Whole-grain consumption and the metabolic syndrome: a favorable association in Tehranian adults

BACKGROUND: Although dietary guidelines recommend increased intake of grain products to prevent chronic diseases, epidemiologic data regarding whole-grain intake association with metabolic syndrome are sparse. OBJECTIVE: To evaluate the relationship between whole-grain intakes, metabolic syndrome and metabolic risk factors in Tehranian adults. DESIGN: Population-based cross-sectional study. SETTING: Tehran, the capital of Iran. SUBJECTS: A representative sample of 827 subjects (357 men and 470 women) aged 18-74 y. METHODS: Usual dietary intake was assessed using a food frequency questionnaire. The procedure developed by Jacobs et al was used to classify grain products into whole and refined grains. Weight and height were measured according to standard protocols and body mass index was calculated. Fasting blood samples were taken for biochemical measurements and blood pressure was assessed according to standard methods. Hypertriglyceridemia, hypercholestrolemia, high LDL, low HDL and metabolic syndrome were defined according to ATP III guidelines and hypertension based on JNC VI. Diabetes was defined as fasting plasma glucose level of > or = 126 mg/dl or 2-h postchallenge blood glucose level of > or = 200 mg/dl. Subjects were categorized based on quartile cut-points of whole- and refined-grain intake. RESULTS: Mean (+/-s.d.) consumptions of whole and refined grains were 93+/-29 and 201+/-57 g/day, respectively. Both men and women reported higher intakes of refined grain than of whole grains. Compared with subjects in the lower quartile category, those in the upper category of whole-grain intake had lower prevalence of metabolic risk factors. Conversely, those in the higher category of refined-grain intake had higher prevalence of metabolic risk factors, except for diabetes. After controlling for confounders, a significantly decreasing trend was observed for the risk of having hypertriglyceridemia (odds ratios among quartiles: 1.00, 0.89, 0.74, 0.61, respectively), hypertension (1.00, 0.99, 0.93, 0.84) and metabolic syndrome (1.00, 0.84, 0.76, 0.68). Higher consumption of refined grains was associated with higher odds of having hypercholestrolemia (1.00, 1.07, 1.19, 1.23), hypertriglyceridemia (1.00, 1.17, 1.49, 2.01), hypertension (1.00, 1.22, 1.48, 1.69) and metabolic syndrome (1.00, 1.68, 1.92, 2.25). CONCLUSION: Whole-grain intake is inversely and refined-grain intake is positively associated with the risk of having metabolic syndrome. Recommendations to increase whole-grain intake may reduce this risk.     

Associations of whole-grain,refined-grain,and fruit and vegetable consumption with risks of all-cause mortality and incident coronary artery disease and ischemic stroke: the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND: Recent epidemiologic study results showed that subjects who had high intakes of whole-grain foods had lower risks of death and heart disease than did subjects who had low intakes. However, the findings were inconsistent for fruit and vegetable intake. OBJECTIVE: The relations of whole-grain, refined-grain, and fruit and vegetable intakes with the risk of total mortality and the incidence of coronary artery disease (CAD) and ischemic stroke were studied in the Atherosclerosis Risk in Communities (ARIC) cohort (baseline: age 45-64 y, n = 15,792). DESIGN: Proportional hazards regression analyses were used to assess the relations of whole-grain, refined-grain, and fruit and vegetable intakes with the risk of death and the incidence of CAD and ischemic stroke, with adjustment for age, sex, ethnicity, energy intake, and cardiovascular disease risk factors. Dietary intakes were assessed by using a food-frequency questionnaire. RESULTS: Over an 11-y follow-up period, whole-grain intake was inversely associated with total mortality and incident CAD. The relative hazards of death for quintiles 2-5 of fruit and vegetable intake were 1.08 (95% CI: 0.88, 1.33), 0.94 (0.75, 1.17), 0.87 (0.68, 1.10), and 0.78 (0.61, 1.01), respectively; P for trend = 0.02. An inverse association between fruit and vegetable intake and CAD was observed among African Americans but not among whites (P for interaction = 0.01). The risk of ischemic stroke was not significantly related to whole-grain, refined-grain, or fruit and vegetable consumption. CONCLUSION: These observational findings suggest a beneficial effect of whole-grain and fruit and vegetable consumption on the risks of total mortality and incident CAD but not on the risk of ischemic stroke.     

