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September 2013

Dietary flavonols and flavonol-rich foods intake and the risk of breast cancer.

Laboratory and animal studies suggest that dietary flavonols may reduce breast cancer risk but there are limited epidemiological studies. We computed flavonol intakes from dietary data collected by validated food frequency questionnaires in 1991 and 1995 from 90,630 women in the Nurses Health Study II. Using multivariate relative risks (RR) and 95% confidence intervals (95% CI), we evaluated the association of flavonol intake with breast cancer risk in women who were premenopausal and aged between 26 and 46 years at baseline in 1991. During 8 years of follow-up, we documented 710 cases of invasive breast cancer. The multivariate RR (95% CI), comparing highest to lowest quintiles of cumulative average intake, was 1.05 (0.83, 1.34; p-value for test of trend=0.96) for the sum of flavonols and there were no associations seen between individual flavonols such as kaempferol, quercetin and myricetin and breast cancer risk. The multivariate RR (95% CI), comparing highest to lowest quintiles of cumulative average intake, was 0.94 (0.72, 1.22; p-value for test of trend=0.54) for sum of flavonol-rich foods. Among the major food sources of flavonols, we found a significant inverse association with intake of beans or lentils but not with tea, onions, apples, string beans, broccoli, green pepper and blueberries. The multivariate RR (95% CI), comparing the highest category (2 or more times a week) of cumulative average beans or lentils intake with the lowest category (less than once a month), was 0.76 (0.57, 1.00; p-value for test of trend=0.03). While we found no overall association between intake of flavonols and risk of breast cancer, there was an inverse association with intake of beans or lentils that merits further evaluation.

Int J Cancer. 2005 Apr 20;114(4):628-33

Legume intake and the risk of cancer: a multisite case-control study in Uruguay.

BACKGROUND: Previous studies have suggested that a high intake of legumes may decrease the risk of stomach and prostate cancer and some other cancers. However, the evidence is still limited. To further explore the association between legume intake and cancer risk we conducted a case-control study of 11 cancer sites in Uruguay between 1996 and 2004, including 3,539 cancer cases and 2,032 hospital controls. RESULTS: The highest versus the lowest tertile of legume intake was associated with a significant decrease in the risk of cancers of the oral cavity and pharynx (OR = 0.48, 95% CI: 0.34-0.68), esophagus (OR = 0.54, 95% CI: 0.38-0.77), larynx (OR = 0.55, 95% CI: 0.40-0.77), upper aerodigestive tract (OR = 0.50, 95% CI: 0.40-0.63), stomach (OR = 0.69, 95% CI: 0.49-0.97), colorectum (OR = 0.43, 95% CI: 0.32-0.59), kidney (OR = 0.41, 95% CI: 0.24-0.71), and all sites combined (OR = 0.68, 95% CI: 0.59-0.78). No significant association was observed between legume intake and cancers of the lung (OR = 1.03, 95% CI: 0.83-1.27), breast (OR = 0.89, 95% CI: 0.65-1.20), prostate (OR = 0.87, 95% CI: 0.64-1.18) or bladder (OR = 0.82, 95% CI: 0.57-1.17). Similar results were found for both beans and lentils. CONCLUSION: Higher intake of legumes was associated with a decreased risk of several cancers including those of the upper aerodigestive tract, stomach, colorectum, and kidney, but not lung, breast, prostate or bladder. Further investigations of these associations in prospective cohort studies are warranted.

Cancer Causes Control. 2009 Nov;20(9):1605-15

Dietary risk factors for colon cancer in a low-risk population.

