. Back then, it was a matter of novelty, convenience, and, yes, taste.
What did we do to our pancreases eating such insulin-stimulating foods through childhood, teenage years, and into early adulthood? Did our eating habits as children and young adults create diabetes many years later? Could sugary breakfast cereals, snacks, and candy in virtually unlimited quantities have impaired our pancreas’ ability to produce insulin, leading to pre-diabetes and diabetes many years later?
A phenomenon called glucose toxicity underlies the development of diabetes and pre-diabetes. Glucose toxicity refers to the damaging effect that high blood sugars (glucose) have on the delicate beta cells of the pancreas, the cells that produce insulin. This damage isirreversible: once it occurs, it cannot be undone, and the beta cells stop producing insulin and die. The destructive effect of high glucose levels on pancreatic beta cells likely occurs through oxidative damage, with injury from toxic oxidative compounds like superoxide anion and peroxide. The pancreas is uniquely ill-equipped to resist oxidative injury, lacking little more than rudimentary anti-oxidative protection mechanisms.
Glucose toxicity that occurs over many years eventually leaves you with a pancreas that retains only 50% or less of its original insulin producing capacity. That’s when diabetes develops, when impaired pancreatic insulin production can no longer keep up with the demands put on it.
(Interesting but unanswered question: If oxidative injury leads to beta cell dysfunction and destruction, can antioxidants prevent such injury? Studies in cell preparations and animals suggest that anti-oxidative agents, such as astaxanthin and acetylcysteine, may block beta cell oxidative injury. However, no human studies have yet been performed. This may prove to be a fascinating area for future.)
Now that 50% of American have diabetes or pre-diabetes, how much should we blame on eating habits when we were younger? I would wager that eating habits of youth play a large part in determining potential for diabetes or pre-diabetes as an adult.
The lesson: Don’t allow children to repeat our mistakes. Letting them indulge in a lifestyle of soft drinks, candy, pretzels, and other processed junk carbohydrates has the potential to cause diabetes 20 or 30 years later, shortening their life by 10 years. Kids are not impervious to the effects of high sugar, including the cumulative damaging effects of glucose toxicity.
Here's a half-truth I often encounter in low-carb discussions:
Saturated fat increases large LDL particles
For those of you unfamiliar with the argument, I advocate a low-carbohydrate approach, specifically elimination of all wheat, cornstarch, and sugars, to reduce expression of the small LDL pattern (not to mention reduction of triglycerides, relief from acid reflux and irritable bowel, weight loss, various rashes, diabetes, etc). Small LDL particles have become the most common cause for heart disease in the U.S., exploding on the scene ever since agencies like the USDA and American Heart Association have been advising the public to increase consumption of "healthy whole grains."
This has led some to make the pronouncement that saturated fat increases large LDL, thereby representing a benign effect.
Is this true?
It is true, but only partly. Let me explain.
There are two general categories of factors causing small LDL particles: lifestyle (overweight, excess carbohydrates) and genetics (e.g., variants of the gene coding for cholesteryl-ester transfer protein, or CETP).
If small LDL is purely driven by excess carbohydrates, then adding saturated fat will reduce small LDL and increase large LDL.
If, on the other hand, your small LDL is genetically programmed, then saturated fat will increase small LDL. In other words, saturated fat tends to increase the dominant or genetically-determined form of LDL. If your dominant genetically-determined form is small, then saturated fat increases small LDL particles.
So to say that saturated fat increases large LDL is an oversimplification, one that can have dire consequences in the wrong situation.
University of Toronto nutrition scientist, Dr. David Jenkins, was the first to quantify the phenomenon of "glycemic index," describing how much blood sugar increased over 90 minutes compared to glucose. The graph is from their 1981 study, The glycemic index of foods: a physiologic basis for carbohydrate exchange. The research originated with an effort to characterize carbohydrates for diabetics to gain better control over blood sugar.
Since Dr. Jenkins’ original work, thousands of clinical studies have been performed by others exploring this concept. The food industry has also devoted plenty of effort exploiting it (e.g., low-glycemic index noodles, low-glycemic index cereals, etc.).
Most Americans are now familiar with the concept of glycemic index. You likely know that table sugar has a high glycemic index (60), increasing blood sugar to a similar degree as white bread (glycemic index 71). Oatmeal (slow-cooked) has a lower glycemic index (48), since it increases blood sugar less than white bread.
A number of studies have shown that when low glycemic index foods replace high glycemic index foods (e.g., whole wheat bread in place of cupcakes), people are healthier: less diabetes, less heart attack, less high blood pressure. Books have been written about glycemic index, touting its benefits for health and weight control. Health-conscious people will try to substitute low-glycemic index foods for high-glycemic index foods.
So what’s not to like here?
There are several fundamental flaws with the notion that low-glycemic index foods are good for you:
1) Check your blood sugar after a low-glycemic index food like oatmeal. Most non-diabetic adults will show blood sugars in the 140 to 200 mg/dl range. The more central (visceral) fat you have, the higher the value will be. In other words, an apparently “healthy” whole grain food like oatmeal can generate extravagantly high blood sugars. Repeated high blood sugars of 125 mg/dl or greater after eating increase heart disease risk by 50%.
2) Foods like whole wheat pasta have a low glycemic index because the blood sugar effect over the usual 90 minutes is increased to a lesser degree. The problem is that it remains increased for an extended period of up to several hours. In other words, the blood sugar-increasing effect of pasta, even whole grain, is long and sustained.
3) Low-glycemic index foods trigger other abnormalities, such as small LDL particles, triglycerides, and c-reactive protein (a measure of inflammation). While they are not as bad as high-glycemic index foods, they are still quite potent triggers.
Low-glycemic index foods trigger the very same responses as high-glycemic index foods—they’re just less bad. But less bad does not equate to good. Low-glycemic index foods cause weight gain, trigger appetite, increase blood pressure, and lead to the patterns that cause heart disease.
High-glycemic index foods are bad for you. This includes foods made with white flour (bagels, white bread, pretzels). Low-glycemic foods (whole grain bread, whole wheat crackers, whole wheat pasta) are less bad for you—but they are not necessarily good.
Don’t be falsely reassured by foods because they are billed as “low-glycemic index.” View low-glycemic index foods as indulgences, something you might have once in a while, since a slice of whole grain bread is really not that different from a icing-covered cupcake.
