Glycemic Index

In 2014, the global burden of diabetes was 422 million people – 8.5% of the global adult population, according to the World Health Organization (WHO, 2016a). As explained, the WHO has developed a “Global strategy on diet, physical activity, and health.”  Their aim is to “focus on population-wide approaches to promote healthy diet and regular physical activity, thereby reducing the growing global problem of overweight people and obesity” (WHO, 2016b, np).

After learning about the WHO’s campaign and Thrifty Theory in their anthropology class, Addison decided to start eating healthy. Instead of eating white bread, Addison now eats whole wheat bread. In fact, Addison popped into the local bulk food store and made sure that s/he had all kinds of healthy snacks. No more candy bars and potato chips for Addison – instead, Addison bought dried dates, raisins, and oven baked pretzels. Pineapple, mango, and watermelon were incorporated into Addison’s diet. Instead of eating potatoes with every dinner, Addison bought sweet potatoes, parsnips, rutabaga, white rice, and couscous. Cranberry juice and rice cakes were on the grocery list as was. Finally, for those mornings that s/he is in a rush s/he opted for Cornflakes over Coco Pops – bad bad Coco Pops. Addison is off to a healthy new diet.

A glycemic load (GL) is a measure that accounts for how much carbohydrate is in the food you eat, and how much each gram of carbohydrate in the food will raise your blood glucose level.

According to the Canadian Diabetes Association, consuming foods with a low glycemic load not only help control blood sugar levels, but helps control cholesterol levels, lowers the risk of developing type 2 diabetes, lowers the risk of developing heart disease, and helps control appetite. Your daily glycemic load for all meals and snacks should total 100 or less per day. As for Addison, the choices are not that great. In fact, all of the choices that have been made by him/her will have a significant impact on her daily glycemic load.

Image result for glycemic index

In order to determine the GL of your food, you need to refer to the glycemic index (GI). The glycemic index has been calculated by researchers who have studied and measured how particular foods raise a person’s blood glucose (sugar) level. It is a scientifically established measurement and should play a role in our dietary choices. For example, some people think that they are eating healthy when they reach for a whole wheat sandwich rather than a white bread sandwich. While it is true that while bread is high in the glycemic index (GI=103), whole wheat bread isn’t much better for you – it has a significant impact on the amount of sugar in your body because it is still high in the glycemic index (GI=71). As we have already learned, in our Energy and the NRG Survey unit, once our blood-borne glucose levels are full, our body will convert anything that we digest into fat.

To calculate the glycemic load of your food, multiply the food’s glycemic index by the grams of carbohydrates in the food you are consuming. Divide that number by 100. I’m going to use Subway in this example because they have advertised their submarine sandwiches as a healthy choice. On the nutritional information they offer, a Cold Cut Combo lists a calorie count of 430. Take off the meat and it’s only 230 calories. This calculation, however, is based upon a 6-inch sandwich that boasts 9-Grain bread and vegetables. The sub, as advertised, does not include condiments like mayonnaise or dressings. It does not include cheese.

At the College, I rarely see people order a sub like the one Subway promotes in their nutritional guide or by Jared Fogle. Instead, students (and professors) go for the works. In an effort to help people in Ontario make healthy choices, Ontario passed a Healthy Menu Act in 2017.  Under this new law, businesses are required to publish the calories of a meal next to its price. Interestingly, some of that information is not accurate according to the business’s own published data. For example, Subway lists, next to the price of its 12-inch Cold Cut Combo, that it carries a caloric load of 600 calories. Hmmm.

Subway does, however, offer a “Calculate Yours” nutritional tool that can help us figure out exactly what we are consuming. I decided to use it and this is what I came up with: A foot-long Cold Cut Combo submarine sandwich with Italian bread, cheddar cheese, mayonnaise, dressing, and vegetables comes in at a whopping 1240 calories! 81 grams of this 524-gram meal comes from fat, and there are 90 grams of carbohydrates to be found in the sandwich (see the screenshot below).