Is intake of breakfast cereals related to total and cause-specific mortality in men?

BACKGROUND: Prospective studies suggested that substituting whole-grain products for refined-grain products lowers the risks of type 2 diabetes and cardiovascular disease (CVD) in women. Although breakfast cereals are a major source of whole and refined grains, little is known about their direct association with the risk of premature mortality. OBJECTIVE: We prospectively evaluated the association between whole- and refined-grain breakfast cereal intakes and total and CVD-specific mortality in a cohort of US men. DESIGN: We examined 86,190 US male physicians aged 40-84 y in 1982 who were free of known CVD and cancer at baseline. RESULTS: During 5.5 y, we documented 3114 deaths from all causes, including 1381 due to CVD (488 myocardial infarctions and 146 strokes). Whole-grain breakfast cereal intake was inversely associated with total and CVD-specific mortality, independent of age; body mass index; smoking; alcohol intake; physical activity; history of diabetes, hypertension, or high cholesterol; and use of multivitamins. Compared with men who rarely or never consumed whole-grain cereal, men in the highest category of whole-grain cereal intake (> or = 1 serving/d) had multivariate-estimated relative risks of total and CVD-specific mortality of 0.83 (95% CI: 0.73, 0.94; P for trend < 0.001) and 0.80 (0.66, 0.97; P for trend < 0.001), respectively. In contrast, total and refined-grain breakfast cereal intakes were not significantly associated with total and CVD-specific mortality. These findings persisted in analyses stratified by history of type 2 diabetes, hypertension, and high cholesterol. CONCLUSIONS: Both total mortality and CVD-specific mortality were inversely associated with whole-grain but not refined-grain breakfast cereal intake. These prospective data highlight the importance of distinguishing whole-grain from refined-grain cereals in the prevention of chronic diseases.     

Whole-grain and fiber intakes and periodontitis risk in men

BACKGROUND: Diabetes and hyperglycemia increase periodontitis risk, severity, and extent. Increased whole-grain and fiber intakes are associated with improved insulin sensitivity and may therefore affect periodontitis risk. OBJECTIVE: The objective was to examine the associations between whole-grain and fiber intakes and periodontitis risk. DESIGN: We prospectively followed 34,160 male US health professionals aged 40-75 y at the outset. We updated medical and lifestyle information biennially with questionnaires and diet every 4 y by using a validated food-frequency questionnaire. We excluded men reporting periodontitis, myocardial infarction, stroke, and hypercholesterolemia before 1986 and those with incomplete dietary data. All diabetics were excluded. Periodontitis was determined by a report of professionally diagnosed disease and validated by a diagnosis of periodontitis by a periodontist from a blinded review of radiographs. RESULTS: Men in the highest quintile of whole-grain intake were 23% less likely to get periodontitis than were those in the lowest quintile (multivariate RR: 0.77; 95% CI: 0.66, 0.89; P for trend < 0.001) after adjustment for age, smoking, body mass index, alcohol intake, physical activity, and total energy intake. Periodontitis was not associated with refined-grain intake (multivariate RR comparing extreme quintiles of intake: 1.04; 95% CI: 0.89, 1.23; P for trend = 0.37). Cereal fiber was inversely related to periodontitis risk (multivariate RR comparing extreme quintiles of intake: 0.85; 95% CI: 0.73, 0.99; P for trend = 0.03), but the association was not significant after adjustment for whole-grain intake. CONCLUSION: Increasing whole grain in the diet without increasing total energy intake may reduce periodontitis risk.     

