GI Q&A with Prof Jennie Brand-Miller
‘I’ve read that dairy products cause an increase in insulin secretion. Their GI is around 25–50 but their insulin index is three times higher. Is this a problem? ’
All protein foods (yes that includes meat, fish and eggs) stimulate insulin secretion – that's why you may see them described as being ‘insulinogenic’ to use the technical term. However, the proteins in milk may be more insulinogenic than in other protein foods because they are meant to help baby mammals grow and develop.
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. It is thought that milk may contain a unique combination of amino acids that together are more insulin stimulating than alone. There is no evidence that this either increases your risk of weight gain or lifestyle-related diseases like type 2 diabetes.
The disparity between glucose and insulin response is not unique to dairy foods. We have found that certain sweets and baked products also do this. Chocolate may also contain amino acids that stimulate insulin secretion.
‘I read a paper in Medical Hypotheses by Bodo C. Melnik about the need to avoid dairy foods. It basically said that milk protein consumption is a key factor in promoting most chronic diseases of Western societies. What's your view?’
This viewpoint is not new and I know quite a few people who support it. While all the theory makes sense, it doesn’t stack up in epidemiological studies (which are ‘natural’ experiments). In fact, in Western countries, dairy consumption is often associated with better insulin sensitivity, lower weight gain and lower cardiovascular disease risk (and one mechanism maybe the low GI of most dairy products).
To me, a whole race of people (Caucasians) have a genome that is shaped by milk drinking during our evolutionary past and we have high levels of lactase throughout life because it was such a useful food source. So I find it hard to accept that it’s harmful to Caucasians, even in adulthood. Perhaps, the rest of the human race are not so lucky. But even then, I think of milk as the secretion of the mammary gland designed for growth of a newborn mammal – how could it be both safe at that time and then harmful later? I think we should keep an open mind on this one.
GI testing by an accredited laboratory
Dr Alexandra Jenkins
Glycemic Index Laboratories
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Toronto, Ontario M5C 2X3 Canada
Phone +1 416 861 0506
Research Manager, Sydney University Glycemic Index Research Service (SUGiRS)
Human Nutrition Unit, School of Molecular and Microbial Biosciences
NSW 2006 Australia
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