β-glucan in barley

It is thought that barley cultivation began 8000–10 000 years ago in the ‘Fertile Crescent’ of the Middle East and thus barley has been considered to be one of the founding crops of Old World agriculture.

The active ingredient thought to provide barley its health benefits is β-glucan. β-Glucan is a plant cell wall polysaccharide that is found in a range of tissues in barley including the grain, where it constitutes approximately 70% dry weight (w/w) of endosperm primary cell walls.

β-Glucan is a type of soluble fiber, linear homopolysaccharides composed of D-glucopyranosyl residues linked via a combination of β-(1→4) and β-(1→3) linkages.

This polysaccharide accumulates throughout barley endosperm development. β-glucans are predominantly found in the internal aleurone and subaleurone cell walls. The content of β-glucan varies with environmental conditions during endosperm development and is regulated by (1 → 3,1 → 4)-β-glucan endohydrolase to facilitate endosperm cell-wall degradation during germination.

Of cereal grains, oats and barley contain the highest level of β-glucan at 3–7 and 3–11% (dry weight basis), respectively.

Its beneficial role in insulin resistance, dyslipidemia, hypertension, and obesity is being continuously documented. The fermentability of β-glucans and their ability to form highly viscous solutions in the human gut may constitute the basis of their health benefits. Among the dietary fiber sources, cereal β-glucans have been shown to be one of the most effective fiber types to prevent type 2 diabetes and cardiovascular diseases.
β-glucan in barley