Whole-grain intake is favorably associated with metabolic risk factors for type 2 diabetes and cardiovascular disease in the Framingham Offspring Study

BACKGROUND: The influence of whole grains on cardiovascular disease risk may be mediated through multiple pathways, eg, a reduction in blood lipids and blood pressure, an enhancement of insulin sensitivity, and an improvement in blood glucose control. OBJECTIVE: The objective was to examine the association between diets rich in whole- or refined-grain foods and several metabolic markers of disease risk in the Framingham Offspring Study cohort. DESIGN: Whole-grain intake and metabolic risk markers were assessed in a cross-sectional study of 2941 subjects. RESULTS: After adjustment for potential confounding factors, whole-grain intake was inversely associated with body mass index (: 26.9 in the lowest and 26.4 in the highest quintile of intake; P for trend = 0.06), waist-to-hip ratio (0.92 and 0.91, respectively; P for trend = 0.005), total cholesterol (5.20 and 5.09 mmol/L, respectively; P for trend = 0.06), LDL cholesterol (3.16 and 3.04 mmol/L, respectively; P for trend = 0.02), and fasting insulin (205 and 199 pmol/L, respectively; P for trend = 0.03). There were no significant trends in metabolic risk factor concentrations across quintile categories of refined-grain intake. The inverse association between whole-grain intake and fasting insulin was most striking among overweight participants. The association between whole-grain intake and fasting insulin was attenuated after adjustment for dietary fiber and magnesium. CONCLUSION: Increased intakes of whole grains may reduce disease risk by means of favorable effects on metabolic risk factors.     

Whole-grain consumption and risk of coronary heart disease: results from the Nurses' Health Study.

BACKGROUND: Although current dietary guidelines for Americans recommend increased intake of grain products to prevent coronary heart disease (CHD), epidemiologic data relating whole-grain intake to the risk of CHD are sparse. OBJECTIVE: Our objective was to evaluate whether high whole-grain intake reduces risk of CHD in women. DESIGN: In 1984, 75521 women aged 38-63 y with no previous history of cardiovascular disease or diabetes completed a detailed, semiquantitative food-frequency questionnaire (SFFQ) and were followed for 10 y, completing SFFQs in 1986 and 1990. We used pooled logistic regression with 2-y intervals to model the incidence of CHD in relation to the cumulative average diet from all 3 cycles of SFFQs. RESULTS: During 729472 person-years of follow-up, we documented 761 cases of CHD (208 of fatal CHD and 553 of nonfatal myocardial infarction). After adjustment for age and smoking, increased whole-grain intake was associated with decreased risk of CHD. For increasing quintiles of intake, the corresponding relative risks (RRs) were 1.0 (reference), 0.86, 0.82, 0.72, and 0.67 (95% CI comparing 2 extreme quintiles: 0.54, 0.84; P for trend < 0.001). After additional adjustment for body mass index, postmenopausal hormone use, alcohol intake, multivitamin use, vitamin E supplement use, aspirin use, physical activity, and types of fat intake, these RRs were 1.0, 0.92, 0.93, 0.83, and 0.75 (95% CI: 0.59, 0.95; P for trend = 0.01). The inverse relation between whole-grain intake and CHD risk was even stronger in the subgroup of never smokers (RR = 0. 49 for extreme quintiles; 95% CI: 0.30, 0.79; P for trend = 0.003). The lower risk associated with higher whole-grain intake was not fully explained by its contribution to intakes of dietary fiber, folate, vitamin B-6, and vitamin E. CONCLUSIONS: Increased intake of whole grains may protect against CHD.     

Intakes of whole grains, bran, and germ and the risk of coronary heart disease in men

