We have mostly explored how dietary sugars can damage proteins within our bodies (and within our joints specifically).  But what is the effect of eating foods that are already sugar damaged (glycated) before we eat them.  As with the browned crust of our bread and browned skin of a turkey, we consume many foods that have been glycated (browned or sugar damaged proteins) before we consume them. Is there a consequence to eating these foods? 

This is a question that has received much more attention in recent years.  There is now strong evidence that people who have conditions such as diabetes, obesity, and others may experience negative effects from consuming sugar-damaged proteins from their food—sometimes called dietary glycotoxins. The early evidence also suggest that there might even be negative effects in healthy people. 

People with diabetes are the most carefully studied group at risk to these glycotoxins.  In one study, two groups of people with diabetes consumed a diet low in glycotoxins and then switched to a diet 5 times higher in glycotoxins.  Doctors wanted to see whether the diets high in glycotoxins caused a rise in inflammation chemicals in the blood and in white blood cells.

The inflammation chemicals measured have cumbersome names like TNFα and CRP. (Please bear with us, as we briefly discuss these technical terms.)  On the diet high in glycotoxin, TNFα increased by 86 percent.  On the low glycotoxin diet, TNFα decreased by 20 percent. On the diet high in glycotoxin, C-reactive protein increased by 35 percent.  On the low glycotoxin diet, CRP decreased by 20 percent.  A molecule that injures blood vessels (VCAM-1) declined by 20 percent on the low glycotoxin diet and rose by 4 percent on the high glycotoxin diet.

Inflammation Molecule           High Glycotoxin               Low Glycotoxin
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TNFα                                          86% increase                  20% decrease
CRP                                            35% increase                  20% decrease
VCAM-1                                      4% increase                  20% decrease

The doctors in this study concluded that dietary glycotoxins (which they also called A.G.E.s) trigger the release of inflammation in people with diabetes.  They wrote that, “Thus in diabetes, environmental (dietary) AGEs promote inflammatory mediators, leading to tissue injury.”  They also noted that reducing the glycotoxins in the diet “suppresses these effects” of inflammation.  

[Vlassara, H, Cai, W, Crandall, J, Goldberg, T, et al. Inflammatory mediators are induced by dietary glycotoxins, a major risk factor for diabetic angiopathy. Proc Natl Acad Sci U S A 2002;99(24):15596-601.]

These glycotoxins in the diet may also affect people who are generally healthy.  Doctors as Mount Sinai School of Medicine studied 172 young (less than 45 years) and older (older than 65 years) people who did not have any appreciable health problems.  The doctors tested the study subjects’ blood for glycotoxins, for evidence of oxidative stress, and for evidence of insulin resistance.  C-reactive protein was among several of the inflammation chemicals measured. The study clearly showed the dietary glycotoxins were linked to higher inflammation.

[Uribarri, J, Cai, W, Peppa, M,, et al. Circulating glycotoxins and dietary advanced glycation endproducts: two links to inflammatory response, oxidative stress, and aging.  J Gerontol A Biol Sci Med Sci 2007;62(4):427-33.]

 Doctors writing in the American Journal of Pathology make a fairly important statement about their findings of feeding advanced glycation endproducts in the diet (dietary glycotoxins).  They wrote, "We previously showed that the content of advanced glycation end products (AGE) in the diet correlates with serum AGE levels, oxidant stress [free radical stress], organ dysfunction, and lifespan."  These doctors went on to feed a calories restricted diet, which lowered the amount of AGE and the amount of oxidative stress.  These findings add to the evidence that consuming dietary glycotoxins adds to biochemical stress and reducing calories (or reducing intake of glycotoxins) reduces these biochemical stressors. 

[Cai, W, He, JC, Chen, X, et al. Oral Glycotoxins Determine the Effects of Calorie Restriction on Oxidant Stress, Age-Related Diseases, and Lifespan. Am J Pathol 2008;173:327-336.]

So, will reducing your intake of dietary glycotoxins help your joint pain, slow your arthritis, or keep you from getting arthritis?  Doctors aren't yet sure about this. While the early studies on dietary glycotoxins and inflammation are suggestive, they are not yet conclusive. But we do know this.  The types of foods that are low in glycotoxins are foods considered part of a healthy diet and generally part of an anti-inflammatory diet.  Fruits, vegetables, legumes, whole grains rich in fiber, seeds, and nuts are a central part of a low glycotoxin diet.  Those that are not excessively cooked or prepared are even lower in glycotoxins.  Thus, a low glycotoxin diet has the potential to be extremely helpful for anyone who wants to preserve joint health over the long term.  For those wishing short term help, we believe that consuming foods low in glycotoxins would be part of an overall healthy diet. 

Scientists have known for many years that cooking proteins with sugars in the absence of water creates advanced glycation endproducts (A.G.E.).  So, baking, roasting, and broiling cause these glycotoxins to accumulate in the foods we prepare. Cooking with water by boiling, steaming, and a wet saute method is a way to prepare foods low in glycotoxins. 

According to new findings, brown foods, such as brown cookies, brown bread crust, brown basted meats, brown beans, and even brown coffee beans may increase nerve damage, particularly in diabetics who are unusually susceptible to nerve damage.  On the other hand, since steamed and boiled vegetables, whole grains, beans and fruits are made with water, they do not contain significant amounts of A.G.E.s and do not harm susceptible people.  One more reason that you should eat your fruits, vegetables whole grains and beans, fresh, boiled or steamed.

This does not mean that you give up cooking your food.  It merely alerts us to the fact that cooking methods can increase A.G.E. proteins in the body and that they may, when coupled with other factors, contribute to poor health over time.  Eating more whole foods and ensuring that your protective nutrient defenses are in place is one approach minimizing the A.G.E. effect.  Nutrient defenses are turning out to be a vital insurance policy.

Oxidative stress-inducing carbonyl compounds from common foods: novel mediators of cellular dysfunction.

HIGH LEVELS OF GLYCATING AGENTS IN BEVERAGES

Methylglyoxal: its presence and potential scavengers

Methylglyoxal: Its Presence in Beverages and Potential Scavengers

A detailed summary of how dietary sugars damage joint proteins