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.     

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.     

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 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   

Whole- and refined-grain intakes and the risk of hypertension in women

BACKGROUND: Prospective studies linking whole- and refined-grain intakes with the risk of hypertension, a major cardiovascular disease risk factor, remain limited. OBJECTIVE: We aimed to determine whether baseline intake of whole or refined grains is associated with subsequent development of hypertension. DESIGN: We conducted a prospective cohort study in 28 926 female US health professionals aged >or=45 y who were free of baseline cardiovascular disease, cancer, and hypertension in 1992. Baseline whole- and refined-grain intakes were assessed from semiquantitative food-frequency questionnaires. We identified 8722 incident cases of hypertension from annual questionnaires during 10 y of follow-up. RESULTS: After adjustment for known hypertension risk factors, the relative risks (RRs) (and 95% CIs) of incident hypertension were 1.00 (reference), 0.96 (0.89, 1.03), 0.95 (0.88, 1.02), 0.92 (0.85, 0.99), and 0.89 (0.82, 0.97) across the increasing quintiles of baseline whole-grain intake (P for trend = 0.007). When functional cutoffs were used, women who consumed 0.5 to <1, 1 to <2, 2 to <4, and >or=4 whole-grain servings/d had multivariate RRs (95% CIs) of 0.93 (0.87, 1.00), 0.93 (0.87, 0.99), 0.92 (0.85, 0.99), and 0.77 (0.66, 0.89), respectively, compared with those who consumed <0.5 whole-grain servings/d. In contrast, refined-grain intake was not associated with the risk of hypertension. The multivariate RRs of hypertension across the increasing quintiles of refined-grain intake were 1.00, 0.97, 0.94, 0.99, and 0.97 (P for trend = 0.80). CONCLUSION: Higher whole-grain intake was associated with a reduced risk of hypertension in middle-aged and older women, which suggests a potential role for increasing whole-grain intake in the primary prevention of hypertension and its cardiovascular complications.     

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.     

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 grains, bran, and germ in relation to homocysteine and markers of glycemic control, lipids, and inflammation 1

BACKGROUND: Intake of whole grains is inversely associated with risk of diabetes and ischemic heart disease in observational studies. The lower risk associated with high whole-grain intakes may be mediated through improvements in glycemic control, lipid profiles, or reduced inflammation. OBJECTIVE: The aim was to examine whether the intake of whole grains, bran, and germ is related to homocysteine, plasma markers of glycemic control (fasting insulin, hemoglobin A1c, C-peptide, and leptin), lipids (total cholesterol, triacylglycerol, HDL cholesterol, and LDL cholesterol), and inflammation (C-reactive protein, fibrinogen, and interleukin 6). DESIGN: This was a cross-sectional study of the relations of whole grains, bran, and germ intakes with homocysteine and markers of glycemic control, lipids, and inflammation in 938 healthy men and women. RESULTS: Whole-grain intake was inversely associated with homocysteine and markers of glycemic control. Compared with participants in the bottom quintile of whole-grain intake, participants in the highest quintile had 17%, 14%, 14%, and 11% lower concentrations of homocysteine (P < 0.01), insulin (P = 0.12), C-peptide (P = 0.03), and leptin (P = 0.03), respectively. Inverse associations were also observed with total cholesterol (P = 0.02), HDL cholesterol (P = 0.05), and LDL cholesterol (P = 0.10). Whole-grain intake was not associated with the markers of inflammation. Whole-grain intake was most strongly inversely associated with markers of glycemic control in this population. CONCLUSION: The results suggest a lower risk of diabetes and heart disease in persons who consume diets high in whole grains.     

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.     

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.     

Effect of whole grains on insulin sensitivity in overweight hyperinsulinemic adults

