health guides

As for following a low-glycaemic-load diet, the American Diabetes Association’s recommendations emphasise high-fibre and low-glycaemic-load carbohydrates based on the current evidence.

Carbohydrates and glycaemic load

Carbohydrates are classified as either simple or complex based on the length of the carbohydrate chains that compose them, but better measures of carbohydrate quality have been developed:

• The glycaemic index tells us how a food affects blood sugar levels in comparison to a similar amount of a glucose drink, table sugar, or white bread.
• Glycaemic load takes into account both the effect of a food on blood sugar levels and the amount of carbohydrates in a typical serving. For example, the carbohydrates in a carrot have a strong effect on blood glucose levels, so it has a high glycaemic index; however, a carrot is mostly water, so its carbohydrate content in a typical serving is small. Therefore, its glycaemic load is low.

Estimating daily glycaemic load

The meta-analysis looked at data from 24 studies to find a relationship between daily glycaemic load and diabetes risk:

• The people in the studies reported their daily food intake on questionnaires.
• Glycaemic load values were assigned for each food.
• The glycaemic loads of the foods eaten in an average day were added to determine an initial daily glycaemic load.
• Because some people eat a lot and others eat less, each person’s initial daily glycaemic load was adjusted to reflect the daily glycaemic load for a person with the same diet eating 2,000 calories per day.

Low-glycaemic-load diet can prevent diabetes

The researchers found that eating a low-glycaemic-load diet was protective against diabetes. Their analysis showed:

• The range of daily glycaemic loads across the studies was approximately 60 to 280 grams.

• For every 100-gram decrease in daily glycaemic load, diabetes risk dropped by 45%.

• The protective effect of a low daily glycaemic load was stronger in women.

• European Americans seemed to benefit more from a low-glycaemic-load diet than people of other ethnicities.

“Altogether, our meta-analysis supports that glycaemic load is an important and underestimated dietary characteristic that, among others, contributes significantly to the incidence of type 2 diabetes,” the study’s authors said.

Reduce your daily glycaemic load

Here are some general ways to decrease your daily glycaemic load:

• Choose whole and colourful fruits and vegetables. Many fruits and vegetables have low glycaemic values. Fibre and complex carbohydrates contribute to their low glycaemic effects. The glycaemic load of some fruits and vegetables is further decreased by their high water and low carbohydrate content, while some starchy fruits and vegetables like bananas and russet potatoes have relatively higher glycaemic loads. Try berries, citrus fruits, greens, brassicas, squashes, and tomatoes.
• Use whole grains. Choose brown rice over white rice and whole or steel cut oats over instant rolled oats. Cooling carbohydrate foods like potatoes, rice, and pasta after cooking them increases their content of resistant starch (indigestible carbohydrates) and lowers their glycaemic loads, so consider having these foods in salads or other unheated dishes. Breads made with whole grains and sourdough fermentation are a better choice than white yeasted breads.
• Snack on nuts. Nuts and seeds have very low glycaemic loads. Keep nut portions to 1 ounce.

(Am J Clin Nutr 2013;97:584–96)