PhD candidate, University of Wollongong
Are the cardiovascular benefits of whole grains purely due to the cereal fibre content?
My research interest is to explore the association between whole grain intake and biomarkers of cardiovascular disease (CVD) risk, in comparison to the association of non-whole grain, high-cereal fibre intake. The aim of this is to investigate the relative contribution of the fibre component of cereals to the overall protective effects attributed to whole grain intake.
The research will provide further insight into the benefits of whole grain cereals and contribute to the evidence informing public health strategies targeting prevention of cardiovascular disease.
Abstract: Higher intake of whole grains has been associated with a lower risk of major chronic diseases, such as type 2 diabetes mellitus and cardiovascular disease (CVD), although limited prospective evidence exists regarding whole grains' association with mortality.To examine the association between dietary whole grain consumption and risk of mortality.We investigated 74 341 women from the Nurses' Health Study (1984-2010) and 43 744 men from the Health Professionals Follow-Up Study (1986-2010), 2 large prospective cohort studies. All patients were free of CVD and cancer at baseline.Hazard ratios (HRs) for total mortality and mortality due to CVD and cancer according to quintiles of whole grain consumption, which was updated every 2 or 4 years by using validated food frequency questionnaires.We documented 26 920 deaths during 2 727 006 person-years of follow-up. After multivariate adjustment for potential confounders, including age, smoking, body mass index, physical activity, and modified Alternate Healthy Eating Index score, higher whole grain intake was associated with lower total and CVD mortality but not cancer mortality: the pooled HRs for quintiles 1 through 5, respectively, of whole grain intake were 1 (reference), 0.99 (95% CI, 0.95-1.02), 0.98 (95% CI, 0.95-1.02), 0.97 (95% CI, 0.93-1.01), and 0.91 (95% CI, 0.88-0.95) for total mortality (P fortrend < .001); 1 (reference), 0.94 (95% CI, 0.88-1.01), 0.94 (95% CI, 0.87-1.01), 0.87 (95% CI, 0.80-0.94), and 0.85 (95% CI, 0.78-0.92) for CVD mortality (P fortrend < .001); and 1 (reference), 1.02 (95% CI, 0.96-1.08), 1.05 (95% CI, 0.99-1.12), 1.04 (95% CI, 0.98-1.11), and 0.97 (95% CI, 0.91-1.04) for cancer mortality (P fortrend = .43). We further estimated that every serving (28 g/d) of whole grain consumption was associated with a 5% (95% CI, 2%-7%) lower total morality or a 9% (95% CI, 4%-13%) lower CVD mortality, whereas the same intake level was nonsignificantly associated with lower cancer mortality (HR, 0.98; 95% CI, 0.94-1.02). Similar inverse associations were observed between bran intake and CVD mortality, with a pooled HR of 0.80 (95% CI, 0.73-0.87; P fortrend < .001), whereas germ intake was not associated with CVD mortality after adjustment for bran intake.These data indicate that higher whole grain consumption is associated with lower total and CVD mortality in US men and women, independent of other dietary and lifestyle factors. These results are in line with recommendations that promote increased whole grain consumption to facilitate disease prevention.
Pub.: 07 Jan '15, Pinned: 30 Aug '17
Abstract: The Australian Dietary Guidelines recommend Australians choose mostly whole-grain and/or high-fibre varieties within the grains (cereal) foods category, with other groups specifying a whole grain Daily Target Intake of 48 g for Australians aged 9 years or above. The USA and UK report estimates of whole grain intake that are low and declining, and no comprehensive studies on whole grain intake in the Australian population are available. The present study aimed to determine national estimates of whole grain intake, compared with current recommendations.A recently updated whole grain database was applied to the most current population dietary intake data. Single 24 h dietary recall intake data were reviewed against age group, sex, relative to energy intake and whole grain recommendations.Australia.Australians (2-85 years) participating in the 2011-13 Australian Health Survey (n 12 153).The median daily whole grain intake was 21 g for adults (19-85 years) and 17 g for children/adolescents (2-18 years), or 28 and 23 g/10 MJ per d, respectively. Approximately 30 % of children/adolescents consumed no whole grains on the day of the survey. Whole grain intake was lowest for the age group 14-18 years (8·7 g/d). Of all participants aged ≥9 years, 73 % did not reach the recommended Daily Target Intake of 48 g.Whole grain intake in Australia is below recommendations in all age groups. Adolescents may be a key target for campaigns to increase whole grain consumption. This study provides the first quantification of absolute whole grain intake from all food sources in a national sample of Australians.
