Intakes of whole grains, bran, and germ and the risk of coronary heart disease in men 1 3

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1 See corresponding editorial on page 1459 Intakes of whole grains, bran, and germ and the risk of coronary heart disease in men 1 3 Majken K Jensen, Pauline Koh-Banerjee, Frank B Hu, Mary Franz, Laura Sampson, Morten Grønbæk, and Eric B Rimm ABSTRACT 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 wholegrain, bran, and germ intakes (with the use of new quantitative measures) with the incidence of CHD. Design: This was a prospective cohort study of male health professionals aged 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 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. Am J Clin Nutr 2004;80: KEY WORDS Whole grains, bran, germ, prospective population study, coronary heart disease INTRODUCTION Intake of whole grains is associated with a reduced incidence of fatal and nonfatal coronary heart disease (CHD) in many large prospective population studies (1 4). Other studies that support this beneficial association have reported a similar association with intake of specific foods with a high whole-grain content, such as whole-wheat bread (5), whole-grain bread (6), and some breakfast cereals (7). These studies suggest a 20 30% reduced risk of CHD in persons with a daily intake of 3 servings of whole-grain food items. Whole grains have a high content of nutrients that are related to beneficial health effects in observational studies. Constituents such as fiber, vitamin E, vitamin B-6, minerals, antioxidants, and phytoestrogens are found in the bran and germ components of whole grains (8). In refined-grain products, the endosperm is separated from the bran and germ before milling, which leaves these refined products relatively nutrient poor (9). Because bran and germ can easily be added to food during processing or cooking, it is important to consider whether these components contribute to the reduced CHD risk independently or whether wholegrain products yield a greater benefit than do the sum of the parts. Currently, most epidemiologic studies have used a definition of whole-grain foods developed by Jacobs et al (1) to calculate the number of servings of whole-grain products. By this definition, a single serving of dark bread, brown rice, popcorn, wheat germ, bran, cooked oatmeal, bulgur, couscous, and breakfast cereals with a whole-grain or bran content 25% by weight are classified equally as whole-grain products. This relatively qualitative classification may have methodologic limitations because the amount of whole grain in each serving can vary considerably. Furthermore, this classification does not allow a separate analysis of the bran and germ contents of whole grains, for which the nutrient composition and health effects may differ (8, 10). Recently, the Food and Drug Administration (FDA) approved a health claim for whole-grain foods that contain 51% wholegrain ingredients by weight per reference amount customarily consumed (RACC) (11). To date, there are no data to support the 51% cutoff as a minimum requirement nor are there data to support the exclusion of added bran or germ from this health claim. The effect of whole grains from all foods, whether the 1 From the Department of Nutrition, Harvard School of Public Health, Boston (MKJ, PK-B, FBH, MF, LS, and EBR); the Centre for Alcohol Research, National Institute of Public Health, Copenhagen (MKJ and MG); the Department of Preventive Medicine, The University of Tennessee Health Science Center, Memphis (PK-B); the Department of Epidemiology, Harvard School of Public Health, Boston (FBH and EBR); and the Channing Laboratory, Department of Medicine, Brigham and Women s Hospital, Harvard Medical School, Boston (FBH and EBR). 2 Supported by research grants HL35464 and CA55075 from the National Institutes of Health and a scholarship from the Danish Research Foundation (to MKJ). The Kellogg Company provided unrestricted funding of the development of the whole-grain database. 3 Reprints not available. Address correspondence to EB Rimm, Department of Nutrition, Harvard School of Public Health, 665 Huntington Avenue, Boston, MA erimm@hsph.harvard.edu. See corresponding editorial on page 000. Received March 23, Accepted for publication June 21, Am J Clin Nutr 2004;80: Printed in USA American Society for Clinical Nutrition

