1 November 2006

GI News Briefs

What’s best for baby?
Being born big is not better when it comes to babies. We now know from a number of studies that a baby’s birth weight can set the pattern for life, predicting long-term risk of obesity and chronic disease. A new study published in the American Journal of Clinical Nutrition suggests that the GI of the mother’s diet during pregnancy may be another important key to producing a healthy weight baby who will grow up to be a healthy child and adult. The study compared the effects of two diets on 62 healthy pregnant women. The overall quality of both the diets was good, with food and nutritional intakes in line with recommendations for pregnant women. Lead researcher Dr Robert Moses writes that the babies of the mothers eating the low GI diet were of normal size, but were smaller and had less body fat than the babies of the mothers eating the moderate–high GI ‘high fibre-low sugar’ diet during the pregnancy. Interestingly, the women in the low GI group were more likely to report that they found the diet easy to follow than the women in the high fibre-low sugar group. One of the researchers, Prof Jennie Brand-Miller, told GI News that: ‘I think the most important take home message from the pregnancy study is that the GI appears to have a more important effect on birth weight than any single dietary factor, including amount of protein, fat or amount or carbohydrate.’
AJCN 2006;84:807–12


Eat to beat acne
A diet rich in lean protein and low GI carbs can improve acne by 50 per cent in 12 weeks or less according to researchers from Australia’s RMIT University. These results are similar to that seen in published trials with successful topical therapies. The group presented their findings at the European dermatology conference in Greece in September. The detailed article describing the study methods and results is currently being peer reviewed and will be published in a scientific journal in 2007.

For the 12-week trial, 43 teenage boys with moderate to severe acne were randomly assigned either to a low GL (45% carbohydrate and 25% protein) diet including low GI carbs and lean protein or the control diet including carb staples with a moderate to high GI. Each boy was given an individualised dietary plan along with some training in using food scales and keeping food records. Low level acne skin wash was standardised for all the boys and their acne was assessed every four weeks by an expert dermatologist who did not know the dietary group of the subjects. According to lead researcher Dr Neil Mann, ‘the acne of the boys on the higher protein-low GI diet improved by more than half. This diet reined in the high insulin levels that could be responsible for acne. When you go through puberty you produce a lot of growth hormone that actually makes you temporarily insulin resistant. In conjunction with a high glycemic load diet common in western societies this causes chronically high insulin levels. With such high levels of insulin you're going to get blockages in the pores and extra oil building up under the skin. A diet high in processed foods pushes glucose and insulin levels higher, exacerbating the problem, but low GI foods do the opposite. Low GI carbohydrates and lean protein-rich foods help to reduce insulin levels that affect the hormones associated with acne.’

Macronutrient composition of the low GL diet

What hormone's that?
Acne is formed when the sebaceous gland (oil gland) produces extra sebum (oil). At the same time the gland becomes blocked due to cells lining the follicle duct expanding under the action of insulin related growth factors such as IGF-1. This causes a build-up of sebum within the gland which gets bigger. As a result bacteria grow within the gland and eventually bursts causing inflammation and redness. The main hormones that play a role are:


  • Androgens (male hormones)
    When the levels of active androgens increase it causes more oil to be produced within the gland.
  • Insulin-like growth factor -1 (growth hormone)
    When IGF-1 becomes more active, it causes the gland to become blocked.
For more information contact: neil.mann@rmit.edu.au


Anonymous said...

I can understand the low-GI carbohydrate diet moderating insulin response to some extent, but I wonder what impact the 'lean protein' had in the context of Holt et al's insulin index, which seemed to show a substantial insulinogenic response from some protein foods.
Is Mann saying that 'fat' is a strong contributor here or have I missed something?

Thanks, Paul Rogers

Anonymous said...

I haven't read the complete scientific report, but the lean vs. red meats would probably contribute to overall function of our processing systems; the more the body has to process (particularly saturated fats) to maintain homeostasis, the less it has to give to its other functions, including insulin monitoring and metabolizing.
Belinda RHN

Anonymous said...

The protein sources that are very insulinogenic (like white bread) are milk and yoghurt, which makes perfect sense, because insulin increases IGF-1, which in turn increases growth, which is beneficial when you're a child (or a small animal). After weaning, you don't need that, and in fact the only mamal that continues to eat dairy foods is modern man.
Some epidemiological studies have shown that fat free dairy consumption could prevent type 2 diabetes, but there also other epidemiological studies showing the opposite and a small studie with children has shown that milk causes insulin resistance, while red meat doesn't.
To get a better picture about acne, I sugest you go to www.thepaleodiet.com and buy Dr. Loren Cordain's book about acne (It's the best I read and mentions Dr. Mann's study).

Anonymous said...

