1 June 2008

Your Questions Answered

I am curious why cereals like Bran Flakes and Sultana Bran that look so healthy, and everyone assumes are healthy, actually have a high GI?


Bran Flakes and Sultana Bran (Raisin Bran in the US) are fibre-rich breakfast cereals designed to keep you ‘healthy on the inside’ as the ads say. But sadly they are high GI and digested in a flash because the long cooking times, the presence of lots of water, the flaking process and finally the toasting all conspire to make the starch very accessible. Here’s how Prof Jennie Brand-Miller describes what happens in The New Glucose Revolution.

‘Grinding, milling, flaking, popping and puffing grains radically changes nature's architecture and makes it easier for water to be absorbed and digestive enzymes to attack the food. This is why many foods made from fine flours tend to have a high GI value. The larger the particle size, the lower the GI value, as the diagram below shows. One of the most significant alterations to our food supply came with the introduction, in the mid-19th century, of steel-roller mills. Not only did they make it easier to remove the fibre from cereal grains, but also the particle size of the flour became smaller than ever before. Prior to the 19th century, stone grinding produced quite coarse flours that resulted in slower rates of digestion and absorption. When starch is consumed in ‘nature’s packaging’ – whole intact grains that have been softened by soaking and cooking – the food will have a low GI. For example, cooked pearl barley’s GI value is 25 and most cooked legumes have a GI of between 30 and 40 whether home cooked or canned.


I was diagnosed with PCOS about 20 years ago with most of the standard symptoms. My doctor did a glucose tolerance test, which came out to be normal. Why I am not showing any signs of insulin resistance, if PCOS is supposed to be caused by it?
Insulin resistance is the most common cause and 70–80% of women with PCOS have insulin resistance. But a glucose tolerance test doesn't pick up insulin resistance. It picks up the inability of the pancreas to deal with insulin resistance. If your pancreas has lots of ‘puff’, your glucose tolerance will remain normal, perhaps all your life. Only a fraction of people with insulin resistance go on to develop impaired glucose tolerance. Nonetheless, high insulin levels can cause other problems downstream, and the ovaries are particularly sensitive. Any woman with diagnosed PCOS also needs to have the actual cause of the problem pinpointed so she gets the right treatment for her and thus the best outcomes. Some of the other causes are anorexia, bulimia, stress, excessive exercise, high blood levels of prolactin and tumors of the adrenal glands, ovaries or pituitary gland. And for some women the cause is unknown. There’s a really excellent paper by Dr Warren Kidson on PCOS called ‘The Polycystic Ovary Syndrome – A Starting Point Not a Diagnosis’ which you can download here.



Anonymous said...

Is there a low or safe GI smoothie available? Regular smoothies give me a sugar high for about 5 minutes and then I feel wiped out.Please email me at lfkriz@cox.net

GI Group said...

The best option for a low GI smoothie would be low fat milk or soy milk, reduced fat yoghurt and berries. However, it may be worth chatting to a registered dietitian about your specific problem to find out what's going on.

Graham said...

I am interested in grinding and flaking my own grain for home baking and muesli. Health food shops provide "organic grain" at ridiculously high prices. Can I use grain from ordinary country co-op or produce stores? Can you do an article on the whole business of using grain for low GI.
With Thanks
Graham Anderson

GI Group said...

Hi Graham, great topic for a future article. We will follow up on this and feature it in a forthcoming issue (July or August), so please watch this space.

busylizzycat said...

Couldn't figure out where to post a question so I'm posting it here in hopes that it will get some attention. I was diagnosed with hyperinsulinism 30 yrs. ago and since then have tried to be conscientious about food choices. The rules have changed a lot in that time - thanks to The New Glucose revolution and your web-site I've learned much more about a healthy diet for me. Recently I was diagnosed with hypothyroidism (TSH = 100+, now down to 76 with thyroid hormone). Based on family history and symptoms my GP suspects that I also have celiac disease and has recommended that I also follow a gluten-free diet, certainly until my thyroid levels are under control. The hypoglycemic diet and the gluten free diets seem very contradictary eg. most gluten free product & recipes rely heavily on rice, potato & corn & often sugar, yet barley, whole wheat etc. are forbidden. It is very confusing & I really need help figuring out what to eat........liz@lubricon.ca

GI Group said...

Hi Busy Lizzy:
We spoke to our dietitians and they say it is really important that you have a biopsy to test for coeliac disease before starting a gluten-free diet. If this test confirms that you have coeliac disease, you might like to check out a copy of Kate Marsh's Low GI Gluten-free Living which will help in combining the 2 diets. Our dietitians emphasise that it's vital you are properly tested first.

Anonymous said...

I'm not sure if this is the correct place to ask a question, but here goes!

I am in the UK. There is a brand of Stem Ginger oat biscuits which claim to be Low GI. (Not using your logo however.)

