• New analysis of landmark scurvy study le

    From ScienceDaily@1:317/3 to All on Mon Aug 16 21:30:38 2021
    New analysis of landmark scurvy study leads to update on vitamin C needs


    Date:
    August 16, 2021
    Source:
    University of Washington
    Summary:
    Review of a landmark, 1944 study on adequate vitamin C levels
    leads researchers to challenge the WHO's recommended daily amounts.



    FULL STORY ==========================================================================
    It was wartime and food was scarce. Leaders of England's effort to wage
    war and help the public survive during World War II needed to know:
    Were the rations in lifeboats adequate for survival at sea? And, among
    several experiments important for public as well as military heath,
    how much vitamin C did a person need to avoid the deadly disease scurvy?

    ==========================================================================
    In one experiment at the Sorby Research Institute in Sheffield, called the "shipwreck" experiment, volunteers were fed only what the navy carried
    in lifeboats. The grueling experiment resulted in more water and less
    food being carried in lifeboats.

    One of the more robust experiments run on human subjects during this
    time in England, which has had long-lasting public health consequences,
    was a vitamin C depletion study started in 1944, also at Sorby. This
    medical experiment involved 20 subjects, most of whom were conscientious objectors living in the building where many experiments, including the shipwreck experiment, were conducted. They were overseen by a future Nobel Prize winner, and detailed data was kept on each participant in the study.

    "The vitamin C experiment is a shocking study," said Philippe Hujoel, lead author of a new study on the Sorby vitamin C experiment, a practicing
    dentist and professor of oral health sciences in the UW School of
    Dentistry. "They depleted people's vitamin C levels long-term and created life-threatening emergencies. It would never fly now." Even though two
    trial participants developed life-threatening heart problems because
    of the vitamin C depletion, Hujoel added, none of the subjects were
    permanently harmed, and in later interviews several participants said
    they would volunteer again given the importance of the research.

    Because of the war and food shortages, there was not enough vitamin
    C available, and they wanted to be conservative with the supplies,
    explained Hujoel, who is also an adjunct professor of epidemiology. The
    goal of the Sorby investigators was not to determine the required vitamin
    C intake for optimal health; it was to find out the minimum vitamin C requirements for preventing scurvy.



    ========================================================================== Vitamin C is an important element in your body's ability to heal wounds
    because the creation of scar tissue depends on the collagen protein,
    and the production of collagen depends on vitamin C. In addition to
    knitting skin back together, collagen also maintains the integrity of
    blood vessel walls, thus protecting against stroke and heart disease.

    In the Sorby trial, researchers assigned participants to zero, 10 or 70 milligrams a day for an average of nine months. The depleted subjects
    were then repleted and saturated with vitamin C. Experimental wounds were
    made during this depletion and repletion. The investigators used the
    scar strength of experimental wounds as a measure of adequate vitamin
    C levels since poor wound healing, in addition to such conditions as
    bleeding gums, are an indication of scurvy.

    In the end, the Sorby researchers said 10 milligrams a day was enough
    to ward off signs of scurvy. Partly based on these findings, the WHO
    recommends 45 milligrams a day. Hujoel said that the findings of the re-analyses of the Sorby data suggest that the WHO's recommendation is
    too low to prevent weak scar strength.

    In a bit of scientific detective work, Hujoel said he tracked down
    and reviewed the study's data, and with the aid of Margaux Hujoel, a
    scientist with Brigham and Women's Hospital/Harvard Medical School, put
    the data through modern statistical techniques designed to handle small
    sample sizes, techniques not available to the original scientists. The
    results of their work were published Monday in the American Journal of
    Clinical Nutrition.

    The Hujoels discovered that the data from this unique study -- which
    has been a cornerstone used by WHO and other agencies for establishing
    healthy levels of vitamin C in humans -- needed more than an "eyeball
    method" of data assessment.

    "It is 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," the researchers wrote.

    "Robust parametric analyses of the (Sorby) trial data reveal that an
    average daily vitamin C intake of 95 mg is required to prevent weak
    scar strength for 97.5% of the population. Such a vitamin C intake is
    more than double the daily 45 mg vitamin C intake recommended by the
    WHO but is consistent with the writing panels for the National Academy
    of Medicine and (other) countries," they add.

    The Hujoels' study also found that recovery from a vitamin C deficiency
    takes a long time and requires higher levels of vitamin C. Even an average daily dose of 90 milligrams a day of vitamin C for six months failed to
    restore normal scar strength for the depleted study participants.

    ========================================================================== Story Source: Materials provided by University_of_Washington. Original
    written by Jake Ellison. Note: Content may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Philippe P Hujoel, Margaux L A Hujoel. Vitamin C and scar strength:
    analysis of a historical trial and implications for collagen-related
    pathologies. The American Journal of Clinical Nutrition, 2021;
    DOI: 10.1093/ajcn/nqab262 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2021/08/210816135454.htm

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