Nutrition Facts and Tips

Best Guide for Choosing Low Glycemic Index Foods with Charts

The Glycemic Index (GI) for a food is based on how quickly or slowly the carbohydrate in the food is processed and absorbed and increases your blood glucose levels. The rating system essentially depends on the amount and type of carbohydrate in foods. Foods with low GI score tend to release glucose into the blood stream slowly and steadily. By contrast, foods with a high GI score tend release glucose rapidly. GI is assessed compared with pure glucose that is arbitrarily given a GI score of 100. If a food has a GI of 30, this means that its update rate into the blood stream is only 30% compared with pure glucose.

The GI value relates to how quickly the food is broken down, digested and absorbed from the stomach and intestine. If you eat teaspoon of glucose it is absorbed very quickly and enters the blood stream as pure glucose. It you eat a teaspoon of rolled oats the absorption is slower because the carbohydrate is encased in fiber. Similarly the carbohydrate in rolled oats is mostly starch, which must be broken down into glucose or other simple sugars before the body can use it to support its metabolism. Similarly proteins and fats take longer to break down and these foods have a low GI scores.

Why is the Glycemic Index Important

Foods with low GI scores are good choices for people trying to lose or control their weight through their diet and food choices. Foods with low GI tend to promote satiety, that is they maintain the feeling of 'being full' for longer. They help delay the onset of 'hunger pangs'. Low-glycemic foods take longer to digest and release sugar gradually. Eating a high GI food can cause a sudden increase in blood sugar. Often this is followed by the onset of 'hunger feelings' as the body craves for more sugar, leading to snacking and overeating.

For example eating 250 g of rolled oats in muesli or porridge for breakfast will delay the onset of 'hunger pangs' for longer that eating 250 g of 'coco pops' (a sugary processed cereal). Rolled oats has a GI of 51 compared with 77 for 'Coco Pops'. For a 100 g serve, rolled oats has 67 g of carbohydrate, 1 g of sugars and 10 g of fiber. In comparison 'Coco Pops' has 86 g of carbohydrate, 33 g of sugars and 2 g of fiber. The type of carbohydrate, as well as its relative concentration, in the food affect the rate at which it is digested and absorbed into the blood stream, and this is reflected in the GI score.

On the other hand, high-glycemic foods help with energy recovery after exercise. They also help people recover from low blood glucose levels (hypoglycemia) which can be harmful.

Glycemic Load Index

Critics of the GI system state that the index does not take into account the quantity of the food and amount of carbohydrate being eaten. To overcome the these issues, researchers developed the Glycemic Load Index (GL), which takes account of the quantity of the food, and cabohydrate being eaten as well as the calculate Glycemic Index value for the food. It is calculated by multiplying the GI by the number of carbohydrates in a standard serving of the food (in grams), and then dividing that number by 100.

The higher the GL, the greater the expected increase in blood glucose it stimulates, and in the insulinogenic effect of the food. The long-term consumption of high quantities foods in the diet with a relatively high GL is thought to be associated with an increased risk of coronary heart disease and type 2 diabetes.

An apple, for example, which is regarded a low GL food, has a GI of 40 and contains 15 grams of carbobydrate per 100 g. So the GL for an apple weight is 6 [(40 x 15)/100 = 6]. By comparison the GL for 100 g of rolled oats is 34 compared with 101 for 'Coco Pops', comparing the foods mentioned previously.

Glycemic Index Catgeories

The GL values for various foods can also be broken down into three ranges:

• Low GL: 1 to 10
• Medium GL: 11 to 19
• High GL: 20 or more

Low Glycemic Index foods?

Most vegetables

• Artichokes
• Bok choy
• Broccoli
• Brussels sprouts
• Cabbage
• Cauliflower
• Celery
• Crookneck squash
• Cucumbers
• Eggplant
• Green beans
• Green peas
• Leafy greens such as spinach, collards, kale, and beet
• Lettuce
• Mushrooms
• Onions
• Peppers including bell peppers and jalapeno
• Snow peas
• Tomatoes
• Zucchini

>Certain Fruits

• Apples
• Avocado
• Blueberries
• Cherries
• Coconut
• Cranberries
• Dried apricots
• Grapefruit
• Olives
• Oranges
• Peaches
• Pears
• Plum
• Strawberries
• Unripe banana

Whole or Minimally Processed Grains

• Barley
• Oat bran and rice bran cereals
• Sourdough bread
• Wheat tortilla
• Whole wheat
• Whole-grain pasta
• Whole-grain pumpernickel bread
• Wheat tortilla

Dairy and Dairy-Substitute Products

• Cheese
• Cottage cheese
• Milk
• Plain yogurt
• Soy milk and yogurt

Miscellaneous

• Eggs and egg whites
• Fats such as lard, shortening and butter
• Fish and shellfish
• Mayonnaise
• Meat such as beef and pork
• Nuts and nut butters
• Oils such as extra virgin olive oil and canola oil
• Poultry such as chicken and turkey
• Seeds such as pumpkin, chia, sunflower and flax seeds

Table 1. Glycemic Index for Common Foods in Low, Moderate and High Categories

Table 2. Glycemic Index and Glycemic Load for 100 g servings of Common Food