Whops!!
My appologizes Nicky.

Randy

Also an excellent point. The body takes time to settle down
and eventually the gut bacteria would have produced a new
environment - probably quite different to that during the
transition period.

Here is the actual study abstract:
http://aem.asm.org/cgi/content/abstract/73/4/1073

Note the period of the study:

"In this study, 19 healthy, obese (body mass index range, 30
to 42) volunteers were given in succession three different
diets: maintenance (M) for 3 days (399 g carbohydrate/day)
and then high protein/medium (164 g/day) carbohydrate (HPMC)
and high protein/low (24 g/day) carbohydrate (HPLC) each for
4 weeks. Stool samples were collected at the end of each
dietary regimen."

Only 4 weeks. My immediate reaction is to wonder what the
results would be after 12 months. Or longer.

As a side issue, there have been a few shows recently with
titles like "The Worst Jobs in History" and "World's Worst
Jobs".

The lab assistants who collected and examined the samples
for this study would surely qualify.

Cheers, Alan, T2, Australia.
d&e, metformin 1500mg, ezetrol 10mg
Everything in Moderation - Except Laughter.
--
http://loraldiabetes.blogspot.com
Latest: The Quality of ADA Dietary Advice

Adam Wrote:

How was this "almost no dietary trial. Find the abstract below.

Don't understand what you mean. Fiber is one of the carbohydrates
involved in feeding gut bacteria, the others are, resistant starch,
plant structural polysaccharides and mucin.

References:

Reduced dietary intake of carbohydrates by obese subjects results in
decreased concentrations of butyrate and butyrate-producing bacteria
in feces.Duncan SH, Belenguer A, Holtrop G, Johnstone AM, Flint HJ,
Lobley GE.
Microbial Ecology Group, Rowett Research Institute, Greenburn Road,
Bucksburn, Aberdeen AB21 9SB, UK.

Weight loss diets for humans that are based on a high intake of
protein but low intake of fermentable carbohydrate may alter microbial
activity and bacterial populations in the large intestine and thus
impact on gut health. In this study, 19 healthy, obese (body mass
index range, 30 to 42) volunteers were given in succession three
different diets: maintenance (M) for 3 days (399 g carbohydrate/day)
and then high protein/medium (164 g/day) carbohydrate (HPMC) and high
protein/low (24 g/day) carbohydrate (HPLC) each for 4 weeks. Stool
samples were collected at the end of each dietary regimen. Total fecal
short-chain fatty acids were 114 mM, 74 mM, and 56 mM (P < 0.001) for
M, HPMC, and HPLC diets, respectively, and there was a
disproportionate reduction in fecal butyrate (18 mM, 9 mM, and 4 mM,
respectively; P < 0.001) with decreasing carbohydrate. Major groups of
fecal bacteria were monitored using nine 16S rRNA-targeted
fluorescence in situ hybridization probes, relative to counts obtained
with the broad probe Eub338. No significant change was seen in the
relative counts of the bacteroides (Bac303) (mean, 29.6%) or the
clostridial cluster XIVa (Erec482, 23.3%), cluster IX (Prop853, 9.3%),
or cluster IV (Fprau645, 11.6%; Rbro730 plus Rfla729, 9.3%) groups. In
contrast, the Roseburia spp. and Eubacterium rectale subgroup of
cluster XIVa (11%, 8%, and 3% for M, HPMC, and HPLC, respectively; P <
0.001) and bifidobacteria (4%, 2.1%, and 1.9%, respectively; P =
0.026) decreased as carbohydrate intake decreased. The abundance of
butyrate-producing bacteria related to Roseburia spp. and E. rectale
correlated well with the decline in fecal butyrate.

PMID: 17189447 [PubMed - indexed for MEDLINE]

Understanding the effects of diet on bacterial metabolism in the large
intestine.
PMID: 17448155

Two routes of metabolic cross-feeding between Bifidobacterium
adolescentis and butyrate-producing anaerobes from the human gut.
the other due to cross-feeding of partial breakdown products from
complex substrates.
PMID: 16672507

Randy

Found the full study PDF if you're interested:
http://aem.asm.org/cgi/reprint/73/4/1073

"Experimental dietary regimen. The volunteers were weight
stable (less than 2-kg change in recent months) on entry to
the trial and were then offered an energy maintenance (M)
diet (based on 1.6 resting metabolic rate) for 3 days.
This diet comprised 13% protein, 52% carbohydrate, and 35%
fat as calories.

Subjects were then offered ad libitum two diets, which were
either a high-protein, low-carbohydrate (HPLC; 30% protein,
4% carbohydrate, 66% fat as calories) diet or a
high-protein, moderate-carbohydrate (HPMC; 30% protein, 35%
carbohydrate, 35% fat) diet,

[My comment: that's not far from the LoBAg 30 of Gannon and
Nuttall
http://ajpendo.physiology.org/cgi/content/abstract/291/4/E786]

each supplied for 4 weeks in a randomized crossover design.
Between the two main diet periods and at the end of the
study the subjects were given the maintenance diet for 3
days. All meals were of the same
energy density (5.5 MJ/kg), and daily intakes were recorded
by weight. Daily macronutrient intakes were calculated using
the Windiet software program (Robert Gordon University,
Aberdeen, United Kingdom), based on the type and quantity of
each ingredient consumed and published food composition
tables (24). Diet intake was analyzed (Johnstone et al.,
submitted) for maintenance, HPMC, and HPLC diets (Table 1)."

"TABLE 1. Dietary intake (g/day) indicating mean values for
7 days preceding fecal sample (3 days for maintenance diet)

Diet         Fat  Protein   Carb    NS   Starch
Maintenance 122.9   94.3   398.8   27.9   187.3
HPMC         74.3  127.2   163.6   11.7    95.3
HPLC        126.0  119.5    23.9    6.1     2.7"

[Note:
HPMC = high-protein, moderate-carbohydrate
HPLC = high-protein, low-carbohydrate
NS = Nonstarch polysaccharides]

By my standards HPLC was both extreme low-carb and extreme
high-fat.

The crossover method also has problems for me when used in a
dietary trial. Three days is hardly long enough to get rid
of residual effects from the previous month and there is
also the effect of shocking the body twice.

In searching the pdf the only time the word fibre or fiber
appears is in the references (45, 49).

One wonders whether the correct title should have been a
"Reduced Dietary Intake of Dietary Fibre by Obese Subjects
Results in Decreased Concentrations of Butyrate and
Butyrate-Producing Bacteria in Feces".

As a digression, I could not find any reference to the
subjects weight differences between start and finish or A1c
variations.

With all the expenses involved in a trial like this, how
much extra would it have cost to put them on the scales or
take blood samples to look at glucose and lipid changes and
similar factors? Or did they, intending to maximise their
grant funding with separate papers on those subjects?

Finally, I think they summed up well in their final
paragraph:

"The present study was of limited duration, and it is
unknown whether the relatively short period of reduced
butyrate and SCFA supply to the colonic mucosa would have
long-term consequences for gut health. Such considerations
may become important if low-carbohydrate diets are consumed
for longer periods without ensuring that adequate forms of
appropriate fermentable substrates comprise part of the
diet."

Words like "limited" and "unknown" and "may" suggest to me
that the only conclusion that can be reached is that further
study over a longer term with a better-designed trial is
warranted.

Cheers, Alan, T2, Australia.
d&e, metformin 1500mg, ezetrol 10mg
Everything in Moderation - Except Laughter.
--
http://loraldiabetes.blogspot.com
Latest: The Quality of ADA Dietary Advice