GI studies inconclusive, says Grain Foods Foundation

Related tags Nutrition Glycemic index Carbohydrate

A campaign designed to combat the glycaemic index momentum is being
launched in the US by the Grain Foods Foundation and public
relations firm Mullen, reports Lorraine Heller.

Members of the foundation's clinical advisory board claim the studies that support the use of the glycaemic index (GI) diet as a preventative measure against weight gain and certain diseases are insubstantial and inconsistent.

The move comes as increased media, consumer and retail interest in the regime, which promotes foods with a slow release of sugar, are fast making it the next nutritional trend, after the fall of the low-carb diet.

"The utility of the glycaemic index and glycaemic load (GL) with regard to health and weight control is overstated and not backed by a fair amount of published research,"​ said Dr Glenn Gaesser, co-chair of the Grain Food Foundation's clinical advisory board.

"Those who promote GI are just looking at selective studies and stating a hypothesis,"​ he added.

"Most of the studies that support the glycaemic index are extracted from large, nation-wide healthcare data sets. So in reality, there are few new GI studies being published. And careful examination of these studies shows that many of the conclusions being reported by the media are simply not supported by the studies themselves."

It is precisely this inconclusive data which prevents major American health organizations from endorsing the use of GI as a dietary tool, claims Dr Gaesser.

The American Diabetes Association, the American Dietetic Association and the National Academy of Science are amongst organizations that do not recognize the regime.

Diabetes UK recognizes a low-GI diet as providing certain benefits for diabetes sufferers, though it does not officially endorse the regime.

While there have been studies revealing how the glycaemic load, which refers to blood sugar levels derived from portion sizes, has not been associated with an increased diabetes risk, the glycaemic index has generally been confirmed to reduce the risk.

However, one study conducted on 116,671 women and published in the American Journal of Clinical Nutrition revealed how the higher diabetes risk associated with high GI was entirely eliminated by higher cereal fibre intake (at least 4.4g a day).

"No one knows how this works exactly. As with all epidemiological research, there are no control groups, just the science of obsevation and association. What it does show us, though, is that it might make more sense to encourage high fibre diets than low Gi diets,"​ Dr Gaesser told

"There has been much more consistent data published on fibre-rich food than on GI,"​ he added.

Further research in the American Journal of Clinical Nutrition and Cancer Epidemiology, Biomarkers & Prevention reveals how body weight decreased with a higher GL, suggesting that carbohydrate and grain consumption could in fact be more beneficial for weight loss than low GI foods.

"People in general like carbohydrates and grain foods, they always have and they always will,"​ said Dr Gaesser.

"With the GI craze we have a case of the tail wagging the dog- everyone is following along for fear of losing market share."

"The glycaemic index is likely to have similar short-term effects on the food industry as low-carb. But the impact won't be long term. In terms of weight control, Americans want a quick-fix, and these diets just don't provide that. Americans are just as fat now as they were ten years ago, before low-carb, and they'll be just as fat in ten years after GI. People will realize it's just a fad, they won't see results in their waist lines, they'll get through it and GI will be a thing of the past."

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