Vitamin C has only been linked to diseases that happen when people don't get enough, but researchers at the Children's Medical Centre Research Institute at UT Southwestern say they have learnt something new about it. In the peer-reviewed Proceedings of the National Academy of Sciences, they say that a lack of vitamin C for a short time may help guard against schistosomiasis, a disease caused by a parasite that affects almost 250 million people around the world. 

A gene called GULO lets most animals make their own vitamin C. Because people lost this gene over time, vitamin C has to come from food. Loss like this is generally considered neutral, giving no one an advantage. The new study indicates that idea is wrong because schistosomes, flatworms that live in human blood vessels, need vitamin C from their host in order to grow. 

The scientists looked at the differences between normal mice and mice that didn't have the Gulo gene. They did this by working together with counterparts in China and the United States. The disease killed most regular mice that got schistosomes. On the other hand, only 5% of mice that couldn't make vitamin C died, which shows that the deficiency was strongly linked to life. 

Dr Michalis Agathocleous, who led the study, said, "Our work changed my view of vitamins." "This study shows that a temporary lack of a vitamin can help an animal that is infected with a germ that needs that vitamin." He said that worms need vitamin C every day to lay eggs, but the host won't get hurt until after months without it. 

The World Health Organisation and other global health groups say that schistosomiasis is a disease that spreads through dirty waterways and affects people who are poor. Other research has shown that the parasites rely on their host's metabolism a lot to stay alive. The new results are in line with earlier lab work that showed how important vitamin C is for schistosome egg production. 

Researchers say that prolonged vitamin C deficiency is dangerous. It causes scurvy and is connected to blood cancers like myeloid leukaemia. In the study, mice given vitamin C sometimes avoided scurvy and still gained protection. These findings showed that timing, not lack of vitamin C, shaped the result. 

Dr Agathocleous said the work might help figure out why humans lost the ability to make vitamin C. He did say, though, that it is difficult to show what advantages evolution has. Future research will look into how vitamin C levels affect infections and malignancies, but these studies won't suggest that low vitamin C should be used as a treatment. 

For people people who haven't gotten rid of schistosomiasis yet, the study raises fresh questions about how to control parasites and the diets of their hosts. Experts say the results shouldn't change what the public is told, but they should help people learn more about how diseases function and how they might be changed by things like evolution, infection, and food in ways that are different in different parts of the world.