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Seven recent research studies: folate & depression; grain, cancer & weight control; protein & increased cardiovascular disease

It's been a while since I wrote a blog post on diet.  However there is a good deal of accuracy in the comment "You are what you eat".  This is definitely an area it's crucial to consider for improvements in stress, health & wellbeing.  So in previous posts, I have highlighted the importance of diet for prevention of anxiety & depression - see "New research shows diet's importance in preventing depression"; encouraged us to "Eat 5 to 9 portions of fruit & veg daily"; bemoaned our behaviour in "Vegged out & fruitless: lifestyle & health"; discussed "Preventing cancer through lifestyle choices"; looked at "How much should I weigh if I don't want to die early?" and asked "Would you like to be 14 years younger - it's largely a matter of choice!".  There are many more resources reachable through the "Good knowledge" page on "Alcohol & food" and through clicking on relevant search terms in the "Tag cloud".

Seven recent research studies add further weight to the huge mountains of evidence highlighting the importance of these areas.  So Miyaki & colleagues reported that "Our cross-sectional study suggested an inverse, independent relation of energy-adjusted folate intake with depression score and prevalence of depressive symptoms" (see below for abstracts and links to all research studies mentioned).  McCullough et al found that "Flavonoid consumption was associated with lower risk of death from CVD. Most inverse associations appeared with intermediate intakes, suggesting that even relatively small amounts of flavonoid-rich foods may be beneficial." (click here for dietary sources).  Ye & colleagues reported in their systematic review that "compared with never/rare consumers of whole grains, those consuming 48-80 g whole grain/d (3-5 serving/d) had an ~26% lower risk of type 2 diabetes ... ~21% lower risk of CVD ... and consistently less weight gain during 8-13 y".  There are two papers on the large European Prospective Investigation into Cancer and Nutrition (EPIC) reporting further details on how high fibre intake - from cereals & vegetables even more than from fruit - is linked to lower death rates from cardiovascular, digestive & inflammatory diseases as well as colorectal cancer.  Van de Laar & colleagues showed that over 24 year follow-up "Lower lifetime intake of fiber during the course of young age is associated with carotid artery stiffness in adulthood. Promoting consumption of fiber-rich foods among the young may offer a means to prevent accelerated arterial stiffening in adulthood and related cardiovascular sequelae."  Finally Lagiou et al showed in a study of over 43,000 women followed up for about 15 years that low carbohydrate/high protein diets put people at significant risk of increased cardiovascular disease - a wake-up call here!

Miyaki, K., Y. Song, et al. (2012). "Folate intake and depressive symptoms in Japanese workers considering SES and job stress factors: J-HOPE study." BMC Psychiatry 12(1): 33. (Free full text available) BACKGROUND:Recently socioeconomic status (SES) and job stress index received more attention to affect mental health. Folate intake has been implicated to have negative association with depression. However, few studies were published for the evidence association together with the consideration of SES and job stress factors. The current study is a part of the Japanese study of Health, Occupation and Psychosocial factors related Equity (J-HOPE study) that focused on the association of social stratification and health and our objective was to clarify the association between folate intake and depressive symptoms in Japanese general workers. METHODS: Subjects were 2266 workers in a Japanese nationwide company. SES and job stress factors were assessed by self-administered questionnaire. Folate intake was estimated by a validated, brief, self-administered diet history questionnaire. Depressive symptoms were measured by Kessler's K6 questionnaire. "Individuals with depressive symptoms" was defined as K69 (in K6 score of 0-24 scoring system). Multiple logistic regression and linear regression model were used to evaluate the association between folate and depressive symptoms. RESULTS:Several SES factors (proportion of management positions, years of continuous employment, and annual household income) and folate intake were found to be significantly lower in the subjects with depressive symptom (SES factors: p<0.001; folate intake: P=0.001). There was an inverse, independent linear association between K6 score and folate intake after adjusting for age, sex, job stress scores (job strains, worksite supports), and SES factors (p=0.010). The impact of folate intake on the prevalence of depressive symptom by a multiple logistic model was (ORs[95% CI]: 0.813 [0.664-0.994]; P =0.044). CONCLUSIONS:Our cross-sectional study suggested an inverse, independent relation of energy-adjusted folate intake with depression score and prevalence of depressive symptoms in Japanese workers, together with the consideration of SES and job stress factors were considered.

