A Novel Barley Cultivar (Himalaya 292) with A Specific Gene Mutation in Starch Synthase IIa Raises Large Bowel Starch and Short-Chain Fatty Acids in Rats

Abstract

Himalaya 292 (Hordeum vulgare, var. himalaya 292) is a novel, hull-less barley cultivar with a single nucleotide change in the gene encoding starch synthase IIa (EC 2.4.1.21). This leads to loss of enzyme activity, resulting in a grain with less total starch and a higher proportion of amylose. These changes, plus higher total and soluble nonstarch polysaccharides (NSP), could increase its resistant starch (RS) content. Accordingly, rats were fed a diet containing stabilized whole-grain barley flours from Himalaya 292 or two commercial varieties (Namoi or fed a diet containing whole-grain barley Himalaya or Waxiro) or wheat or oat bran at equivalent NSP concentrations for 14 d. There were favorable significant changes in a number of bowel health-related indices. Fecal output by rats fed Himalaya 292 was higher than by those fed Namoi or oat bran, whereas total large bowel digesta mass was higher than in those fed Waxiro. Cecal starch concentrations and pools were higher in rats fed Himalaya 292 than in all other groups. Fecal and cecal digesta pH was lower in rats fed Himalaya 292 than in all other groups except that fed oat bran. Colonic digesta pH was lower in rats fed Himalaya 292 than in those fed wheat bran or Namoi. Fecal total SCFA excretion was higher in rats fed Himalaya 292 than in those fed Namoi or oat bran. Although cecal total SCFA pools did not differ among groups, colonic SCFA were higher in rats fed Himalaya 292 than in those fed Namoi or Waxiro. These data indicate that changes in Himalaya 292 grain composition result in greater RS with consequent alterations in large bowel SCFA and pH when fed to rats.