2 WHOLE GRAINS, BRAN, AND GERM AND RISK OF CHD 1493 whole-grain content is or 25% or 50% by weight, should be quantitatively the same. Also, if much of the benefit of whole grains can be attributed to particular subcomponents of the grains, such as the bran or germ, this too should be clarified. In the Health Professionals Follow-Up Study, we developed a new whole-grain food-composition database and estimated the daily intake of whole grains (in g) from all foods and from only those foods that meet Jacobs et al s (1) and the FDA s classification criteria. We also estimated the intakes of bran and germ (in g/d), both the amounts added to foods and naturally occurring in whole grains) to evaluate the association between daily intake of whole grains, bran, and germ and CHD risk in men. SUBJECTS AND METHODS Study population The Health Professionals Follow-Up Study was initiated in 1986, when male dentists, veterinarians, pharmacists, optometrists, osteopathic physicians, and podiatrists between 40 and 75 y of age completed a detailed self-administered foodfrequency questionnaire (FFQ) and medical-history questionnaire. The participants have been followed with repeated questionnaires on lifestyle and health every 2 y and with detailed FFQs every 4 y. Participants were included in the present analysis if they had 70 missing items on the 131-item FFQ and their reported daily energy intake was within the range of 800 and 4200 kcal/d at baseline. Men with prevalent cardiovascular disease, diabetes, or cancer at baseline were excluded because of possible changes in diet after diagnosis. A total of men remained for this analysis. Dietary assessment Dietary information was collected with a validated semiquantitative FFQ, which was described in detail elsewhere (12, 13). Briefly, the questionnaire was designed to assess average food intakes over the previous year and included questions regarding the consumption of grain foods such as cooked and cold breakfast cereals, white and dark bread, white and brown rice, and pasta. The men were asked to specify the brand and type of cold breakfast cereal usually eaten. For each food, a commonly used unit or portion size was specified along with 9 possible response categories for frequency of intake ranging from never to 6 or more times per day. The FFQ included open-ended questions regarding the usual serving size and frequency of consumption of foods not listed on the FFQ. The portions were converted to gram weights per serving, and intakes of nutrients were computed by multiplying the frequency of consumption of each unit of food by the nutrient content in grams. The whole-grain content of all grain foods (rice, bread, pasta, and breakfast cereals) was determined by assigning whole-grain values according to the dry weight of whole-grain ingredients. Bran and germ values were assigned after review of the literature to determine the percentage of bran, germ, and endosperm of the different grains. The natural bran or germ corresponded to the amount that would typically be found in the type of whole grain, and the added amount was any bran or germ beyond that estimated from the natural amount. Product labels and nutrient and ingredient information provided by General Mills Inc, Kellogg, Post, and other breakfast cereal manufacturers were used to derive the amounts of whole grain, naturally occurring bran and germ, and added bran and germ in 250 brand name cereals. Manufacturers product information was also used to develop whole-grain profiles for commercially prepared foods, such as bran muffins. The recipe for other cooked breakfast cereal on the FFQ was based on Cream of Wheat (Kraft Foods, Parsippany, NJ) selected on the basis of marketplace shelf spacing of hot cereals. For the question on dark bread, we used a composite of 7 types of commercially prepared bread: whole wheat, cracked wheat, wheat bran, oatmeal, whole oat, oat bran, and rye. Recipes were written for each type of bread by using product labels, and the final composite for dark bread was developed by using a weighted average based on observation of shelf space in local supermarkets. Cookbooks, such as The Joy of Cooking, were used to create recipes for home-prepared bakery items. Whole grains were considered in their intact and pulverized forms, for which, by definition, they must contain the expected proportion of bran, endosperm, and germ for the specific grain types. The following ingredients in the database were designated as whole grains: whole wheat and whole-wheat flour, whole oats and whole-oat flour, whole cornmeal and whole-corn flour, brown rice and brown-rice flour, whole barley, whole rye and rye flour, bulgur, buckwheat, popcorn, amaranth, and psyllium. Wheat bran, corn bran, oat bran, rice bran, and wheat germ that were added to foods either during processing or by participants while cooking were considered to be added bran and germ, respectively. Intake of whole grains (in g/d) was estimated from 1) all grain foods, 2) foods with 25% whole-grain content per RACC (on a dry-weight basis), and 3) foods with 51% wholegrain content per RACC (on a dry-weight basis), both including and excluding added bran and germ. Total bran and germ consumption were estimated in a similar manner and further subdivided into their natural and added components. The glycemic load of each food was calculated by multiplying the carbohydrate content per serving of each food item by the glycemic index value. To provide the participants