BACKGROUND: Previous studies have suggested that a daily intake of 3 servings of whole-grain foods is associated with a reduced risk of coronary heart disease (CHD). However, methods for the assessment of whole-grain intake differ. Furthermore, any additional effects of added bran and germ, which are components of whole grains, have not been reported. OBJECTIVE: The objective was to evaluate the association of whole-grain, bran, and germ intakes (with the use of new quantitative measures) with the incidence of CHD. DESIGN: This was a prospective cohort study of 42,850 male health professionals aged 40-75 y at baseline in 1986 who were free from cardiovascular disease, cancer, and diabetes. Daily whole-grain, bran, and germ intakes were derived in grams per day from a detailed semiquantitative dietary questionnaire. RESULTS: During 14 y of follow-up, we documented 1818 incident cases of CHD. After cardiovascular disease risk factors and the intakes of bran and germ added to foods were controlled for, the hazard ratio of CHD between extreme quintiles of whole-grain intake was 0.82 (95% CI: 0.70, 0.96; P for trend=0.01). The hazard ratio of CHD in men with the highest intake of added bran was 0.70 (95% CI: 0.60, 0.82) compared with men with no intake of added bran (P for trend < or = 0.001). Added germ was not associated with CHD risk. CONCLUSION: This study supports the reported beneficial association of whole-grain intake with CHD and suggests that the bran component of whole grains could be a key factor in this relation.     

Relation between changes in intakes of dietary fiber and grain products and changes in weight and development of obesity among middle-aged women

BACKGROUND: Although increased consumption of dietary fiber and grain products is widely recommended to maintain healthy body weight, little is known about the relation of whole grains to body weight and long-term weight changes. OBJECTIVE: We examined the associations between the intakes of dietary fiber and whole- or refined-grain products and weight gain over time. DESIGN: In a prospective cohort study, 74,091 US female nurses, aged 38-63 y in 1984 and free of known cardiovascular disease, cancer, and diabetes at baseline, were followed from 1984 to 1996; their dietary habits were assessed in 1984, 1986, 1990, and 1994 with validated food-frequency questionnaires. Using multiple models to adjust for covariates, we calculated average weight, body mass index (BMI; in kg/m(2)), long-term weight changes, and the odds ratio of developing obesity (BMI > or = 30) according to change in dietary intake. RESULTS: Women who consumed more whole grains consistently weighed less than did women who consumed less whole grains (P for trend < 0.0001). Over 12 y, those with the greatest increase in intake of dietary fiber gained an average of 1.52 kg less than did those with the smallest increase in intake of dietary fiber (P for trend < 0.0001) independent of body weight at baseline, age, and changes in covariate status. Women in the highest quintile of dietary fiber intake had a 49% lower risk of major weight gain than did women in the highest quintile (OR = 0.51; 95% CI: 0.39, 0.67; P < 0.0001 for trend). CONCLUSION: Weight gain was inversely associated with the intake of high-fiber, whole-grain foods but positively related to the intake of refined-grain foods, which indicated the importance of distinguishing whole-grain products from refined-grain products to aid in weight control.     

Dietary fiber and whole-grain consumption in relation to colorectal cancer in the NIH-AARP Diet and Health Study

BACKGROUND: Whether the intake of dietary fiber can protect against colorectal cancer is a long-standing question of considerable public health import, but the epidemiologic evidence has been inconsistent. OBJECTIVE: The objective was to investigate the relation between dietary fiber and whole-grain food intakes and invasive colorectal cancer in the prospective National Institutes of Health-AARP Diet and Health Study. DESIGN: The analytic cohort consisted of 291 988 men and 197 623 women aged 50-71 y. Diet was assessed with a self-administered food-frequency questionnaire at baseline in 1995-1996; 2974 incident colorectal cancer cases were identified during 5 y of follow-up. The Cox proportional hazards model was used to estimate the relative risks (RRs) and 95% CIs. RESULTS: Total dietary fiber intake was not associated with colorectal cancer. The multivariate RR for the highest compared with the lowest intake quintile (RR(Q5-Q1)) was 0.99 (95% CI: 0.85, 1.15; P for trend = 0.96). In analyses of fiber from different food sources, only fiber from grains was associated with a lower risk of colorectal cancer (multivariate RR(Q5-Q1): 0.86; 95% CI: 0.76, 0.98; P for trend = 0.01). Whole-grain intake was inversely associated with colorectal cancer risk: the multivariate RR(Q5-Q1) was 0.79 (95% CI: 0.70, 0.89) for the whole cohort (P for trend < 0.001). The association with whole grain was stronger for rectal than for colon cancer. CONCLUSIONS: In this large prospective cohort study, total dietary fiber intake was not associated with colorectal cancer risk, whereas whole-grain consumption was associated with a modest reduced risk.     