Pub.: 09 Jun '17, Pinned: 30 Aug '17
Abstract: Food composition data is essential for calculating consumption based on reported dietary intake. Inclusion of the whole grain content of foods in food composition databases is limited. In Australia, quantification of whole grain composition does not include all foods within the current survey database, AUSNUT (Australian Food, Supplement and Nutrient) 2011-13. This study aimed to update an existing Australian whole grain database to include all foods and food products within AUSNUT 2011-13 (n = 5741). Whole grain content (g) per 100 g was calculated using a systematic recipe-based approach, and input from industry stakeholders, product packaging, and ingredient lists. Overall 590 foods were identified as containing whole grain. Cereals and cereal products formed the majority (43%) of the database. Foods with whole grain content 100.0 g/100 g were raw or puffed whole grains, whole grain flours, and ready to eat cereals made from 100% whole grains. Considerable variation in whole grain content exists between and within food groups. The updated database may be a useful tool for assessing whole grain content of Australian food intake data. Application will allow estimation of whole grain intake in highly varied Australian population groups.
Pub.: 11 May '16, Pinned: 30 Aug '17
Abstract: Although whole-grain consumption has been associated with a lower risk of cardiovascular diseases (CVD) and mortality in the general population, the association of whole grain with mortality in diabetic patients remains to be determined. This study investigated whole grain and its components cereal fiber, bran, and germ in relation to all-cause and CVD-specific mortality in patients with type 2 diabetes mellitus.We followed 7822 US women with type 2 diabetes mellitus in the Nurses' Health Study. Dietary intakes and potential confounders were assessed with regularly administered questionnaires. We documented 852 all-cause deaths and 295 CVD deaths during up to 26 years of follow-up. After adjustment for age, the highest versus the lowest fifths of intakes of whole grain, cereal fiber, bran, and germ were associated with 16% to 31% lower all-cause mortality. After further adjustment for lifestyle and dietary risk factors, only the association for bran intake remained significant (P for trend=0.01). The multivariate relative risks across the fifths of bran intake were 1.0 (reference), 0.94 (0.75 to 1.18), 0.80 (0.64 to 1.01), 0.82 (0.65 to 1.04), and 0.72 (0.56 to 0.92). Similarly, bran intake was inversely associated with CVD-specific mortality (P for trend=0.04). The relative risks across the fifths of bran intake were 1.0 (reference), 0.95 (0.66 to 1.38), 0.80 (0.55 to 1.16), 0.76 (0.51 to 1.14), and 0.65 (0.43 to 0.99). Similar results were observed for added bran alone.Whole-grain and bran intakes were associated with reduced all-cause and CVD-specific mortality in women with diabetes mellitus. These findings suggest a potential benefit of whole-grain intake in reducing mortality and cardiovascular risk in diabetic patients.
Pub.: 12 May '10, Pinned: 30 Aug '17
Abstract: Studies of whole grain and chronic disease have often included bran-enriched foods and other ingredients that do not meet the current definition of whole grains. Therefore, we assessed the literature to test whether whole grains alone had benefits on these diseases.The objective was to assess the contribution of bran or cereal fiber on the impact of whole grains on the risk of type 2 diabetes (T2D), obesity and body weight measures, and cardiovascular disease (CVD) in human studies as the basis for establishing an American Society for Nutrition (ASN) position on this subject.We performed a comprehensive PubMed search of human studies published from 1965 to December 2010.Most whole-grain studies included mixtures of whole grains and foods with ≥25% bran. Prospective studies consistently showed a reduced risk of T2D with high intakes of cereal fiber or mixtures of whole grains and bran. For body weight, a limited number of prospective studies on cereal fiber and whole grains reported small but significant reductions in weight gain. For CVD, studies found reduced risk with high intakes of cereal fiber or mixtures of whole grains and bran.The ASN position, based on the current state of the science, is that consumption of foods rich in cereal fiber or mixtures of whole grains and bran is modestly associated with a reduced risk of obesity, T2D, and CVD. The data for whole grains alone are limited primarily because of varying definitions among epidemiologic studies of what, and how much, was included in that food category.
Pub.: 28 Jun '13, Pinned: 30 Aug '17
Abstract: The U.S. FDA defines whole grains as consisting of the intact, ground, cracked, or flaked fruit of the grains whose principal components, the starchy endosperm, germ, and bran, are present in the same relative proportions as they exist in the intact grain. We evaluated the effect of applying the FDA definition of whole grains to the strength of scientific evidence in support of claims for risk reduction of cardiovascular disease (CVD). We concluded that using the FDA definition for whole grains as a selection criterion is limiting, because the majority of existing studies often use a broader meaning to define whole grains. When considering only whole grain studies that met the FDA definition, we found insufficient scientific evidence to support a claim that whole grain intake reduces the risk of CVD. However, a whole grain and reduced risk of CVD health claim is supported when using a broader concept of whole grain to include studies that considered intake of fiber-rich bran and germ as well as whole grain. This type of analysis is complicated by diversity in nutrients and bioactive components among different types of whole grains.
Pub.: 25 Sep '09, Pinned: 30 Aug '17