overall dietary glycemic loads, the glycemic load of the individual foods was then multiplied by the average number of servings consumed of that food per day and this was summed over all the foods (14). Case ascertainment Nonfatal myocardial infarction and fatal CHD occurring between 1986 and 31 January 2000 were considered as endpoints. Myocardial infarction was first identified by self-reports on biennial questionnaires and then confirmed by medical records with the use of World Health Organization criteria (15). Deaths were reported by next of kin, postal authorities, or the National Death Index. Fatal CHD was confirmed by medical records or autopsy reports. Further details of the confirmation of endpoints are published elsewhere (16). Statistical analysis All reported nutrient intakes (including vitamins and minerals), except alcohol, were adjusted for total energy intake by the residual method (13, 17). After energy adjustment, all nutrients, except alcohol intake and the measurements of added bran and germ, were categorized into quintiles. Because many participants did not consume supplemental bran or germ, we created a separate category of no intake as a reference for each, an additional 4 equal categories for added bran intake, and 2 equal

3 1494 JENSEN ET AL categories for intake of added germ. To reduce within-person variation and best represent long-term dietary intake, we calculated cumulative averages of food and nutrient intakes from the repeated FFQs. Because changes in diet after the development of the intermediate conditions angina, hypercholesterolemia, hypertension, and diabetes may confound the associations between diet and disease (18), dietary information was not further updated among persons reporting these conditions. Nondietary covariates were updated at each biennial follow-up. Person-time was calculated for each participant from the date of return of the 1986 questionnaire to the date of the first CHD event, death, or 31 January Data were analyzed by means of Cox Proportional hazard regression, stratified by age (in mo). Multivariate analyses included intakes of whole grains and added bran and germ simultaneously and were further adjusted for energy intake (kcal/d in quintiles), smoking (never, past, and current smoker of 15, 16 24, or 24 cigarettes/d), alcohol intake (0, , , , or 30 g/d), family history of myocardial infarction (yes or no), use of vitamin E supplements (yes or no), physical activity [metabolic equivalents (MET)-h/wk, in quintiles], intake of fats (saturated, polyunsaturated, and trans; g/d in quintiles), and daily servings of fish, fruit, and vegetables (quintiles). A separate inclusion of body mass index (BMI; in kg/m 2 ) was considered because it could be both a confounder as well as a mediator. Studies have suggested that whole grains can affect body weight regulation by influencing insulin sensitivity and satiety (19). Because this potential intermediate effect of BMI on the relation between whole grains and CHD would imply a reduction in total energy, we repeated this analysis while removing total energy from the multivariate model. Categories for BMI were as follows: 21, , , , , , and 31. In other exploratory analyses, we evaluated whether the associations for whole grains were independent of important constituents, such as dietary fiber, folate, magnesium, glycemic load, vitamins B-6 and E, and manganese by including them in the multivariate model. Furthermore, intermediate endpoints such as diabetes, hypertension and hypercholesterolemia were included to address potential mechanistic pathways. The association between intake of total bran and germ (total intake including both the natural bran and germ from whole grains and the bran and germ added during processing or cooking) and CHD was additionally estimated in multivariate models (without whole-grain intake in the model). To minimize residual confounding, we performed additional analyses of the association between intake of whole grain and CHD in subgroups of men who, at baseline, reported to be never smokers, to be less active (MET-h/wk 18), to have a BMI 25, to not have hypercholesterolemia, to not use vitamin E supplements, and to not drink alcohol. To test the health effects of foods that qualified for the FDA whole-grain health claim, we repeated the analyses for intake of whole grains, bran, and germ only from foods with a whole-grain content 51% of dry weight. Tests of linear trends across categories of the dietary exposures were performed by assigning the medians of intakes in the categories as continuous variables. All statistical analyses were performed by using SAS program software (version 8.2; SAS Institute Inc, Cary NC). RESULTS Cold breakfast cereals were the largest source of whole grains, contributing 33% of total intake. Brown rice, dark bread, and TABLE 1 Whole-grain content of different foods and examples of generic breakfast cereals on the 1998 food-frequency questionnaire 1 Food (serving size) Amount Whole grain Whole grain g g % Bran muffin, 1 small Oat-bran bread, 1 slice Wheat-bran bread, 1 slice Cracked-wheat bread, 1 slice Oatmeal cookie (fat free), 1 cookie Oatmeal bread, 1 slice Rye bread, 1 slice Whole-wheat crackers, Whole-wheat bread, 1 slice Dark bread, 1 slice Popcorn, 1 cup Cooked brown rice, 1 cup Cooked oatmeal, 1 cup Cooked Cream of Wheat, 1 cup Breakfast cereal 4 Puffed rice Corn flakes Low-fat granola with raisins Bran flakes Shredded wheat Toasted oats Whole grain is grain without added bran or germ. 2 Brown rice and oatmeal are considered to be 100% whole grain on a dry weight basis. 