Thursday, October 10, 2013

Blood glucose levels in birds are high yet HbA1c levels are low: Can vitamin C have anything to do with this?

Blood glucose levels in birds are typically two-four occasions greater than these in mammals of similar measurement. But birds typically reside 3 instances more time than mammals of equivalent size. This is paradoxical. Large glucose stages are typically linked with accelerated senescence, but birds seem to age a lot slower than mammals. A number of explanations have been proposed for this, 1 of which is associated to the development of advanced glycation endproducts (AGEs).

Glycation is a approach whereby sugar molecules “stick” to protein or unwanted fat molecules, impairing their function. Glycation prospects to the formation of AGEs, which appear to be associated with a host of illnesses, which includes diabetic issues, and to be implicated in accelerated growing older (or “ageing”, with British spelling).

The graphs below, from Beuchat & Chong (1998), display the glucose stages (at rest and prior to feeding) and HbA1c stages (share of glycated hemoglobin) in birds and mammals. HbA1c is a evaluate of the degree of glycation of hemoglobin, a protein discovered in crimson blood cells. As such HbA1c (presented in percentages) is a very good indicator of the fee of AGE development inside of an animal’s physique.

The glucose stages are calculated in mmol/l they need to be multiplied by eighteen to get the respective measures in mg/dl. For example, the 18 mmol/l glucose level for the Anna’s (a hummingbird species) is equal to 324 mg/dl. Even at that substantial degree, properly earlier mentioned the stage of a diabetic human, the Anna’s hummingbird species has an HbA1c of much less than five, which is decrease than that for most insulin delicate people.

How can that be?

There are a handful of achievable reasons. Birds appear to have advanced better mechanisms to control mobile permeability to glucose, making it possible for glucose to enter cells very selectively. Birds also seem to have a larger turnover of cells the place glycation and therefore AGE formation outcomes. The lifespan of purple blood cells in birds, for case in point, is only 50 to 70 % that of mammals.

But one particular of the most fascinating mechanisms is vitamin C synthesis. Not only is vitamin C a strong antioxidant, but it also has the potential to reversibly bind to proteins at the web sites in which glycation would arise. That is, vitamin C has the prospective to substantially minimize glycation. The extensive greater part of birds and mammals can synthesize vitamin C. Humans are an exception. They have to get it from their diet program.

This might be 1 of the numerous causes why isolated human groups with standard diet programs high in fruits and starchy tubers, which direct to temporary blood glucose elevations, have a tendency to have very good well being. Fruits and starchy tubers in common are good sources of vitamin C.

Grains and seeds are not.


Beuchat, C.A., & Chong, C.R. (1998). Hyperglycemia in hummingbirds and its effects for hemoglobin glycation. Comparative Biochemistry and Physiology Element A, one hundred twenty(3), 409–416.

Holmes D.J., Fl├╝ckiger, R., & Austad, S.N. (2001). Comparative biology of aging in birds: An update. Experimental Gerontology, 36(4), 869-883.
Title: Blood glucose levels in birds are high yet HbA1c levels are low: Can vitamin C have anything to do with this?
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