The betaine and choline content of a whole wheat flour compared to other mill streams

Abstract

Diets that contain high levels of whole grains have been associated with a reduced risk of several chronic diseases (Marquart et al., 2002). A whole grain, as defined by AACC International, should consist of the bran, germ and endosperm in the same proportions as found in nature (AACC, 1999). Whole grains are an important source of dietary fiber, resistant starch, vitamins, minerals and other bioactive nutrients that can play a role in protecting against chronic disease (Slavin, 2003). One of these nutrients is betaine (also known as trimethyl glycine or glycine betaine), an osmolyte and methyl donor shown to protect internal organs and improve vascular risk factors (Craig, 2004). As an osmolyte, it helps protect a variety of cells from osmotic stress. Betaine also plays an important role in cell biochemistry, donating a methyl group to homocysteine to produce methionine and ultimately S-adenosyl-methionine. Betaine accumulates in many plants under stress from drought, high salinity or low temperature. Cereal plants with betaine accumulation include wheat, barley and rye; those with little or no accumulation include rice, millet and sorghum (Kishitani et al., 1994). It has been suggested that betaine may be a factor in whole grain protection against coronary artery disease (Liu et al., 2000; Vos, 2000). Another of these nutrients is choline. Choline and betaine are structurally very similar, and choline is largely oxidized to betaine in the body. Choline is also metabolized to acetylcholine and phosphatidylcholine, and is essential for the normal function of cells (Zeisel, 2006). An early study showed that betaine and choline are nutrients in whole wheat which vary depending on wheat variety (Waggle et al., 1967). In addition, this study determined that these nutrients are particularly rich in the germ and bran. Recently, a USDA database has been developed showing the betaine and choline content of foods (Howe et al., 2004; Zeisel et al., 2003). Wheat-based foods can be important sources of betaine, and high levels were again found in wheat germ and bran. Finally, this database has been used recently to show that a periconceptual diet high in betaine and choline is associated with a reduced risk of infant neural tube defects (Shaw et al., 2004). Another epidemiological study shows that intake of choline and betaine predicts plasma homocysteine concentrations (Cho et al., 2006). Further epidemiological studies will emerge that utilize this new database to investigate other chronic diseases. The objective of this study was to produce seven mill streams of wheat flour using a pilot mill to determine the effect of milling conditions on betaine and choline content.