Whole-grain intake and the prevalence of hypertriglyceridemic waist phenotype in Tehranian adults

BACKGROUND: Although dietary guidelines recommend increased intake of grain products to prevent chronic diseases, no epidemiologic data associate whole-grain intake with hypertriglyceridemic waist (HW) phenotype. OBJECTIVE: We aimed to evaluate the relation between whole-grain intakes and the prevalence of HW phenotype in adults in Tehran, Iran. DESIGN: Whole-grain intake, serum triacylglycerol concentration, and waist circumference (WC) were assessed in a population-based, cross-sectional study of 827 Iranian subjects (357 men and 470 women) aged 18-74 y. HW phenotype was defined as serum triacylglycerol concentrations > or =150 mg/dL and concurrent WC > or = 80 cm (men) and > or =79 cm (women). RESULTS: Mean (+/-SD) consumption of whole and refined grains was 93 +/- 29 and 201 +/- 57 g/d, respectively. Subjects in the highest quartile of whole-grain intake had a significantly lower prevalence of HW (29%) than did those in the lowest quartile (44%; P < 0.05). Conversely, those in the highest quartile of refined-grain intake had a significantly higher prevalence of HW (45%) than did those in the lowest quartile (27%; P < 0.05). After control for potential confounding factors, a significantly decreasing trend was observed for the risk of HW phenotype across quartiles of whole-grain intake (odds ratios among quartiles: 1.00, 0.95, 0.90, and 0.78, respectively; P for trend = 0.02). Higher consumption of refined grains was associated with better odds of HW phenotype (by quartile: 1.00, 1.38, 1.65, and 2.1; P for trend = 0.01). CONCLUSION: Whole-grain intake is inversely and refined-grain intake is positively associated with the risk of HW.     

A prospective study of whole-grain intake and risk of type 2 diabetes mellitus in US women

OBJECTIVES: This study examined the association between intake of whole vs refined grain and the risk of type 2 diabetes mellitus. METHODS: We used a food frequency questionnaire for repeated dietary assessments to prospectively evaluate the relation between whole-grain intake and the risk of diabetes mellitus in a cohort of 75,521 women aged 38 to 63 years without a previous diagnosis of diabetes or cardiovascular disease in 1984. RESULTS: During the 10-year follow-up, we confirmed 1879 incident cases of diabetes mellitus. When the highest and the lowest quintiles of intake were compared, the age and energy-adjusted relative risks were 0.62 (95% confidence interval [CI] = 0.53, 0.71, P trend < .0001) for whole grain, 1.31 (95% CI = 1.12, 1.53, P trend = .0003) for refined grain, and 1.57 (95% CI = 1.36, 1.82, P trend < .0001) for the ratio of refined- to whole-grain intake. These findings remained significant in multivariate analyses. The findings were most evident for women with a body mass index greater than 25 and were not entirely explained by dietary fiber, magnesium, and vitamin E. CONCLUSIONS: These findings suggest that substituting whole- for refined-grain products may decrease the risk of diabetes mellitus.     

