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Vegetable cellulose partly broken down in men

Effect of fiber from fruits and vegetables on metabolic responses of human subjects: fiber intakes, fecal excretions, and apparent digestibilities.

Overview

Kelsay JL et al.. Am J Clin Nutr 1981 · PMID 6269418 · DOI 10.1093/ajcn/34.9.1849

In 12 men eating fruits and vegetables, 42% of cellulose and 88% of hemicellulose were broken down in the gut.

Does the study support the specific claim? No · Methodological quality: moderate

Study explained simply

What did the researchers want to find out?: Measure fibre fractions' digestibility.
How was the study done?: Controlled feeding.
How many people, animals or samples were studied?: 12 men.
What was actually found?: Cellulose 42%, hemicellulose 88%.
How large was the observed effect?: See results.
What do the results mean in everyday life?: Gut microbes use a large part of vegetable fibre.
What are the study's limitations?: Small; old methods.
What does it say about Elawady's specific claim?: Contradicts the claim.
Do the results apply to Germany and Europe?: Applicable.
What can explicitly not be concluded from this study?: Cannot measure health effects.

What are the apparent digestibilities of fibre fractions from fruits and vegetables in humans?

Study design: Other – Controlled feeding study (fruit/vegetable diet vs juice diet, 26 days each)
Population: 12 men
Country: USA
Period: not stated in abstract
Sample size: 12
Inclusion and exclusion criteria: not stated in abstract

Exposure / intervention: High-fibre diet with fruits and vegetables
Comparator: Low-fibre diet with fruit and vegetable juices
Endpoints: Apparent digestibility of hemicellulose, cellulose, lignin; faecal output
Statistical methods: Linear regression

Results: High-fibre diet apparent digestibility: hemicellulose 88%, cellulose 42%, lignin 18%; low-fibre (juice) diet fibre mostly hemicellulose, 95% digestible; fibre intake rather than disappearance influenced faecal volume.
Absolute risks: not reported
Authors' conclusion: Fibre intakes rather than fibre disappearance influenced faecal volume.

Cellulose 42% digested (stats/C-VEG-01_cellulose.py).

Direct evidence that cellulose from whole vegetables is partly fermented in humans.

none

Industrialised adults.

Replicates Slavin 1981.

Multidimensional assessment
Multidimensional assessment
Authenticity of the source	verified
Methodological quality	moderate
Risk of bias	some concerns
Precision of results	low
Directness	direct
Reproducibility	replicated
Consistency with the overall evidence	consistent
Regional transferability	high
Adequacy of the interpretation (by the archive)	not applicable

none