Blue lupin kernel fiber may boost colon health: RCT
Data from a double-blind, controlled crossover trial with 92 people indicated that, while all the fiber sources tested - blue lupin fiber (Lupinus angustifolius cv. Boregine), white lupin fiber (Lupinus albus cv. Typ Top), soya fiber, and citrus fiber – led to changes in the gut, the blue lupic fiber in particular was found to improve colonic function.
“The findings of the present study confirm that dietary fiber from different plant sources often demonstrate unique physiological effects in the gut, which is in line with the inconsistent data achieved from a number of studies investigating an association between dietary fiber consumption and occurrence of colorectal cancer,” they wrote in the Nutrition Journal.
The US food fiber industry has been valued at around $500 million by Frost & Sullivan. The US defines ‘dietary fiber’ and non-digestible food plant carbohydrates and lignin, while ‘added fiber’ refers to fiber added to foods during food processing. Total Fiber is a combination of the two.
Data from a 2008 International Food Information Council survey found 77% of people are proactively trying to consume additional fiber. Despite such good intentions, however, many Americans only achieve about 50% of their recommended amount of 25 to 30 grams of fiber daily.
Packaged Facts estimated that in 2004, 91% of all fiber food ingredient sales were of conventional, insoluble-type fibers, which contains cellulose, hemicellulose and lignin and cannot be dissolved in water.
The remaining 9% share was split evenly between conventional, soluble-type fibers and emerging, novel fibers. The market researcher projected that insoluble fibers will decrease to 53.3% by 2014, while the share for the mostly new or newly refined conventional, soluble-type fibers will decrease slightly to 7.4%.
The Jena-based scientists randomly assigned the participants to one of three groups, and half of each group received 25 grams of a legume fiber per day (blue lupin fibre, white lupin fibre, and soya fibre), and the other half received 25 grams of citrus fiber per day for two weeks. This was followed by a two week ‘washout’ before crossing over to the other intervention.
Results showed that, for the 76 people who completed the study, the lupin fiber supplementations increased daily fecal weight and fecal dry matter by 1.76 and 1.64 grams of feces per gram of additional dietary fiber contributed by blue and white lupin, respectively.
In additional, both lupin fiber supplements were associated with significantly increased levels of short-chain fatty acids (SCFAs).
“SCFA, particularly n-butyrate, are an important energy source for colonocytes [cells that line the colon],” wrote the researchers. “In addition, n-butyrate is able to reduce the risk of malignant changes through regulation of colonocyte differentiation. Due to the enhanced SCFA formation, both lupin fibre interventions could elevate n-butyrate excretion significantly (blue lupin: 60%, white lupin: 65%) and the faecal concentration slightly (blue lupin: 23%, white lupin: 12%).
“Increased SCFA concentration lowers the pH value, which consequently decreases the formation of carcinogenic substances,” they added.
Taking all the results together, the researchers concluded that dietary fiber intake can be enhanced using blue lupin up to about 50 grams per day.
Source: Nutrition Journal
2013, 12:101, doi:10.1186/1475-2891-12-101
“Effects of legume kernel fibres and citrus fibre on putative risk factors for colorectal cancer: a randomised, double-blind, crossover human intervention trial”
Authors: A. Fechner, K. Fenske, G. Jahreis