Glycemic Index

One of the main reasons we often suggest restricting carbohydrate foods is their influence on blood sugar and insulin secretion. However, carbohydrates are a very diverse set of foods. For years, many nutrition authorities followed a few simple rules. These were that refined carbohy­drates affect blood sugar more than whole foods and that simple carbohydrates found in fruits and juices affect blood sugar more than complex carbohydrates. However, recent research indicates this is not always the case.

What Is The Glycemic Index?

The glycemic index (GI) is a numerical system that rates carbohydrate foods according to how quickly they raise the circulating blood sugar level. The index is determined by feeding people the amount of a food that provides 50 grams of carbohydrate. Then blood sugar is measured to assess the effects of the food on blood sugar. Textbooks, unfortun­ately, use two rating systems. In some books, each food is rated on a scale from 0 to 100. In others, white bread is used as a standard of 100 and all foods are rated in relation to white bread. Other testing may include a comparison with the absorption of 50 grams of pure glucose, which is used as a reference food and has a GI value of 100.

A low number on the glycemic index means the food has less effect on the blood sugar level. A high number indicates the food places more strain on the sugar-handling mechanisms of the body and is thus less desirable for blood sugar control. Current glycemic index ratings are; low - 55 or less, medium - 56-69 and high - 70-100.

The glycemic index of a food is a complex phenomenon. Here are a few notes on the phenom­enon:

  • It can depend not only on the type of food, but also the ripeness, the way it is cooked, pro­cessing, the variety and particle size.
      1. Generally, the longer a food is cooked, the faster its sugars will be digested and absorbed, raising the GI value.
      1. Unripe fruit contains complex carbohydrates that break down into sugars as the fruit ripens. The riper the fruit, the higher its GI value.
      1. Generally speaking, the more processed a food is, the higher its GI value.
  • To some degree, the index is also individual. That is, a particular food may affect one person somewhat differently than another.
  • People rarely eat one food at a time, however, experiments indicate that a mixed meal reflects the indices of the individual foods in the meal.
      1. Both fat and acid slow down the rate at which a food is digested and absorbed, resulting in a lower GI value. Adding fats or acids, such as avocado or lemon juice, will lower the GI value of a meal.
  • Not all foods have been tested.
  • The glycemic index is only one measure of a food. Other consideration such as total pro­tein, fat and carbohydrate, mineral and vitamin content of the food, additives, preservatives, pesticide residues and overall quality also need to be considered in planning a diet.

Summary Of The Index

Here is summary, by category, of how various carbohydrate foods compare:

Bakery Foods: The best are sponge cake, pound cake, banana cake, pastry and pizza. The worst are donuts and waffles.
Beverages: The best are cow's milk (whole or skim), unsweetened almond milk and soy milk. The worst are soft drinks and colas. Note that some soy milks have much more sweeteners in them than others. This will change (and worsen) their glycemic index.
Breads: The best are barley breads, oat bran breads and rye breads. The worst are white bread, Wonder bread, baguettes, bagels and French bread.
Breakfast Cereals: The best are Rice Bran, All Bran, oatmeal and Special K. The worst are Rice Chex, Cornflakes and Rice Krispies.
Cereal Grains: The best are barley, rye, bulgur and parboiled rice. The worst are white rice, tapioca, cornmeal and millet.
Cookies: The best is oatmeal. Among the worst is Vanilla Wafers.
Crackers: The best is Rye Crisp bread. The worst are rice cakes and puffed rice crackers.
Dairy: The best is low-fat yogurt, chocolate milk with Nutrasweet and milk. The worst are custard and ice cream.
Fruit: The best are cherries, grapefruit, dried apricots, fresh pears and apples. The worst are watermelon, pineapple, cantaloupe and raisins.
Legumes: The best are soybeans, lentils, kidney beans, butter beans and split peas. The worst are canned beans, baked beans, pintos and broad beans.
Pasta: The best are spaghetti, fettucini and ravioli. The worst are rice pasta, macaroni and cheese and instant noodles.
Root vegetables: The best are yams, sweet potatoes and boiled white potatoes. The worst are parsnips, baked potato, instant potatoes, micro­wave potatoes and french fries.
Snack foods: The best are peanuts and pop­corn. The worst are dates, pretzels, jelly beans and corn chips.
Soups: Soups are all fairly good, such as tomato soup or lentil soup.
Sugars: The best are fructose and lactose. The worst are glucose, maltose, maltodextrin and sucrose.
Starchy Vegetables: The best are dried peas and green peas. The worst is pumpkin. Other vegetables such as leafy vegetables, zucchini, spinach, broccoli, celery, etc. do not contain very many carbohydrates.

Some Surprises

Note how many common foods are high on the glycemic index. These include baked potatoes, baked beans, french fries, soda pop, instant pota­toes, donuts, waffles, Corn Flakes, Rice Krispies and macaroni and cheese. Space does not permit long lists of the index, but the native or traditional foods are far superior to any of these.

For some foods, the ripeness matters. For example, an unripe banana has an index of 43, whereas an overripe banana has an index of 76. Pizza, it turns out, has a very good index, perhaps because of the combination of foods it contains. In general, foods that have more fat and more protein have a much better glycemic index.

Long-grain brown rice has a low glycemic index, whereas white rice, short-grain rice and sweet rice have considerably higher indexes. Yams, sweet potatoes and boiled potatoes are fairly good, but baked potatoes have a high glycem­ic index. Fructose has a rather low glycem­ic index. However, high-fructose corn syrup is not the same thing as fructose. Corn syrup is a mix­ture of fructose and glucose and has a much higher glycemic index.

Soy milk can have a very low glycemic index. However, soy milks with sweeteners such as rice bran syrup or barley malt have a higher glycemic index.

In summary, we still recommend limiting carbohydrate foods for many people based on their mineral analyses and symptoms. Eating more leafy and cruciferous vegetables is a wise idea for everyone, as they are low in carbohydrates and rich in minerals, vitamins and fiber.

However, the glycemic index can help us choose the best carbohydrates to eat to reduce blood sugar spikes which increase insulin require­ments and disturb body chemistry. The glycemic index also supports the idea of eating traditional and indigenous foods for improved health. Choosing low glycemic index foods may also help balance the calcium/magnesium ratio on a hair analysis.

There are many GI index lists that can be found on the internet along with books written by Jennie Bran-Miller, an authority on the glycemic index. One site that is rather handy is from the University of Sidney which will calculate a specific food.

This material is for educational purposes only
The preceding statements have not been evaluated by the
Food and Drug Administration
This information is not intended to diagnose, treat, cure or prevent any disease.

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