Whole grains

The American Society for Nutrition brought together researchers to review the evidence regarding the health benefits associated with whole grains. Current scientific evidence indicates that whole grains play an important role in lowering the risk of chronic diseases, such as coronary heart disease, diabetes, and cancer, and also contribute to body weight management and gastrointestinal health.
Journal of Nutrition, May 2011;141(5):1011S-22S. Epub March 30, 2011

In a cross-over study conducted at the UK’s University of Surrey, researchers asked 14 healthy normal-weight adults to consume either two whole grain rolls (totaling 48g of whole wheat) or two control rolls with their normal diets. While researchers did not find the decrease in appetite they had been seeking, they were surprised to find a significant decrease in the subjects’ systolic blood pressure during the three weeks they ate the whole wheat rolls, and an increase in systolic pressure during the white-bread phase of the trial.
British Journal of Nutrition, April 18, 2011: 1-4 [Epub ahead of print]

Researchers at Tufts University, including Nicola McKeown, analyzed data from 2834 Framingham Heart Study participants aged 32-83 years old, to assess the relationship between whole grain consumption and body fat distribution. They found that people with the highest whole grain intake had less subcutaneous abdominal fat (fat under their skin) and less visceral abdominal fat (fat around their organs), while those with the highest refined grain intake had more of both types of abdominal fat, especially visceral fat. Visceral fat has been linked to higher risk for diabetes and heart disease.
American Journal of Clinical Nutrition. November 2010; 92(5):1165-71.

In a randomized control trial of 233 healthy, middle-aged volunteers, subjects spent 4 weeks consuming a run-in diet of refined grains, and then were randomly allocated to the control diet (refined), a whole wheat diet, or a whole wheat and whole oats diet for 12 weeks. Each group consumed 3 daily portions of the specific grains. Systolic blood pressure and pulse pressure were significantly reduced by 6 and 3 mm HG, respectively, in the whole grains groups compared to the control refined group. Researchers at the University of Aberdeen concluded that this blood pressure decrease would decrease the incidence of coronary artery disease and stroke by 15-25% respectively.
American Journal of Clinical Nutrition, October 2010; 92(4):733-40. Epub August 4, 2010

O’Neil and colleagues conducted secondary analysis of cross-sectional data from 1999-2004 National Health and Nutrition Examination Survey to examine the association between whole grain intake and overall diet quality and nutrient intake in adults 19-50 years and 51+ years.  For both groups, the study found that those eating the most whole grains had significantly higher amounts of fiber, energy and polyunsaturated fats in their diet. Intake of all micronutrients, except vitamin B-12 and sodium, was also higher among those who consumed the most whole grains. Additionally, added sugars, monounsaturated fats, saturated fats and cholesterol intake was lower in the diets of those who consumed the most whole grains.
Journal of the American Dietetic Association, Oct 2010;110(10):1461-8.

Penny Kris-Etherton and Kristin Harris at Penn State’s Department of Nutrition Sciences, reviewed research on whole grains and coronary heart disease risk in an effort to explain mixed results from one study to another. They concluded that, “due to the varying nutrition compositions of different whole grains, each could potentially affect CHD risk via different mechanisms.” Whole Grains high in soluble fiber tend to decrease LDL cholesterol and improve insulin response, for example, while those high in insoluble fiber may have a prebiotic effect, while lowering glucose and blood pressure. While intervention studies have not proven the observered epidemiological link between whole grains and weight loss, visceral fat loss has been shown. Differences in processing of whole grains may also affect their heart-healthy potential.
Current Atherosclerosis Reports, September 7, 2010 [Epub ahead of print]

Some carbohydrates found especially in whole grains resist digestion and instead are processed by the body through fermentation in the lower colon. This process creates short chain fatty acids (SCFAs) that show an intriguing range of health benefits. Researchers at Lund University in Sweden carried out an intervention study with 5 healthy women and 10 healthy men, offering each of them 8 different cereal-based dinners in random order on separate evenings. In the mornings, all subjects ate identical breakfasts, after which their glucose response and their blood concentration of butyrate, a SCFA, were measured. Whole grain evening meals high in indigestible carbohydrates, such as barley kernels, resulted in higher butyrate concentrations and lower glucose response than refined-grain meals such as white wheat bread. The researchers hypothesize that this may explain why whole grain is protective against type 2 diabetes and cardiovascular disease.
Journal of Nutrition, September 1, 2010 [Epub ahead of print]

Scientists at the National Institutes of Health, Louisiana State, and SUNY Buffalo worked together to follow 259 healthy pre-menopausal women for two years, to see if whole grain consumption lowered levels of C-reactive protein. They found that women who ate even small amounts of whole grains – up to one serving a day – had, on average, 11.5% lower concentration of hs-CRP in their blood. Women eating a full serving (16g of a 100% whole grain food, in this study) or more of whole grain had, on average, 12.3% lower CRP levels. Since earlier research has found that higher CRP levels are associated with adverse reproductive outcomes, the researchers postulate that whole grain consumption has the potential to improve the health of young women of child-bearing age.
Journal of Nutrition. September 2010; 140(9):1669-1676. doi: 10.3945/jn.110.124164

Project EAT (Eating Among Teens)-II revealed that intake of whole grains among adolescents was lower than recommended amounts. The study of 792 adolescents and 1,668 young adults also discovered a correlation between certain factors and whole grain intake. Home availability of whole-grain bread, self-efficacy to consume at least 3 daily servings of whole grains, and preference for the taste of whole-grain bread were associated with eating more whole grains during adolescence and young adulthood, while fast food intake was associated with eating fewer whole grains.
Journal of the American Dietetic Association, Feb 2010;110(2):230-7.

Nicola McKeown and a team of Tufts researchers studied 434 older (age 60 to 80) adults, comparing their diet to their body fat and abdominal fat composition. No significant association was found between body composition and intake of total fiber or vegetable and fruit fiber. Whole grain intake and cereal fiber intake, however, correlated strongly with lower BMI, lower total percent body fat and lower abdominal (“trunk fat”) mass in older adults.
Journal of Nutrition, October 2009; 139(10);1950-1955. DOI:10.3945/jn.108.103762