) for individuals who consumed fried foods <1, 1-3, 4-6, or ≥7 times/wk were 1.00 (reference), 1.15 (0.97, 1.35), 1.39 (1.30, 1.49), and 1.55 (1.32, 1.83), respectively, for T2D and 1.00 (reference), 1.06 (0.98, 1.15), 1.23 (1.14, 1.33), and 1.21 (1.06, 1.39), respectively, for CAD. Associations were largely attenuated when we further controlled for biennially updated hypertension, hypercholesterolemia, and body mass index.

CONCLUSIONS

Frequent fried-food consumption was significantly associated with risk of incident T2D and moderately with incident CAD, and these associations were largely mediated by body weight and comorbid hypertension and hypercholesterolemia.

Racial/ethnic disparities in short sleep duration by occupation: the contribution of immigrant status

Sleep duration, associated with increased morbidity/mortality, has been shown to vary by race and occupation. Few studies have examined the additional influence of immigrant status. Using a nationally-representative sample of 175,244 US adults from the National Health Interview Survey from 2004 to 2011, we estimated prevalence ratios (PRs) for short sleep duration (<7 h/per day) among US- and non-US born Blacks and Latinos by occupation compared to their White counterparts using adjusted Poisson regression models with robust variance. Non-US born participants' mean age was 46 years, 55% were men, 58% were Latino, and 65% lived in the US ≥ 15 years. Short sleep prevalence was highest among US- and non-US born Blacks in all occupations, and the prevalence generally increased with increasing professional/management roles in Blacks and Latinos while it decreased among Whites. Adjusted short sleep was more prevalent in US-born Blacks compared to Whites in professional/management (PR = 1.52 [95% confidence interval (CI): 1.42-1.63]), support services (PR = 1.31 [95% CI: 1.26-1.37]), and laborers (PR = 1.11 [95% CI: 1.06-1.16]). The Black-White comparison was even higher for non-US born Black laborers (PR = 1.50 [95% CI: 1.24-1.80]). Similar for non-US born Latinos, Latinos born in the US had a higher short sleep prevalence in professional/management (PR = 1.14 [95% CI: 1.04-1.24]) and support services (PR = 1.06 [95% CI: 1.01-1.11]), but a lower prevalence among laborers (PR = 0.77 [95% CI: 0.74-0.81]) compared to Whites. Short sleep varied within and between immigrant status for some ethnicities in particular occupations, further illuminating the need for tailored interventions to address sleep disparities among US workers.

Fruit and vegetable consumption and mortality from all causes, cardiovascular disease, and cancer: systematic review and dose-response meta-analysis of prospective cohort studies

OBJECTIVE

To examine and quantify the potential dose-response relation between fruit and vegetable consumption and risk of all cause, cardiovascular, and cancer mortality.

DATA SOURCES

Medline, Embase, and the Cochrane library searched up to 30 August 2013 without language restrictions. Reference lists of retrieved articles.

STUDY SELECTION

Prospective cohort studies that reported risk estimates for all cause, cardiovascular, and cancer mortality by levels of fruit and vegetable consumption.

DATA SYNTHESIS

Random effects models were used to calculate pooled hazard ratios and 95% confidence intervals and to incorporate variation between studies. The linear and non-linear dose-response relations were evaluated with data from categories of fruit and vegetable consumption in each study.

RESULTS

Sixteen prospective cohort studies were eligible in this meta-analysis. During follow-up periods ranging from 4.6 to 26 years there were 56,423 deaths (11,512 from cardiovascular disease and 16,817 from cancer) among 833,234 participants. Higher consumption of fruit and vegetables was significantly associated with a lower risk of all cause mortality. Pooled hazard ratios of all cause mortality were 0.95 (95% confidence interval 0.92 to 0.98) for an increment of one serving a day of fruit and vegetables (P=0.001), 0.94 (0.90 to 0.98) for fruit (P=0.002), and 0.95 (0.92 to 0.99) for vegetables (P=0.006). There was a threshold around five servings of fruit and vegetables a day, after which the risk of all cause mortality did not reduce further. A significant inverse association was observed for cardiovascular mortality (hazard ratio for each additional serving a day of fruit and vegetables 0.96, 95% confidence interval 0.92 to 0.99), while higher consumption of fruit and vegetables was not appreciably associated with risk of cancer mortality.

CONCLUSIONS

This meta-analysis provides further evidence that a higher consumption of fruit and vegetables is associated with a lower risk of all cause mortality, particularly cardiovascular mortality.

Glycemic index, glycemic load, and risk of type 2 diabetes: results from 3 large US cohorts and an updated meta-analysis

BACKGROUND

Epidemiologic evidence for the relation between carbohydrate quality and risk of type 2 diabetes (T2D) has been mixed.

OBJECTIVE

We prospectively examined the association of dietary glycemic index (GI) and glycemic load (GL) with T2D risk.

DESIGN

We prospectively followed 74,248 women from the Nurses' Health Study (1984-2008), 90,411 women from the Nurses' Health Study II (1991-2009), and 40,498 men from the Health Professionals Follow-Up Study (1986-2008) who were free of diabetes, cardiovascular disease, and cancer at baseline. Diet was assessed by using a validated questionnaire and updated every 4 y. We also conducted an updated meta-analysis, including results from our 3 cohorts and other studies.