I went on a low carb lean protein diet for 6 weeks and in this time I did notice my skin looking better than it had in years. My pores were a lot smaller and my skin wasn't oily by midday like usual. I looked great. So I believe that diet has everything to do with how ones skin reacts.

GI Group said...

Note that the diet was NOT low carbohydrate. We do not support low carb diets. The carb content in this study was 45%. Low GL does not equate to low carb as many have confused.

In practise it is best to concentrate on lowering the GI of the diet. This is easily achieved by following the points we outlined in our "Food For Thought" article.

Best...GI Group

Anonymous said...

So, GI meets the CSIRO diet eh?

I guess I'll have to read the paper, but I will be interested to see if insulin levels were compared across diets and to see if the diets were isoenergetic.

Paul Rogers

Anonymous said...

Re the question about the impact of lean protein and the contribution of fat.

Starting at the end of your comment about fat. We certainly made no claims about fat and kept it constant in both groups during the study. So not sure where you are going on that one.

The dietary protein increase is to offset some carb intake to minimise glucose response, as it is difficult to find a palatable low GI carb diet with enough low GI foods the boys would eat to keep the glucose response and insulin response down. Remember we set out to make the diet isocaloric with their baseline intake, so any reduction in carb had to be balanced with an increase in another macronutrient. Also the primitive diets we based the study concept on were also higher in protein than normal western intakes, many well above 35% energy as protein. We stuck at 25% energy as protein as a healthy safe level.

The insulin index is a complex issue and you must read the data on insulin index tables carefully and see just how the figures are calculated, they involve a ratio that takes into account glucose response which for protein is extremely small, hence an exaggerated value for insulin response is obtained. If you actually do studies with higher protein levels in a real diet like us you will see some reduction in insulin levels and an improvement in insulin sensitivity.

Hope this helps.

Anonymous said...

Prof Mann, thanks for the comment. I wasn't going anywhere with fat, only trying to understand where the 'lean protein' was involved. Now I understand that there is an increase in protein and a decrease in overall carbohydrate, which was not made clear in the article I read.
I am still keen to know if the diets were isoenergetic (isocaloric) throughout the study. If the boys ate less than the controls would that not lessen insulin repsonse and confound the study? Restrictive, high-protein diets inevitably return lower energy intake . . . satiation from extra protein etc. I'm in the dark a bit here, and of course don't mind me too much . . . just being the Paleo sceptic.

Regards, Paul Rogers

Anonymous said...

Hi Paul,
The diets were designed to be isocaloric with each boy's own baseline diet whether they were in the control group or test group.It would be pointless to have all diets of all boys isocaloric with each other because there were very different body sizes and activity levels, so one size energy diet does not fit everyone. Some of the boys in the higher protein diet lost weight because their energy intake did fall a small amount, which is very probably due to the satiating effect of higher protein foods and low GI foods. This was despite daily contact and monitoring their intakes and provision of numerous food items low in GI and higher in protein. Our papers being reviewed at this time all report this and show the statistical calculations and adjustments for weight loss and discuss possible ramifications of weight loss for the study and acne control per se.

In the real world application dermatologists and dietitians are indicating to us that they are not concerned about the weight loss as a negative but rather see it as an extra advantage of the diet approach used. As we show in our papers the boys on the test diet all achieved very good scores for all nutrients with an RDI and were within range for all recommended dietary macronutrients, fibre etc. So according to the Australian NRVs the diet was extremely acceptable and the feedback from the subjects from a subjective view point was a big positive. Hope this helps

Anonymous said...

If it works it could be a useful tool in any case.

Thanks, Paul Rogers

Anonymous said...

Where can I buy chickpea flour in America? I would like to buy organic chickpea flour or regular chickpea flour. And where is best place to buy chana dal beans?

hermin said...

hi Neil - thanks for sharing your interesting research findings - just wondering if the source of protein matters? (e.g. animal based vs plant based, fish [contains omega 3 fatty acids] vs soy [contains more of omega 6]). thanks and i'm looking forward to see the hard copy of your paper!

Anonymous said...

Foods like chickpea flour (also called garbanzo bean flour) and chana dal beans are normally available in organic or health/natural food shops. Check out The Whole Foods Market. They have a website where you can locate your nearest store: www.wholefoodsmarket.com

It's also well worth while checking out the Bobs Redmill site as they manufacture this flour. www.bobsredmill.com

You'll also find these foods in Asian groceries, especially ones selling Indian ingredients, and Middle Eastern and other ethnic produce stores.

Another good source of information are gluten-free websites. There's an incredible directory by a Canadian dietitian called 'Gluten-free Diet' which is a very comprehensive resource guide for these sorts of products. You can buy it from Amazon. We did.