A second look at old research suggested that the recommended dose for vitamin C is far too low. Here is the abstract of the recently published  paper:

A double-blind controlled trial initiated in 1944 has led to the common narrative that a 10-mg daily vitamin C intake is adequate to prevent and treat impaired wound healing, and by inference, other collagen-related diseases such as heart disease or stroke. The WHO relies on this narrative to set the recommended nutrient intake for vitamin C. This narrative, however, is based on what is known as the eyeball method of data assessment. The 1944 trial published individual participant data on scar strength providing an opportunity to statistically probe the validity of the 10-mg narrative, something which has not yet been done. The findings show that a vitamin C intake that averages to 10 mg/d over a mean follow-up of 11.5 mo was associated with a 42% weakened scar strength when compared with 80 mg vitamin C intake/d (P < 0.001). The observed dose-response curve between scar strength and vitamin C intake suggests that the daily vitamin C intake needed to prevent collagen-related pathologies is in the range recommended by the National Academy of Medicine and the European Food Safety Authority (75 to 110 mg/d), not the WHO recommendation (45 mg/d). The findings also show that a vitamin C intake that averages to 65 mg/d over a mean follow-up of 6.5 mo failed to restore the normal wound-healing capacity of vitamin C-depleted tissues; such tissues had a 49% weaker scar strength when compared with nondepleted tissues (P < 0.05). Thus, average daily vitamin C intakes ∼50% higher than the WHO recommends may fail to treat existing collagen-related pathologies. It is concluded that the prior lack of statistical analyses of a landmark trial may have led to a misleading narrative on the vitamin C needs for the prevention and treatment of collagen-related pathologies.

The lead author of the recent re-analysis, Professor Philippe Hujoel from the Department of Epidemiology, School of Public Health, University of Washington, Seattle, said: “The vitamin C experiment is a shocking study. They depleted people’s vitamin C levels long-term and created life-threatening emergencies. It would never fly now. The findings of the re-analyses of the Sorby data suggest that the WHO’s recommendation is too low to prevent weak scar strength. Robust parametric analyses of the trial data reveal that an average daily vitamin C intake of 95mg is required to prevent weak scar strength for 97.5 percent of the population. Such a vitamin C intake is more than double the daily 45mg vitamin C intake recommended by the WHO but is consistent with the writing panels for the National Academy of Medicine and (other) countries.”

The original research of 1944 was headed by the British-German biologist and Nobel-prize winner Sir Hans Adolf Krebs. At the time, researchers conducted an experiment that controlled and monitored vitamin C consumption of just 20 volunteers. They were each given varying amounts of vitamin C,  which helps the body to produce collagen – and given wounds to observe how quickly their scar tissue healed. The research aimed to ascertain how much vitamin C navy members living off rations is required in order to prevent them from developing scurvy, rather than how much is needed to boost health overall.

Prof Hujoel concluded that: “The failure to reevaluate the data of a landmark trial with novel statistical methods as they became available may have led to a misleading narrative on the vitamin C needs for the prevention and treatment of collagen-related pathologies.”

7 Responses to We need to more than double the daily vitamin C intake recommended by the WHO

  • Ahhhh, Vitamin C. Sounds like SCAM propaganda.
    Question: can Vitamin C be Patented? Answer: NO, then that makes it SCAM.
    Question: can Vitamin C be found in Nature? Answer YES – then that makes it SCAM.
    No NHS doctor would dream of recommending or prescribing Vitamin C.

    • Mike Grant,

      No NHS doctor would dream of recommending or prescribing Vitamin C.

      Although I haven’t prescribed it myself, Vitamin C is on the formulary and I have certainly seen it prescribed for a number of different indications.

    • I don’t know about Vitamin C and the NHS, but in Australia, my GP certainly recommended that I take Vitamin D after a blood test showed that I had lower levels than I should have.

      I wouldn’t have thought that the normal 1000IU vitamin D capsules or tablets would ever be prescribed here – certainly no prescription is necessary to buy them, and I’ve also never had prescriptions issued to me for any other medication that my GP recommended where a prescription wasn’t necessary to buy them (e.g. for Ventolin, which is non-prescription here).

  • Interesting stuff. Clearly research ethics have changed from the days of the Sorby trial although this was a wartime period. The current NHS guidance is for a vitamin c intake of 40 mg a day for adults 18 -64, which is a expected to be obtained from our every day diet. I don’t know if studies have been done about actual dietary intake of vitamin C.

    Vitamin supplements are recommended by the NHS for babies and youngsters.

    I wonder if this latest re-analysis of the Sorby trial will stimulate more research?

  • I think anyone with a moderately decent diet gets more than 10mg, so maybe this is not really a huge problem?,cantaloupe%20%28see%20Table%202%29%20%5B%208%2C%2012%20%5D.

    Also the recommendation for adults in US is 90mg, so who is recommendng 10 mg?

    • Who is recommending 10mg/day? Presumably the 1944 paper mentioned in the first line of the abstract.

      The point of the quoted abstract isn’t to argue that 10mg/day isn’t enough, it’s arguing that the WHO’s recommendation of 45mg/day isn’t enough.

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