Our diets are filled with sugars that damage joint tissue through the well-defined chemcial reaction called glycation. While there are many different types of sugars, the sugars most frequently consumed and most commonly known to contribute to sugar damage of joints include:

1. Glucose
2. Fructose
3. Galactose

Two other molecules found in our foods are even more powerful at damaging proteins of the joints (and other tissues).  These are called:

1. Glyoxal

2. Methylglyoxal

Glucose is in common table sugar.  Glucose and fructose are found in high fructose corn syrup in large amounts.   Galactose (part of the milk sugar lactose) is found in milk products, such as milk and ice cream.  Fructose is twice as strong at glycating our joint proteins as is glucose. In lab tests, glycation of blood hemoglobin was more than 7 times greater with fructose than with glucose.  The rate of protein cross-linking was 10 times greater with fructose than with glucose. This makes fructose one of the most troubling dietary sugars for those wishing to preserve joint health.  On the other hand, it means that by reducing your intake of this dietary sugar, you might significantly slow the damage that might have occurred to your joints over time. 

[Bunn, HF, Higgins, PJ. Reaction of monosaccharides with proteins: possible evolutionary significance. Science 1981;213:222-224.]

Let's put this in some perspective.  In general, sugar intake in the U.S. has increased from 119 pounds in 1970 to 142 pounds in 2003.  With specific reference to fructose, our intake in 1970 was just under 1 gram per day. In 1997, the average American consumed more than 40 grams per day—a greater than 80-fold increase.  This is important to consider.  We have taken one of the most powerful agents that glycate (sugar damage) our joint proteins and we have increased our consumption of that agent by some 80 times.

We can look at this another way.  A 20 ounce soft-drink contains about 30 grams of fructose (that's something like 8 teaspoons).  Drinking this would raise blood fructose levels about 4 times the base levels.  Some soft drinks contain as much 60 grams of fructose.  With the capacity of fructose to damage joint proteins, we have to look seriously at how this may contribute to increasing rates of arthritis. On the positive side, we can eliminate these sugars from our diets, which is one step to reduce the biochemical stress on our joints.

Even more worrisome than fructose, glucose, and galactose is the substance called glyoxal, which is 200 times more potent at glycating our tissues than is glucose.  According to the Annals of the New York Academy of Sciences, glyoxal has recently  been found in “shockingly high amounts” in some of our most common soft drinks.  Soft drinks, then, contain large amounts of fructose and large amounts glyoxal.  With our current rates of consumption of such beverages, it is no wonder that some of these biochemical changes have become so common.

[INSERT TABLE OF WHERE THESE SUGARS ARE FOUND]

(Tan, D, Wang, Y, Lo, Cy, Sang, S, Ho, CT. Methylglyoxal: Its Presence in Beverages and Potential Scavengers. Ann NY Acad Sci 2008;1126:72-75.)

We should also understand two other features of these sugars related to glycation of joint proteins.  Glycated proteins increase free radical stress, which is a process well known to damage cell membranes found in joint tissue.  Moreover, this process of glycation by sugars  depletes the human body of a range of nutrients that are important for repair and for energy.  Ironically, some of the nutrients depleted by sugar damaged proteins are the same nutrients needed to detoxify these sugar damaged proteins.

The solution is to reduce intake of these sugars and increase our intake of nutrients that are protective against these processes.

Metabolism. 2008 Sep;57(9):1211-20.

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