In a 6-year prospective study, the authors examined the relation between diet and incident colon cancer among 32,051 non-Hispanic white cohort members of the Adventist Health Study (California, 1976-1982) who, at baseline, had no documented or reported history of cancer. The risk of colon cancer was determined from proportional hazards regression with adjustment for age and other covariates. The authors found a positive association with total meat intake (risk ratio (RR) for > or =1 time/week vs. no meat intake = 1.85, 95% confidence interval (CI) 1.19-2.87; p for trend = 0.01) and, among subjects who favored specific types of meat, positive associations with red meat intake (RR for > or =1 time/week vs. no red meat intake = 1.90, 95% CI 1.16-3.11; p for trend = 0.02) and white meat intake (RR for > or =1 time/week vs. no white meat intake = 3.29, 95% CI 1.60-6.75; p for trend = 0.006). An inverse association with legume intake (RR for >2 times/week vs. <1 time/week = 0.53, 95% CI 0.33-0.86; p for trend = 0.03) was observed. Among men, a positive association with body mass index was observed (relative to the RR for tertile III (>25.6 kg/m2) vs. tertile I (<22.5 kg/m2) = 2.63, 95% CI 1.12-6.13; p for trend = 0.05). A complex relation was identified whereby subjects exhibiting a high red meat intake, a low legume intake, and a high body mass experienced a more than threefold elevation in risk relative to all other patterns based on these variables. This pattern of putative risk factors would likely contribute to increases in both insulin resistance (high body mass, high red meat intake) and glycemic load (low legume intake), a synergism that, if causal, implicates hyperinsulinemic exposure in colon carcinogenesis. The overall findings from this cohort identify both red meat intake and white meat intake as important dietary risk factors for colon cancer and raise the possibility that the risk due to red meat intake reflects a more complex etiology.

Am J Epidemiol. 1998 Oct 15;148(8):761-74

Chemopreventive effect of raw and cooked lentils (Lens culinaris L) and soybeans (Glycine max) against azoxymethane-induced aberrant crypt foci.

Although lentils (Lens culinaris L) contain several bioactive compounds that have been linked to the prevention of cancer, the in vivo chemopreventive ability of lentils against chemically induced colorectal cancer has not been examined. Our present study examined the hypothesis that lentils could suppress the early carcinogenesis in vivo by virtue of their bioactive micro- and macroconstituents and that culinary thermal treatment could affect their chemopreventive potential. To accomplish this goal, we used raw whole lentils (RWL), raw split lentils (RSL), cooked whole lentils (CWL), and cooked split lentils (CSL). Raw soybeans (RSB; Glycine max) were used for the purpose of comparison with a well-studied chemopreventive agent. Sixty weanling Fischer 344 male rats, 4 to 5 weeks of age, were randomly assigned to 6 groups (10 rats/group): the control group (C) received AIN-93G diet, and treatment leguminous groups of RWL, CWL, RSL, CSL, and RSB received the treatment diets containing AIN-93G+5% of the above-mentioned legumes. After acclimatization for 1 week (at 5th to 6th week of age), all animals were put on the control and treatment diets separately for 5 weeks (from 6th to 11th week of age). At the end of the 5th week of feeding (end of 11th week of age), all rats received 2 subcutaneous injections of azoxymethane carcinogen at 15 mg/kg rat body weight per dose once a week for 2 consecutive weeks. After 17 weeks of the last azoxymethane injection (from 12th to 29th week of age), all rats were euthanized. Chemopreventive ability was assessed using colonic aberrant crypt foci and activity of hepatic glutathione-S-transferases. Significant reductions (P < .05) were found in total aberrant crypt foci number (mean +/- SEM) for RSB (27.33 +/- 4.32), CWL (33.44 +/- 4.56), and RSL (37.00 +/- 6.02) in comparison with the C group (58.33 +/- 8.46). Hepatic glutathione-S-transferases activities increased significantly (P < .05) in rats fed all treatment diets (from 51.38 +/- 3.66 to 67.94 +/- 2.01 micromol mg(-1) min(-1)) when compared with control (C) diet (26.13 +/- 1.01 micromol mg(-1) min(-1)). Our findings indicate that consumption of lentils might be protective against colon carcinogenesis and that hydrothermal treatment resulted in an improvement in the chemopreventive potential for the whole lentils.

