AGEs stand for “advanced glycation end products“. AGEs are promoters of high oxidative stress and, as such, they are known to play an important role in the development of cardiovascular disease in diabetics.
AGEs are produced by our bodies internally under certain conditions, such as hyperglycemia. They are also present in fairly high amounts in the typical Western diet. Research published in the Journal of the American Diet Association (Goldberg et al 2004) and in Critical Review of Food Science and Nutrition (O’Brien and Morrissey 1989), show that AGEs are present in high levels in dietary mixtures of proteins, lipids, and sugars processed under elevated temperatures, such as broiling, roasting, or grilling.
HIgh AGE foods and flow-mediated dilation
According to a recent article in Diabetes Care (October 2007), a single ingestion of a drink high in AGEs results in an immediate impairment of a normal blood vessel function, known as “flow-mediated dilation” or FMD. FMD is the expected dilation of arteries that occurs as a response to decreased blood flow (a.k.a. ischemia).
Impairment of FMD is widely accepted as an early indication of endothelial dysfunction, a precursor to atherosclerosis. It is postulated that repeated disturbances of endothelial function over time may lead to cardiovascular disease both in diabetics and non-diabetics.
The authors of the study, Jaime Uribarri and colleagues, had previously demonstrated that a diet rich in AGEs impaired FMD. However, because that diet also contained other substances that can cause the vasodilatory defect, they wanted to repeat the study using a “food” that was “free of carbohydrates or lipids or other known vasoactive substances.”
The researchers created the high AGEs food by combining caffeine-free Coca-Cola light with glucose and concentrating it by a rotary evaporation process. The article states that the resultant beverage is AGE-rich, but free of glucose or lipids (it’s not clear to me what happened to the glucose they added to the diet Coke—but heck, I am not a chemist so I just have to take the researchers word for this.)
Anyway, 44 diabetic subjects and 10 non-diabetic subjects got to drink this concoction to see what it did to their FMD. It turns out both diabetics and non-diabetics had a reduction of FMD after drinking the AGE-rich drink. There was no change in FMD when the subjects were asked to drink water.
The authors speculate that ingestion of diets rich in high-AGE foods could, over time, cause multiple insults to the body’s blood vessels and, eventually result in permanent endothelial dysfunction and overt vascular disease.
The accompanying editorial
An accompanying editorial by Dandona et al., in the same journal, points out that a reduction in FMD has been associated with an increase in cardiovascular risk. And that multiple studies over the past 10 decades have shown associations between diet and alterations in FMD. One study cited in the editorial (Plotnik et al, JAMA, 1997) documented a predictable reduction in FMD related to eating high-fat, high-carbohydrate fast food. This was prevented by pretreatment with antioxidants.
We are just beginning to scratch the surface of the relationship between ingestion of certain macronutrients and the relationship to insults to the vascular system. Although we know certain foodstuffs, such as saturated and trans-fats, are bad for us, this new line of research on AGEs opens up a whole new avenue to explore—the relationship between how we combine foods, process and cook foods, and their impact on our vascular (and thus our entire body’s) health and well-being.
I look forward to exploring more research on this fascinating and important topic.