Your genetic makeup affects how your body processes nutrients in the food you eat. And the nutrients in turn can have an effect on certain genetic activities within your body.
For instance, the nutrient folate, contained in a variety of fruits and vegetables, can turn off certain genes. In doing so, folate can protect against some cancers. So turning off a gene that stimulates cancer growth is a good thing.
But some phytochemicals may also silence genes that suppress cancer growth, and that could have the opposite effect, allowing cancer to spread. Scientists are studying the relationship between a variety of phytochemicals and their actions on various genes.
Source: Special Report Supplement to Mayo Clinic Health Letter June 014