Researchers say that, while ageing had the biggest effects on these molecular changes their accumulation is reduced by selenium and vitamin D and increased by high blood folate and obesity. A study carried out at the Institute of Food Research (IFR) led by Dr Nigel Belshaw examined the cell lining of the gut walls from volunteers attending colonoscopy clinic.
Researchers looked for specific epigenetic modifications of the volunteers' genes that have been associated with the earliest signs of the onset of bowel cancer an age-related disease.
The investigators studied the relationship between the occurrence of these epigenetic marks – known as DNA methylation – at genes known to be affected in cancer and the levels of some nutrients in the volunteers' blood.
Bowel cancer
The biggest influence on gene methylation was age. However, the findings, published in the journal Aging Cell, showed that volunteers with higher vitamin D status tended to show lower levels of methylation, and a similar effect was observed for selenium status. The B vitamin folate is essential for health, but in this study, high folate status was associated with increased levels of epigenetic changes linked with bowel cancer.
These findings are consistent with some epidemiological studies suggesting that excessive folate intakes may increase risk in some people. The researchers intend to investigate the mechanism for the observed effect of folate on DNA methylation in a follow-up study.
Obesity is also a risk factor for bowel cancer. This study found relationships between body size and epigenetic changes. How excess body weight induces these epigenetic changes, and the consequences for gut health, are currently being investigated by IFR.