100G has:
66.6G available carbs
5.5G fibre
17.8G sugar
14.9G fat
of which 5.7G is saturated fat

The second ingredient is demerara sugar and they contain palm fruit oil.

Are these biscuits actually low GI?

Anonymous said...

Wow! Thanks so much for your quick response. I have ordered the book (sounds like just what the Dr. ordered!)and will ask about the biopsy. He seems to think that my negative results from blood tests for celiac resulted from my strict adherence to my hypoglycemic regime and is most concerned about getting my thyroid levels "normalized" first. Your advice makes sense and is much appreciated. Busy Lizzy

GI Group said...

Stem ginger oat biscuits. Well they sound delicious! But whether or not they are low GI is something we can't guess at. It is unlikely that a reputable company would make such a claim without having the product tested. To set your mind at rest, your best bet is to contact the manufacturer and ask some leading questions such as:
1. Where were they tested and what's the actual GI?
2. By what method (in vivo or in vitro)as it makes a difference if the GI testing is done in real people or a glass tube?
We take it you are talking about Nairns. If that's the case, here are the contact details:
Kim MacKenzie
90 Peffermill Road, Edinburgh, Scotland EH16 5UU
Tel: +44 (0) 131 620 7000
On their website they say: 'If you have any comments ... please complete our comments questionnaire.' (You will find the questionnaire on their website under Contact Us). We would be interested to fin out what the GI is.

beruang said...

i find it really interesting that some high fat products claim to be low GI (e.g. biscuits, cake). well, i think, they DO have a lower GI than their low-fat counterparts, because fat blunts the rise in blood sugar levels. but a lot of fat (esp. bad fats like palm oil) wouldn't be good for health, would it? (except for occasional treats, of course).

GI Group said...

GI News spoke to Nairns. Here's what they said: 'All Nairn's oat biscuits have had their Glycaemic Index measured following the FAO/WHO method, an in vivo method. The GI value for the Nairn's Stem Ginger oat biscuits is 55.'

jemeh said...

In reading "The New Glucose Revolution" because I have celiac disease you use psyllium in many of your recipes for the fiber. I am allergic to psyllium and wonder what you recommend to replace it--maybe more than one suggestion. Thanks. jemeh@prodigy.net

GI Group said...

Hi Jemeh. This is definitely a tough one. We referred it to author of Low GI Gluten-free Eating Made Easy, Kate Marsh.

"There really isn't a substitute for psyllium. There is Benefibre for a fibre supplement if someone wanted it just to increase fibre in their diet, but it's not for use in cooking. And other rich sources of soluble fibre (eg oat bran) contain gluten. All I could suggest is using more legume flours and rice bran to give a lower GI but obviously you couldn't just substitute in recipes as the cooked product would have a very different texture."

Anonymous said...

I have tried to tell several persons that "brown rice" is not low GI, and most will argue with me based on them being "expert" or from the 2002 GI standards.
How did those 2002 standards come about, and why does nobody else in the subject of GI have brown rices rated as high as you do? How many different ways are there to eat brown rice and check your blood sugar? Is there really anything subjective about the results? Please explain the descrepancy between your assesment of brown rice, and that of others in the industry.
bruce ritchie

GI Group said...

Bruce, we have forwarded your question to Prof Jennie Brand-Miller and the test team at Sydney University Glycemic Index Research Service and will post a response asap.

hermin said...

hi Bruce,
just some thoughts:
in my understanding, the GI of brown rice can vary depending on:

- cooking method (boiling, steaming or parboiling).
- length of cooking time (usually, the longer you cook it, the higher the GI)
- the type/varieties of rice (long-grain rice such as Doongara would have a lower GI)

hope this helps :)

hermin said...

this means that the GI testing on brown rice could end up with different GI values if they use different cooking methods (i noticed some boiled the rice while some others steamed it), or different types of rice (Calrose vs Doongara) for example.

now if i make a brown rice sushi and test it for GI, probably it would turn out to be low GI. it's because the cooking method is unique (involves the addition of vinegar, which lowers the rise in blood sugar).

GI Group said...

GI values for brown rice typically range from about 60-87. There is only one value that we are aware of that shows a low GI value for brown rice (Brown rice, steamed, GI = 50 from the USA). The 'Brown rice, steamed (USA)' value is from a published scientific paper from 1981, in which, (unfortunately) the authors have not included any further details about the rice (ie specific cultivar or grain length) used in their study.

However, this rice was not tested by itself, the rice had fat and protein added to it (in the form of corn oil and casein). Both protein and fat delay the rate of gastric emptying and act to slow down the rate of carbohydrate digestion - that partly explains why the researchers in that particular study have seen a lower overall glycaemic response for the rice. Factors that will influence a GI response of rice include cooking time/method, starch content, growing conditions etc.