McCullough, M. L., J. J. Peterson, et al. (2012). "Flavonoid intake and cardiovascular disease mortality in a prospective cohort of US adults." Am J Clin Nutr 95(2): 454-464. Background: Flavonoids are plant-based phytochemicals with cardiovascular protective properties. Few studies have comprehensively examined flavonoid classes in relation to cardiovascular disease mortality. Objective: We examined the association between flavonoid intake and cardiovascular disease (CVD) mortality among participants in a large, prospective US cohort.Design: In 1999, a total of 38,180 men and 60,289 women in the Cancer Prevention Study II Nutrition Cohort with a mean age of 70 and 69 y, respectively, completed questionnaires on medical history and lifestyle behaviors, including a 152-item food-frequency questionnaire. Cox proportional hazards modeling was used to calculate multivariate-adjusted hazard RRs and 95% CIs for associations between total flavonoids, 7 flavonoid classes, and CVD mortality. Results: During 7 y of follow-up, 1589 CVD deaths in men and 1182 CVD deaths in women occurred. Men and women with total flavonoid intakes in the top (compared with the bottom) quintile had a lower risk of fatal CVD (RR: 0.82; 95% CI: 0.73, 0.92; P-trend = 0.01). Five flavonoid classes-anthocyanidins, flavan-3-ols, flavones, flavonols, and proanthocyanidins-were individually associated with lower risk of fatal CVD (all P-trend < 0.05). In men, total flavonoid intakes were more strongly associated with stroke mortality (RR: 0.63; 95% CI: 0.44, 0.89; P-trend = 0.04) than with ischemic heart disease (RR: 0.90; 95% CI: 0.72, 1.13). Many associations appeared to be nonlinear, with lower risk at intakes above the referent category. Conclusions: Flavonoid consumption was associated with lower risk of death from CVD. Most inverse associations appeared with intermediate intakes, suggesting that even relatively small amounts of flavonoid-rich foods may be beneficial. (for dietary sources, see http://flavo.vtt.fi/flavonoidsources.htm).

Ye, E. Q., S. A. Chacko, et al. (2012). "Greater whole-grain intake Is associated with lower risk of type 2 diabetes, cardiovascular disease, and weight gain." Journal of Nutrition 142(7): 1304-1313. Whole-grain and high fiber intakes are routinely recommended for prevention of vascular diseases; however, there are no comprehensive and quantitative assessments of available data in humans. The aim of this study was to systematically examine longitudinal studies investigating whole-grain and fiber intake in relation to risk of type 2 diabetes (T2D), cardiovascular disease (CVD), weight gain, and metabolic risk factors. We identified 45 prospective cohort studies and 21 randomized-controlled trials (RCT) between 1966 and February 2012 by searching the Cumulative Index to Nursing and Allied Health Literature, Cochrane, Elsevier Medical Database, and PubMed. Study characteristics, whole-grain and dietary fiber intakes, and risk estimates were extracted using a standardized protocol. Using random effects models, we found that compared with never/rare consumers of whole grains, those consuming 48-80 g whole grain/d (3-5 serving/d) had an ~26% lower risk of T2D [RR = 0.74 (95% CI: 0.69, 0.80)], ~21% lower risk of CVD [RR = 0.79 (95% CI: 0.74, 0.85)], and consistently less weight gain during 8-13 y (1.27 vs 1.64 kg; P = 0.001). Among RCT, weighted mean differences in post-intervention circulating concentrations of fasting glucose and total and LDL-cholesterol comparing whole-grain intervention groups with controls indicated significantly lower concentrations after whole-grain interventions [differences in fasting glucose: -0.93 mmol/L (95% CI: -1.65, -0.21), total cholesterol: -0.83 mmol/L (-1.24, -0.42); and LDL-cholesterol: -0.72 mmol/L (-1.34, -0.11)]. Findings from this meta-analysis provide evidence to support beneficial effects of whole-grain intake on vascular disease prevention. Potential mechanisms responsible for whole grains' effects on metabolic intermediates require further investigation in large intervention trials.