3 Kraft Foods, Parsippany, NJ. 4 Reference amounts customarily consumed. cooked oats contributed 18%, 17%, and 15%, respectively (data not shown). In Table 1, the calculation of the whole-grain contribution of individual foods and examples of generic breakfast cereals are shown. The mean intake of whole grains ranged from 3.3 g/d in the lowest quintile to 49.6 g/d in the top quintile. Compared with the lower intake categories, a higher whole-grain intake was associated with a lower BMI, more physical activity, less smoking, a lower prevalence of hypertension, and a higher prevalence of hypercholesterolemia (Table 2). Men in the highest quintile of whole-grain intake also had a higher intake of bran, germ, and fiber and a higher daily glycemic load. Among participants with the lowest intake of whole grains, carbohydrate intake accounted for 44% of the total energy intake, whereas participants with the highest whole-grain intake consumed 55% of total calories in the form of carbohydrates. Generally, men with higher intakes of whole grains consumed more protein, vegetables, fruit, dark breads, and brown rice but had lower intakes of alcohol, fat, and doughnuts. The distribution of the lifestyle and health characteristics across intakes of bran and germ was similar to the distribution for whole grain (data not shown). During 14 y of follow-up, we confirmed 1818 cases of CHD (1261 nonfatal myocardial infarction and 557 fatal CHD). In age-adjusted analyses, we found a strong inverse association between whole-grain intake and risk of fatal and nonfatal CHD. We saw no differences between fatal and nonfatal CHD; therefore, we combined endpoints in the remaining analyses (data not shown). Compared with men in the lowest quintile of wholegrain intake, the hazard ratio (HR) for risk of overall CHD was

4 WHOLE GRAINS, BRAN, AND GERM AND RISK OF CHD 1495 TABLE 2 Age-standardized baseline characteristics and energy-adjusted nutrient intakes of subjects by quintile of whole-grain intake in Quintile of mean whole-grain intake (g/d) 1 ( ) 2 ( ) 3 ( ) 4 ( ) 5 ( ) P for trend 2 BMI (kg/m 2 ) Physical activity (MET-h/wk) Smokers (%) Family history of MI (%) Hypertension (%) Hypercholesterolemia (%) Aspirin use (%) Married (%) Nutrient intake Added bran (g/d) Total bran (g/d) Added germ (g/d) Total germ (g/d) Total energy (kcal/d) Total fiber (g/d) Cereal fiber (g/d) Carbohydrate (g/d) Daily glycemic load Protein (g/d) Alcohol (g/d) Fat (g/d) Total Saturated trans Polyunsaturated Food intake (servings/d) Vegetables Fruit Fish Dark breads Breakfast cereals Oats Brown rice White bread Pasta White rice Doughnuts Muffins and biscuits All nutrients, except alcohol, were energy adjusted. MI, myocardial infarction; MET, metabolic equivalents. 2 Values obtained by using median whole-grain intake continuously. 3 x SE (all such values) (95% CI: 0.55, 0.74) among men in the top quintile (Table 3). Adjustment for potential confounders and risk factors for CHD, other than BMI, attenuated this association (HR: 0.82; 95% CI: 0.70, 0.96; P for trend 0.01). We also modeled wholegrain intake as a continuous variable in this multivariate analysis and found that each 20-g increment in whole-grain intake corresponded to a 6% reduction in CHD risk (95% CI: 0, 13%). We explored different ways to address the potentially mediating effects of BMI on the relation between whole-grain intake and CHD. However, when BMI was included in the multivariate model, the overall relation did not change (Table 3) and removal of total energy from this model also did not substantially alter the association (data not shown). Additional adjustment for constituents of whole grains, such as fiber, folate, magnesium, and vitamins B-6 and E attenuated the association; however, there was still a tendency for an inverse association (P for trend 0.06) (Table 3). A large proportion ( person-years) of the study population did not consume products with supplemental bran, yet among consumers the quartiles of added bran included a large variation in intake (Table 4). Compared with nonconsumers of added bran, age-adjusted HRs among the consumers showed a strong inverse association with CHD. Additional adjustment for potential confounders only modestly attenuated this association when the top quartile was compared with nonusers (HR: 0.70; 95% CI: 0.60, 0.82; P for trend ). Further control for BMI and whole-grain constituents did not appreciably attenuate the risk estimates. In general, the intake of supplemental germ was very low. In this study population, 66% did not consume added germ. The

