Glycemic Index and Label Reading

By Melissa Majumdar, RD, LDN, CPT

A while back, I received this question from a blog follower:

"Is there a way to determine glycemic index by looking at the label?"

The answer is yes and no. The glycemic index (GI) of an item has been determined in a laboratory setting by comparing the rate of glucose, or in some cases white bread, entering the blood to sugar. Much of this research has been conducted and published through the University of Sydney in Australia. Their database is online and can be a good reference, although some of their foods will differ in ingredients and processing from American food. Assigned GIs are determined by feeding an amount of food equaling 50 grams of carbohydrates to fasting *healthy* participants and measuring the blood sugar changes over time. Unfortunately, not much research has been done showing the glycemic response within the diabetic clientel. In Australia, they even put the glycemic index rating right on the front of a product!

Many factors influence the glycemic index of a food including the fiber, protein, and fat content, manufacturing and processing practices, and other ingredients. For example, even though they are both oats, steel cut oats will have a much lower glycemic index than its highly processed cousin instant oats. Keep in mind that glycemic response differs from person to person due to genetics, hormones, activity, etc. Also, if the food is eaten in combination with other foods, the overall glycemic affect changes. Take a plain piece of bread which contains mostly carbohydrates and it will register high on the glycemic index scale (slightly lower if whole grain and less processed). Add some jelly to the toast and the glycemic affect increases; add peanut butter or turkey and the glycemic index is lower. Keep in mind that a low glycemic food does not necessarily translate to a healthy food. Despite its high sugar content, ice cream has an extremely low glycemic index because the high saturated fat content slows the absorption of sugar.

In short, the least amount of processing and more whole grains and fiber, the lower glycemic index. The more protein or fat contained within the food, the lower the glycemic index. Take home message: pay more attention to overall quality and quantity of the food than just the GI. Even a low GI food eaten in larger portions has a greater affect on blood sugars than a small portion of a high GI rated food. This principle is described as glycemic load and takes into account portion size (GL = GI x amount of carbohydrates)/100. Consider carrots - they have a relatively high glycemic index but the amount of carrots it takes to equal 50 grams of carbohydrates is about 87 baby carrots, not the traditional amount eaten!

Learn more about balancing your glycemic intake with your diet by getting a personalized Nutrition Plan from an EB Nutrition Registered Dietitian!

Chia - Seeds, NOT Pet

I was recently asked about the nutrition content and benefits of chia seeds. These edible seeds are actually the same seed used to have your "pet plant" grow its hair. The seed has its roots in Mexican history, with Aztecs using it as a staple food in their diets. Chia seeds are a nutritional supplement similar to flax. By sprinkling chia seeds on your cereal, yogurt, smoothies, and salads or sandwiches, you are adding a significant amount of protein, essential fatty acids, fiber, and vitamins and minerals.

Chia seeds absorb an absorbidant amount of water, creating a gelatinous structure as the seed swells and expands. This gel, like other soluble fibers, creates a barrier in the gut, thus slowing the absorption of carbohydrates into sugars. This gives chia seeds a low glycemic index, meaning they provide sustained energy. This is not only beneficial for diabetics trying to avoid blood sugar peaks and valleys, but beneficial for the general population. We will all experience an influx of blood sugars after eating simple, white, and processed carbohydrates. With the sharp rise in blood sugar, our body secretes an equal amount of insulin to help our cells quickly take in the sugar (glucose) and bring our blood sugars sharply back down. As blood sugars reach a low, you may feel weak, jittery, and hungry before you have actually metabolized the calories. Including foods rich in fiber, like chia seeds, fruits and vegetables with skins, beans, lentils, nuts, seeds, whole grains, and oats, helps stabalize your energy, maintain regularity, and keep cholesterol levels at bay.