BACKGROUND: Epidemiologic studies have found whole-grain intake to be inversely associated with the risk of type 2 diabetes and heart disease. OBJECTIVE: We tested the hypothesis that whole-grain consumption improves insulin sensitivity in overweight and obese adults. DESIGN: This controlled experiment compared insulin sensitivity between diets (55% carbohydrate, 30% fat) including 6-10 servings/d of breakfast cereal, bread, rice, pasta, muffins, cookies, and snacks of either whole or refined grains. Total energy needs were estimated to maintain body weight. Eleven overweight or obese [body mass index (in kg/m(2)): 27-36] hyperinsulinemic adults aged 25-56 y participated in a randomized crossover design. At the end of each 6-wk diet period, the subjects consumed 355 mL (12 oz) of a liquid mixed meal, and blood samples were taken over 2 h. The next day a euglycemic hyperinsulinemic clamp test was administered. RESULTS: Fasting insulin was 10% lower during consumption of the whole-grain than during consumption of the refined-grain diet (mean difference: -15 +/- 5.5 pmol/L; P = 0.03). After the whole-grain diet, the area under the 2-h insulin curve tended to be lower (-8832 pmol.min/L; 95% CI: -18720, 1062) than after the refined-grain diet. The rate of glucose infusion during the final 30 min of the clamp test was higher after the whole-grain diet (0.07 x 10(-4) mmol.kg(-1).min(-1) per pmol/L; 95% CI: 0.003 x 10(-4), 0.144 x 10(-4)). CONCLUSION: Insulin sensitivity may be an important mechanism whereby whole-grain foods reduce the risk of type 2 diabetes and heart disease.     

Changes in whole-grain, bran, and cereal fiber consumption in relation to 8-y weight gain among men

BACKGROUND: Epidemiologic studies that directly examine changes in whole-grain consumption in relation to weight gain are sparse, and characterization of this association has been obscured by methodologic inconsistencies in the assessment of whole grains. OBJECTIVE: We aimed to ascertain the associations between changes in new quantitative estimates of whole-grain intake and 8-y weight gain among US men. DESIGN: The study was conducted in a prospective cohort of 27 082 men aged 40-75 y at baseline in 1986. Data on lifestyle factors were obtained periodically by using self-reported questionnaires, and participants measured and reported their body weight in 1986 and 1994. RESULTS: In multivariate analyses, an increase in whole-grain intake was inversely associated with long-term weight gain (P for trend < 0.0001). A dose-response relation was observed, and for every 40-g/d increment in whole-grain intake from all foods, weight gain was reduced by 0.49 kg. Bran that was added to the diet or obtained from fortified-grain foods further reduced the risk of weight gain (P for trend = 0.01), and, for every 20 g/d increase in intake, weight gain was reduced by 0.36 kg. Changes in cereal and fruit fiber were inversely related to weight gain. No associations were observed between changes in refined-grain or added germ consumption and body weight. CONCLUSIONS: The increased consumption of whole grains was inversely related to weight gain, and the associations persisted after changes in added bran or fiber intakes were accounted for. This suggests that additional components in whole grains may contribute to favorable metabolic alterations that may reduce long-term weight gain.     

Magnesium intake is related to improved insulin homeostasis in the framingham offspring cohort

OBJECTIVE: Higher dietary intake of magnesium may protect against development of type 2 diabetes. The aim of this study was to examine the association between dietary magnesium intake and metabolic risk factors for diabetes. METHODS: We examined cross-sectional associations between magnesium intake and fasting glucose and insulin, 2-hour post-challenge plasma glucose and insulin, and insulin resistance assessed by the homeostasis model (HOMA-IR) in 1223 men and 1485 women without diabetes from the Framingham Offspring cohort. Magnesium intake was assessed by a food frequency questionnaire and magnesium intake was categorized into quintile categories. Geometric mean insulin, glucose, 2-hour post challenge plasma glucose and insulin concentrations and HOMA-IR were estimated across quintile categories of magnesium intake using Generalized Linear Models. RESULTS: After adjustment for potential confounding factors, magnesium intake was inversely associated with fasting insulin (mean: 29.9 vs 26.7 microU/mL in the lowest vs highest quintiles of magnesium intake; P trend <0.001), post-glucose challenge plasma insulin (86.4 vs 72 microU/mL; P trend <0.001), and HOMA-IR (7.0 vs 6.2; P trend <0.001). No significant association was found between magnesium intake and fasting glucose or 2-hour post challenge glucose. CONCLUSIONS: Improved insulin sensitivity may be one mechanism by which higher dietary magnesium intake may reduce the risk of developing type 2 DM.     

Greater whole-grain intake is associated with lower risk of type 2 diabetes, cardiovascular disease, and weight gain

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.     

