Eight for apples, 46 for muffins


What does food do – time to move beyond the glycaemic index

It’s time to get smarter about food labelling according to Dr John Monro, speaking at the international chemistry conference in Melbourne this week.

“We need to know not just what is in the food, but what the food is going to do in our bodies,” he says. John is a researcher with the New Zealand Institute for Plant and Food Research.

“And we need easy to follow guides that make sense when we’re pushing our trolleys around the supermarket.”

He is proposing a new food value that acts like a nutrient value – the glycaemic glucose equivalent. In effect it tells you how much glucose consumed would have the same impact on blood sugar as an amount of food , such as a serving. Blood sugar is one of the keys to metabolism and control of diabetes.

He says the glycaemic index – which compares only the carbohydrates in foods – used well is a good tool. But it doesn’t go far enough and it’s poorly understood by consumers. For one thing, people eat foods, not just the carbohydrates in them, and also, the glycaemic index is accurate only when you compare equal amounts of carbohydrates in food, which is difficult to do in the supermarket where almost all foods differ in carbohydrate content. Another important difference is that the glycaemic index does not change with increasing food intake, whereas the glycaemic glucose equivalent depends on how much food is consumed.

His index is much simpler. A typical apple would score a 8 because it has the same impact on blood sugar as eight grams of glucose and two apples would score 16. A typical muffin would score 46 because it has the same effect as 46 grams of glucose.

The “glycaemic impact” which is the glucose equivalents score for a quantity of food, has the support of the American Association of Cereal Chemists and meets the expectations of the US FDA who are looking for whole food measurements that apply to amounts of food that people usually consume.

The work has just been published in the Journal of Nutrition: Monro JA, Mishra S  Glycaemic impact as a property of foods is accurately measured by an available carbohydrate method that mimics the glycaemic response. Journal of Nutrition 140, 1328-1334, (2010) (Issue 7, July)


From chemical analysis to practical nutrition: Bridging the gap

J. A. Monro

New Zealand Institute for Plant and Food Research, Palmerston North, New Zealand

Chemical analysis of the composition of foods has been important in providing nutrient information for food labels, and food labels have been used to guide food choices. However, food labels say what a food is, whereas consumers are interested primarily in what a food does, because that determines its impact on health.

Determining what a food does, and communicating its efficacy to consumers in a useful way requires a different approach than in simple food analysis and labelling. Sample preparation, analyte extraction, food properties and allowances for the body’s reaction to a food when taken in amounts customarily consumed per eating occasion may need to be accounted for.

The principles involved are illustrated with respect to two body reactions to foods of interest to consumers – bowel regularity and blood glucose response – that have long been incorrectly inferred from dietary fibre and available carbohydrate values, respectively, in food labels.