5 1496 JENSEN ET AL TABLE 3 Hazard ratios (and 95% CIs) of coronary heart disease in men according to the cumulative average of whole-grain intake Quintile of whole-grain intake P for trend Median intake (g/d) Number of cases Person-years Age-adjusted model (0.77, 1.01) 0.80 (0.69, 0.92) 0.69 (0.60, 0.80) 0.64 (0.55, 0.74) Multivariate model (0.84, 1.11) 0.94 (0.82, 1.09) 0.86 (0.74, 1.01) 0.82 (0.70, 0.96) 0.01 Exploratory models BMI (0.83, 1.10) 0.94 (0.81, 1.09) 0.86 (0.74, 1.01) 0.84 (0.71, 0.98) 0.02 BMI constituents (0.82, 1.11) 0.96 (0.82, 1.11) 0.88 (0.75, 1.04) 0.85 (0.71, 1.02) 0.06 BMI intermediates (0.86, 1.14) 0.97 (0.84, 1.12) 0.90 (0.77, 1.06) 0.88 (0.75, 1.03) Includes added bran intake, added germ intake, age, energy intake, smoking, alcohol intake, physical activity, family history of myocardial infarction, use of vitamin E supplement, and intakes of fats (saturated, polyunsaturated, and trans), fruit, vegetables, and fish. 2 Includes dietary fiber, folate, glycemic load, dietary vitamin B-6, vitamin E, magnesium, and manganese. 3 Includes updated measures of hypertension, hypercholesterolemia, and diabetes. mean intake among those with a reported intake of added germ was 0.99 g/d. Results from the age-adjusted model suggested an inverse association between germ intake and CHD; however, little benefit remained after multivariate adjustment (Table 5). In multivariate models of total bran and germ intake (added bran and germ plus bran and germ found in whole grain), the dose-dependent association for total bran and CHD was comparable with that observed for similar levels of added bran intake alone. The multivariate analyses of total germ did not show an association with CHD (data not shown). Because men with hypercholesterolemia reported a higher intake of whole grains (Table 2), presumably due in part to changes in diet after diagnosis, we reanalyzed the association between whole-grain intake and CHD after exclusion of the 3086 men who reported hypercholesterolemia at baseline. After exclusion of these men, the multivariate-adjusted inverse relation was similar to that presented in Table 3. Compared with men in the bottom quintile of whole-grain intake, the multivariateadjusted HR for CHD was 0.82 (95% CI: 0.69, 0.98) among men in the top quintile. Analyses in the other subgroups of CHD risk factors from our multivariate model showed essentially similar associations between whole-grain intake and CHD among men TABLE 4 Hazard ratios (and 95% CIs) of coronary heart disease in men according to cumulative average of added bran intake who were never smokers, were nondrinkers, had a BMI 25, did not take vitamin E supplements, or had lower levels of physical activity (data not shown). To address whether the new FDA classification of whole-grain foods (restricted to those with 51% whole-grain content per RACC) would change these results, we repeated all multivariate analyses using only foods with a whole-grain content 51% of total weight in our calculation of whole-grain intake (mean intake in fifth quintile roughly equal to mean intake in fourth quintile in analysis of whole grain from all foods). The estimates for the highest quintile of this analysis (HR: 0.88; 95% CI: 0.75, 1.03) were virtually the same as for the fourth quintile in the total whole-grain analysis (Table 3). DISCUSSION In this prospective study of male health professionals, we found an inverse association between whole-grain intake and incidence of CHD. Additionally, for intake of bran, the finding was even stronger. The inverse associations for both whole grains and bran were attenuated but not eliminated by adjustment Category of added bran intake to to P for trend Median intake (g/d) Number of cases Person-years Age-adjusted model (0.67, 0.90) 0.72 (0.62, 0.84) 0.69 (0.59, 0.80) 0.60 (0.52, 0.70) Multivariate model (0.69, 0.94) 0.78 (0.67, 0.91) 0.79 (0.68, 0.93) 0.70 (0.60, 0.82) Exploratory models BMI (0.70, 0.95) 0.79 (0.67, 0.92) 0.80 (0.68, 0.93) 0.72 (0.61, 0.84) BMI constituents (0.70, 0.96) 0.80 (0.68, 0.94) 0.82 (0.69, 0.96) 0.71 (0.59, 0.85) BMI intermediates (0.81, 1.10) 0.92 (0.79, 1.08) 0.94 (0.80, 1.10) 0.82 (0.70, 0.96) Includes added bran intake, added germ intake, age, energy intake, smoking, alcohol intake, physical activity, family history of myocardial infarction, use of vitamin E supplement, and intakes of fats (saturated, polyunsaturated, and trans), fruit, vegetables, and fish. 2 Includes dietary fiber, folate, glycemic load, dietary vitamin B-6, vitamin E, magnesium, and manganese. 3 Includes updated measures of hypertension, hypercholesterolemia, and diabetes.

