Public Release: 

Fat transforms vitamin C from 'good cop' into 'bad cop'

[Fat transforms ascorbic acid from inhibiting to promoting acid-catlysed N-nitrosation Online First Gut 2007; doi: 10.1136/gut.2007.12857]

BMJ Specialty Journals

Fat in the stomach may cause vitamin C to promote, rather than prevent, the formation of certain cancer causing chemicals, reveals research published ahead of print in the journal Gut.

The researchers analysed the impact of both fat (lipid) and vitamin C (ascorbic acid) on nitrite chemistry in the upper (proximal) stomach, which is especially vulnerable to pre-cancerous changes and tumour growth.



The researchers replicated the chemical conditions of the proximal stomach and measured the formation of nitrosamines, oxygen, and nitric oxide.



Fat remains in the proximal stomach for some time after a meal and also makes up a substantial amount of the cells lining the stomach, say the authors.

Nitric oxide is formed when vitamin C reacts with nitrite in acid. However, the nitric oxide can diffuse into fat and then react with oxygen to form nitrosoamine generating chemicals.

The findings may be relevant to the recent observations that vitamin C supplements fail to reduce cancer risk, say the authors.

