Postprandial plasma betaine and other methyl donor-related responses after consumption of minimally processed wheat bran or wheat aleurone, or wheat aleurone incorporated into bread

Abstract

The bran and particularly the aleurone fraction of wheat are high in betaine and other physiological methyl donors, which may exert beneficial physiological effects. We conducted two randomised, controlled, cross-over postprandial studies to assess and compare plasma betaine and other methyl donor-related responses following the consumption of minimally processed bran and aleurone fractions (study A) and aleurone bread (study B). For both studies, standard pharmacokinetic parameters were derived for betaine, choline, folate, dimethylglycine (DMG), total homocysteine and methionine from plasma samples taken at 0, 0·5, 1, 2 and 3 h. In study A (n 14), plasma betaine concentrations were significantly and substantially elevated from 0·5 to 3 h following the consumption of both bran and aleurone compared with the control; however, aleurone gave significantly higher responses than bran. Small, but significant, increases were also observed in DMG measures; however, no significant responses were observed in other analytes. In study B (n 13), plasma betaine concentrations were significantly and substantially higher following consumption of the aleurone bread compared with the control bread; small, but significant, increases were also observed in DMG and folate measures in response to consumption of the aleurone bread; however, no significant responses were observed in other analytes. Peak plasma betaine concentrations, which were 1·7 -1·8 times the baseline levels, were attained earlier following the consumption of minimally processed aleurone compared with the aleurone bread (time taken to reach peak concentration 1·2 v. 2·1 h). These results showed that the consumption of minimally processed wheat bran, and particularly the aleurone fraction, yielded substantial postprandial increases in plasma betaine concentrations. Furthermore, these effects appear to be maintained when aleurone was incorporated into bread.

The contribution of wheat to human diet and health

“…Intervention studies with aleurone-rich foods (Price et al 2010) and with wholegrain foods (Ross and Bruce 2011) have also shown that increased total intakes and plasma concentrations of betaine were associated with improvements in a number of biomarkers of health, including decreased total plasma homocysteine and LDL cholesterol. A more recent study has shown that the consumption of minimally processed wheat bran, and particularly the aleurone fraction, resulted in substantial postprandial increases in plasma betaine concentrations, including when aleurone fractions were incorporated into bread (Keaveney et al 2015). EFSA have accepted a health claim relating to betaine, but this can only be applied to products containing at least 500 mg/ portion (contributing to a daily intake of 1.5 g) (http:// ec.europa.eu/nuhclaims/).…”

“…A more recent study has shown that the consumption of minimally processed wheat bran, and particularly the aleurone fraction, resulted in substantial postprandial increases in plasma betaine concentrations, including when aleurone fractions were incorporated into bread (Keaveney et al. ). EFSA have accepted a health claim relating to betaine, but this can only be applied to products containing at least 500 mg/portion (contributing to a daily intake of 1.5 g) (http://ec.europa.eu/nuhclaims/).…”

Bioavailability and metabolism of phenolic compounds from wholegrain wheat and aleurone‐rich wheat bread

“…The whole‐wheat kernel is usually processed to obtain the bran fraction that contains 45–50% of the aleurone layer. The aleurone layer is a metabolically active monolayer that is the innermost part of the bran and represents 5–8% of the wheat kernel . The aleurone layer is usually removed during milling for its firm attachment to the external integuments .…”

Enhancing mineral bioavailability from cereals: Current strategies and future perspectives

“…, ), and plasma levels of betaine and other methyl donors (Keaveney et al . ) are enhanced following consumption of aleurone‐enriched breads. Interestingly, a recent in vitro study has suggested that iron availability from wholewheat bread is equal to or even greater than that from fortified white bread (Nikooyeh & Neyestani ).…”

“…White bread containing 20% aleurone has comparable micronutrient content to wholewheat bread (Brouns et al 2012). Furthermore, human feeding studies have shown that the bioavailability of folate (Fenech et al 1999(Fenech et al , 2005, and plasma levels of betaine and other methyl donors (Keaveney et al 2015) are enhanced following consumption of aleurone-enriched breads. Interestingly, a recent in vitro study has suggested that iron availability from wholewheat bread is equal to or even greater than that from fortified white bread (Nikooyeh & Neyestani 2017).…”