6 WHOLE GRAINS, BRAN, AND GERM AND RISK OF CHD 1497 TABLE 5 Hazard ratios (and 95% CIs) of coronary heart disease in men according to cumulative average of added germ intake Category of added germ intake P for trend Median intake (g/d) Number of cases Person-years Age-adjusted model (0.74, 0.97) 0.80 (0.70, 0.91) Multivariate model (0.81, 1.06) 0.95 (0.83, 1.09) 0.43 Exploratory models BMI (0.81, 1.07) 0.98 (0.85, 1.12) 0.70 BMI constituents (0.81, 1.07) 0.99 (0.86, 1.14) 0.90 BMI intermediates (0.84, 1.10) 0.98 (0.85, 1.13) Includes whole-grain intake, added bran intake, age, energy intake, smoking, alcohol intake, physical activity, family history of myocardial infarction, use of vitamin E supplement, and intakes of fats (saturated, polyunsaturated, and trans), fruit, vegetables, and fish. 2 Includes dietary fiber, folate, glycemic load, dietary vitamin B-6, vitamin E, magnesium, and manganese. 3 Includes updated measures of hypertension, hypercholesterolemia, and diabetes. for other CHD risk factors. We did not find an association between intake of germ and CHD, however, the intake of germ was very low in this population and on the basis of our analysis we cannot rule out the potential health effects of the germ component of whole grains. Although we adjusted for several confounding factors, the possibility of uncontrolled confounders still remains. In general, a greater intake of whole grains and bran and germ was related to an overall healthier diet and lifestyle. A particular point of concern may be confounding by the generally high intake of dietary fiber, which has been shown to be related to a reduced risk of CHD in several prospective studies (20, 21). Participants with a high whole-grain intake in this study also consumed more dietary fiber, which was not accounted for by cereal fiber alone (Table 2). Although we adjusted for intake of added bran, fruit, and vegetables in our multivariate analyses, residual confounding may still have been present. Additionally, more subtle behavioral and psychosocial factors related to whole-grain intake might also be important with regard to disease risk. However, the Health Professional Follow-Up Study is a relatively homogenous cohort with regard to educational attainment and socioeconomic status. We performed several stratified analyses to address concerns of residual confounding by healthy participant characteristics associated with whole-grain intake and found no discrepant results in subgroups including never smokers and nondrinkers. Furthermore, if uncontrolled confounding were to explain the inverse association between bran intake and CHD, we would expect a similar effect for germ intake, which was similarly associated with healthier lifestyles and dietary habits (data not shown). However, after the adjustment for potential confounders, germ intake was unrelated to CHD. It is likely that some measurement error existed in our calculation of the intake of whole grains, bran, and germ (in g/d). However, any measurement error and resulting misclassification are likely to be unrelated to CHD and would thus tend to attenuate any association between these exposures and CHD. Our results of whole-grain intake (in g/d) and CHD confirm the results of previous individual studies and meta-analyses of servings of whole-grain foods or products with a whole-grain content 25% (22). In the Atherosclerosis Risk in Communities Study, 3 daily servings of whole grain was associated with a relative risk of 0.71 (95% CI: 0.53, 0.95) for incident coronary artery disease (4) and in the Nurses Health Study (3), the corresponding relative risk of CHD was 0.75 (95% CI: 0.59, 0.95). Jacobs et al reported associations between the same amount of whole grain and relative risks for mortality from CHD of 0.76 (95% CI: 0.56, 1.02) and 0.82 (95% CI: 0.63, 1.06) in a Norwegian cohort study (6) and in the Iowa Women s Health Study (1), respectively. In comparison, we found that the risk of CHD is reduced by 15% when the intake of whole grain is 25 g/d. As a direct comparison with these results, it can be pointed out that one serving of toasted oats provides 25 g whole grain, but such an intake could also be achieved by consuming one serving of lowfat granola with raisins and a slice of rye bread; both of these foods would not be considered to be whole grain according to the FDA definition. Because our analyses of whole grains from all sources and only from foods that contain 51% whole-grain ingredients were similar, our results suggest that the effects of whole grains are independent of the whole-grain concentration of the food source. Thus, the beneficial effects of high intakes of whole grain can be achieved regardless of the food source. The recent FDAapproved health claim for whole-grain foods that contain 