1 January 2006

GI News Briefs

Tesco Tests

The results of GI testing of 140 foods commercially available in the UK for the supermarket giant Tesco are published for the first time in the British Journal of Nutrition. The testing, conducted by the Oxford Brookes team led by Prof. Jeya K. Henry, found that the majority of GI values of UK foods compared well with published values of foods in the International Table of Glycemic Index and Glycemic Load Values (2002). However, there were a few exceptions such as fruit loaf (higher) and bran flakes (lower), highlighting the importance of testing foods in their country of consumption wherever possible. The number of ready-to-eat meals (24) in the list make this report a welcome addition to the GI database. Most of the mixed meals had a low GI. Cottage pie, shepherds pie and sausage and mash which all include plenty of mashed potato had medium GI values. In his conclusion Henry emphasises that ‘it is important to test the GI of composite meals, instead of trying to calculate the GI from GI tables.’
British Journal of Nutrition (2005), 94, 922–930

Comment from Professor Jennie Brand-Miller: The decision making behind the common cut-offs for high and low GI (70 or higher, 55 or lower) was based on the scatter of GI values among single foods. These cut-offs are probably not appropriate for mixed meals. If the future holds more testing of composite meals, then the cut-offs need to be redefined, specifically for mixed meals, taking into account the observed range. It’s important to remember that the GI was introduced to rank the glycemic nature of the carbohydrate in individual foods. The purpose was to exchange one carbohydrate source with another in a mixed meal situation. That application remains valid and shifts the focus away from lowering glycemia at all costs (not a good idea), towards overall nutritionally balanced meals.

Getting Satisfaction
Feeling satisfied isn’t what you normally expect on a diet. Hunger is a pretty big challenge—which is why overly restrictive diets are so hard to stick to. Few of us have the long-term grit to ignore that gnawing feeling in the gut. However, more than 25 studies around the world have already confirmed that low GI foods are more filling, delay hunger pangs for longer, and/or reduce energy intake for the remainder of the day compared with their high GI counterparts.


Now a new Weight Watchers International Germany study in a real life setting led by F. Bellisle of Nutrition, Hotel-Dieu Paris adds weight to the evidence. Sixty-five women were recruited as they started the Weight Watchers points program. One group of 30 followed the regular program for 12 weeks. The other group of 35 followed a modified program, with special emphasis on low GI foods. Over the 12 weeks the researchers asked the women to rate hunger and desire to eat (they used visual analogue scales on one day per week, several times a day: before and after each meal or snack, and in between). The women in the low GI group consistently revealed a lower intensity of hunger and desire to eat, especially during the afternoon! The researchers conclude that: ‘The subjective benefits of the low glycemic index diet may be a worthwhile contribution to the motivation of dieters, even though they did not predict improvement in objective outcome measures.’
Obesity Reviews 2005; 6 (Suppl 1)


In a more academic setting, CSIRO diet gurus Manny Noakes and Peter Clifton with J Bowen also report that the GI affects acute satiety in a small cross over study with 19 obese men. The men were given four liquid ‘breakfast’ preloads (80% energy from whey, calcium, lactose or glucose). For the next three hours subjective appetite ratings and plasma glucose, insulin, amino acids, cholecystokinin (CCK), ghrelin and gastric emptying were measured. At a buffet lunch that followed the researchers then assessed how much the men ate. They found that energy intake, appetite ratings and ghrelin were greater three hours after the high GI ‘preload’ compared with the low GI and protein preloads.
—CSIRO Health Sciences and Nutrition.

What Kids Want
Thanks to vigorous low fat campaigns, many kids have been consuming more carbs and less fat in recent years. But the result hasn’t quite been what the health professionals expected. The highly processed high GI convenience foods and soft drinks has increased the glycemic load in children’s diet and can be linked to the increase in child obesity and risk of metabolic syndrome. Anette E Buyken and her colleagues at the Research Institute of Child Nutrition in Dortmund looked at the diets of healthy German school children aged 7–8 to see how much the GI and GL of diets in 2002 had changed from 1990 and 1996. They also looked at the kinds of carbs the kids were eating to see how much (if at all) they had changed.


They found that compared with 1990, the 2002 children’s diet was slightly higher in GI (56.5 vs 55.1) and GL (17.5 vs 16.7). According to Buyken ‘the most important finding is that the ‘tolerated food groups’ comprising sweets, sweetened soft drinks, cakes and cookies, and salty snacks had the largest impact on the overall dietary GL, even exceeding the impact of bread and rolls. We had expected bread and rolls, the most important carbohydrate source in Germany, to contribute the most to the dietary GL. Another interesting finding is the small impact of potatoes on the overall dietary GL in all three time periods.’ They also found that generally speaking the children in the lowest GI tertile, but not those in the lowest GL tertile, had a better dietary nutrient profile and made more favourable food choices.

She concludes that: ‘partial replacement of high-GI ‘tolerated food groups’ for foods with a low dietary GI, especially fruits and vegetables, may help to reverse the observed slight increases in the GI and GL since 1990, and to enhance the overall dietary quality in children.’
British Journal of Nutrition (2005), 796–803


Melissa S. Green said...

The Weight Watchers findings certainly square with what I've experienced the past few days, as I've begun to apply GI (&, within reason, GL) to my own diet. It's just been a week now. I am prediabetic, & am working to lose weight through diet & exercise as well as to keep my blood glucose levels on an even keel. So far, I haven't felt like I was starving even once; yet I have good energy levels, & have lost a pound already.

I do have a question about GI for foods that haven't yet been tested. Do you have any suggestions of the best methodology for someone with a reliable glucose monitor to make personal estimates of GI for themselves of untested foods?

