ASCORBIC ACID COMPETES WITH SUGAR IN THE IMMUNE SYSTEM
By Dr. James Howenstine, MD.
December 25, 2006
Nearly every animal converts sugar into ascorbic acid (Vitamin C). Human beings, primates and guinea pigs are the only organisms unable to do this. The enzyme L-gulonolactone oxidase that accomplishes this chemical reaction does not work in these beings. This forces these beings to obtain ascorbic acid from food or supplements. Research studies suggest that humans would produce about 2 to 4 grams of Vitamin C daily under normal conditions and about 15 grams daily[1] when under stress.
http://www.ncbi.nlm.nih.gov/pubmed/18160753 said:RESULTS: A significant decrease in FBS, TG, LDL, HbA1c and serum insulin was seen in the group supplemented with 1000 mg vitamin C. The dose of 500 mg vitamin C, however, did not produce any significant change in any of the parameters studied.
INTERPRETATION & CONCLUSION: Our results indicate that daily consumption of 1000 mg supplementary vitamin C may be beneficial in decreasing blood glucose and lipids in patients with type 2 diabetes and thus reducing the risk of complications.
High dose vitamin C (2,000 mg per day) has been shown to reduce the accumulation of sorbitol, a metabolic by-product of glucose metabolism, known to cause chronic complications in the diabetic patient.206 Studies also show that vitamin C supplementation inhibits the glycosylation of proteins (the complexing of protein with sugar), a process that is elevated several-fold in diabetes. Because insulin facilitates the transport of ascorbic acid into cells, many diabetics do not have sufficient vitamin C within their cells despite adequate dietary intake. This chronic deficiency of vitamin C in the diabetic is problematic and leads to vascular disorders, elevated blood cholesterol and depression of the immune system.206 Accordingly, high dose supplementation with vitamin C is an issue of primary concern for the diabetic or pre-diabetic sufferer. Recent studies reveal that vitamin C supplementation, alone, provides a more effective means of correcting sorbitol accumulation than current pharmaceutical approaches.200, 207
1. Sorbitol (in high antioxidant environment + without ONOO-) Fructose
2. Sorbitol (in excess free radical environment + with ONOO-) Toxic metabolites
The second reaction yielding toxic metabolites deplete antioxidants in cells leading to an
increase in superoxide and DNA fragmentation that can initiate cancer cell development.
This process puts the diabetic patient with excess sorbitol at a higher risk of cancers and
explains the higher incidence of cancers in the diabetic population
Even the water-soluble vitamin C can cause diarrhoea at levels of 2000mg a day, which is lower than the amount some people take in the hope of staving off colds.
A question of need
Taking vitamins and food supplements is neither good nor bad, but unnecessary for most of us. There is a lot to be said for saving the money and splashing out once in a while on a nutritious and delicious well-balanced meal at a ritzy restaurant instead.
Many studies have since shown that vitamins from supplements do not act on the body in the same way as vitamins from foods.
Apples and pills
Take apples: they are a rich source of vitamin C, which builds up the immune system. But when researchers at Cornell University in New York compared the effects of apples and vitamin C tablets, the results were quite startling.
The apples contained many other naturally occurring chemicals in addition to vitamin C, including antioxidants called flavanoids and polyphenols that are thought to protect against cancer.
This meant that eating a small apple (100g) gave an antioxidant effect equivalent to taking 1500mg of vitamin C – and you'd have to take a mega-dose supplement to achieve that.
One of the study’s authors, Professor Chong Yong Lee, said: 'Some of the chemicals we found in apples are known to be anti-allergenic, some are anti-carcinogenic, anti-inflammatory and anti-viral. Now I have a reason to say an apple a day keeps the doctor away.'
In contrast, a 2004 Cochrane review of studies found there was not enough evidence that 2000mg vitamin C supplements prevented colds in the general population. More recently, the US Women's Health Study found a link between vitamin C supplements and an increased risk of hardening arteries in some people with diabetes.
A good diet is best
Also called the sorbitol/aldose reductase pathway, the polyol pathway may be implicated in diabetic complications that result in microvascular damage to nervous tissue, and also to the retina and kidney.
Glucose is a highly reactive compound, and it must be metabolized or it will find tissues in the body to react with. Increased glucose levels, like those seen in diabetes, activates this alternative biochemical pathway, which in turn causes a decrease in glutathione and an increase in reactive oxygen radicals. The pathway is dependent on the enzyme aldose reductase. Inhibitors of this enzyme have demonstrated efficacy in animal models in preventing the development of neuropathy.
The pathway is dependent on the enzyme aldose reductase. Inhibitors of this enzyme have demonstrated efficacy in animal models in preventing the development of neuropathy
jaykay"
I condense the above post to one line : An apple a day keeps the doctor away . I shall stick with my apple!
Instead, sorbitol accumulation takes place in the cells of
diabetic patients, known to be associated with chronic complications in diabetic patients.
A high dose vitamin C (2000mg per day) has been shown to reduce the accumulation of
sorbitol (Davie et al, 1992, Effect of Vitamin C on Glycosylation of Proteins, Diabetes
41:167-73). The antioxidant vitamin C is known to suppress the polyol pathway activity
induced by high glucose (Vinson et al, 1989, In
The polyol pathway converts glucose to fructose. Because fructose and its metabolites fructose-3-phosphate and 3-deoxyglucosone are more potent nonenzymatic glycation agents than glucose, the flux of glucose through the polyol pathway would increase advance glycation end products (AGE) formation. AGE, as well as binding of AGE to their receptors, are known to cause oxidative stress.
It is remarkable that these effects were achieved by increasing the dietary availability of thiamine to diabetic rats by as little as 20 times the minimum daily allowance – although this was sufficient to prevent thiamine deficiency.
In a paper entitled "High prevalence of low plasma thiamine concentration in diabetes linked to a marker of vascular disease", published in Diabetologia on 4th August, the team found that thiamine concentration in blood plasma was decreased 76% in type 1 diabetic patients and 75% in type 2 diabetic patients.
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