Chuang, S.-C., T. Norat, et al. (2012). "Fiber intake and total and cause-specific mortality in the European Prospective Investigation into Cancer and Nutrition cohort." Am J Clin Nutr 96(1): 164-174. Background: Previous studies have shown that high fiber intake is associated with lower mortality. However, little is known about the association of dietary fiber with specific causes of death other than cardiovascular disease (CVD).  Objective: The aim of this study was to assess the relation between fiber intake, mortality, and cause-specific mortality in a large European prospective study of 452,717 men and women.  Design: HRs and 95% CIs were estimated by using Cox proportional hazards models, stratified by age, sex, and center and adjusted for education, smoking, alcohol consumption, BMI, physical activity, total energy intake, and, in women, ever use of menopausal hormone therapy.  Results: During a mean follow-up of 12.7 y, a total of 23,582 deaths were recorded. Fiber intake was inversely associated with total mortality (HRper 10-g/d increase: 0.90; 95% CI: 0.88, 0.92); with mortality from circulatory (HRper 10-g/d increase: 0.90 and 0.88 for men and women, respectively), digestive (HR: 0.61 and 0.64), respiratory (HR: 0.77 and 0.62), and non-CVD noncancer inflammatory (HR: 0.85 and 0.80) diseases; and with smoking-related cancers (HR: 0.86 and 0.89) but not with non-smoking-related cancers (HR: 1.05 and 0.97). The associations were more evident for fiber from cereals and vegetables than from fruit. The associations were similar across BMI and physical activity categories but were stronger in smokers and participants who consumed >18 g alcohol/d.  Conclusions: Higher fiber intake is associated with lower mortality, particularly from circulatory, digestive, and non-CVD noncancer inflammatory diseases. Our results support current recommendations of high dietary fiber intake for health maintenance.

Murphy, N., T. Norat, et al. (2012). "Dietary fibre intake and risks of cancers of the colon and rectum in the European Prospective Investigation into Cancer and Nutrition (EPIC)." PLoS One 7(6): e39361. BACKGROUND: Earlier analyses within the EPIC study showed that dietary fibre intake was inversely associated with colorectal cancer risk, but results from some large cohort studies do not support this finding. We explored whether the association remained after longer follow-up with a near threefold increase in colorectal cancer cases, and if the association varied by gender and tumour location. METHODOLOGY/PRINCIPAL FINDINGS: After a mean follow-up of 11.0 years, 4,517 incident cases of colorectal cancer were documented. Total, cereal, fruit, and vegetable fibre intakes were estimated from dietary questionnaires at baseline. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards models stratified by age, sex, and centre, and adjusted for total energy intake, body mass index, physical activity, smoking, education, menopausal status, hormone replacement therapy, oral contraceptive use, and intakes of alcohol, folate, red and processed meats, and calcium. After multivariable adjustments, total dietary fibre was inversely associated with colorectal cancer (HR per 10 g/day increase in fibre 0.87, 95% CI: 0.79-0.96). Similar linear associations were observed for colon and rectal cancers. The association between total dietary fibre and risk of colorectal cancer risk did not differ by age, sex, or anthropometric, lifestyle, and dietary variables. Fibre from cereals and fibre from fruit and vegetables were similarly associated with colon cancer; but for rectal cancer, the inverse association was only evident for fibre from cereals. CONCLUSIONS/SIGNIFICANCE: Our results strengthen the evidence for the role of high dietary fibre intake in colorectal cancer prevention.

