From: Kofi on
Might be mediated via AMPK.

Br J Nutr. 2010 Jan;103(1):82-90. Epub 2009 Aug 7.
Adaptation of colonic fermentation and glucagon-like peptide-1 secretion
with increased wheat fibre intake for 1 year in hyperinsulinaemic human
subjects.
Freeland KR, Wilson C, Wolever TM.
Department of Nutritional Sciences, University of Toronto, Toronto,
Ontario, Canada.

High cereal fibre intake is associated with reduced risk for type 2
diabetes, but wheat fibre had little or no effect on glycaemic control
or oral glucose tolerance in clinical trials lasting 4-12 weeks. To
explain this discrepancy, we hypothesised that colonic adaptation to
increased wheat fibre intake takes many months but eventually results in
increased SCFA production and glucagon-like peptide-1 (GLP-1) secretion.
Thus, the primary objective was to determine the time-course of the
effects of increased wheat fibre intake on plasma acetate, butyrate and
GLP-1 concentrations in hyperinsulinaemic human subjects over 1 year.
Subjects with fasting plasma insulin >or= 40 pmol/l were randomly
assigned by computer to receive either a high-wheat fibre cereal (fibre
group; 24 g fibre/d; twenty assigned; six dropped out, fourteen
included) or a low-fibre cereal (control group; twenty assigned; six
dropped-out, fourteen included) daily for 1 year. Acetate, butyrate and
GLP-1 were measured during 8 h metabolic profiles performed every 3
months. There were no differences in body weight in the fibre group
compared with the control group. After 9 months baseline-adjusted mean 8
h acetate and butyrate concentrations were higher on the high-fibre than
the control cereal (P < 0.05). After 12 months on the high-fibre cereal,
baseline-adjusted mean plasma GLP-1 was 1.3 (95 % CI 0.4, 2.2) pmol/l (P
< 0.05) higher than at baseline (about 25 % increase) and 1.4 (95 % CI
0.1, 2.7) pmol/l (P < 0.05) higher than after 12 months on control. It
is concluded that wheat fibre increased SCFA production and GLP-1
secretion in hyperinsulinaemic humans, but these effects took 9-12
months to develop. Since GLP-1 may increase insulin sensitivity and
secretion, these results may provide a mechanism for the epidemiological
association between high cereal fibre intake and reduced risk for
diabetes.

PMID: 19664300 [PubMed - indexed for MEDLINE]
From: Tim on
Check backposts by Thomas Carter He brings up whole grains I think as
a source of butyrate in the gut.