Read Wheat Belly: Lose the Wheat, Lose the Weight and Find Your Path Back to Health Online
Authors: William Davis
The story doesn’t end at greater levels of AGEs. Higher AGE blood levels spark the expression of oxidative stress and inflammatory markers.
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The receptor for AGEs, or RAGE, is the gatekeeper to an assortment of oxidative and inflammatory responses, such as inflammatory cytokines, vascular endothelial growth factor, and tumor necrosis factor.
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AGEs therefore set an army of oxida-tive and inflammatory responses in motion, all leading to heart disease, cancer, diabetes, and more.
AGE formation is therefore a continuum. But while AGEs form at even normal blood glucose levels (fasting glucose 90 mg/dl or less), they form faster at higher blood sugar levels. The higher the blood glucose, the more AGEs form. There really is
no
level of blood glucose at which AGE formation can be expected to cease entirely.
Being nondiabetic does
not
mean that you will be spared such fates. AGEs accumulate in nondiabetics and wreak their age-advancing effects. All it takes is a little extra blood sugar, just a few milligrams above normal, and—voilà—you’ve got AGEs doing their dirty work and gumming up your organs. Over time, you too can develop all the conditions seen in diabetes if you have sufficient AGE accumulation.
Along with 25.8 million diabetics, there are 79 million prediabetics in the United States today.
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There are many more Americans who don’t yet meet the ADA criteria for prediabetes, but still experience plenty of high blood sugars after consuming some amount of carbohydrate that increases blood sugar—i.e., blood sugars high enough to trigger more AGEs than normal. (If you doubt that blood sugars increase after eating, say, an apple or
a slice of pizza, just pick up a simple glucose meter from your pharmacy. Test your blood sugar one hour after consuming the food of interest. More often than not, you will be shocked to see how high your blood glucose soars. Remember my two slices of whole wheat bread “experiment”? Blood glucose 167 mg/dl. That’s not uncommon.)
While eggs don’t increase blood sugar, nor do raw nuts, olive oil, pork chops, or salmon, carbohydrates do—all carbohydrates, from apples and oranges to jelly beans and seven-grain cereal. As we discussed earlier, from a blood sugar standpoint, wheat products are worse than nearly all other foods, skyrocketing blood sugar to levels that rival those of a full-blown diabetic—even if you’re nondiabetic.
Remember, the “complex” carbohydrate contained in wheat is the unique variety of amylopectin, amylopectin A, a form distinct from amylopectin in other carbohydrates such as black beans and bananas. The amylopectin of wheat is the form most readily digested by the enzyme amylase, thus explaining the greater blood sugar-increasing property of wheat products. The more rapid and efficient digestion of wheat amylopectin means higher blood sugars over the ensuing two hours after consumption of wheat products, which in turn means greater triggering of AGE formation. If AGE formation was a contest, wheat would win nearly all the time, beating out other carbohydrate sources such as apples, oranges, sweet potatoes, ice cream, and chocolate bars.
Thus, wheat products such as your poppy seed muffin or roasted vegetable focaccia are triggers of extravagant AGE production. Put 2 and 2 together: Wheat, because of its unique blood glucose-increasing effect, makes you age faster. Via its blood sugar/AGE-increasing effects, wheat accelerates the rate at which you develop signs of skin aging, kidney dysfunction, dementia, atherosclerosis, and arthritis.
While we’ve focused so far on AGEs that form in the body and are largely derived from consumption of carbohydrates, there is a second source of AGEs that come directly from the diet: animal products. This can get awfully confusing, so let’s start from the beginning.
AGEs originate from two general sources:
Endogenous AGEs.
These are the AGEs that form within the body, as we’ve discussed. The main pathway to forming endogenous AGEs starts with blood glucose. Foods that increase blood glucose increase endogenous AGE formation. Foods that increase blood glucose the most trigger the greatest AGE formation. This means that all carbohydrates, all of which increase blood glucose, trigger endogenous AGE formation. Some carbohydrates increase blood glucose more than others. From an endogenous AGE viewpoint, a Snickers bar triggers AGE formation only modestly, while whole wheat bread triggers AGEs vigorously, given the greater blood glucose-increasing effect of whole wheat bread.