Or even tested foods! -- this morning, understanding that oatmeal (i.e., porridge) has a fairly decent GI, I had about cup of oatmeal with a third of a cup of soymilk. My blood glucose an hour later was 181 mg/dL (whole blood); another hour & it had come down to 85 mg/dL. I have read that my goal should be to be less than 140 mg/dL two hours after a meal, & I was well within that. But I'm still concerned about the 181. Would a level like that indicate a food that has too high a GI for me personally? Or is that spike within acceptable ranges for a nondiabetic? Again, what would be my best methodology for methodically estimating how foods are affecting my blood glucose levels?

I have since learned from the GI database at U. of Sydney that rolled oats have tested very differently between Australia, Canada, & the U.S. -- with the U.S. the highest -- which I guess has something to do with how food is processed on its way to market. Another factor that might have affected the oatmeal is that we have long had a practice of soaking the oatmeal overnight with a slight amount of acidopholus, as a sort of "pre-digester" to make the food more easily digested. (A practice recommended in some natural foods books.) Would that "pre-digestion" then lead to the food converting more quickly into blood glucose once eaten, than if we'd left the acidopholus out?

Thank you for your outstanding work in helping us get our metabolisms back on the right track!

Anonymous said...

Keep up the good work!

I am diabetic, and I found that even steel cut oats (lower GI) can cause a big blood glucose spike to 180 or 200 if I ate the size portion I used to eat.

With a smaller portion I was able to keep the spike to 140 or so.

I read the Dr. Bernsteins books, and now I keep the after meal spikes under 110 mostly.

The American Diabetic Association suggests keeping it to 180 or under. The American College or Endicronologists suggests 140 or lower.

I shared a chinese meal with a diabetic friend who offered me rice while he ate a good size portion of it. I said I could not control my BG with rice. He said his doctor told him 180 or under after 2 hours was acceptable.

He then spent the rest of the meal telling me about his "staghorn" kidney stones (calcified vessels in his kidneys) and a long list of other very serious problems.


I think his doctor's advice of 180 BG is killing my friend slowly.

Not for me!

Melissa S. Green said...

180! - that seems high. I am taking my advice from How to Prevent and Treat Diabetes with Natural Medicine by Michael Murray, N.D. and Michael Lyon, M.D. (which is where I first heard of GI & GL). They give as goals 80-110 mg/dL before breakfast (fasting), 80-130 before other meals, < 140 two hours after a meal, 110-140 at bedtime. And I'd like to keep the spike between eating & the two hours after eating at some reasonable level too.

Anonymous said...

Sounds like Drs. Murray and Lyon are giving better advice than the ADA.

I think the 181 you got was due to carb count more than glycemic index. You really have to watch both.

I can get up to 180 or 200 eating cashews (low gi) unless I watch the quantity.

Dr. Bernstein recommends 85 bg before, during, and after meals, and I have yet to consistently meet that. Even so, my last A1C was 5.1 and I can feel my feet again!

Melissa S. Green said...

Yes, I think you're probably right about the carb load being too high, rather than the oatmeal itself being high GI. Though I do think that soaking the oatmeal overnight w/ a bit of acidopholus to make it more digestible may be upping its GI from what it would be without the acidopholus. As Gretchen Becker says (in Prediabetes: "What You Need to Know to Keep Diabetes Away, "Make your food more difficult to eat" -- i.e., slower to digest, to slow down the entry of glucose into the blood.

Congratulations on feeling your feet again!

Anonymous said...

"slower to digest" is really the key to low gi food.

If you are brave, you can slow down the glucose release from any carb meal by drinking about 2 tbsp vinegar before the meal. It slows down your stomach emptying.

I am brave (ok, I am an idiot) and I tried it.

It does work.
Ugh! I will never do that again!

A vinegar and oil dressing on a salad makes more sense!

Ginseng Berry (Not root) is reputed to lower bg and sure seems to work for me. It is slow acting, so I take it 1.5 hours or so before a meal with 500mg of metformin. It seems to work better sometimes than others.

Dr. Bernstein says that Alpha Lipoic Acid is an insulin mimic, and it can help. The brand does seem to matter. I got some from my local drug store and it did nothing. I got the "R" version from Netrition. (The "R" version of alpha lipoic acid is supposed to work better - and it does!)

The label suggests taking 15 minutes before a meal, and that works for me.

My local drug store also sells the "R" alpha lipoic acid under the brand name "Insulow" - it works fine, and is more expensive.

Using the metformin and supplements together with a low gi, limited carb meal, I get bg rise of between 0 to 5 points with meals.

Seems ok to me!


Melissa S. Green said...

"bg rise of between 0 to 5 points with meals" -- wow, that sounds pretty good.

I learned last Friday that as little as 1/4 to 1/2 tsp. of cinnamon also lowers BG, & assists insulin sensitivity. Tried it the last couple of days: my fasting BG this morning was 7 points lower than it has been, & seems to be helping with postprandial BG too. Add that to low-GI eating, & I seem to be well on my way towards integrating a healthy diet.

GI Group said...

Testing the GI of foods on yourself is theoretically possible however the result would likely be quite inaccurate. Keep in mind that when we test a food, it occurs in a highly controlled environment. Ten subjects must meet certain health criteria, be tested three times with a standard glucose drink and have three fasting blood samples taken to ensure accuracy. If the fasting sample is not accurate, for example, it can greatly affect the total area under the curve which is paramount for assessing the GI. Lastly, it is extremely important that the equipment used to measure blood glucose levels be of the highest standard. Self-monitoring devices are suitable for checking your own glucose levels but do not give the precision and reproducibilty necessary for GI testing.