The recommended daily intake for vitamin C should be doubled, scientists have claimed as current levels were informed by a “shocking” Second World War study.
The World Health Organisation advises a daily intake of 45mg of a day based on a study conducted in 1944 by The Sorby Research Institute. The NHS advises a similar dose of 40mg.
The now-defunct research facility responsible for the guidelines was created to assess the nutrition levels of British citizens at a time when food supplies were short.
Scientists at University of Washington have now revisited the research which informed the current guidelines and described the methods as “shocking”.
The current guidelines for vitamin C intake are not based on maximising overall health, but staving off scurvy, scientists say.
Modern scientists and health professionals have failed until now to comprehensively re-examine the 77-year-old research according to the university which said recommended dosages should now be upgraded.
In findings published in the American Journal of Clinical Nutrition, lead author Professor Philippe Hujoel said: "The vitamin C experiment is a shocking study.
‘It would never fly now’
"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.”
He added: “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 per cent 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."
Vitamin C which is found in citrus fruits and some vegetables helps to protect cells and maintain healthy skin, bones, blood vessels and cartilage. It also aids the healing of wounds.
Experiment based on just 20 volunteers
Prof Hujoel said: “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 1944 research 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 who refused to join the military.
The conscientious objectors 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 of rations required in order to prevent them from developing the life-threatening condition scurvy, rather than how much is needed to boost health overall.
Scurvy was prevalent at the time, with some figures suggesting more members of the Navy were killed at sea by the disease than by the enemy.
Re-examining the research, University of Washington academics used modern statistical techniques designed to handle small sample sizes, which would not have been available at the time of the experiment.
The method – known as the "eyeball" – proved that data assessment used at the time was insufficient and misinterpreted.