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Discussions with one of my favorite ophthalmic researchers, Stuart Richer, OD, PhD, chief investigator of the Lutein, Antioxidant Supplement Trial (LAST), usually get me ginned up about a particular nutrient and its effect on the eye.
Dr. Richer wrote his doctoral dissertation on Vitamin C. This gives him exceptional expertise on this subject so I listen carefully when he speaks about one of my favorite vitamins.
Linus Pauling wrote in the foreword of Dettman, Kalokerinos, and Dettman's Vitamin C is Nature's Miraculous Healing Missile, "The juice of lemons and oranges are antiscorbutics never enough to be commended. And, without boasting, I can affirm that I have never observed in my whole practice so many happy effects by any one simple medicine as by lemons."
Unfortunately, humans do not have the ability to make their own vitamin C like most other mammals. Therefore, we must obtain vitamin C through our diet and from supplements.
Vitamin C is required for the synthesis of collagen, the structural component of blood vessels, tendons, ligaments, and bone. It plays an important role in the synthesis of the neurotransmitter norepinephrine, which is particularly critical to eye and brain function. It is also required for the synthesis of carnitine, the chemical molecule essential for the transport of fat to cellular organelles called mitochondria for conversion to energy.
Mitochondria are responsible for producing the ATP energy required for cellular function, including in the retina. Mitochondrial diseases associated with the eyes include macular degeneration, retinitis pigmentosa, diabetic retinopathy, optic atrophy, cataracts, and drooping eyelids (ptosis).
I must mention that supplemental Vitamin C has also been suggested in a number of studies to have an inhibitory effect on carcinogenesis because of its free-radical scavenging activity against oxidative DNA damage. It is suggested to control the transcription level expression of genotoxic metabolites that can lead to mutagenesis.
Vitamin C Recommended Daily Allowance (RDA)
Unfortunately, the vitamin C RDA continues to be based primarily on the prevention of deficiency diseases like scurvy, rather than the prevention of chronic degenerative diseases and the promotion of optimal health. The current vitamin C RDA is only 90 mg per day for males and 75 mg per day for females.
The Linus Pauling Institute at Oregon State University reports that most of the information regarding vitamin C and the prevention of chronic disease is based on prospective studies that assess vitamin C intake in large numbers of people who are followed over time to determine whether they develop specific chronic diseases.
We find it disturbing that data from the National Institutes of Health clearly indicates that plasma and circulating cells in healthy subjects require approximately 400 mg per day of supplemental vitamin C to reach cellular saturation associated with optimal health.
Vitamin C & Coronary Heart Disease
Results from the First National Health and Nutrition Examination Study (NHANES I) Epidemiologic Follow-up Study suggest that the risk of death from cardiovascular disease was 42% lower in men and 25% lower in women who consumed more than 50 mg per day of dietary vitamin C, and who regularly took vitamin C supplements, which equaled about 300 mg per day.
The Nurses Health Study, which followed more than 85,000 women for more than 16 years, also suggests a daily intake of more than 350 mg of vitamin C to be cardio-protective.
A recent pooled analysis of 9 prospective cohort studies, including more than 290,000 adults who were free of coronary heart disease at baseline and followed for an average of 10 years, found that those who took more than 700 mg/day of supplemental vitamin C had a 25% lower risk of coronary heart disease than those who did not take supplemental vitamin C.
This analysis makes one wonder why the Institute of Medicine has not increased the Vitamin C RDA for adults. The Institute of Medicine has set the safe upper limit for vitamin C supplementation at 2,000 mg per day, primarily to prevent adults from experiencing diarrhea and other gastrointestinal disturbances, which go away with the discontinuation or reduction of high-dose vitamin C supplementation.
Food Sources
The three highest food sources of vitamin C are:
Sweet red peppers (282 mg per one cup serving)
Strawberries (82 mg per one cup serving)
Orange juice (75 mg per one cup serving)
Vitamin C Supplementation
Supplemental ascorbic acid vitamin C is inexpensive and available in many forms. Natural and synthetic L-abcorbic acid is chemically identical and there appears to be no difference in their biological activity or bioavailability.
Ascorbyl palmitate, on the other hand, is a vitamin C that has been esterified to palmitic acid, resulting in a longer-chain fat-soluble form of vitamin C with a longer half-life. Ascorbyl palmitate easily crosses cell membranes and protects fats from peroxidation. It works best when taken in combination with ascorbic acid.
Biosyntrx multiples, Oculair and Macula Complete, include 500 mg of vitamin C, as a mixture of ascorbic acid and ascorbyl palmitate.
Ellen Troyer, MT MA
Biosyntrx Chief Research Officer |
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