Re: Guar vs. Psyllium (and Meta Analysis of Guar)

[Guest guest]

From Jeff Novick Sent: Thursday, June 17, 2004 6:35 AM

> Interesting PDF monograph on psyllium and its benefits.

> I use it as a handout.

>

> http://www.thorne.com/pdf/journal/7-2/psyllium_monograph.pdf

>

Psyllium is 35% soluble fiber, 65% insoluble fiber. Because psyllium

is 2/3 insoluble (non-absorbed indigestible hemicellulose) fiber,

it *speeds up* bowel transit time.

Guar gum is 100% soluble fiber, and *delays* intestinal transit time,

which means a longer time between meals and theoretically improved

satiety with guar.

A healthy diet does require both kinds of fiber (soluble, insoluble).

Both are beneficial.

---------------

I have done a cursory examination of a meta-analysis research

paper that Dowling kindly obtained for us. That meta study

showed *lack* of effectiveness of guar for losing weight.

Here is why the paper reported *lack* of effect:

** All studies used in the pooled meta analysis (except 4 of them)

were for durations less than 12 weeks time. Some of them were

for only 2 weeks on guar. That helps account for the

reported lack of effect for weight loss.

** Some of the studies had a very low number of participants

(less than 10), resulting in absence of statistical significance.

** The studies were done for blood sugar control, not for weight

loss, so weight was not carefully monitored, but taken as a

secondary measurement.

** Of those 4 studies lasting longer than 12 weeks, 2 of them

showed weight loss averages of 4 to 6 Lbs.

** The final meta study results were " variance weighted " .

Because of this fact, one study with only 9 participants

and of very short duration (only 2 weeks on guar)

received a high statistical weight of 56 percent --

while all the remaining studies pooled together were given

a total combined weight of only 44 percent altogether.

When one short meaningless study with few participants dominates

the statistics to account for 56% of all results, and the other

studies are mostly of short meaningless duration too, a final

report of " no effect " is easy to understand.

-- Warren