Punching holes in pop-science theory: Whole grains may cut inflammatory biomarkers in obese kids
Levels of inflammatory markers such as C-reactive protein and soluble intercellular adhesion molecule-1 decreased by 22% and 28%, respectively, over six weeks, compared with increases of 12% and 6%, respectively in the control group, report researchers from Isfahan University of Medical Sciences in Iran.
“To the best of our knowledge, the present study was the first examining the effects of whole-grain intake on inflammation among overweight children,” they wrote.
‘Whole grains are an important part of the solution to systemic inflammation’
Commenting on the study’s findings, Cynthia Harriman, director of Food and Nutrition Strategies at Oldways / The Whole Grains Council, told us that the carefully-crafted randomized controlled crossover trial is the latest study to, “punch holes in the pop-science theory, promoted in some sensationalist best-sellers, that all grains (even whole grains) promote inflammation and ‘leaky gut’– conditions that in turn can lead to auto-immune diseases.
“The counter-evidence to this pseudo-science is very strong, and the evidence linking whole grain consumption with a reduction in inflammation has been growing steadily,” she said. “In 2007, David Jacobs at the University of MN published a study of more than 27,000 post-menopausal women [AJCN, Vol 85, pp. 1606-1614] which showed that eating whole grains reduced the risk of mortality from inflammatory diseases.
Harriman added that epidemiological results have been supported by recent data from human trials. A study by researchers at the University of Nebraska last year reported that eating whole grains (barley, brown rice, or especially a mix of the two) even for a short period altered the gut microbiota in ways that coincided with improvements in systemic inflammation (Gut Microbes, Vol. 4, pp. 340-346).
In addition, Danish researchers reported at the end of 2013 that women who ate whole wheat instead of refined wheat for just 12 weeks had significant increases in beneficial bifidobacteria, and an unexpected decrease in ‘leaky gut’ (Eur. J. Clin. Nutr. Vol. 67, pp. 1316-21).
“Now this new randomized controlled crossover trial, from Iran, reports that inflammation markers decreased significantly in overweight adolescent girls when they made at least half their grains whole for as little as six weeks,” she said.
“Oldways and the Whole Grains Council concur in the belief that systemic inflammation is a serious problem that underlies many chronic diseases. The evidence shows, however, that whole grains are an important part of the solution to systemic inflammation, and not part of the problem.”
For the new study, the Iranian researchers recruited 44 overweight or obese girls aged between 8 and 15, and randomly assigned them to either whole-grain or control groups.
Subjects in the whole-grain group were given a list of whole-grain foods and were asked to obtain half of their daily total grain servings from whole-grain foods each day for 6 weeks, or to avoid consumption of whole grain-rich foods during the control phase of the study. This was followed by four-week washout period before they children were crossed over to the other study group for an additional six weeks. Average whole grain consumption in the active group was 98 grams per day, compared with 11 grams per day in the control group.
Results indicated that, while no significant changes in weight and BMI were observed between the two dietary groups, a significant effect of whole-grain intake was recorded for high-sensitive CRP, soluble intercellular adhesion molecule-1, serum amyloid A (a 17.4% reduction in the whole grain group, compared with a 10% increase in the control group), and leptin (a 10% decrease in the whole grain group, compared with a 39% increase in the control group).
“The mechanisms through which whole-grain intake might affect systemic inflammation remain to be understood,” wrote the researchers. “Whole-grain products are important dietary sources of vitamins, minerals, dietary fiber, phytoesterogens, and antioxidants, which may moderate their beneficial effects on inflammatory markers.”
They added that dietary fiber has also been shown to beneficially impact body weight and lipids oxidation, which may decrease inflammation and oxidative stress. Another possibility is via a blood sugar management mechanism.
“Although the current study has adequate power to detect the significant effects, further studies with longer duration of interventions might be needed to confirm the long-term health benefits of whole grains in children,” they added.
Source: Molecular Nutrition & Food Research
Published online ahead of print, doi: 10.1002/mnfr.201300582
“Whole-grain intake favorably affects markers of systemic inflammation in obese children: A randomized controlled crossover clinical trial”
Authors: P. Hajihashemi, L. Azadbakht, M. Hashemipor, R. Kelishadi, A. Esmaillzadeh