The chias ability to absorb and hold on to water also makes them great hydrators. They help maintain electrolyte (potassium, sodium, chloride) balance which influences hydration as well. Although chia seeds have often been used by endurance runners for this reason, I would not necessarily recommend their use during endurance events. During long periods of exercise, athletes need quick forms of energy. Their are many products available such as GU, Power Gels, Hammer Gels, Clif Shots, and even Gatorade and other sports drinks that consist primarily of glucose. Glucose is your body's preferred source of fuel - all other forms of sugar must be first converted into glucose before your body can utilize the energy. These nutritional gels are made from glucose so that your body can use the fuel immediately, where as the energy from chia seeds will not be utilized until after the longer, more complex carbohydrate bonds are broken down.

The healthy protein and fat in the seeds will also delay digestion, possibly causing gastrointestinal upset. Carbohydrate breakdown starts in the mouth with the secretion of the salivary enzyme amylase, where as protein and fats are not digested until the stomach and small intestine where protease and lipase are produced. Blood flow to the gut is altered during physical activity because the heart, lungs, and muscles take priority. Additionally, for those of us who are not used to diets high in fiber, the chia seeds may create additional "burdens."

Overall, my advise is to use the chia seeds on a regular basis to add omega-3 fatty acids and amino acids as well as fiber into your diet, but to hold out on their usage during athletic events. If you are tempted to try them, make sure to do so before a competitive event or race.

Agave Nectar - The New Black

Melissa Bosslet, RD, LN, CPT

After our quick review of glycemic index and glycemic load, it is time to talk about the nutritional devil: sugar. Sugar, or glucose, is digested very quickly, causing blood sugars to spike. Sugar draws out the body's nutrients, leaving it in a state of stress. The blood sugar roller coaster leads to mood swings, low energy, brain fog, poor concentration, headaches, and hunger. The best way to control blood sugar swings is reducing the glycemic load or sugar in your diet.

SO what do you eat instead of sugar? Agave nectar! Agave has an extremely low glycemic index of 30, meaning it is converted into sugar slower than potatoes, popcorn, oatmeal, and honey to name a few. If you must sweeten, do so with agave.

Agave nectar, or syrup as it is sometimes called, is made form the sap of the agave plant. Most of our agave comes from Mexico. Agave works very well as an alternative to sugar and artificial sweeteners - it is a natural product. It can be substituted for sugar when baking as well. Use about 1/3 to 1/4 less because agave is naturally sweeter. In other words, 1 cup sugar = 3/4 cup agave nectar. Since it is a syrup, or liquid, it is also a good idea to reduce other liquids in the recipe by 1/4. Agave is a good vegan substitute in place of honey, made from bees, and some sugars, which are often processed using tiny animal bones.

Remember, agave is a good substitute for sugar, but it still is adding calories (20 calories in each teaspoon) and does not have a nutritional benefit. So although agave is healthier, I am not promoting it as healthy.

Glycemic Index

Glycemic index is a quantitative way to measure how sugar affects the body. Foods are rated on how fast they enter the blood stream. They are given a "score" or glycemic index, somewhere between 1 and 100, 100 being the carbohydrates are converted to sugar almost immediately. Glucose is given a score of 100 because it is the body's ideal energy source; all sugars are converted to glucose before they are used for energy. The glycemic index is then converted to a glycemic load based on how many grams of carbohydrates the food contains. The larger the portion or the more concentrated source of carbohydrates their is, the higher the glycemic load.

food	carbohydrates	x	glycemic index	÷	100	=	glycemic load
12 oz. regular cola:	40.5	x	90	÷	100	=	36.4
fresh apple (medium)	21	x	54	÷	100	=	11.3
2 Tbsp. agave nectar	32	x	30	÷	100	=	9.6

When searching for a healthy food, consider the glycemic index or glycemic load. White or processed carbohydrates have higher indexes, and whole grains rank lower so they have less effect on blood sugar levels. Also, when carbohydrates are combined with proteins or fats, their efffect on blood sugar levels is decreased.

Glycemic Index of some commonly eaten foods.