Vitamin C, or ascorbic acid as it sometimes referred to, is an important and safe antioxidant.
Vitamin C is essential to many of our bodies systems, from detoxification to collagen formation, as well as the production of neurotransmitters and prevention of cell damage.
In fact, its use in neurotransmitter function, such as the conversion of the feel-good hormone dopamine to downstream hormones, helps explain why the major symptoms of scurvy or a general vitamin C deficiency include fatigue and depression.
Vitamin C Health Benefits
Ascorbic acid acts as an antibacterial, antiviral, anti-histamine, anti-inflammatory, antioxidant and more.
Ascorbic acid, or vitamin C, is a potent antioxidant with increasingly diverse uses in health promotion and disease prevention.
As humans, we are one of the few species that are not able to make vitamin C within our bodies and hence we need to ingest it through our diet or via supplementation.
Vitamin C Sources
Good sources of vitamin C include, berries, citrus, asparagus, avocado, broccoli, chilli, parsley, garlic, onions and many other everyday foods we eat.
Surprisingly, chilli peppers, parsley and garlic are several of the highest sources per 100 grams. Being water-soluble, vitamin C has relatively short life and needs constant replenishing.
Stress, smoking, alcohol and certain medications, including antidepressants, all act to deplete your stores of vitamin C.
Some debate exists around the use of ascorbic acid, specifically around RDAs (daily allowance) and its effectiveness in treating common colds and other illness. It is sometimes referred to as ‘expensive urine’, in that taking more than the RDA of 60 mg, provides very little added benefit and only ends up being flushed down the drain.
‘‘Expensive urine. It’s an old saw and makes one terrific sound byte. Too bad it’s false’, says Dr Andrew Saul Ph.D, a leading specialist in nutritional medicine. ‘It’s the absence of water-soluble vitamins in your urine that indicates vitamin deficiency. If your body excretes vitamins in your urine, that is a sign you are well -nourished and have nutrients to spare.’’
A daily, divided dose, of 1-5000 mg is sometimes used and recommended by integrative medicine doctors.
Interestingly, animals that produce their own vitamin C from glucose make approximately 1 gram per 7 kilos of body weight. Under prolonged stress, this level rises fivefold or more.
If humans could produce our own, someone weighing 70 kilos would be making roughly 10 grams (10,000 mg) or more per day – a remarkably high amount.
To compare this to the established RDA of 60 mg a day, which was the historical measure in order to prevent the onset of scurvy, highlights why a large amount of research and study has gone into re evaluating this figure.
A 2002 study found that doses of 2000 mg are well tolerated, however it also suggests that only 90 mg (for men) was required to prevent disease and for antioxidant effect.
A vast amount of anecdotal and clinical evidence actually supports the effective use of much, much higher doses of ascorbate.
Research has shown that high dose ascorbic acid is selectively toxic to cancer cells. Clinical roles for vitamin C are of great interest due to the idea that oxidative damage is a root cause of a number of modern diseases.
Population studies show that individuals with high intakes of vitamin C have lower risk of a number of chronic diseases, including heart disease, cancer, eye diseases, and neurodegenerative conditions. However, these results may simply reflect a more healthful diet or lifestyle for individuals with a high vitamin C intake.The evidence that ascorbic acid acts as an important antioxidant in many body tissues is convincing.
Vitamin C As A Dry Eye Supplement
Anecdotal and clinical evidence also suggests that Vitamin C has a very beneficial effect in dry eye care.
A Sydney-based surgeon of Opthamology found 1000 mg of ascorbate a day, even in people with normal diets, very effective in reducing dry eye symptoms.
As a potent antioxidant and antiviral, it serves as a strong, natural anti inflammatory. It does this, in part, by acting as an anti-histamine, which has significance for people with dry eyes and specifically for contact lens wearers.
One Optometrist in the UK discovered that by giving his patients high-quality vitamin C supplements he was able to greatly reduce the instances of dry eyes for contact lense users he saw in his practice.
The theory is that swelling of the conjunctival cells, or tiny blood vessels that line the sclera ( the white part of your eye) as a result of raised histamine levels causes friction between the two layers of cells: the bulbar and palpebral.
This causes greater friction when blinking and dry eyes can result.
With increased ascorbic acid levels, histamine is apparently harmlessly converted to hydantoin-5-acetic acid for excretion as water and carbon dioxide.
High blood levels of ascorbic acid have been well documented in studies to lower histamine levels and hence reduce the inflammation trigger so often associated with cases of chronic or severe dry eyes.
The reverse is also true: as plasma levels of ascorbates decrease, there is a significant increase in histamine levels, as reported in the Journal of Nutrition some thirty years ago.
Vitamin C Daily Dose. Are you getting enough?
The diversity of benefits of vitamin C use are clear but deficiencies still appear to be on the rise.
A 2006 study found that approximately 15 percent of the US population is deficient. Some 25 years ago this figure was lower than 5 percent.
As a potential solution for dry eyes it does appear that, along with being vital to general health, vitamin C may well have been overlooked as a very important factor for the health of our eyes.
As heat destroys vitamin C, a fresh, whole food diet with a good portion of raw, not cooked, foods is a great way to increase your levels. Supplements are also cheap and widely available.
Vitamin C is highly beneficial for relieving the inflammatory symptoms associated with dry eyes, not to mention the protective benefits for a number of organs and tissues.
http://www.ncbi.nlm.nih.gov/pubmed/7365537 -Histamine & ascorbic acid in human blood
http://www.ncbi.nlm.nih.gov/pubmed/12134712 – Vitamin C function and status in chronic disease.
http://www.nutritionandmetabolism.com/content/3/1/35 -Marginal vitamin C status is associated with reduced fat oxidation during submaximal exercise in young adults.
Good Health In The 21st Century – Dr C Hungerford 2008