In a completely unexpected research breakthrough, researchers at Albert Einstein College of Medicine have found that vitamin C can kill drug-resistant tuberculosis (TB) bacteria in laboratory conditions. This means adding vitamin C to existing TB drugs could be used to successfully treat drug-resistant TB.
TB is caused upon infection with the bacterium M. tuberculosis. In 2011, TB infected roughly 8.7 million people and killed 1.4 million, according to the WHO.
Worryingly, TB infections that don’t respond to standard drug therapy are growing in incidence. Roughly 650,000 people worldwide have multidrug-resistant TB (MDR-TB), 9% of whom have extensively drug-resistant TB (XDR-TB).
The incidence of TB is especially high in low and middle income countries, which account for more than 95% of TB-related deaths.
The discovery of the TB bacterium’s vulnerability to vitamin C was found while scientists were trying to understand how it becomes resistant to isoniazid, a potent TB drug. To their surprise, when they added isoniazid and a compound called cysteine to isoniazid-sensitive TB bacteria in culture, something totally unexpected happened - the TB bacteria died.
The Einstein team suspected that cysteine was helping to kill TB bacteria by acting as a ‘reducing agent’ and triggering production of reactive oxygen species, also called free radicals, which damages cellular DNA.
They then repeated the experiment using isoniazid and a different reducing agent - vitamin C. Indeed, the combination of isoniazid and vitamin C also killed off the bacteria - but what really amazed them was that vitamin C by itself not only killed off normal TB bacteria, but also the MDR-TB and XDR-TB bacteria.
More research showed them why vitamin C was so lethal - it was causing iron to react with other molecules to create reactive oxygen species, which were killing the TB bacteria.
Based on the evidence of this study, these researchers believe that they now have a rational basis for starting up a clinical trial.
Given that vitamin C is inexpensive, widely available and safe to use, this study suggests an entirely new line of treatment that can be exploited in the near future to fight drug-resistant TB.