Fiber-rich vegetarian diet leads to better gut microflora profile
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Consuming a vegan or vegetarian diet results in different profiles of gut microflora, with lower
levels of potentially pathogenic bacteria such as E. coli, says a new study.
By studying fecal samples from 144 vegetarians and 105 vegans, researchers from the University Hospital in
Tubingen, Germany report that the fiber and carbohydrate content of the diets led to a lower pH in stools, and
such acidic conditions do not support the growth of bacteria like E. coli and Enterobacteriacea.
³The degradation of dietary fibers by exoenzymes mainly leads to greater amount of short-chain fatty acids such
as acetate, propionate and butyrate that create a slightly acidic milieu with values between pH 5.5 and 6.5,´
explained researchers led by
³This effect may have been amplified by germs that grow because of the large amount of fibers. These pH
ranges do not support bacteria such as E. coli and Enterobacteriacea in their growth as they prefer pH ranges
greater than 6.5.´
Gut microbial profiles are increasingly of interest as we begin to understand how gut microbial profiles are linked
to specific conditions. Indeed, other scientists have already reported that microbial populations in the gut are
different between obese and lean people , and that when the obese people lost weight their microflora reverted
back to that observed in a lean person, suggesting that obesity may have a microbial component.
Also, late in 2011 Dr Jeffrey Gordon and his team at the Washington University in St Louis reported that probiotic
bacteria consumed in yogurt may influence carbohydrate metabolism .
More benefits for women?
Writing in the European Journal of Clinical Nutrition , the researchers note that their most relevant finding is the
differential effects of the vegan diet on the pH of the stool: Studies have shown that the pH of stools in
omnivorous women is higher than in men, despite both genders consuming similar amounts of fiber.
However, when men and women adhere to a strict vegan diet rich in fibers for a long time both then differences
in stool pH are no longer observed.
³This indicates that females profit more from maintaining a strict vegan diet than do men,´ wrote the
researchers.
No surprises
Commenting independently on the study¶s findings, Professor Glenn Gibson from the University of Reading in the
UK said that the data only tells ³part of the story´ because of the cultural (conventional) microbiology approach
employed by the researchers.
As such, the non-culturable diversity will be missed, he said. ³Also, it is difficult to be absolutely confident of
colony identities on the plates. They used API which is a biochemical procedure, but gene sequencing is
preferable.
³Having said that, you would expect the flora a vegetarians/vegans to differ from meat eaters: Meat eaters
consume more protein and this leads to less desirable metabolites.
³A high carbohydrate diet (non absorbable CHO, not sugar) should stimulate a more +ve microbiota – e.g.
bifidobacteria and lactobacilli,´ added Prof Gibson.
Stud\ details
The study¶s findings were based on data from vegetarians and vegans and compared with people consuming an
³ordinary omnivorous diet´.1/29/12 Fiber-rich vegetarian diet leads to better gut microflora profile: Stud\
www.nutraingredients-usa.com/content/view/print/601682 2/2
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and Clostridium Vpp.
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“Higher consumption of animal protein is one possible explanation for higher stool pH values in subjects on an
omnivorous diet, as proteolytic putrefactive bacteria are able to increase stool pH by producing alkaline
metabolites,” e[plained Whe VcienWiVWV.
“This speculation is strengthened upon closer examination of the mean pH values. The vegetarians¶ mean pH
value of 6.6 is between that of vegans and of omnivores (6.3 and 6.9, respectively).”
SoXUce: European Journal of Clinical Nutrition
2012, Vol. 66, PageV 53-60; doi:10.1038/ejcn.2011.141
“A vegan or vegetarian diet substantially alters the human colonic faecal microbiota”
AXWhoUV: J ZimmeU, B Lange, eW al.