GI gets a call-up

Thread view:

Enable EMail Alerts

Start New Thread

Thread rating:

diarmidlogan@gmail.com - 24 Mar 2006 23:41 GMT

http://smh.com.au/news/nutrition/gi-gets-a-callup/2006/03/22/1142703438642.html

By Steve Dow

Want to lose weight? Controversial research to be unveiled this week
suggests your bad cholesterol levels could rise if you plump for a
high-protein diet but ignore low-glycaemic index ("GI") foods.

Experts agree that either a diet high in carbohydrate but low in GI, or
a diet high in protein, will help you shed kilograms. Low-GI foods are
those that the body slowly digests and absorbs, such as muesli, pasta
and green salad.

But the authors of a new Sydney University study to be presented at the
National Heart Foundation conference at the weekend suggest the low-GI
approach is crucial for controlling your LDL, or "bad", cholesterol.

The study, headed by PhD student Joanna McMillan-Price, examined 129
men and women aged 18 to 35. They were split into four groups and put
on a diet of varying glycaemic load for 12 weeks. All four diet groups
lost body fat. But the group placed on a high-protein diet with reduced
carbohydrates scored an average LDL cholesterol level 10 per cent
higher than the other groups. Another diet group given just as much red
meat - but combined with significant servings of low-GI carbohydrates -
recorded falls in LDL cholesterol.

Jennie Brand-Miller, a Sydney University professor of human nutrition
and the study co-author, says if you choose low-GI carbs "you can be
protected from any effects of red meat".

High-GI diets, which include processed breads and potatoes, were
associated with high cholesterol, according to the study findings, says
Brand-Miller.

The red meat itself was statistically "not the cause" of the high
cholesterol in this study, although Brand-Miller says the "potential"
for red meat to increase cholesterol is "definitely there" on a
high-protein diet.

The Meat and Livestock Corporation helped fund the study.

The message, says Brand-Miller, is that "if you ignore the GI in your
carbohydrates, then you might see adverse changes in your blood lipids
[fats]".

"Lowering glycaemic load by reducing the GI of carbohydrates is the
most effective mechanism of promoting body fat loss, as well as
improvements in cholesterol level," she says. "Reducing glycaemic load
by increasing protein may also be effective, but it's doubly important
to choose low-glycaemic carbohydrates."

For most people, particularly women, a low glycaemic load "might be
safer to achieve with a high-carbohydrate diet than a high-protein
diet". The group that achieved the best body fat loss and cholesterol
fall was on a high carbohydrate, low-GI diet (see breakout).

The University of Sydney has a big interest in low-GI diets. Experts
including Brand-Miller have authored books such as The New Glucose
Revolution and The Low GI Diet, with sales of more than 2 million.

In Adelaide, the CSIRO has questioned Sydney University's findings as
"out of step". Manny Noakes, an associate professor in CSIRO's human
nutrition department, says she has not seen the full study, but has
heard Brand-Miller present the early stages.

"The comments about high-protein diets are not supported by many other
studies," she says. "Both our own studies and many others show that LDL
cholesterol goes down with these diets."

Noakes is co-author of The CSIRO Total Wellbeing Diet book, which
emphasises more protein from red meat and fish but also includes
wholegrains, vegetables, fruit and milk.

"All of the studies that have been published on moderately high protein
diets that are not like the [highest protein] Atkins diet, all of them
have shown a reduction in LDL, and that's pretty obviously because they
were lean protein foods," says Noakes. "Unless you're on something like
the Atkins diet, in which case there's no change [in LDL].

"And there wasn't necessarily any attention given to GI in those
studies, mostly because the amount of carbohydrate is relatively low
anyway."

Noakes says there are additional benefits of higher protein diets for
weight loss, such as improved levels of iron, zinc and vitamin B12.

http://www.theaustralian.news.com.au/common/story_page/0,5744,18588951%255E23289
,00.html

http://www.commonvoice.com/article.asp?colid=4459