Glycation and the Glycemic Index

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Here’s another excerpt from my 10th book, The Secret of Vigor – How to Overcome Burnout, Restore Biochemical Balance and Reclaim Your Natural Energy

Some of the most popular New Year’s resolutions every year are:
*Lose Weight
*Get in Shape
*Reduce Stress
*Get Healthier
*Win the Lottery

The Secret of Vigor can help you with 4 out of 5 of the most popular resolution goals, so I’ll be posting excerpts from the book for the next several weeks – so please stay tuned for each installment.

If you simply can’t wait, then you can certainly get a copy at or at your favorite library or bookstore.

Glycation and the Glycemic Index
Lab researchers have assigned many foods with a rating known as the glycemic index (GI), which refers to the degree by which the food increases blood-sugar levels. For example, white bread has a GI of 69 and grapefruit has a GI of 26. Not everyone agrees on the GI of every food (more on that issue below).

A food with a high GI will rapidly increase blood-sugar levels, while a food with a low GI will have a less-pronounced effect on blood-sugar levels. The glycemic index has doubtless helped nutrition researchers gain a greater understanding of the metabolic and health properties associated with many foods. For example, several good studies show that long-term consumption of a diet with a high glycemic load (GL, which is an index of GI and total carbohydrate content of the diet) is a significant predictor of systemic inflammation and eventual weight gain, as well as a significant risk factor for diabetes and cardiovascular disease. Unfortunately, the GI and the GL represent only portions of a very complicated metabolic story. To understand this “story,” you might think of the GI and GL as representing a “glycation potential” that must be manifested via changes in oxidative balance and inflammatory balance.

Perhaps the biggest “problem” with the GI and the GL is that they are calculated for isolated foods. Nobody is (or should be) sitting down to a meal composed solely of white bread, puffed rice, or plain macaroni. These are all foods with high GIs and are therefore “banned” by some popular diets. From a purely practical point of view, even trying to determine the GI or GL value of a particular food is nearly impossible outside of a metabolic lab.

For example, something as simple and apparently straightforward as a bowl of rice shows a huge range of measured GI values, which may be due to the different varieties of rice that are available (long grain versus short grain), their fiber content (white versus brown), and even the cooking method used to prepare the rice (boiling versus steaming versus frying). Another example is carrots. Published GI values place carrots into either a “high” GI category of 92 or a “low” GI category of 32.

In addition, the GI and GL values of particular foods are significantly affected by factors that have nothing to do with the actual food, such as cooking methods (longer cooking tends to increase the GI of pasta, rice, and other foods), processing levels (smaller particle sizes tend to increase the GI of flours and other grains), and the levels of fiber, fat, and protein contained in the overall meal (higher levels of each of these components tend to reduce the GI).

Many other factors can significantly influence the GI or GL of a particular food, including the following:
* the ripeness of fruit (riper = a higher GI, due to a higher sugar content)
* the physical form of the food (for example, applesauce has a 25 percent higher GI than a whole apple)
* the proportion of different carbohydrate types in a single food (for example, rice and potatoes can have different levels of amylose, a slowly digested carbohydrate, versus amylopectin, a rapidly digested carbohydrate)
* the shape of the food (for instance, different forms of pasta can range from a GI value of 68 for macaroni to 45 for spaghetti; even linguine has a GI of 68 for thick noodles but scores a GI of 87 for thin noodles)
* processing methods (foods that are “more” processed tend to increase blood-sugar levels faster than those that are “less” processed, but it is exceedingly difficult to know the exact processes of grinding, rolling, and pressing that a product like muffin mix undergoes before it arrives on grocer’s shelves)
* preparation methods (for example, the amount of heat and water used in cooking, the time of cooking, and even the size into which the food particles are chopped prior to cooking)

The problems with the GI have led many dieticians and nutritionists to simplify their recommendations by educating their clients to eat “complex” carbohydrates (starches) instead of “simple” ones (sugars) to help control blood-sugar levels. But this approach does not necessarily ensure consumption of the right foods. For example, white bread, mashed potatoes, and chocolate cake would be a poor example of a meal consisting of “complex” carbohydrates.

In general terms, refined-grain products (“complex” or not) and potatoes tend to rapidly increase blood-sugar levels, unless they are combined with appropriate amounts of protein, fat, and fiber. Nuts, beans, legumes, and minimally processed grains (which may sometimes be labeled as “whole,” even though they have actually been processed) tend to have only a moderate effect on blood-sugar levels. Most fruits and vegetables have a small effect on blood-sugar levels, but even these foods still need to be combined with appropriate metabolic regulators in the form of added protein/fat for optimal glucose control.

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