Nutr Res. 2009 May;29(5):355-62

Cohort study of diet, lifestyle, and prostate cancer in Adventist men.

Dietary and lifestyle characteristics were evaluated in relation to subsequent prostatic cancer risk in a cohort of approximately 14,000 Seventh-day Adventist men who completed a detailed lifestyle questionnaire in 1976 and who were monitored for cancer incidence until the end of 1982. During the 6-year follow-up period, 180 histologically confirmed prostatic cancers were detected among some 78,000 man-years of follow-up. Increasing educational attainment was associated with significantly decreased risk of prostate cancer in this study; age at first marriage was also inversely associated with risk, although this was not significant. There was no relationship between body mass index (as measured by Quetelet’s Index) and risk. A history of prostate “trouble” was associated with a 60% increase in risk which was highly significant. Although there were suggestive relationships between increasing animal product consumption and increased risk, these results did not persist after accounting for the influence of fruit and vegetable consumption. Nor was exposure to the vegetarian lifestyle during the childhood years associated with alterations in subsequent risk. However, increasing consumption of beans, lentils and peas, tomatoes, raisin, dates, and other dried fruit were all associated with significantly decreased prostate cancer risk.

Cancer. 1989 Aug 1;64(3):598-604

Persistent increase of prevalence of metabolic syndrome among U.S. adults: NHANES III to NHANES 1999-2006.

OBJECTIVE: To compare the prevalence in metabolic syndrome (MetSyn) between 1988-1994 and 1999-2006 among U.S. adults of different races or ethnicities. RESEARCH DESIGN AND METHODS: Analysis of data on 6,423 adult men and nonpregnant women aged ≥20 years from Third National Health and Nutrition Examination Survey (NHANES III) and 6,962 participants from the combined NHANES 1999-2006 were done. The revised National Cholesterol Education Program Adult Treatment Panel III definition was used to calculate MetSyn. RESULTS: Both the unadjusted prevalence (27.9 ± 1.1% to 34.1 ± 0.8%, P < 0.001) and age-adjusted prevalence (29.2 ± 1.0% to 34.2 ± 0.7%, P < 0.001) increased from NHANES III to NHANES 1999-2006, respectively. Although MetSyn prevalence was highest in Mexican Americans, significant increases in prevalence occurred among non-Hispanic whites and non-Hispanic blacks, especially among younger women. CONCLUSIONS: The persistent increase of MetSyn among U.S. adults is a serious public health concern because it raises the likelihood of increased prevalence of type 2 diabetes.

Diabetes Care. 2011 Jan;34(1):216-9

Legume intake is inversely associated with metabolic syndrome in adults.

BACKGROUND: Studies on the association between legume intake and metabolic syndrome (MetS) are sparse. The objective of this study is to evaluate the association between legume intake, MetS, and its components. METHODS: This study was conducted on 80 subjects (48% female) with MetS as cases and 160 age and gender-matched healthy controls. Anthropometric measures, blood pressure, fasting blood glucose, and lipid profiles were evaluated by standard methods. Dietary data were collected using a food frequency questionnaire (FFQ) and legume intake was determined. MetS was defined according to the definition of the Adult Treatment Panel III. RESULTS: The mean (SD) intake of legumes was 1.4 (0.9) servings/week for cases and 2.3 (1.1) servings/week for control subjects (P < 0.05). After adjustment for potential confounders, decreases in mean systolic blood pressure, fasting blood glucose, and increase in HDL cholesterol levels were observed across increasing quartile categories of legume intake. After adjustments for life style and food groups, subjects in the highest quartile of legume intake had lower odds of having MetS compared with those in the lowest quartile [odds ratio (OR): 0.25; 95% CI: 0.11 - 0.64, P < 0.05], an association that weakened after adjustment for body mass index (BMI), but remained significant (OR: 0.28; 95% CI: 0.12 - 0.81, P < 0.05). CONCLUSIONS: Legume intake is inversely associated with the risk of having MetS and some of its components.

