YOGHURT IS A LOW GI FOOD
The Sydney University GI Research
Service (SUGiRS), established in 1995 to provide a reliable commercial
GI testing laboratory, has tested a variety of yoghurts over the past 20
years – plain, flavoured, full fat, and diet. Over the same period of
time, numerous studies in peer-reviewed journals have shown that high
yoghurt intake is associated with a reduced risk of type 2 diabetes.
Although several mechanisms could explain this association, Prof Tom
Wolever recently addressed the glycemic and insulinemic impact of
yoghurt in Nutrition Today.
“There is evidence that low GI and low GL (glycemic
load) diets are associated with a reduced risk of type 2 diabetes. The
93 GI values for yoghurt in the University of Sydney’s GI database have
an average of 34 and most (9 out of 10) of the yoghurts are low GI. The
43 plain yoghurts in the database have a lower GI (average GI = 27) than
the 50 sweetened yoghurts (average GI = 41). This difference is not
explained by sugar, per se, but rather by the higher
protein-to-carbohydrate ratio in plain yoghurt. Although yoghurt has a
low GI, its insulinemic index is higher than its GI. High insulin
responses may be deleterious because hyperinsulinemia is associated with
an increased risk of type 2 diabetes. Nevertheless, this may not be a
concern for yoghurt because, although its insulinemic index is higher
than its GI, the insulinemic index of yoghurt is within the range of
insulinemic index values for non-dairy low-GI foods. In addition, mixed
meals containing dairy protein elicit insulin responses similar to those
elicited by mixed meals of similar composition containing non-dairy
protein. Because the GI of yoghurt is lower than that of most other
carbohydrate foods, exchanging yoghurt for other protein and
carbohydrate sources can reduce the GI and GL of the diet, and is in
line with recommended dietary patterns, which include whole grains,
fruits, vegetables, nuts, legumes, fish, vegetable oils, and yoghurt.”
What’s the Insulinemic Index? Prof Jennie Brand-Miller explained this recently.
“One
of insulin’s many functions is to act as a growth hormone designed to
drive nutrients into cells – not just glucose but also amino acids, the
building blocks of new tissue. When we eat carb-rich foods our blood
glucose levels rise and our pancreas then releases insulin (a hormone)
that drives the glucose out of our bloodstream and into our body’s cells
where our body can use it as an immediate source of energy or store it
as glycogen. What many people don’t realise is that protein foods (meat,
fish, eggs and dairy foods) also stimulate insulin secretion – that’s
why you may see them described as insulinogenic.”
Scientists
at the University of Sydney have been researching the food insulin
index or FII for more than 20 years. “The FII looks at how much insulin
the body normally releases in response to a whole food or meal (its
carbohydrate and the quantity and quality of its protein and fat). Some
foods need more insulin to help utilise them, while other foods need
much less. Choosing foods with a lower FII can help reduce your overall
insulin demand on your pancreas or insulin requirements,” says dietitian
and diabetes educator Dr Kirstie Bell.
