Vitamin C synthesis

The Restoration of Vitamin C Synthesis in Humans” (Levy) claims that we use much more vitamin C than we eat and that we are therefore making it in our bodies but in insufficient amounts. The process has been impaired in some way but can be restored via supplementation with olive leaf extract.

Evidence that humans can synthesise ascorbic acid:

  • The concentration of ascorbic acid in the umbilical blood of infants can be up to four times greater than that in the mother’s blood – De Souza
  • Concentrations in the brains of foetuses can be eleven times that of adults
  • Research on breast-fed babies showed that vitamin C blood levels persisted at a level 200% higher than that of the mother, and that there was no correlation with the vitamin C levels measured in the breast milk. – Salmenperä
  • The vitamin C blood levels in the breast-fed infants were also noted to maintain themselves at the same or higher concentrations than the vitamin C-supplemented infants fed by bottle
  • In infants in a Bantu community in South Africa, researchers demonstrated that despite extraordinarily minimal amounts of vitamin C intake (3 to 8 mg/day), the symptoms of scurvy or vitamin C deficiency were never seen. – Andersson et al
  • An adult female continued to show high blood levels of vitamin C as the vitamin C intake was progressively decreased. – Cummings
  • Another woman went 149 days without any significant dietary vitamin C intake, and she never developed any deficiency symptoms.

The recommended daily intake of vitamin C is 50 to 100 mg but the Levy paper claims, without reference unfortunately, that the body uses ten to one hundred times this amount. In addition to this, we have the accepted fact that there is no storage of any substantial amount of the vitamin in the body which leads to the inevitable hypothesis that we must be synthesising at least some vitamin C in our bodies even as adults.

Vitamin C synthesis usually occurs in the liver where glucose is converted to ascorbic acid according to the following metabolic pathway: D-glucose → D-glucuronic acid → L-gulonic acid → L-gulonolactone oxidase (GULO) → L-ascorbic acid

The problem is with the production of the GULO enzyme, which happens naturally in almost all mammals but appears to be defective in adult humans to a greater or lesser degree.

The vitamin C requirements of humans seem to vary greatly within the population and this is assumed now to be because we are all synthesising ascorbic acid to some extent and it is variations of this ability that is giving rise to the observed differences.

What appears to happen is that foetuses, infants and children are manufacturing sufficient amounts of vitamin C but this ability is lost in childhood, leaving an adult population having to obtain the nutrient via dietary sources.

Since synthesis is usually in the liver, the paper suggests that toxic intake during childhood in developed countries is somehow responsible for damaging the liver, thereby impairing the manufacturing process. Against this maybe is the fact that Guinea Pigs and many apes have also lost the ability to synthesise.

Restoration of the synthesis is achieved in part at least by the supplementation of olive leaf extract which contains a polyphenol hydroxytyrosol (HT). Volunteers showed increases in blood concentrations of between 5% and 200% the day after the first dose and increases were still seen 10 days after stopping the dosage.

The mechanism by which this is happening is unclear but there are indications that the synthesis is still happening in the liver and that the HT is somehow facilitating the production of the GULO enzyme. So we do not have a new production method but rather a revitalisation of the existing process.

Alcohol induced oxidative stress in volunteers who were taking Olive Leaf Extract produced the reaction shown right. As alcohol levels shot up so did the vitamin C levels plummet as the vitamin was used to combat the oxidative stress.

However, as the alcohol levels subsided, the vitamin C levels then displayed a sharp rise despite the fact that no extra vitamin C had been consumed. So interpretation is that the body is responding in a dynamic fashion by creating extra ascorbic acid as and when needed. This then seems preferable to continuous supplementation which would not respond in the same way and, moreover, would supply extra ascorbic acid when not needed, thereby necessitating regulation or excretion of excess.

The authors of the paper therefore recommend lifetime supplementation of Olive Leaf Extract together with cortisol to facilitate absorption: “The fight or flight response to increased oxidative stress clearly demonstrates that vitamin C and cortisol are actually designed by nature to interact together to optimize the antioxidant impact needed to resolve the disease-causing oxidation that always results from toxins, infections, and stress” – Levy


The Restoration of Vitamin C Synthesis in Humans
Authors: Thomas E. Levy, MD, JD, Hunninghake, MD

Ascorbic acid in foetal human brain. – Adlard B, De Souza – S, Moon S (1974)
Archives of Disease in Childhood 49:278-282. PMID: 4830116

Vitamin C nutrition during prolonged lactation: optimal in infants while marginal in some mothers – L Salmenperä

An investigation of the rarity of infantile scurvy among the South African Bantu. The British Journal of Nutrition 10:101-105.
Authors: Andersson M, Walker A, Falcke H (1956)

Can some people synthesize ascorbic acid? – Cummings M (1981)
The American Journal of Clinical Nutrition 34:297-298.

Guinea pigs can synthesize ascorbic acid when injected with L-gulonolactone oxidase

Individuality in Vitamin C needs – Williams and Deason

Vitamin C and cortisol: synergistic infection and toxin defense. – Levy T (2021)