Wednesday, December 05, 2007

Losing the plot

I started reading Dr Dandona's work with his paper on the generation of free radicals by various white blood cells under the influence of glucose. I rather liked this, being as anti hyperglycaemia as I am. I especially liked the vitamin E depletion he found. And the rise in lipid oxidation products (TBARS).

When he went on to look at cream and protein I became a little uneasy. Protein came out quite well, despite the rather odd choice of the highly insulin provoking casein. Chicken does not do this. No evidence of an increase in lipid oxidation. But cream came out rather badly.

Cream provoked a marked increase in lipid oxidation products. As I generally live on cream this is of some interest to myself. There were a few oddities though. The TBARS peaked at 60 minutes. The cream chylomicrons peaked at 2h. This is peculiar, and Dandona says as much. It is worth noting that cream is predominantly saturated fat plus monounsaturated fat while TBARS are generated from PUFA, especially those with three or more double bonds. So I'm not quite sure what is happening here. It is worth noting that the TBARS per unit chylomicrons did not change significantly and it is hard to tell if the TBARS simply reflect the amount of lipid in the bloodstream available for oxidation. As glucose contains no lipids all TBARS produced by glucose must come from body damage.

By the time that Dandona moved on to other calorie sources he had abandoned TBARS as a marker of anything and was using NF-kappaB binding as his marker of inflammation, and eventually C reactive protein. Unfortunately he never went back to look at cream and CRP, which I would have found interesting.

More worrying was how he he trotted out a load of garbage about low fat diets and even quoted Ornish of all people (No, I refuse to reference Ornish. His yoga, relaxation and group support appear to ameliorate the worst effetcs of his awful diet. Yeugh).

We know what low fat diets do to the oxidation status of LDL cholesterol.

So I'm getting a bit uncomfortable with Dandona here.

The next substance to be checked for free radical generation and NF-kappaB binding was alcohol. This came through with flying colours on both counts. Using Dandona's approach alcohol looks like the perfect calorie source to avoid cellular damage. Hmmmmmmmm

Finally came fructose. Fructose came out of testing looking as good as alcohol, but without the intoxicant effects. Now we truly have a super food, no free radical generation, no increase in NF-kappaB binding, no increase (or even a non significant decrease) in CRP. Eurika.

And if you obtain your fructose from orange juice you get a truckload of antioxidants too. Wow. THE perfect drink for diabetics must be gin and orange! Here's what Dandona has to say:

"Our data are relevant to patients with diabetes since oxidative and inflammatory stress are markedly increased in this condition and may contribute to accelerated atherosclerosis. Clearly, the choice of foods that either do not increase or actually decrease oxidative and inflammatory stress in diabetic subjects is important"

"orange juice or fructose taken in equicaloric amounts to 75 g glucose does not cause either oxidative stress or inflammation in contrast to glucose"

Now just a minute.

If you actually measure the amount of post prandial fructose in the blood of diabetic patients it is nicely correlated with the severity of retinopathy. Whether this is a causal association cannot be determined from the Japanese study. But if you consider that fructose is much better at glycosylating proteins than glucose you can see there is a biological mechanism.

From the retinopathy abstract

"The increased prevalence of retinopathy in the high Meal Post Prandial Fructose group suggests that fructose is associated with retinopathy in patients with type 2 diabetes".

By this stage I'm off Dandona. It's a pity, I got some nice data from his studies, but he's lost the plot.

Any diabetic wanting to keep their vision would do well to pour the orange juice, with its antioxidants, down the sink. Cream would my choice, TBARS and all. Why?

No glucose spike, no insulin spike, no fructose spike.


PS Why does fructose come out so well in Dandona's assay? The liver churns out uric acid as fast as it can when it sees fructose coming, so it's not surprising that CRP trended downwards. Dandona was too busy with NF-kappaB etc to bother measuring urate. Checking urate would be a good idea before recommending fructose to people with metabolic syndrome. Also the body hates fructose so much it keeps it out of the systemic circulation as much as it can, so it never provides much fuel for white blood cells to generate reactive oxygen species.

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