Glycemic indexes: what are they and how do they affect our health?

Is it already Friday? Where has the week gone?

My week has been pretty uneventful and consisted of; working, climbing, writing and finishing off Smallville lol; good timing because school resumes next week! My courses this coming semester include a pharmacology class, a biochem. Class, and two nutrition classes (one worth two credits). Looking forwarded to them :)!

Here’s a picture taken by my friend Will in Ontario :)
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By the end of 2011, the UN stated that non-communicable diseases (including heart disease, obesity and diabetes), for the first time, have outpaced infectious diseases as a main threat to human health around the world. What is causing this shift? Today our sugar consumption has gone way up along with the consumption of high glycemic index foods. Could this be the answer? This blog will be on glycemic indexes (GI) and their implications towards our health, hope you enjoy! :)

Sugar consumption has dramatically increased, being especially prominent in our youth and children. At the same time, the prevalence of chronic diseases such as obesity and diabetes has dramatically increased. Considerable evidence links low GI diets with good health while higher GI diets are associated with chronic diseases. Furthermore, recent work indicates that high-GI foods increase our hunger and decrease our satiety. Today, we have a great availability for energy rich foods. Approximately 35% of U.S. adults fall into the pre-diabetic range, while an estimate 12.0% have diabetes. Diabetes, when diagnosed during midlife, is associated with the loss of 10 years off of lives; much of this is related with diabetes relation to heart disease. Diabetics are at a two to fourfold higher risk for heart disease. According to the National Health and Nutrition Examination Survey from 2009 to 2010, 33% of adult Americans were overweight and 36% were obese!

So how does GI work? GI is widely known yet, for some reason, is controversial in its use; it is a kinetic parameter describing a foods ability to raise blood glucose. Food can be categorized on a scale from 0-100 depending on blood sugar effects and then be put into 3 categories; 1) Low GI(up to 55), 2) medium GI(56-70) and 3) high GI(over 70). Lower GI foods have lower rates of glucose entrance into our blood and therefore a lower insulin response. Slower digested carbohydrate rich diets are associated with a reduced risk for heart disease, diabetes and cataract risk. Before I move on, I think that it’s important to mention that, while table sugar has a GI of 65, white bread’s average GI is around 71.

What determines the GI of a given food?

In order to understand GI’s we have to first understand carbohydrates. Carbohydrates (a.k.a. sugar) can be split up into the following categories; monosaccharaides, disaccharides and polysaccharides. Monosaccharaides include glucose (the main sugar we use for energy), galactose and fructose. Disaccharides (two sugar molecules) include sucrose (table sugar, glucose + fructose), lactose (milk sugar, glucose + galactose) and maltose (a building block for starch, glucose + glucose). Finally, our polysaccharides include our starches (polymers of glucose), and non-starches.

Starch can be divided into rapidly digestible, slowly digestible and resistant; starches with higher amylose content tend to be more resistant to digestion than ones with higher amylopectin. Rapidly digestible starches will raise our blood glucose faster and cause an episode of hypoglycaemia (with an increased risk for insulin resistance and diabetes). Slowly digested starches provide a more sustained glucose release, without the spike associated with rapidly digested starches and with prolonged energy availability (with improvements in insulin sensitivity). And finally, resistant starch is not digested in our small intestine but fermented by our gut micro-flora (beneficial for our colon health). So why have I told you all of this?

Our body can only absorb monosaccharaides, so polysaccharides must be broken down into their monomers (single molecule) before we can use them. Glucose is the easiest monomer for our bodies to use since it doesn’t require further modifications (our bodies use glucose). Fructose and galactose on the other hand require further processing (in our liver) before we can use them. As a result, in sucrose and lactose (glucose + fructose, galactose + glucose), while the glucose can be quickly used, the galactose or fructose molecules will need to be sent to the liver for processing.The need for further processing results in a lower blood sugar spike. GI’s are dictated by the monosaccharaides present in carbohydrates as well as other factors including refinement.Since starches are strings of glucose molecules, depending on their refinement, amylose content and amylopectin content, they may result in a spike in our blood glucose.This is why breads can have a higher GI than sugar (which contains fructose and glucose); so does that mean all grains are high GI?

Grains consist of a large variety of foods, in turn there is a variety of GI’s associated with them. Generally, the more processed or refined a carbohydrate is, the higher the GI (lower GI grains include barley and bulgur wheat). Breads (both white and whole grain) are generally made with pulverized grains rather than cracked grains; as a result, their GI’s are quite high. If you want a lower GI grain, look to ones in a more natural state (e.g. cracked or whole) since it takes longer to digest. Pasta is a bit different, when cooked ‘al dente’ (just tender) and eaten in moderate amounts it has a lower GI than when well cooked (comes down to the ease of digestion). So my answer to the above question, like most things; it depends.

