Imagine a juicy piece of barbecued meat, marinated in a sweet BBQ sauce and grilled over flaming charcoal until it is a nice brown color with crispy pieces on the outside. Sounds good? Imagine your internal organs processed in the same way and you have a picture of the formation of advanced glycation end-products (AGEs), one of the most harmful processes associated with chronic inflammation. AGEs are the products of sugars and proteins binding together and, in the human cells, it is damage that cannot be undone. While all human tissue is subject to damage by AGEs, the lining of blood vessels in diabetics is especially sensitive leading to heart disease, long-lived nerve cells rapidly accumulate damage resulting in neuropathy, microvascular destruction leads to retinopathy and nephropathy, and AGEs are implicated in the destruction of beta cells in the pancreas. Where do these AGEs come from?
Exogenous AGEs come from your food and drink. Basically, any food preparation with high heat that involves browning is creating AGEs … browned meats, bread crust, caramel coloring in processed foods, and even my beloved dark roast coffee beans. Raw foods and foods cooked in the presence of water contain far less AGEs. Water prevents the proteins and sugars from binding. An example would be a raw chicken breast which contains a moderate amount of AGEs with 7686 units. If you boil it, you will increase the AGEs about 50%, microwaving increases AGEs two-fold, broiling increases AGEs eight-fold, and frying will multiply AGEs ten-fold. It’s not just about meat. Roasted nuts are one of the highest sources of AGEs. Healthy fresh butter has four times as much AGEs by weight as roasted meat. In general, processed meat and other processed foods are much higher in AGEs. See list of AGEs in common foods here.
Advocates of raw vegan diets point out that this way of eating has far less AGEs because raw fruits and vegetables have very little AGEs and cooked meat is never consumed. Makes sense in theory, but studies of long-term vegetarians have shown that they actually have similar or higher levels of plasma AGEs than people eating normal American diets. How can this be? It seems that vegans eat a relatively high carb diet with lots of fructose from fruits and zero carnisone or taurine from meat. This brings us to the other source of AGEs.
Endogenous AGEs are produced in the human body when sugars bind with proteins. Diabetics are especially susceptible to this process which is believed to be the source of most diabetic complications. The best way for diabetics to lower their plasma AGEs level is to lower their A1c which correlates highly with AGEs. As AGEs are a product of inflammation, they also correlate highly with CRP. Limiting carbohydrate in the diet is one of the best ways to minimize the production of AGEs. One sugar is especially deadly – fructose, which is far too abundant in the modern diet. According to Wikipedia:
Endogenous glycations occur mainly in the bloodstream to a small proportion of the absorbed simple sugars: glucose, fructose, and galactose. It appears that fructose and galactose have approximately ten times the glycation activity of glucose, the primary body fuel.
Meat, as I have explained, can be cooked into a high-AGEs food, but it is also a source of two substances that inhibit the production of AGEs in the human body. The amino acids carnosine and taurine are only available in animal protein. For this reason, a low carb diet with little fructose and abundant animal protein may be the best diet for diabetics trying to limit damaging AGEs. Ironic, as cooked meat is one of the highest sources of exogenous AGEs.
Besides carnosine and taurine, there are several nutritional supplements which reduce the production of AGEs. The vitamins benfotiamine (lipid soluble thiamine), alpha lipoic acid (ALA) and lycopene (found in tomatoes) are well known as beneficial in preventing diabetic complications. Some phytonutrients are helpful including quercetin, EGCG (green tea extract), curcumin (turmeric extract), resveratrol (found in red wine) and others.
How to reduce AGEs? Keep your blood sugar low, eat low-carb, enjoy fresh raw veggies, cook with water, limit browned foods, avoid fructose like the plague, restrict processed foods, get enough animal protein, and consider supplements to inhibit the production of AGEs.