51% whole-grain ingredients by weight or the alternative definition of a 25% cutoff may be too restrictive and exclude a substantial number of helpful foods that contain whole grain but do not meet an arbitrary threshold. Labeling food products with a health claim based simply on grams of whole grain may prove a good guide for consumers who want to be efficient in their selection of foods high in whole grains. The mechanisms by which whole grains contribute to health benefits remain to be elucidated. It is known that whole grains are a rich source of many nutrients and phytochemicals such as fiber, minerals (calcium, magnesium, potassium, phosphorous, selenium, manganese, zinc, and iron), vitamins (especially high in vitamins B and E), phenolic compounds, phytoestrogens (lignans), and related antioxidants (8). These compounds all have important biological functions, which as a whole could make an important contribution to the reduction of CHD risk. Intake of whole-grain foods and fiber-rich diets have been associated with a lower risk of obesity (23, 24) and diabetes (25, 26), an increased insulin sensitivity (27), and reduced cholesterol concentrations

7 1498 JENSEN ET AL (28). However, results from clinical studies that specifically use whole-grain foods are both sparse and inconsistent in their reported effects on serum cholesterol (29, 30), postprandial glucose and insulin responses (31 34), obesity (33), and hypertension (29). Furthermore, several of these trials were conducted among highly restrictive populations or were too short to capture the potential CHD benefits of a diet high in whole grains. We found a strong inverse association between bran intake and CHD in this cohort of men. To our knowledge, only Liu et al (3) have addressed the independent effects of the whole-grain components and CHD. In the Nurses Health Study, the inverse association between servings of bran and CHD was stronger than for any other grain-food item. One of the main explanations for the beneficial effects of bran intake is the high concentration of dietary fiber. Jacobs et al (35) showed that fiber from whole grains was more strongly related to a reduced risk of total cancer and CHD mortality than was fiber from refined grains. The authors suggest that the botanically linked fiber and phytochemicals in the bran could provide additional health benefits over that of fiber alone (35). In our study, adjustment for fiber and the micronutrient constituents did not have an appreciable effect on the reported inverse association between bran intake and CHD. This finding suggests that other benefits may arise from additional protective constituents in the bran or interactive effects between the constituents (9, 22). Experimental studies suggest that the effects of bran on CHD risk factors may be dependent on the food sources. Although we did not assess different sources of bran, most of the added bran consumed was derived from wheat and oats in this cohort. Oat bran is particularly linked with reduced serum cholesterol (36, 37), whereas these effects have not been reported for wheat bran (29, 32). The effect of oat bran on cholesterol suggested from clinical trials was too small to explain the reduction in risk of CHD that we found when we compared the highest with the lowest quintiles of bran intake. Additional scientific studies relating bran from different sources to CHD are warranted. If the benefit of supplemental bran is confirmed, the FDA should consider revising the health claim for whole grains to explicitly include the benefits from added bran. In conclusion, we found an inverse relation between the intake of whole grains and bran with CHD risk in a large-scale prospective study of US male health professionals. We cannot rule out the possibility of residual confounding from reported lifestyle characteristics or the existence of an unmeasured factor associated with high intakes of whole grain being responsible for the reduction in CHD. However, given the specificity of our findings for bran and whole grains, whole grains should be considered an important modifiable risk factor for CHD, and further studies to investigate the additional benefit from the bran and germ components of whole grains are warranted. We thank Al Wing and Eilis O Reilly for computer programming assistance and Walter Willet for insightful comments on the manuscript. All authors were involved in the critical revision of the manuscript and gave final approval of the submitted manuscript. MKJ, PK-B, MF, LS, FBH, MG, and EBR contributed to the study design, analysis, and interpretation of the data. MF and LS developed the whole-grain database. MKJ drafted the manuscript. None of the authors had any conflicts of interest. 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