And some concluding thoughts, chronic diseases are reaching epidemic proportions in modern societies; clearly something’s going wrong. While the use of glycemic index is, for some reason, controversial, I believe that they should be used more frequently. Why is the use of glycemic indexes controversial? Why do our food guides continue to have such high refined grain content? Reduced glycemic indexes are associated with a reduction in chronic diseases (including diabetes, obesity, cancer, heart disease, etc.), and are therefore good concepts to incorporate into our diets (Glycemic index reference tables can be found pretty easily online). Hopefully this post has shed some light on glycemic indexes!

Hope you all have a great day!
Jen

Aller E, Abete I, Astrup A, Martinez A, Baak M. (2011) Starches, Sugars and Obesity. Nutrients; 3(3): 341–369.

Chiu C, Liu S, Willett W, Wolever T, Brand-Miller J, Barclay A, and Taylor A. (2011) Informing food choices and health outcomes by use of the dietary glycemic index. Nutr Rev.; 69(4): 231–242.

Foster-Powell K, Holt S, Brand-Miller J. (2002) International table of glycemic index and glycemic load values: 2002. Am J Clin Nutr;76(1): 5-56.

Goff LM, Cowland DE, Hooper L, Frost GS. (2012) Low glycaemic index diets and blood lipids: A systematic review and meta-analysis of randomised controlled trials. doi:10.1016/j.numecd.2012.06.002.

Khardori R, Nguyen D. (2012) Glucose control and cardiovascular outcomes: reorienting approach. doi: 10.3389/fendo.2012.00110.

Sonestedt E, Overby N, Laaksonen D, Birgisdottir B. (2012) Does high sugar consumption exacerbate cardiometabolic risk factors and increase the risk of type 2 diabetes and cardiovascular disease? Food Nutr Res.; 56: 10.3402/fnr.v56i0.19104.

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59 comments on “Glycemic indexes: what are they and how do they affect our health?

  1. Wonderful info and much needed! Thank you once again for an info. rich post!

  2. HF says:

    Some great points in here, which are clearly present in the scientific literature but frequently omitted by other posts I have read.

    Nice one.

  3. NutriSue says:

    Well written Jen, thanks for sharing!

    • Thanks for the comment! I honestly had no idea that using ‘a diabetic’ wasn’t the best wording, I will most definitely keep that in mind for the future. This blog is a big learning curve for me, I appreciate all the feedback I can get so I can continue to improve. Thanks for letting me know!

      • NutriSue says:

        No worries! Everyone seems to use the word ‘Diabetics’, even people with diabetes. Sometimes without really thinking about it. I was recently speaking to a woman with diabetes and she referred to herself as a diabetic. I told her about why I don’t use the term and she said that made her think about it and felt that diabetes didn’t define who she was either. Sometimes we just need a bit of a nudge and to see a different point of view to make us think differently. I hope that doesn’t sound self-righteous. I’m not trying to come across that way. I’m really into questioning things and looking at different sides of things we sometimes take for granted.

  4. Good info as always! I love your climbing pics! They inspire me! :)

  5. Table sugar is 65. Mashed white-potato: 70!
    Most people think they’re “eating smart” by eating mashed white potatoes; but they might actually be better off eating straight brown sugar!

    • Only looking at GI is probably not the best measure of good nutriiton. Adding a lot of fat to the potatoes will lower the GI, but probably does not improve their healthiness. Looking at only one factor of food has been one source of our bad nutrtition.

      • NutriSue says:

        I agree with this. The glycemic index may be a good guide, but looking at foods in isolation (not considering what they are eaten with, as well as the ripeness of the food ie; bananas) may give a false sense of how certain foods affect blood glucose levels. Also, this may be a matter of semantics, but I have diabetes and prefer to be referred to as someone ‘with diabetes’ as opposed to ‘diabetic’. Diabetes does not define who I am. And luckily, by choosing my foods wisely and eating whole foods, I’m able to keep my blood glucose levels in check!

      • I certainly don’t think that GI should be the primary focus in your diet, but definitely a consideration.Thanks for your comment! :)

  6. jimlien says:

    Reblogged this on Jim's Primal Suit and commented:
    This is probably one of the better condensed explanations of the Glycemic Index that I’ve read. Worth a read and it’s cited which makes it even better. GI plays a huge role in managing body composition and is one of the reasons why primal nutrition is low carb in nature. Primal/paleo foods tend to have lower GI values which reduces the amplitude of blood sugar and insulin spikes.

  7. moxyjen says:

    I think some reasons the GI is controversial are because we don’t always eat foods in isolation, and not everyone’s body is the same, making specific charts only applicable to part of the population. I have reactive hypoglycemia, and do very poorly with added sugar, even if I mind the limitations on my carbohydrate consumption in one sitting. Potatoes are a staple for me, but I always eat them with meat, which I was told slows the absorption. Since I cut out sugar and made potatoes my primary source of carbohydrate, my sugar levels have evened out. Counting carbs and eating what works was my strategy and it doesn’t seem to relate to the GI at all.