van de Laar, R. J., C. D. Stehouwer, et al. (2012). "Lower lifetime dietary fiber intake is associated with carotid artery stiffness: the Amsterdam Growth and Health Longitudinal Study." Am J Clin Nutr 96(1): 14-23. Background: Fiber intake is associated with lower cardiovascular disease risk. Whether arterial stiffness is influenced by lifetime fiber intake is not known. Any such association could explain, at least in part, the cardioprotective effects attributed to fiber intake.Objective: The objective was to investigate whether a lower intake of fiber (and fiber-rich foods) throughout the course of young life (ie, from adolescence to adulthood) is associated with arterial stiffness in adulthood.  Design: This was a longitudinal cohort study among 373 participants in whom dietary intake was assessed between the ages of 13 to 36 y (2-8 repeated measures, median of 5), and arterial stiffness estimates of 3 large arteries (ultrasonography) were ascertained at age 36 y.Results: After adjustment for sex, height, total energy intake, and other lifestyle variables, subjects with stiffer carotid arteries consumed less fiber (in g/d) during the 24-y study than did those with less stiff carotid arteries, as defined on the basis of the highest compared with the lowest sex-specific tertiles of the distensibility and compliance coefficients (reversed) and Young's elastic modulus: -1.9 (95% CI: -3.1, -0.7), -2.3 (-3.5, -1.1), and -1.3 (-2.5, -0.0), respectively. Furthermore, subjects with stiffer carotid arteries were characterized by a lower lifetime consumption of fruit, vegetables, and whole grains-deleterious associations that could be explained, to a great extent, by related low fiber intake.  Conclusions: Lower lifetime intake of fiber during the course of young age is associated with carotid artery stiffness in adulthood. Promoting consumption of fiber-rich foods among the young may offer a means to prevent accelerated arterial stiffening in adulthood and related cardiovascular sequelae.

Lagiou, P., S. Sandin, et al. (2012). "Low carbohydrate-high protein diet and incidence of cardiovascular diseases in Swedish women: prospective cohort study."  BMJ 344: e4026.  OBJECTIVE: To study the long term consequences of low carbohydrate diets, generally characterised by concomitant increases in protein intake, on cardiovascular health. DESIGN: Prospective cohort study. SETTING: Uppsala, Sweden. PARTICIPANTS: From a random population sample, 43 396 Swedish women, aged 30-49 years at baseline, completed an extensive dietary questionnaire and were followed-up for an average of 15.7 years. MAIN OUTCOME MEASURES: Association of incident cardiovascular diseases (ascertained by linkage with nationwide registries), overall and by diagnostic category, with decreasing carbohydrate intake (in tenths), increasing protein intake (in tenths), and an additive combination of these variables (low carbohydrate-high protein score, from 2 to 20), adjusted for intake of energy, intake of saturated and unsaturated fat, and several non-dietary variables.  RESULTS: A one tenth decrease in carbohydrate intake or increase in protein intake or a 2 unit increase in the low carbohydrate-high protein score were all statistically significantly associated with increasing incidence of cardiovascular disease overall (n=1270)-incidence rate ratio estimates 1.04 (95% confidence interval 1.00 to 1.08), 1.04 (1.02 to 1.06), and 1.05 (1.02 to 1.08). No heterogeneity existed in the association of any of these scores with the five studied cardiovascular outcomes: ischaemic heart disease (n=703), ischaemic stroke (n=294), haemorrhagic stroke (n=70), subarachnoid haemorrhage (n=121), and peripheral arterial disease (n=82). CONCLUSIONS: Low carbohydrate-high protein diets, used on a regular basis and without consideration of the nature of carbohydrates or the source of proteins, are associated with increased risk of cardiovascular disease.

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