Carbohydrates, dietary fiber, and incident type 2 diabetes in older women

BACKGROUND: Dietary carbohydrates may influence the development of type 2 (non-insulin-dependent) diabetes, for example, through effects on blood glucose and insulin concentrations. OBJECTIVE: We examined the relations of baseline intake of carbohydrates, dietary fiber, dietary magnesium, and carbohydrate-rich foods and the glycemic index with incidence of diabetes. DESIGN: This was a prospective cohort study of 35988 older Iowa women initially free of diabetes. During 6 y of follow-up, 1141 incident cases of diabetes were reported. RESULTS: Total grain, whole-grain, total dietary fiber, cereal fiber, and dietary magnesium intakes showed strong inverse associations with incidence of diabetes after adjustment for potential nondietary confounding variables. Multivariate-adjusted relative risks of diabetes were 1.0, 0.99, 0.98, 0.92, and 0.79 (P for trend: 0.0089) across quintiles of whole-grain intake; 1.0, 1.09, 1.00, 0.94, and 0.78 (P for trend: 0.005) across quintiles of total dietary fiber intake; and 1.0, 0.81, 0.82, 0.81, and 0.67 (P for trend: 0.0003) across quintiles of dietary magnesium intake. Intakes of total carbohydrates, refined grains, fruit and vegetables, and soluble fiber and the glycemic index were unrelated to diabetes risk. CONCLUSION: These data support a protective role for grains (particularly whole grains), cereal fiber, and dietary magnesium in the development of diabetes in older women.     

Whole-grain intake is inversely associated with the metabolic syndrome and mortality in older adults

BACKGROUND: Whole-grain intake has been inversely associated with the metabolic syndrome in middle-aged populations, but the association has not been investigated in older adults. The metabolic consequence of consuming high whole-grain diets may differ in elderly persons, who are prone to greater insulin resistance and impaired glucose tolerance. OBJECTIVE: The aim of the present study was to examine the cross-sectional association between whole- and refined-grain intake, cardiovascular disease risk factors, prevalence of the metabolic syndrome, and the incidence of cardiovascular disease mortality in the same cohort of older adults. DESIGN: The nutritional status of 535 healthy persons aged 60-98 y was determined from 1981 to 1984. The subjects kept a 3-d food record and had their blood tested for metabolic risk factors. The metabolic syndrome was defined based on criteria set by the third report of the National Cholesterol Education Program. The vital status of the subjects was identified in October 1995. RESULTS: The results showed a significant inverse trend between whole-grain intake and the metabolic syndrome (P for trend = 0.005) and mortality from cardiovascular disease (P for trend = 0.04), independent of demographic, lifestyle, and dietary factors. Fasting glucose concentrations and body mass index decreased across increasing quartile categories of whole-grain intake (P for trend = 0.01 and 0.03, respectively), independent of confounders, whereas intake of refined grain was positively associated with higher fasting glucose concentrations (P for trend = 0.04) and a higher prevalence of the metabolic syndrome (P for trend = 0.01). CONCLUSION: Whole-grain intake is a modifiable dietary risk factor, and older and young adults should be encouraged to increase their daily intake to > or = 3 servings/d.     

The consumption of lycopene and tomato-based food products is not associated with the risk of type 2 diabetes in women

Lycopene is a major carotenoid with potent antioxidant properties that may provide protection against the development of type 2 diabetes mellitus (DM). In this study we examined the association between baseline dietary intakes of lycopene, lycopene-containing foods, and the subsequent development of type 2 DM in a large prospective cohort study. We analyzed a total of 35,783 women from the United States, aged > or =45 y and free from self-reported cardiovascular disease, cancer, and DM at baseline. Intakes of lycopene and total and individual tomato-based food products were assessed by a 131-item-validated semiquantitative food-frequency questionnaire. During a median follow-up of 10.2 y, 1544 cases of incident type 2 DM were documented. After adjusting for age, total energy intake, randomized treatment assignment, body mass index, and other known DM risk factors, the multivariate-adjusted relative risks and 95% CI of type 2 DM across increasing quintiles of dietary lycopene, were 1.00 (baseline), 1.10 (0.94-1.29), 1.10 (0.94-1.29), and 1.07 (0.91-1.26) (P linear trend = 0.56). Compared with women who consumed <1.5 servings/wk total tomato-based food products, women who consumed 1.5 to <4, 4 to <7, 7 to <10, and > or =10 servings/wk had multivariate relative risks (95% CI) of 1.03 (0.88-1.20), 1.02 (0.87-1.20), 1.09 (0.89-1.33), and 1.04 (0.80-1.36), respectively (P linear trend = 0.54). The associations for individual tomato-based food products were similar to the results for the combination of all tomato products. Our study found little evidence for an association between dietary intake of lycopene or lycopene-containing foods and the risk of type 2 DM.     