Arch Iran Med. 2012 Sep;15(9):538-44

A legume-based hypocaloric diet reduces proinflammatory status and improves metabolic features in overweight/obese subjects.

BACKGROUND: The nutritional composition of the dietary intake could produce specific effects on metabolic variables and inflammatory marker concentrations. This study assessed the effects of two hypocaloric diets (legume-restricted- vs. legume-based diet) on metabolic and inflammatory changes, accompanying weight loss. METHODS: Thirty obese subjects (17 M/13F; BMI: 32.5 ± 4.5 kg/m(2); 36 ± 8 years) were randomly assigned to one of the following hypocaloric treatments (8 weeks): Calorie-restricted legume-free diet (Control: C-diet) or calorie-restricted legume-based diet (L-diet), prescribing 4 weekly different cooked-servings (160-235 g) of lentils, chickpeas, peas or beans. Body composition, blood pressure (BP), blood biochemical and inflammatory marker concentrations as well as dietary intake were measured at baseline and after the nutritional intervention. RESULTS: The L-diet achieved a greater body weight loss, when compared to the C-diet (-7.8 ± 2.9% vs. -5.3 ± 2.7%; p = 0.024). Total and LDL cholesterol levels and systolic BP were improved only when consuming the L-diet (p < 0.05). L-diet also resulted in a significant higher reduction in C-reactive protein (CRP) and complement C3 (C3) concentrations (p < 0.05), compared to baseline and C-diet values. Interestingly, the reduction in the concentrations of CRP and C3 remained significantly higher to L-diet group, after adjusting by weight loss (p < 0.05). In addition, the reduction (%) in CRP concentrations was positively associated with decreases (%) in systolic BP and total cholesterol concentration specifically in the L-diet group, independent from weight loss (p < 0.05). CONCLUSION: The consumption of legumes (4 servings/week) within a hypocaloric diet resulted in a specific reduction in proinflammatory markers, such as CRP and C3 and a clinically significant improvement of some metabolic features (lipid profile and BP) in overweight/ obese subjects, which were in some cases independent from weight loss.

Eur J Nutr. 2011 Feb;50(1):61-9

Effect of Dehulling and Cooking of Lentils (Lens Culinaris, L.)on Serum Glucose and Lipoprotein Levels in Streptozotocin-Induced Diabetic Rats.

This study was conducted to investigate the effect of lentils on serum glucose and serum lipid levels in diabetic rats. Forty adult male Sprague-Dawley rats, 12 weeks of age weighing 220-290g, were used. Diabetes was induced by streptozotocin at a level of 35 mg/kg intra-peritoneally. The animals were randomly divided into five groups, eight animals each: a casein diet (control), raw whole lentil (RWL), cooked whole lentil (CWL), raw dehulled lentil (RDL) and cooked dehulled lentil (CDL). Animals were fed with experimental diets for six weeks, sacrificed and blood samples were taken. Serum glucose level of the CDL group (387.9 ± 53.3 mg/dl) was significantly lower (P<0.05) than that of the control, RDL and RWL groups (529.0 ± 11.7, 538.6 ± 45.0, 542.1 ± 32.2 mg/dl respectively). In addition, HDL concentration of CWL group (66.3 ± 1.9 mg/dl) was significantly higher (P<0.01) than that of the control, RWL and RDL groups (54.9 ± 3.5, 50.8 ± 4.2, 54.0 ± 3.4 mg/dl respectively). However, there was no significant difference in serum glucose and serum HDL between the CDL and CWL groups. No significant differences (p>0.05) were detected in triglycerides, total cholesterol and LDL cholesterol among the experimental groups. It is concluded that cooked lentils rather than raw lentils was more effective in lowering blood glucose and improving HDL cholesterol in diabetic rats. There was no difference between whole and dehulled lentils with regard to effects on blood glucose and HDL cholesterol levels.

Malays J Nutr. 2010 Dec;16(3):409-18