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Nutrition Diet, supplements, weightloss, health & longevity

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Old 03-09-2005, 02:57 PM   #1
Rene Renteria
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After reading the “About oatmeal...” thread, I did a search of PubMed using "insulin response food digestion profile" as the search terms. A couple of interesting abstracts turned up that may address the general concerns there. I didn't look at the paper, but the abstract has some good info to consider when making grain choices: ct&list_uids=3142566
BMJ. 1988 Oct 15;297(6654):958-60.

Wholemeal versus wholegrain breads: proportion of whole or cracked grain and the glycaemic response.

Jenkins DJ, Wesson V, Wolever TM, Jenkins AL, Kalmusky J, Guidici S, Csima A, Josse RG, Wong GS.

Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Ontario, Canada.

STUDY OBJECTIVE--To determine the effect on the glycaemic response to bread of the ratio of whole cereal grains to milled flour. DESIGN--Randomised assignment of groups of diabetic volunteers to test and control meals, taken after an overnight fast. Test foods were also analysed for in vitro digestion with human saliva. SETTING--Tertiary care centre. PATIENTS--Groups of six drawn from pool of 16 volunteers with diabetes mellitus (11 men, five women; mean age 64 (SE 3); 10 taking insulin, five taking oral agents, one controlled by diet; other characteristics comparable). INTERVENTIONS--All patients took standard white bread control meals on three occasions spanning the study and on different mornings took test meals containing varying ratios of whole cereal grains (barley or cracked wheat) to milled flour (75:25, 50:50, 0:100). All meals contained 50 g available carbohydrate and were eaten in 15 minutes. Capillary blood samples were taken for determination of glucose concentrations every 30 minutes for three hours. END POINT--Glycaemic index of foods (= increase in area under blood glucose concentration curve for test food divided by increase in area under curve for white bread control X 100). MEASUREMENTS AND MAIN RESULTS--Significant trend to lower glycaemic index with increasing proportion of whole cereal grains in test bread (p less than 0.05) and lower in vitro digestibility (p less than 0.001). Breads containing up to 75% whole grain were considered palatable. CONCLUSIONS--Breads containing a high proportion of whole cereal grains may be useful in reducing the postprandial blood glucose profile in diabetics because they are more slowly digested. These breads should be called "wholegrain" in distinction to "wholemeal" breads made from milled flour.

Other groups are trying to model the insulin/glucose interaction to be able to make predictions about insulin dose and diet. Of course, diabetics are typically used for these studies (funded by the NIH), although I would think that more studies of healthy people would be valuable (perhaps these have been done). This study had an interesting conclusion: ct&list_uids=10994512
IMA J Math Appl Med Biol. 2000 Jun;17(2):169-84. Related Articles, Links

Prediction of a glucose appearance function from foods using deconvolution.

Yates TL, Fletcher LR.

The glycaemic response of an insulin-treated diabetic patient goes through many transitory phases, leading to a steady state glycaemic profile following a change in either insulin regimen or diet. Most models attempting to model the glucose and insulin relationship try to model the effect of oral or injected glucose rather than that from the digestion of food. However, it is clear that a better understanding of the glycaemic response would arise from consideration of intestinal absorption from the gut. It is assumed that this type of absorption can be modelled by a so-called glucose appearance function (systemic appearance of glucose via glucose absorption from the gut) predicting the glucose load from the food....We suggest that a gastric emptying curve with a possible gastric delay is the way forward in regulating the appearance of glucose via gut absorption....

So maybe some searching around for research on what controls gastric emptying would help tweak a diet. I know Mark Twight has written some info on this in his book _Extreme Alpinism_, in the context of getting food digested during exercise. I assume there is a big literature on this somewhere, involving Olympic cyclists and marathon runners, for example.

Would having a bunch of almonds (for fat) with a high GI bread help control the insulin response from the bread? Does that olive oil dripping from a nice piece of foccacia do the same? I don't know. Maybe Google does...

Gorgeous day here in San Francisco, warm and sunny.
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Old 03-09-2005, 05:28 PM   #2
Brian Hand
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Rene, this is one of the big problems with insulin indexes and glycemic indexes; calculating them for individual foods is not that meangingful when the foods are normally consumed as part of a meal.

Adding oil to an otherwise low fat meal definitely slows the absorption of carbs and protein. I know a number of people who have observed this directly with their glucometers. Of course Zone ratios ensure that there is some fat to slow down the carbs in every meal. By the way, fiber also has this effect.
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Old 03-09-2005, 08:55 PM   #3
Robert Wolf
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My understanding is that one must keep mixed meals fairly small( I remember 500cal as a number, not sure how reliable that is) to avoid a larger than normal insulin response. Most Zone type meals are good in this regard but if one goes overboard a mixed meal can be more than additive with regard to insulin response, irrespective of glucose response.

Some things which do influence gastric emptying include fat content, acid (adding a table spoon of lemon juice is helpfull here).

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