Vitamin C Enjoys a Clinical Renaissance: New Research Demonstrates Numerous Benefits

​Historically, there have been misguided and erroneous suggestions of the effectiveness of Vitamin C in promoting longevity, preventing, and treating the common cold, and a montage of other poorly evidenced health claims.  Unfortunately, follow-up studies failed to confirm these extravagant claims. For a fair amount of time, clinicians shelved Vitamin C as a therapy and existed only in the world of supplements, full of puffery and hyperbole, with little science behind the claims.  However, recent double-blind controlled studies point to its use for many chronic and acute conditions, leading to a renaissance for this crucial nutrient.

dsm-firmenich’s plant in Scotland is the only Western producer of Vitamin C.

Humans rely solely on dietary intake to maintain the body pool of vitamin C. In most vertebrates, l-gluconolactone oxidase catalyzes the decisive step in ascorbic acid biosynthesis. Those vertebrates maintain a Vitamin C blood level equivalent to an incredible nine grams of Vitamin C dose per day for an average human.

Evolution has made the gene responsible for Vitamin C manufacture inactive in primates, flying mammals, guinea pigs, and some bird and fish species, thereby disabling its formation by the body. This evolutionary event may have resulted in an adaptational process where several physical adaptations have improved our ability to prevent Vitamin C deficiency.  These adaptations change the movement of drugs within the body, including more efficient absorption, recycling, and renal reuptake of Vitamin C compared to Vitamin C synthesizing species.
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The higher Vitamin C blood levels in other mammals prompted scientists to speculate similar blood levels might have beneficial effects.  From this came a microscience of megadosing Vitamin C, with little scientific evidence to support it, primarily anecdotal accounts.  However, some of the observations, particularly that of Vitamin C for allergy treatment, where good study evidence supports the conclusion that it alleviates the symptoms of allergic rhinitis by raising the plasma ascorbic acid levels.

Citrus Fruits Contain High Levels of Vitamin C

Recent double-blind controlled studies indicate that Vitamin C has some positive uses in clinical treatments. Most studies focus on reducing blood pressure, helping with upper respiratory infections, treating sepsis, dealing with metabolic syndrome, healing bones, and managing periodontal disease.

Fast facts from recent double-blind controlled study meta-analyses:

• The administration of intravenous vitamin C may lead to a relaxation of blood vessels and a reduced need for mechanical ventilation in the critically ill, but it does not reduce overall mortality.
• A tendency towards a mortality reduction with intravenous high-dose vitamin C monotherapy.
• There is compelling evidence that vitamin C shortens the duration of mechanical ventilation, but the magnitude of the effect is a function of the duration of ventilation.
• Although scientists discovered no preventive effects, vitamin C intake reduced the duration of upper respiratory tract infection in children.
• For sepsis patients, an improved survival if they were treated with vitamin C treatment for three to four days.
• Studies demonstrated that vitamin C has the potential to accelerate bone healing after a fracture, increase type I collagen synthesis, and reduce oxidative stress parameters.
• Statistically, there is highly significant evidence that vitamin C can shorten the length of ICU stays.
• Vitamin C contributes to a reduced risk of periodontal disease.
• Observations suggest the importance of metabolic syndrome patients having an adequate vitamin C intake through food, beverages, or supplements to maintain its concentration in the systemic circulation and potentially reverse metabolic syndrome.
• Vitamin C has clinical benefits in patients with infections due to many herpes viruses.

​One problem is that the Recommended Dietary Allowance (RDA) of 90 mg/day for adult men and 75 mg/day for adult women is meager, and many people feel that amount results in a subclinical deficiency. Given the benign risk profile for Vitamin C, supplementation in greater quantities, and perhaps even much larger quantities, appears to have little hazard and possibly much benefit.