Fructose, glycemic load, and quantity and quality of carbohydrate in relation to plasma C-peptide concentrations in US women

BACKGROUND: Circulating C-peptide concentrations are associated with insulin resistance and the development of type 2 diabetes. However, associations between fructose and the quantity and quality of total carbohydrate intake in relation to C-peptide concentrations have not been adequately examined. OBJECTIVE: We assessed the association of dietary fructose, glycemic load, and carbohydrate intake with fasting C-peptide concentrations. DESIGN: Plasma C-peptide concentrations were measured in a cross-sectional setting in 1999 healthy women from the Nurses' Health Study I and II. Dietary fructose, glycemic load, and carbohydrate intake were assessed with the use of semiquantitative food-frequency questionnaires. RESULTS: After multivariate adjustment, subjects in the highest quintile of energy-adjusted fructose intake had 13.9% higher C-peptide concentrations (P for trend = 0.01) than did subjects in the lowest quintile. Similarly, in the multivariate model, subjects in the highest quintile of glycemic load had 14.1% (P for trend = 0.09) and 16.1% (P for trend = 0.04) higher C-peptide concentrations than did subjects in the lowest quintile after further adjustment for total fat or carbohydrate intake, respectively. In contrast, subjects with high intakes of cereal fiber had 15.6% lower (P for trend = 0.03) C-peptide concentrations after control for other covariates. CONCLUSIONS: Our results suggest that high intakes of fructose and high glycemic foods are associated with higher C-peptide concentrations, whereas consumption of carbohydrates high in fiber, such as whole-grain foods, is associated with lower C-peptide concentrations. Furthermore, our study suggests that these nutrients play divergent roles in the development of insulin resistance and type 2 diabetes.     

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.     

Epidemiological support for the protection of whole grains against diabetes

The epidemic of type 2 diabetes among children, adolescents and adults is increasing along with the increasing prevalence of overweight and obesity. Overweight is the most powerful modifiable risk factor for type 2 diabetes. Intake of wholegrain foods may reduce diabetes risk. Three prospective studies in 160000 men and women examined the relationship of whole-grain or cereal-fibre intake with the risk of type 2 diabetes. Each study used a mailed Willett food-frequency questionnaire and similar methods of quantifying wholegrain foods and cereal fibre.The self-reported incident diabetes outcome was more reliably determined in the two studies of health-care professionals than in the study of Iowa women. Risk for incident type 2 diabetes was 21-27% lower for those in the highest quintile of whole-grain intake, and 30-36% lower in the highest quintile of cereal-fibre intake, each compared with the lowest quintile. Risk reduction persisted after adjustment for the healthier lifestyle found among habitual whole-grain consumers. Observations in non-diabetic individuals support an inverse relationship between whole-grain consumption and fasting insulin levels. In feeding studies in non-diabetic individuals insulin resistance was reduced using whole grains or diets rich in whole grains. Glucose control improved with diets rich in whole grains in feeding studies of subjects with type 2 diabetes. There is accumulating evidence to support the hypothesis that whole-grain consumption is associated with a reduced risk of incident type 2 diabetes; it may also improve glucose control in diabetic individuals.     

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.     

Phylloquinone intake, insulin sensitivity, and glycemic status in men and women

BACKGROUND: Limited evidence suggests that vitamin K may have a beneficial role in glucose homeostasis. No observational data exist on the associations between vitamin K intake and insulin sensitivity. OBJECTIVE: We aimed to examine associations between vitamin K intake and measures of insulin sensitivity and glycemic status in men and women aged 26-81 y. DESIGN: We assessed the cross-sectional associations of self-reported phylloquinone (vitamin K(1)) intake with insulin sensitivity and glycemic status in the Framingham Offspring Cohort. Dietary and supplemental phylloquinone intakes were assessed by using a food-frequency questionnaire. Insulin sensitivity was measured by fasting and 2-h post-oral-glucose-tolerance test (OGTT) insulin, the homeostasis model assessment of insulin resistance (HOMA-IR), and the insulin sensitivity index (ISI(0,120)). Glycemic status was assessed by fasting and 2-h post-OGTT glucose and glycated hemoglobin (HbA(1c)). RESULTS: Higher phylloquinone intake was associated with greater insulin sensitivity and glycemic status, as measured by 2-h post-OGTT insulin and glucose and ISI(0,120), after adjustment for age, sex, waist circumference, lifestyle characteristics, and diet quality [2-h post-OGTT insulin: lowest and highest quintile, 81.0 and 72.7 microU/mL, respectively (P for trend = 0.003); 2-h post-OGTT glucose: 106.3 and 101.9 mg/dL, respectively (P for trend = 0.009); ISI(0,120): 26.3 and 27.3 mg L(2)/mmol mU min (P for trend = 0.009)]. Phylloquinone intake was not associated with fasting insulin and glucose concentrations, HOMA-IR, or HbA(1c). CONCLUSION: Our findings support a potential beneficial role for phylloquinone in glucose homeostasis in men and women.     

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.