  8. bezzymates says:

    Thank you for posting such beneficial info. Also, I wanted to express my appreciation for visiting my little blog. Your “likes” are encouraging. :)

  9. ahappylass says:

    Great post! I am a full-time member of the health and wellness industry (if you could call it that) in a small town in the Midwest. Sometimes I wish I could just shake people until they absorbed this information. My only question: I get pretty confused with all the terminology you use. Without putting too much extra work into your next post, can you just add in which whole foods the words closely relate to? Like fructose is highest in ____kind of fruit…
    Thanks again for the concise and well supported post. It is very much appreciated.

  10. cfanningtx says:

    Fantastic post with great info!

  11. Norma Chang says:

    Great info. If people will think more about what they put into their mouth we would be a much healthier nation.

  12. Lisa says:

    Wow. Great info. I’m blown away that non-communicable are a bigger threat around the world.

  13. This was awesome! Thanks – I think i am on sensory overload…my head is spinning in information!

  14. sjanettdegeus says:

    Interesting thougs, thanks for sharing! Love the picture also! Man I do miss climbing!

  15. Mudinyeri says:

    Nice look at the GI. Thanks for putting it together and for liking my nocouchforyou.wordpress.com blog article on power foods and eating for lean muscle.

  16. Vitality2day says:

    Great info! Thank you for a well researched post. This explains why fruit never gives me suger highs, whereas candy, cake etc makes me feel high and the hung over. Not a pleasant feeling. Talking about pasta. I have heard that the longer it takes to cook it, the lower the GI :)

  17. Sweet Information, no pun intended! I climb as well. Originally from Boulder, CO but now live in Mallorca Spain and it rocks. Tons of free water soloing. Hasta luego

  18. Thanks for more good info. Regarding the reason GI being controversial is it can miss a lot about the overall healthfulness of a food. Like looking at foods only by content of iron, or magnesium. It is a helpful guide for sure. One of the problems is adding fats to carbohydrates lowers the GI, though wouldn’t be considered adding health – for example, bread with lots of butter is lower in GI than dry bread. Also, GI of individual foods does not determine the GI of a whole meal, which is how we generally eat.

  19. Great article. The University of Sydney hosts the international GI database. They have done GI studies on thousands of food items and you can find just about anything that you eat listed there.
    I wrote a post in November about runners eating Fig Newtons for energy and discussed their GI. It’s amazing that you don’t hear more about the GI in the news.
    http://imarunnerandsocanyou.wordpress.com/2012/11/27/fig-newtons-and-the-glycemic-index/

  20. [...] to macerate the fruit 2 – 3 tablespoons of sugar or maple syrup if you are obsessed with the glycemic index, like me Either of sleeve of cookies or a stale cake, cut into cubes 1 can of whipped cream or 2 [...]

  21. interesting indeed. on another note, love climbing!

  22. Bev says:

    More food for thought!! Your posts will make be a better eater yet! Love the pic too!

  23. isowhey ian says:

    Good post Jen, its good to get a comprehensive description of the GI – one does wonder how bad this situation is going to get with such unhealthy eating. It costs a fortune in medical expenses, but, especially in America, money talks and big corporations (eg Sugar) want people to keep eating unhealthy foods to keep their profits up. We need to educate people I believe to reverse this..

    • I think we really need to decouple our nutrition recommendations with our economy as well… it also doesn’t help the situation when there are SOOOOO many different views on nutrition, causes a lot of confusion even among people in the field of nutrition.

  24. [...] yourself about diet and exercise, know what foods do(e.g. their GI #) how the body works, read [...]

  25. Prosey says:

    This morning I had a bowl of organic oatmeal with some dates, cinammon and nutmeg soaked overnight in almond milk and boiled this morning for about 5 minutes or less – yummy delicious and that’ll keep me going till lunch time. Never fails.

  26. Great pic! I was very surprised to learn how much higher baked potatoes are on the glycemic index than table sugar or white bread. One of the trail races I ran served baked potato wedges at the aid stations :)

  27. Another great post as always! I shared your blog with the author of Eat to Live, I hope you don’t mind.

  28. Outstanding information. Thanks.

  29. beangoesgreen says:

    Very informative and well-presented!

  30. Rami says:

    This is a great article Jen! The only thing that seems missing is a ‘metabolic’ clarification around why higher GI foods should be avoided…

    In simple terms, because of glucose’s high affinity to react with other molecules, our bodies strictly regulate blood glucose levels to a limited amount of only 5 grams in total.

    Insulin is secreted to manage glucose levels in the blood (insulin also does many other things). More importantly, studies have shown that insulin has 3 effects as it relates to weight management: 1. insulin stimulates lipogenesis. 2. insulin inhibits gluconeogenesis. 3. insulin inhibits autophagy.

    Each of these 3 effects contribute to the chronic deterioration of your body’s metabolic processes.

    I recommend all readers to look each one of them up on Google (or whatever search engine you use) and learn more about them.

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