Incorporation of 25 grams of the company’s Promitor-branded resistant starch increased faecal output by 20 per cent without any significant gastrointestinal (GI) side effects, according to findings published in the International Journal of Food Sciences and Nutrition.
“The utility of resistant starch as a food ingredient and the excellent tolerability profile are encouraging, as GI side effects associated with increased consumption of certain dietary fibres can be an impediment to continued consumption,” wrote the researchers, led by Kevin Maki, PhD, from Provident Clinical Research, a contract research organisation.
“The [type 3 novel resistant starch] employed in the current study possesses functional properties, such as high crystallinity and heat stability, which make it particularly resilient to high temperature cooking environments such as baking and extrusion.
“Accordingly, it maintains its status as a dietary fibre under these extreme conditions unlike some other resistant starch ingredients,” they added.
Low-down on RS
Resistant starch (RS) is so called because of its ability to resist digestion in the small intestine, unlike most other starches. Instead, RS passes through to the large intestine where it acts like dietary fibre and improves digestive health.
Resistant starch occurs naturally in foods such as unripe bananas and cooked and cooled potatoes, but commercially produced RS ingredients have started to appear on the market in order to allow food manufacturers to incorporate the ingredient into their products.
This has provided the industry with another means to tap into opportunities gleaned from the growing trend for health and wellness foods, with resistant starch fitting squarely into the low-glycaemic food trend, as well as health product positioning such as prebiotic fibre and healthy digestive system claims.
“The faster food moves through the digestive tract, the less frequently harmful compounds, such as carcinogens, come in contact with the digestive system,” explained Tate & Lyle’s Lisa Sanders, PhD, RD. “The added bulk also helps to dilute any harmful compounds that may exist and minimize their negative impact on the colon.”
Maki and his co-workers recruited 14 men and women with an average age of 32.5 and an average BMI of 26.8 kg/m2. The subjects underwent an initial 14-day period consuming a low-fibre diet, and were then randomly assigned to receive an additional 25 grams wheat bran or resistant starch for a further 14 days. After this time, they underwent a 7-day washout period before being crossed over to the other intervention.
Results showed an increase in daily faecal output by 20 and 35 per cent following consumption of the starch and wheat bran interventions, respectively, while no differences were observed in bowel frequency between the baseline period and the two interventions.
“This [latter result] is not entirely surprising, given that studies have shown that while stool weight increases with greater fibre consumption, there is a plateau effect for both intestinal transit time and faecal frequency,” said the researchers. “Once regularity is achieved (one to three bowel movements daily), the effect of additional dietary fibre is mainly to increases in stool weight, rather than defecation frequency.
“Subjects in the current study had baseline regularity in the normal range, and thus an increase in defecation frequency was not expected,” they added.
The consistency of the faeces was improved with the wheat bran, but not with the resistant starch, added the researchers.
Source: International Journal of Food Sciences and Nutrition
Volume 60, Issue 1, Supplement 4, Pages 296-305, doi: 10.1080/09637480903130538
“Beneficial effects of resistant starch on laxation in healthy adults”
Authors: K.C. Maki, L.M. Sanders, M.S. Reeves, V.N. Kaden, T.M. Rains, Y. Cartwright