Question: Cataracts: what are the roles of methylglyoxal and polyols?
Is the polyol pathway activation and methylglyoxal independent causes of cataract formation or are they related to one another? And the answer is a little bit of both. You know, if independent means unrelated, then they’re related. Not independent. But they are independent in the sense that you could have more of one. You know, you could do something that increases one and not the other or at least disproportionately increases one versus the other. So, the polyol pathway, I think the best way to describe that is under conditions of severe hyperglycemia where you have too much sugar to be disposed of in the normal routes. You can use the sugar to synthesize polyols.
Glutathione is needed, among other things, to detoxify methylglyoxal. And methylglyoxal causes cataracts. Now, that's not to say that there aren’t other things going on. I mean, certainly glutathione is also needed to defend against oxidative stress. But then again, this might not be the only way that oxidative stress contributes to cataracts, but oxidative stress increases methylglyoxal generation in part by decreasing the activity of glyceraldehyde 3-phosphate dehydrogenase or GAPDH, which is the enzyme within glycolysis that is responsible for clearing what are known as triose phosphates.
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DISCLAIMER: I have a PhD in Nutritional Sciences and my expertise is in performing and evaluating nutritional research. I am not a medical doctor and nothing herein is medical advice.