Prebiotic in Wheat Bran Boosts and Feeds Gut Bifidobacteria
Research from European and American scientists are confirming that wheat bran contains a special prebiotic fiber called arabinoxylan oligosaccharides which boost bifidobacteria content within the gut, and helps relieve numerous gastrointestinal issues.
In the most recent study â€“ a double-blind study published in the Journal Nutrition â€“ researchers gave 55 healthy men and women 2.2 grams or 4.8 grams of arabinoxylan oligosaccharides or no arabinoxylan oligosaccharides within cereal every day for three weeks.
The researchers tested the subjectsâ€™ levels of bifidobacteria using laboratory analysis of stool samples. This is a standard means of establishing levels of probiotics within the gut â€“ and it allows researchers to track the growth or lack of growth of probiotic colonies.
The researchers measured stool samples throughout the study, and they also measured the subjectsâ€™ serum ferulic acid concentrations as well as other metabolic factors.
The researchers found that bifidobacteria colonization was significantly higher in the subjects who consumed the arabinoxylan oligosaccharide-rich cereals. Furthermore, this improvement was found to be dose-dependent, which means the higher-dose of 4.8 grams per day produced more bifidobacteria colonies than the 2.2 grams per day dose produced. And both of these produced more probiotics than the no arabino-xylan-oligosaccharide cereal produced.
A dose-dependent result is the gold standard in clinical research as it establishes not only effect, but direct effect.
The arabinoxylan oligosaccharide-rich cereals also produced higher levels of antioxidant ferulic acid within the bloodstream.
The researchers concluded:
â€œThese results indicate that arabinoxylan oligosaccharide has prebiotic properties, selectively increasing fecal bifidobacteria, and increases postprandial ferulic acid concentrations in a dose-dependent manner in healthy men and women.â€
Not the first study to find prebiotics in wheat bran
This isnâ€™t the first study that has found this effect. In fact several clinical studies have found this over the past few years.
A study from Catholic University of Leuven researchers gave wheat bran extract containing arabinoxylan oligosaccharide to 63 health adults. They consumed three grams, ten grams or zero grams of the wheat extract for three week periods in succession with two-week washout periods in between.
Before and after each three-week session, the subjects were tested with stool sampling, as well as urine samples for p-cresol content. When levels of p-cresol are higher they indicate greater pathogenic bacteria in the gut and fewer probiotics.
The subjects also completed questionnaires to rate 18 digestive symptoms.
The researchers found that consuming the greater amounts of the wheat extract significantly increased bifidobacteria counts. The 10 grams per day consumption produced the highest probiotic counts â€“ again creating a dose-dependent result.
In addition, consuming greater amounts of the wheat extract significantly decreased levels of urinary p-cresol, while increasing short chain fatty acids â€“ which have been shown to be linked with colon cancer prevention. The wheat extract also reduced pH, which is connected with greater probiotic fermentation in the gut.
The researchers concluded:
â€œWheat bran extract is well tolerated at doses up to 10 g/d in healthy adult volunteers. Intake of 10 grams wheat bran extract per day exerts beneficial effects on gut health parameters.â€
Another study â€“ this from the University of Groningen and the Leuven Food Science and Nutrition Research Center – tested 29 healthy children for three weeks in a placebo-controlled crossover clinical study.
This study gave five grams of a similar wheat bran extract or placebo for three weeks. This study found that the wheat bran extract increased the probiotic bacteria in the gut of the children and also reduced gastrointestinal issues such as flatulence, cramping and abdominal pain among the children consuming the wheat bran extract.
The wheat bran extract group also had lower levels of isobutyric acid and isovaleric acid. Like p-cresol, these are bacteria byproducts seen in greater amounts in dysbiosis. The researchers concluded:
â€œWheat bran extract is well tolerated at doses up 5â€Šg/day in healthy children. In addition, intake of 5â€Šgrams per day exerts beneficial effects on gut parameters, in particular increase of faecal bifidobacteria levels relative to total faecal microbiota, and reduction of colonic protein fermentation.â€
Other studies have confirmed similar results. A 2012 study from the University of Reading gave 30 healthy adults subjects breads enriched with arabinoxylan oligosaccharides or placebo. The researchers found that levels of both bifidobacteria and lactobacilli (healthy intestinal probiotics) were significantly increased in the subjects given the breads enriched with arabinoxylans (added wheat bran).
Another 2012 study of 27 healthy adults utilized wheat bread with or without arabinoxylan oligosaccharide from the bran. The subjects given the arabinoxylan had significantly higher levels of bifidobacteria. They all had greater intestinal probiotic levels.
A 2010 study by researchers from the University Hospital Gasthuisberg in Belgium gave wheat fiber rich in arabinoxylan oligosaccharide or placebo to 20 healthy adults. The subjects given the arabinoxylan had significantly higher levels of bifidobacteria.
All of these studies utilized double-blind placebo-controlled protocols, all were published in peer-reviewed medical journals – such as the British Journal of Nutrition and the Journal Nutrition – and each study resulted in the same finding: Consuming wheat products with arabinoxylan oligosaccharides increased bifidobacteria colonies amongst the subjects and decreased gastrointestinal issues. For example, in the second study the researchers stated:
â€œIn conclusion, consumption of breads with in situ-produced arabinoxylan oligosaccharide may favorably modulate intestinal fermentation and overall gastrointestinal properties in healthy humans.â€
As for the use of in situ from this conclusion, this means that the arabinoxylan oligosaccharide is being produced naturally by the wheat plant. It is a natural part of the wheat bran.
And it is for this very reason (and a few others) that consuming whole wheat products is healthier than those where the bran has been separated during the flour making process â€“ ala white bread.
What about gluten and probiotics?
This probiotic issue is also an important aspect related to some of the negative health issues related to gluten consumption. When our probiotic colonies are low, our ability to break down the various components of not only the bran but the gluten (discussed in depth here).
Gluten and gliadin proteins are contained in the germ, endosperm and bran of wheat. As shown in the research, when our probiotic colonies are reduced, our gutâ€™s ability to consume/degrade these complex molecules is diminished.
When this lack of probiotics is combined with increased intestinal permeability â€“ also called leaky gut syndrome â€“ we have another progression: Glutenin and gliadin sensitivities that result from these large protein complexes getting access to the blood stream before they can be broken down in the gut.
This aspect of food sensitivities occurs with a number of other food proteins as well â€“ not just glutenins and gliadins. Food sensitivities to certain nuts, fruits, beans and other foods are also linked to large proteins not being broken down properly in the gut and marked by immunoglobulins as allergens.
And this doesnâ€™t include the various other negative effects of these large proteins getting through our intestinal barriers and affecting metabolism elsewhere in the body.
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