Interestingly, fructose, another sugar that has exploded in popularity as an ingredient in modern processed foods, increases AGE formation within the body up to several hundredfold more than glucose.
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Occurring as high-fructose corn syrup, fructose often accompanies wheat in breads and baked products. You will be hard-pressed to find processed foods
not
containing fructose in some form, from barbecue sauce to dill pickles. Also note that table sugar, or sucrose, is 50 percent fructose, the other 50 percent being glucose. Maple syrup, honey, and agave syrup are other fructose-rich sweeteners.
Exogenous AGEs.
Exogenous AGEs are found in foods that enter the body as breakfast, lunch, or dinner. In contrast to endogenous AGEs, they are not formed in the body, but are ingested preformed.
Foods vary widely in their AGE content. The foods richest in AGEs are animal products, such as meats and cheese. In particular, meats and
animal products heated to high temperature, e.g., broiling and frying, increase AGE content more than a thousandfold.
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Also, the longer an animal product food is cooked, the richer its AGE content becomes.
An impressive demonstration of the power of exogenous AGEs to impair arterial function was demonstrated when identical diets of chicken breast, potatoes, carrots, tomatoes, and vegetable oil were consumed by two groups of diabetic volunteers. The only difference: The first group’s meal was cooked for ten minutes by steaming or boiling, while the second group’s meal was cooked by frying or broiling at 450°F for twenty minutes. The group given food cooked longer and at a higher temperature showed 67 percent reduced capacity for arterial relaxation, along with higher AGE and oxidative markers in the blood.
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Exogenous AGEs are found in meats that are also rich in saturated fat. It means that saturated fat was wrongly accused of being heart-unhealthy because it often occurred in the company of the real culprit: AGEs. Cured meats, such as bacon, sausage, pepperoni, and hot dogs, are unusually rich in AGEs. So meats are not intrinsically bad; but they can be made unhealthy through manipulations that increase AGE formation.
Beyond the diet prescription of the
Wheat Belly
philosophy, i.e., eliminate wheat while maintaining restricted intake of carbohydrates, it is wise to avoid sources of exogenous AGEs, namely cured meats, meats heated to high temperature (>350°F) for prolonged periods, and anything deep-fried. Whenever possible, avoid well-done and choose meats cooked rare or medium. (Is sashimi the perfect meat?) Cooking in water-based, rather than oil-based, liquids also helps limit AGE exposure.
All that said, AGE science is still in its infancy, with many details yet to be discovered. Given what we know about the potential long-term effects of AGEs on health and aging, however, I do not believe it is premature to start giving some thought to how to reduce your personal AGE exposure. Perhaps you’ll thank me on your hundredth birthday.
There is a widely available test that, while not capable of providing an index of biological age, provides a measure of the
rate
of biological aging due to glycation. Knowing how fast or slow you are glycating the proteins of your body helps you know whether biological aging is proceeding faster or slower than chronological age. While AGEs can be assessed via biopsy of the skin or internal organs, most people are understandably less than enthusiastic about a pair of forceps being inserted into some body cavity to
snip a piece of tissue. Thankfully, a simple blood test can be used to gauge the ongoing rate of AGE formation: hemoglobin A1c, or HbAlc. HbAlc is a common blood test that, while usually used for the purpose of diabetes control, can also serve as a simple index of glycation.
Hemoglobin is the complex protein residing within red blood cells that is responsible for their ability to carry oxygen. Like all other proteins of the body, hemoglobin is subject to glycation, i.e., modification of the hemoglobin molecule by glucose. The reaction occurs readily and, like other AGE reactions, is irreversible. The higher the blood glucose, the greater the percentage of hemoglobin that becomes glycated.
Red blood cells have an expected life span of sixty to ninety days. Measuring the percentage of hemoglobin molecules in the blood that are glycated provides an index of how high blood glucose has ventured over the preceding sixty to ninety days, a useful tool for assessing the adequacy of blood sugar control in diabetics, or to diagnose diabetes.