As a general rule, brown rice does not show significantly different GI values from its corresponding white variety, eg White Calrose and Brown Calrose rice both have GI values in the 80s. This correlation is also seen with white and brown (wholemeal) bread - both these products have repeatedly shown very similar GI values.

Simone said...

A standard glucose tolerance test will not show up insulin resistance even if you have it - you need to check that you had the right type of testing done on your blood to make sure insulin resistance is picked up. My first GTT (organised by my GP) showed up nothing out of the ordinary. It was only when I had a GTT organised by my endocrinologist that was specifically looking for insulin resistance that it was found.

Also, my understanding is that the link between PCOS and insulin resistance isn't really understood properly as yet in terms of whether one causes the other.

Anonymous said...

I have the New Glucose Revolution Shoppers Guide 2008 and on p. 151 raisins are a GI of 64 and on p. 172 a nut and raisin mix is a No GI-do adding peanuts to the raisins cause the raisins to have no GI value? I'm a little confused.

Also from the New Glucose Revolution 3rd Edition-If cranberries-sweetened have a GI of 64 and a load of 19--it's more important to pay attention to the Glycemic Index or Is the Glycemic Load the total result of the Glycemic Index?

Thanks so much!

GI Group said...

We have passed your question on to the authors and will get back as soon as possible. However, tomorrow is July 1 and a new edition of GI News will be here and this one archived. So that's where you have to look.

GI Group said...

Re the nut and raisin mix. The publisher apologises as the GI value of 21 for this was inadvertently omitted. Thanks for your attention to detail -- it will be corrected in the next printing.

In relation to the cranberries, Kaye Foster-Powell says that the GI is intermediate and the GL quite high. This doesn’t make them a bad choice; it just prompts consideration of serving size. The GL is high as a consequence of the high carbohydrate content of dried cranberries (as for any dried fruit) and the way to moderate their glycemic impact is to moderate your serving

Anonymous said...

Thank you guys for getting back to me on all of this!
It does look like though when the nuts are added to the raisins it lowers the GI form 64 to 21, just not to 0 like I thought I saw at 1st.

It would be like eating turkey with cranberry sauce at Thanksgiving--adding the protein lowers the GI?

hermin said...

that's an interesting point. but, in practice, i don't think you would eat a lot of cranberry sauce with the turkey, would you? (i.e. the "main" food would be the turkey, not the sauce)

if so, the overall rise in your blood sugar would be low anyway. in other words, the glycemic load would be low.

Anonymous said...

Well it does seem the protein makes it a lower GI load as with the nuts and raisins.

Question #1

If I was to eat peanut butter that has little GI--it seems that if I ate alot of it at once like I've done sometimes out of the container as I do love peanut butter

Is it safe to eat alot of it glycemicly speaking--the GI doesn't go up if I have alot so then there's not much to worry about as far as a high glycemic load, right?

Question #2

Is would seem like anything with high fructose corn syrup in it would be higher glycemic-I had no fat yoplait yogurt over the weekend as it talks about again in the Shoppers Guide 2008-it is sweetened with Sucralose-Splenda and high fructose corn syrup--

It has 14 sugars like some candy out there and with high fructose corn syrup it seems like the glycemic index would be higher--

Is it because it is mainly dairy that makes it low glycemic?

Thank you ahead of time for your answers and yes I'm looking forward to the 2009 Shoppers Guide!

hermin said...

i think these are interesting questions that people often ask.

question 1 actually highlights how important it is NOT to see food from just its GI. although glycemically speaking it wouldn't raise the blood sugar, it doesn't mean we can eat it a lot. peanut butter has a lot of fat and if we overeat it, we can put on weight. unfortunately overweight and obesity are risk factors of heart disease, stroke and even diabetes.

as for question 2, indeed dairy makes it low GI. high fructose corn syrup contains some glucose too, which brings the GI up.

Anonymous said...

Thanks again for getting back to me!

I wanted to ask about the size amounts listed

For example in The New Glucose Rev 3rd edition p.296 1 cup of Instant oatmeal is a GI of 82
The Shoppers Guide 2008 p.110 it was changed to 3/4 cup

I would think that any amount of instant oatmeal 1/4 cup or 1.5 cups is still going to be a GI of 82 because of the substance

Question #1

Why do the sizes change when any amount could be a GI of 82?

Question #2

I've learned though that the glycemic index won't change when you double the serving size of oatmeal from 1 to 2 cups-but the glycemic load will double--In the 3rd edition it says the glycemic load of instant oatemeal is 17 so doubling the amount makes it a glycemic load of 34

This is correct right?

Question #3

Are there 3 levels that can be defined as what is low, med, and high for a glycemic load

1-7 is low
7-12 is med
13 and above is high

Is that a somewhat correct way to look at the levels of glycemic load?

Thanks for your understanding on all these questions as I'm really interested!