6/2/2022 0 Comments THE GLYCEMIC INDEX# fibre# diabetes management# nutrition
Introduction When we consume carbohydrates in our diet, these are digested and broken down into much simpler sugar molecules (such as glucose) that are then absorbed in the body, to enter the blood stream. When glucose and other simple sugar molecules enter into the blood, it means that the level in the blood stream rises. This rise would then lead to a response in the body. The normal response is the release of insulin from the pancreas which exerts its effect in trying to control the level of glucose that has entered the bloodstream following consumption of a meal. How the insulin does this may be by either facilitating the entry of glucose into the cells to be used for energy, and what extra is not needed as energy, the insulin may also help in the process of converting this extra glucose into fat that is to be stored in the body. So, we see here, the action of insulin in response to glucose entering the blood following consumption of a carbohydrate meal. It is worth noting that not all carbohydrates are the same! Indeed, carbohydrates are a class that encompasses a whole family of sugars, ranging from very simple to more complex structures. Carbohydrates carry then, a varied complexity in their structures and it is this characteristic that makes it an interesting topic when we begin to talk about the theme of glycemic index. What is glycemic index? So, what exactly is the glycemic index? Well, it is a tool. A useful management and control tool. That is, for managing weight, with usefulness in controlling blood sugar levels. As it helps us to make certain decisions about carbohydrate food choice. It gives a numerical value, which is a score. But you may wondering, where did this tool come from? So, this tool has been derived from clinical type investigations that looked into the comparisons between how the body responds to sugars that enter the blood stream following consumption of specific carbohydrate food (50g) with the response to an equal portion of pure glucose in healthy volunteers. So, in the fasting state, the person receives an amount of carbohydrate as food. This may automatically cause a rise in blood glucose level. Then insulin level rises also to control this rise in blood glucose. But what this index is actually measuring is the extent or amount by which the glucose level rises within the blood stream following the consumption of specified food within a set time frame compared to the extent or amount of response of an equal portion of pure glucose in the same time frame. So, it measures an extent or amount within a set time frame, this is a rate. We see that glucose was chosen as the reference point for these investigations. From this point, different carbohydrate foods would be given a specific numerical value that allows for comparison with the glucose value. Pure glucose is given a value of 100. And the scale moves from 0 to 100 and foods may be ranked as low, moderate or high. high- (≥70), moderate- (56-69), or low-GI (≤55) relative to pure glucose (GI=100) The lower the numerical value, the less rapid glucose rise (less spiking) and hence more controlled the response over glucose levels in the body by insulin. So, the glycemic index for glucose is 100 and all other foods are given a value that will be used to compare with the value of glucose. But it also means, that carbohydrate foods can be compared with other carbohydrate foods, all in reference to the glucose value of 100. What is glycemic Load? Glycemic index gives a rate, but the glycemic load gives us more absolute information. It tells us the absolute value for which the glucose in the blood can rise, following consumption of the carbohydrate food. We can receive information from the glycemic load about the amount of glucose that is actually being delivered per serving of that food. So, glycemic index helps us to interpret a response rate, while glycemic load gives us more information about the value of glucose that was delivered per serving of that food, thereby revealing the impact of the food, indicating to us how much a carbohydrate a person may typically consume. What is the relationship between glycemic load and index? Multiply the Glycemic Index rating of a food by number of carbohydrates in a serving, then divide this by 100. i.e [Glycemic index x Grams of carbohydrates] / 100 Glycemic load ranges: Low GL: 10 or less Medium GL: 11 to 19 High GL: 20 or higher To find the amount of available carbohydrates in packaged foods, simply check the nutrition facts label. What is the significance of glycemic index for our health? The glycemic index helps us to take note of the foods that may cause the insulin to linger in the blood more than the usual time, as it works to control blood glucose levels. Foods that carry high glycemic index values are more likely to cause the linger of the insulin in the blood. It is this lingering effect of insulin that may start a cascade of unfavourable health events in the body: -raises serum triglyceride levels and low-density lipoproteins (associated with increased cardiovascular disease risk) -high blood pressure -diabetes -decreased insulin sensitivity -opening pathways that may lead to cellular proliferation, and hence cancer formation Behaviourally: -increased appetite, -sugar cravings -lethargy -mood swings It is the fibre component in the carbohydrate food that allows for the slowing of digestion and hence slower release and greater control of glucose in the blood. Short Arguments for the use of glycemic index -it may be viewed as an objective comparative, management and control tool for making healthier food choices, thereby minimizing risk of insulin-related health problems -Also helps with foods choices that may prevent the onslaught of unpleasant behavioural effects, such as food cravings and lethargy. -Beneficial and useful in weight management, especially in diabetics and pre-diabetics. -May offer therapeutic benefit in the management of epileptic seizures in children, as it relates to stabilizing blood glucose ---------------------------------------------- Short Arguments against the use of glycemic index -information is limited and therefore can be misleading as it does not provide detailed insight into the quality of food. We can have less healthy food with higher content of saturated fat, yet carrying a low glycemic index. A low value does not absolutely suggest a healthier food option, as we need to look at both quantity and quality of all the food components that make up the food. -doesn’t provide absolute information on how much carbohydrate the body is actually receiving per serving of food. For example, watermelon has a high glycemic index of around 80 but a glycemic load of only 5. So, the impact of food consumed is not appreciated with the use of this index. -tool is targeted more specifically towards diabetics, not so much the general population in the management of their care. -Value is applied to a single food as part of the meal, yet when we consume food, we do so through the whole meal (in breakfast, lunch, dinner). The value then does not take into account the response from a mixed or combination of food consumption in the sitting of a meal that is, in the real-world setting. References:
https://www.bouldermedicalcenter.com/understanding-glycemic-index/ https://pubmed.ncbi.nlm.nih.gov/12081850/ https://medicalxpress.com/news/2022-05-glycemic-index-counterproductive-americans-healthier.html Jill Nicholls, Perspective: The Glycemic Index Falls Short as a Carbohydrate Food Quality Indicator to Improve Diet Quality, Frontiers in Nutrition (2022). https://www.frontiersin.org/articles/10.3389/fnut.2022.896333/full https://www.health.harvard.edu/diseases-and-conditions/the-lowdown-on-glycemic-index-and-glycemic-load https://lpi.oregonstate.edu/mic/food-beverages/glycemic-index-glycemic-load https://healthresearchfunding.org/difference-glycemic-index-glycemic-load/ https://pubmed.ncbi.nlm.nih.gov/31374573/
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