Plant foods, fiber, and rectal cancer

BACKGROUND: Associations between colon and rectal cancer and intakes of vegetables, other plant foods, and fiber have stimulated much debate. OBJECTIVE: We examined the association between rectal cancer and plant food and fiber intakes. DESIGN: Data from 952 incident cases of rectal cancer were compared with data from 1205 population-based controls living in Utah or enrolled in the Kaiser Permanente Medical Care Program in northern California RESULTS: Rectal cancer was inversely associated with intakes of vegetables (odds ratio: 0.72; 95% CI: 0.54, 0.98), fruit (0.73; 0.53, 0.99), and whole-grain products (0.69; 0.51, 0.94), whereas a high intake of refined-grain products was directly associated with an increased risk of rectal cancer (1.42; 1.04, 1.92). Similarly, relative to low fiber intakes, high intakes of dietary fiber reduced the risk of rectal cancer (0.54; 0.37, 0.78). The reduced risk of rectal cancer associated with vegetable (0.48; 0.29, 0.80), fruit (0.63; 0.38, 1.06), and fiber (0.40; 0.22, 0.71) intakes was strongest for persons who received the diagnosis after age 65 y. A threshold effect at approximately 5 servings of vegetables/d was needed to see a reduced risk of rectal cancer. CONCLUSIONS: The results suggest that plant foods may be important in the etiology of rectal cancer in both men and women. Age at diagnosis appears to play an important role in the association.     

Whole-Grain Intake in Middle School Students Achieves Dietary Guidelines for Americans and MyPlate Recommendations when Provided as Commercially Available Foods: A Randomized Trial

In accordance with the 2010 Dietary Guidelines for Americans, at least half of total grain intake should be whole grains. Adolescents are currently not consuming the recommended daily intake of whole grains. Research is needed to determine whether whole grains are acceptable to adolescents and whether changing their food environment to include whole-grain foods will improve intake. The aim of this study was to determine the effect of providing refined-grain or whole-grain foods to adolescents, with encouragement to eat three different grain-based foods per day, on total grain and whole-grain intakes. Middle school students (n=83; aged 11 to 15 years) were randomly assigned to either refined-grain or whole-grain foods for 6 weeks. Participants and their families were provided with weekly grains (eg, bread, pasta, and cereals), and participants were provided grain snacks at school. Intake of grains in ounce equivalents (oz eq) was determined through eight baseline and intervention targeted 24-hour diet recalls. Participants consumed 1.1±1.3 oz eq (mean±standard deviation) of whole grains at baseline, out of 5.3±2.4 oz eq of total grains. During intervention, whole-grain intake increased in the whole-grain group (0.9±1.0 to 3.9±1.8 oz eq/day), whereas those in the refined-grain group reduced whole-grain intake (1.3±1.6 to 0.3±0.3 oz eq/day; P<0.002, group by time period interaction). Total grain intake achieved was 6.4±2.1 oz eq/day and did not differ across intervention groups. Providing adolescents with whole-grain foods in their school and home environments was an effective means of achieving recommendations.     

Whole-grain intake and the risk of type 2 diabetes: a prospective study in men

BACKGROUND: Certain dietary components may play a role in the prevention of type 2 diabetes. OBJECTIVE: We examined prospectively the associations between whole- and refined-grain intake and the risk of type 2 diabetes in a large cohort of men. DESIGN: Men from the Health Professionals Follow-up Study without a history of diabetes or cardiovascular disease in 1986 (n = 42898) were followed for 相似文献   

The effects of a whole grain-enriched hypocaloric diet on cardiovascular disease risk factors in men and women with metabolic syndrome