RESULTS

During 3,800,618 person-years of follow-up, we documented 15,027 cases of incident T2D. In pooled multivariable analyses, those in the highest quintile of energy-adjusted GI had a 33% higher risk (95% CI: 26%, 41%) of T2D than those in the lowest quintile. Participants in the highest quintile of energy-adjusted GL had a 10% higher risk (95% CI: 2%, 18%) of T2D. Participants who consumed a combination diet that was high in GI or GL and low in cereal fiber had an ~50% higher risk of T2D. In the updated meta-analysis, the summary RRs (95% CIs) comparing the highest with the lowest categories of GI and GL were 1.19 (1.14, 1.24) and 1.13 (1.08, 1.17), respectively.

CONCLUSION

The updated analyses from our 3 cohorts and meta-analyses provide further evidence that higher dietary GI and GL are associated with increased risk of T2D.

Association between class III obesity (BMI of 40-59 kg/m2) and mortality: a pooled analysis of 20 prospective studies

BACKGROUND

The prevalence of class III obesity (body mass index [BMI]≥40 kg/m2) has increased dramatically in several countries and currently affects 6% of adults in the US, with uncertain impact on the risks of illness and death. Using data from a large pooled study, we evaluated the risk of death, overall and due to a wide range of causes, and years of life expectancy lost associated with class III obesity.

METHODS AND FINDINGS

In a pooled analysis of 20 prospective studies from the United States, Sweden, and Australia, we estimated sex- and age-adjusted total and cause-specific mortality rates (deaths per 100,000 persons per year) and multivariable-adjusted hazard ratios for adults, aged 19-83 y at baseline, classified as obese class III (BMI 40.0-59.9 kg/m2) compared with those classified as normal weight (BMI 18.5-24.9 kg/m2). Participants reporting ever smoking cigarettes or a history of chronic disease (heart disease, cancer, stroke, or emphysema) on baseline questionnaires were excluded. Among 9,564 class III obesity participants, mortality rates were 856.0 in men and 663.0 in women during the study period (1976-2009). Among 304,011 normal-weight participants, rates were 346.7 and 280.5 in men and women, respectively. Deaths from heart disease contributed largely to the excess rates in the class III obesity group (rate differences = 238.9 and 132.8 in men and women, respectively), followed by deaths from cancer (rate differences = 36.7 and 62.3 in men and women, respectively) and diabetes (rate differences = 51.2 and 29.2 in men and women, respectively). Within the class III obesity range, multivariable-adjusted hazard ratios for total deaths and deaths due to heart disease, cancer, diabetes, nephritis/nephrotic syndrome/nephrosis, chronic lower respiratory disease, and influenza/pneumonia increased with increasing BMI. Compared with normal-weight BMI, a BMI of 40-44.9, 45-49.9, 50-54.9, and 55-59.9 kg/m2 was associated with an estimated 6.5 (95% CI: 5.7-7.3), 8.9 (95% CI: 7.4-10.4), 9.8 (95% CI: 7.4-12.2), and 13.7 (95% CI: 10.5-16.9) y of life lost. A limitation was that BMI was mainly ascertained by self-report.

CONCLUSIONS

Class III obesity is associated with substantially elevated rates of total mortality, with most of the excess deaths due to heart disease, cancer, and diabetes, and major reductions in life expectancy compared with normal weight. Please see later in the article for the Editors' Summary.

Long-term associations of nut consumption with body weight and obesity

There is some concern that the high-fat, energy-dense content of nuts may promote weight gain. Nuts, however, are rich in protein and dietary fiber, which are associated with increased satiety. They also contain high amounts of vitamins, minerals, antioxidants, and phytoesterols that may confer health benefits for cardiovascular disease and type 2 diabetes delay and prevention. Therefore, it is important to determine the association between nut consumption and long-term weight change and disease risk to reach scientific consensus and to make evidence-based public health recommendations. Several cross-sectional analyses have shown an inverse association between higher nut consumption and lower body weight. In addition, several independent prospective studies found that increasing nut consumption was associated with lower weight gain over relatively long periods of time. Moreover, high consumption of nuts (especially walnuts) has been associated with lower diabetes risk. Therefore, regular consumption (approximately one handful daily) of nuts over the long term, as a replacement to less healthful foods, can be incorporated as a component of a healthy diet for the prevention of obesity and type 2 diabetes.

C-reactive protein, interleukin-6, soluble tumor necrosis factor α receptor 2 and incident clinical depression

BACKGROUND

Despite an extensive literature on the role of inflammation and depression, few studies have evaluated the association between inflammatory biomarkers and depression in a prospective manner, and results are inconclusive.

METHODS

We conducted a prospective analysis of blood levels of CRP, IL-6 and TNFα-R2 in 4756 women participating in the Nurses׳ Health Study who donated blood in 1990 and were depression-free up to 1996. Participants were followed between 1996 and 2008 for reports of clinical diagnosis depression or antidepressant use. Additionally, we conducted cross-sectional analyses for CRP, IL-6 and TNFα-R2 and antidepressant use at time of blood draw.

RESULTS

After adjustment for body mass index, menopause status, use of anti-inflammatory drugs and other covariates, no significant associations between CRP, IL-6 and TNFα-R2 and incident depression were observed after a follow-up of 6-18 years. However, menopause status appears to modify the association between IL-6 and depression risk. In cross-sectional analyses, TNFα-R2 was associated with antidepressant use (OR=1.96, 95% CI=1.23-3.13, P-trend=0.001), but no significant associations were found for CRP and IL-6.

LIMITATIONS

Depression diagnosis was first assessed in 1996, 6 years after blood draw. However the biomarkers have high within-person correlations with measurements 4 years apart.

CONCLUSIONS

Blood levels of CRP, IL-6 and TNFα-R2 were not associated with incident depression over a follow-up of 6-18 years. In cross-sectional analyses, antidepressant use may be associated with higher levels of TNFα-R2 but no associations with depression or antidepressant use were observed in the prospective analysis.