Consumption of Wheat Aleurone-Rich Foods Increases Fasting Plasma Betaine and Modestly Decreases Fasting Homocysteine and LDL-Cholesterol in Adults

Abstract

There is strong evidence that whole-grain foods protect against heart disease. Although underlying mechanisms and components are unclear, betaine, found at high levels in wheat aleurone, may play a role. We evaluated the effects of a diet high in wheat aleurone on plasma betaine and related measures. In a parallel, single-blinded intervention study, 79 healthy participants (aged 45-65 y, BMI ≥ 25 kg/m(2)) incorporated either aleurone-rich cereal products (27 g/d aleurone) or control products balanced for fiber and macronutrients into their habitual diets for 4 wk. Fasting blood samples were taken at baseline and postintervention (4 wk) from participants. Compared with the control, the aleurone products provided an additional 279 mg/d betaine and resulted in higher plasma betaine (P < 0.001; intervention effect size: 5.2 μmol/L) and lower plasma total homocysteine (tHcy) (P = 0.010; -0.7 μmol/L). Plasma dimethylglycine and methionine, which are products of betaine-mediated homocysteine remethylation, were also higher (P < 0.001; P = 0.027) relative to control. There were no significant effects on plasma choline or B vitamins (folate, riboflavin, and vitamin B-6). However, LDL cholesterol was lower than in the control group (P = 0.037). We conclude that incorporating aleurone-rich products into the habitual diet for 4 wk significantly increases plasma betaine concentrations and lowers tHcy, which is attributable to enhanced betaine-homocysteine methyltransferase-mediated remethylation of homocysteine. Although this supports a role for betaine in the protective effects of whole grains, concomitant decreases in LDL suggest more than one component or mechanism may be responsible.

Betaine supplementation and the metabolic syndrome

“…The authors confirm previous observations that increasing habitual betaine intake increases fasting plasma betaine concentrations to a new set-point (Atkinson et al, 2009;Price et al, 2010). This occurs within days of increasing betaine intake, with a minimal elevation in urinary betaine excretion relative to the dose supplied (Atkinson et al, 2009).…”

“…This cycling is probably the main reason for the minimal change in circulating homocysteine. Others have reported significant reductions in homocysteine in response to more modest supplementation (Olthof et al, 2003;Price et al, 2010), which further supports our conclusion that the study population was betaine replete and inappropriate for assessing the effect on metabolic syndrome patients. Schwab et al (2011) confirm the safety of long-term betaine supplementation.…”

“…Schwab et al (2011) confirm the safety of long-term betaine supplementation. The minimal effect on plasma lipids is interesting in view of suggestions that the effect of betaine on plasma lipids is dose dependent (Konstantinova et al, 2008;Atkinson et al, 2009;Price et al, 2010). There are still many questions that need to be resolved.…”

Whole grains beyond fibre: what can metabolomics tell us about mechanisms?

“…The increase in plasma betaine was the first major metabolite change due to a whole-grain cereal diet that was highlighted using metabolomics, and this may explain some of the other metabolic observations related to changes to phospholipid metabolism and even insulin resistance. Betaine, as a methyl donor, remethylates homocysteine to methionine, a change that has been demonstrated in human subjects using betaine-rich wheat aleurone porridge (25) . In the presence of adequate supplies of betaine, less choline is used for the remethylation of homocysteine, allowing choline to be used for the production of phospholipids that make up a large proportion of cell membranes (31) .…”

“…This same study found that the rye bread diet improved glucose metabolism (reduced urinary C-peptide and plasma insulin) and reduced plasma prostate-specific antigen, a marker of prostate cancer risk (24) . Other studies specifically analysing betaine found that whole-grain-rich or cereal betaine-enriched diets led to an increased amount of circulating betaine (25,26) , and that with very high doses of cereal betaine from the wheat aleurone layer, downstream effects on reducing homocysteine and increasing dimethylglycine and methionine could be measured (25) . In work carried out on post-menopausal women, a group of the population at risk of developing type 2 diabetes, both fasting and post-prandial plasma samples had lower leucine and isoleucine concentrations when fed a whole-grain rye bread compared with refined grain bread (27,28) .…”