A slender person with a normal insulin response who consumes a limited amount of carbohydrates will have approximately 4.0 to 4.8 percent of all hemoglobin glycated (i.e., an HbAlc of 4.0 to 4.8 percent), reflecting the unavoidable low-grade, normal rate of glycation. Diabetics commonly have 8, 9, even 12 percent or more glycated hemoglobin—twice or more the normal rate. The majority of nondiabetic Americans are somewhere in between, most living in the range of 5.0 to 6.4 percent, above the perfect range but still below the “official” diabetes threshold of 6.5 percent.
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In fact, an incredible 70 percent of American adults have an HbAlc between 5.0 percent and 6.9 percent.
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HbA1c does not have to be 6.5 percent to generate adverse health consequences. HbAlc in the “normal” range is associated with increased risk for heart attacks, cancer, and 28 percent increased mortality for every lpercent increase in HbAlc.
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That trip to the all-you-can-eat pasta bar, accompanied by a couple of slices of Italian bread and finished off with a little bread pudding, sends your blood glucose up toward 150 to 250 mg/dl for three or four hours; high glucose for a sustained period glycates hemoglobin, reflected in higher HbAlc.
The lenses of your eyes are the wonderful, naturally engineered optical devices that are part of the ocular apparatus allowing you to view the world. The words you are now reading present images, focused by the lenses on your retina, then transposed into nervous system signals interpreted by your brain as black letter images on white background. Lenses are like diamonds: Without flaws, they are crystal clear, allowing the unimpeded passage of light. Pretty damn amazing, when you think about it.
Flawed, however, and the passage of light will be distorted.
Lenses consist of structural proteins called crystallins that, like all other proteins of the body, are subject to glycation. When proteins in the lenses become glycated and form AGEs, the AGEs cross-link and clump together. Like the little specks that can be seen in a flawed diamond, little defects accumulate in the lenses. Light scatters upon hitting the defects. Over years of AGE formation, accumulated defects cause opacity of the lenses, or cataracts.
The relationship of blood glucose, AGEs, and cataracts is well-defined. Cataracts can be produced within as little as ninety days in lab animals just by keeping blood glucose high.
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Diabetics are especially prone to cataracts (no surprise there), with as much as fivefold increased risk compared to nondiabetics.
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In the United States, cataracts are common, affecting 42 percent of males and females between the ages of fifty-two and sixty-four, and increasing to 91 percent between the ages of seventy-five and eighty-five.
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In fact, no structure in the eye escapes the damaging effects of AGEs, including the retina (macular degeneration), the vitreous (the gellike liquid filling the eyeball), and the cornea.
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Any food that increases blood sugar therefore has the potential to glycate the crystallins of the lenses of your eyes. At some point, injury to the lens exceeds its limited capacity for defect resorption and crystallin renewal. That’s when the car in front of you is lost in a blurry haze, unimproved by putting on your glasses or squinting.
HbAlc—i.e., glycated hemoglobin—therefore provides a running index of glucose control. It also reflects to what degree you are glycating body proteins beyond hemoglobin. The higher your HbAlc, the more you are also glycating the proteins in the lenses of your eyes, in kidney tissue, arteries, skin, etc.
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In effect, HbAlc provides an ongoing index of aging rate: The higher your HbAlc, the faster you are aging.
So HbAlc is much more than just a feedback tool for blood glucose control in diabetics. It also reflects the rate at which you are glycating other proteins of the body, the rate at which you are aging. Stay at 5 percent or less, and you are aging at the normal rate; over 5 percent, and time for you is moving faster than it should, taking you closer to the great nursing home in the sky.
So foods that increase blood glucose levels the most and are consumed more frequently are reflected by higher levels of HbAlc that in turn reflect a faster rate of organ damage and aging. So if you hate your boss at work and you’d like to hasten his approach to old age and infirmity, bake him a nice coffee cake.
You’ll recall that foods made from wheat increase blood sugar more than nearly all other foods, including table sugar. Pitting wheat against most other foods would be like putting Mike Tyson in the ring against Truman Capote: no contest, a blood sugar KO in no time. Unless you’re a premenopausal, size 2, twenty-three-year-old female long-distance runner who, by virtue of minimal visceral fat, vigorous insulin sensitivity, and the advantages of abundant estrogen, enjoys little increase in blood sugar, two slices of whole wheat bread will likely launch your blood sugar into the 150 mg/dl range or higher—more than enough to set the AGE-forming cascade in motion.