BACKGROUND: Whole-grain foods are associated in observational studies with a lower body mass index and lower cardiovascular disease (CVD) risk. However, few clinical trials have tested whether incorporating whole grains into a hypocaloric diet increases weight loss and improves CVD risk factors. OBJECTIVE: The aim of this study was to determine whether including whole-grain foods in a hypocaloric (reduced by 500 kcal/d) diet enhances weight loss and improves CVD risk factors. DESIGN: Obese adults (25 M, 25 F) with metabolic syndrome were randomly assigned to receive dietary advice either to avoid whole-grain foods or to obtain all of their grain servings from whole grains for 12 wk. All participants were given the same dietary advice in other respects for weight loss. RESULTS: Body weight, waist circumference, and percentage body fat decreased significantly (P<0.001) in both groups over the study period, but there was a significantly (P=0.03) greater decrease in percentage body fat in the abdominal region in the whole-grain group than in the refined-grain group. C-reactive protein (CRP) decreased 38% in the whole-grain group independent of weight loss but was unchanged in the refined-grain group (P=0.01 for group x time interaction). Total, LDL, and HDL cholesterol decreased in both diet groups (P<0.05). Dietary fiber and magnesium intakes increased in the whole-grain but not the refined-grain group (P=0.007 and P<0.001, respectively, for group x time interaction). CONCLUSIONS: Both hypocaloric diets were effective means of improving CVD risk factors with moderate weight loss. There were significantly (P<0.05) greater decreases in CRP and percentage body fat in the abdominal region in participants consuming whole grains than in those consuming refined grains.     

Antioxidant vitamins and coronary heart disease risk: a pooled analysis of 9 cohorts

BACKGROUND: Epidemiologic studies have suggested a lower risk of coronary heart disease (CHD) at higher intakes of fruit, vegetables, and whole grain. Whether this association is due to antioxidant vitamins or some other factors remains unclear. OBJECTIVE: We studied the relation between the intake of antioxidant vitamins and CHD risk. DESIGN: A cohort study pooling 9 prospective studies that included information on intakes of vitamin E, carotenoids, and vitamin C and that met specific criteria was carried out. During a 10-y follow-up, 4647 major incident CHD events occurred in 293 172 subjects who were free of CHD at baseline. RESULTS: Dietary intake of antioxidant vitamins was only weakly related to a reduced CHD risk after adjustment for potential nondietary and dietary confounding factors. Compared with subjects in the lowest dietary intake quintiles for vitamins E and C, those in the highest intake quintiles had relative risks of CHD incidence of 0.84 (95% CI: 0.71, 1.00; P=0.17) and 1.23 (1.04, 1.45; P=0.07), respectively, and the relative risks for subjects in the highest intake quintiles for the various carotenoids varied from 0.90 to 0.99. Subjects with higher supplemental vitamin C intake had a lower CHD incidence. Compared with subjects who did not take supplemental vitamin C, those who took >700 mg supplemental vitamin C/d had a relative risk of CHD incidence of 0.75 (0.60, 0.93; P for trend <0.001). Supplemental vitamin E intake was not significantly related to reduced CHD risk. CONCLUSIONS: The results suggest a reduced incidence of major CHD events at high supplemental vitamin C intakes. The risk reductions at high vitamin E or carotenoid intakes appear small.     

A comparison of two methods of measuring food group intake: grams vs servings

Different measurements can be used to quantify food group intake, such as servings, cups, or grams. Dietary recommendations are given in terms of servings (recently expressed as cup and ounce measurements), but research on disease risks often uses grams as the intake measure. Because serving sizes vary among foods within a food group, the method of expressing food group intake (grams vs servings) may impact disease risk analyses. Daily consumption of eight food groups was calculated as both Food Guide Pyramid servings and grams for 206,721 participants in the Multiethnic Cohort Study who completed a quantitative food frequency questionnaire between 1993 and 1996. Mean grams per serving ranged from 25 g for red meat to 172 g for dairy products. Spearman correlation coefficients between intakes as grams per day and servings per day were 0.85 for grains, 0.97 for vegetables, 0.99 for fruit, 0.95 for dairy products, 0.98 for red meat, 0.93 for processed meat, 1.00 for poultry, and 1.00 for fish. Because there was little effect on the ranking of study participants' intakes due to the method of calculating food group consumption, the two measures are interchangeable in disease risk models.