Cold Cut Combo Nutrition

Calculating the Glycemic Load of the Sub . . .

There is a problem here: not all of the carbohydrates come from the bread. In fact, only 82 of the 90 grams of carbohydrates come from the bread. “You gotta be joking,” you say. “Kay, most of them come from the bread.” So, our calculation looks like this:

White baguette style bread is 95 is on the glycemic index. Multiply the glycemic index (GI=95) by the grams of carbohydrates in the meal (82g). The product of the glycemic index and grams is 7790, which is divided by 100. The glycemic load of a Subway Cold Cut Combo without the vegetables is 77.9. The vegetables raise the glycemic load by 0.8 (10 x 8g/100). Therefore the glycemic load for a Cold Cut Combo is approximately 78.7.

The daily recommended glycemic load, according to the Canadian Diabetes Association, is 100 or less. What are the logical consequences of this fact, that is nutritionally and behaviorally speaking? In other words, if this was your first meal of the day, what are your options for the remainder of the day? Jot them down. Your instructor may want to discuss this further in class.

Instead of white or whole wheat, a healthy option would be to choose pumpernickel bread (GI=55/ GL=49.5) – not 9 Grain wheat because that causes the glycemic load to increase even higher. Why choose pumpernickel bread? It’s high in fiber and therefore slows down the release of sugar into an individual’s body. The Following video will provide you with a summary of the glycemic index.

Discussion: Genes and Carbs – The Good, the Bad, and the Ugly

Think of the glycemic load and carbohydrates like this: there are “good carbs” and “bad carbs”. Good carbs are carbohydrates that take a long time for your body to process. They are full of fiber and have a low glycemic load; consequently, sugar is released slowly into your body. Examples of good carbohydrates include apples, bananas, celery, lentils, peanuts and almonds, quinoa, brown rice, peas, kidney beans, and whole grain or pumpernickel bread to name a few.

Thinking back to our genetics and DNA, many of these foods fit into the dietary patterns of our ancestors. Lentils, nuts, beans and peas and vegetable and fruit carbs sustained our hunting and gathering brothers and sisters for 99% of human history. Even whole grains figured into that dietary pattern. It was only with the invention of food processing techniques that refined grains in the last 100 years that we have been eating foods with “bad carbs” that don’t “match” our genetics.

We are also aware, from our discussion about Eating for Your Genes, that our individual genes (specifically AMY1) are set-up to produce more amylase for some individuals and fewer copies of this enzyme that helps digest starch for others. This provides us with a little more insight and questions to consider when we are making dietary decisions.

In contrast, to good carbs, bad carbs are like, to use a cliche, “bulls in a china shop.” They tear around causing havoc. To be sure, bad carbs are refined. They lack the fiber, for example, that whole grain bread offers (natural fiber has been removed during processing). As a result, bad carbs cause blood glucose levels to spike and has been associated with obesity and type 2 diabetes. Our ancestors in the distant and more recent past never experienced spikes in glucose levels. Their carbs were full of fiber.

Examples of bad carbs include “empty calorie” foods like soda pop, white rice, white bread, and white pasta to name a few. Unfortunately, the bad carbs tend to be the foods that we crave – some experts suggest that the spike and crash that follows when one eats bad carbs leads to high-carb food cravings.

Why do we crave these bad foods? This is – so to speak – the ugly aspect of evolution. Sometimes evolutionary adaptations can become mismatched with new environments and therefore maladaptive. For example, research indicates that because humans lost the ability to naturally synthesize vitamin C, we developed a sweet-tooth.

In the end, if we begin to pay more attention to the types of carbohydrates we consume, we may begin to address the epidemic of obesity and type 2 diabetes that has emerged in recent times.

References

WHO. (2016b). Diabetes. http://www.who.int/mediacentre/factsheets/fs312/en/

WHO. (2016a). World Report on Diabetes. http://apps.who.int/iris/bitstream/10665/204871/1/9789241565257_eng.pdf

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