|Ma, Jiantao -|
|Ross, Alastair -|
|Shea, M. Kyla -|
|Bruce, Stephen -|
|Jacques, Paul -|
|Saltzman, Edward -|
|Lichtenstein, Alice -|
|Booth, Sarah -|
|Mckeown, Nicola -|
Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 6, 2012
Publication Date: September 5, 2012
Citation: Ma, J., Ross, A.B., Shea, M., Bruce, S.J., Jacques, P.F., Saltzman, E., Lichtenstein, A.H., Booth, S.L., Mckeown, N.M. 2012. Plasma alkylresorcinois, biomarkers of whole-grain intake, are related to lower BMI in older adults. Journal of Nutrition. 142(10):1859-1864. Interpretive Summary: Nutrition experts believe that whole grains are healthy foods, and many studies have examined their health effects. It is not always easy for people to recognize whether the foods they are eating are made with whole grain. Thus, it is difficult for people to accurately report consumption of whole grains, creating a challenge for researchers. It has been suggested that measuring alkylresorcinols (ARs), a specific compound that appears in the blood (a biomarker) after whole grains have been consumed and digested, may be a better way of estimating whole grain wheat and rye intake. ARs are a group of lipids that are only present in the bran layer (the outer layer) of whole grain wheat and rye. The bran is part of whole grain foods but is stripped away once a grain is refined (to make refined grain foods). Thus, ARs and their byproducts can be found and measured in blood and urine after eating whole grains. Studies have already shown that ARs reflect short-term whole grain wheat and rye intake, and now researchers would like to determine whether ARs also reflect longer-term intake of these whole grains. In this study, our objectives were (1) to determine whether there is a dose-response relationship between whole grains consumed and amounts of ARs in the blood and (2) to determine whether higher amounts of ARs are linked to healthy characteristics, such as a normal body mass index. A “dose-response” relationship means that eating more whole grains translates into higher amounts of ARs in the blood. To uncover the answers to these questions, we examined data collected in people who were participants in a previously conducted, large study of vitamin K supplements. We measured the amounts of ARs in the plasma of blood drawn from 407 participants older than 60 years of age (166 men, 241 women). We measured whole grain intake using a food frequency questionnaire (a tool which allows people to report their usual eating habits over the prior year), and we asked participants about the whole grain foods they typically ate and also if they included added bran in their diet. We found that a dose-response relationship exists between the amount of whole grains consumed and the amount of ARs in the blood. In particular, we found a stronger relationship between the blood AR measure and whole-grain wheat–rich foods. We also found that higher amounts of ARs in the blood are associated with lower body mass index and lower fat mass in the torso, confirming our previous research that showed that eating more whole grains is associated with lower body mass index.
Technical Abstract: Alkylresorcinols (AR) are phenolic lipids found in the bran fraction of whole-grain wheat, rye, and barley. In intervention studies, plasma AR concentration increased in response to greater intakes of whole grain, wheat, and rye. This study examined the cross-sectional associations between plasma AR and habitual whole-grain intake, BMI, and metabolic risk factors in 407 free-living older adults (166 men and 241 women; aged 60-81y; median BMI: 27 kg/m(2)). Plasma AR were measured by liquid chromatography-tandem MS, and whole-grain intakes were estimated by using an FFQ. After adjustment for fasting TG concentrations, median plasma AR concentrations across quartile categories of AR were 5, 14, 27, and 62 nmol/L, respectively. Spearman correlation coefficients between plasma AR and whole-grain wheat-rich foods and total bran intake were 0.31 and 0.27, respectively (both P < 0.0001). After adjustment for multiple covariates, the geometric means of BMI in the lowest and highest quartile category of plasma AR were 27.6 and 26.7 kg/m(2), respectively (P-trend = 0.04). No associations were observed between plasma AR and glucose and insulin. Our study shows a dose-dependent relationship between whole-grain intake and plasma AR and confirms the previously observed inverse relationship between whole-grain intake and BMI using an independent biomarker of whole-grain wheat intake.