You already know you're supposed to eat your vegetables. But a new study shows a healthy diet could go so far as to impact your genetics.

Scientists at the Research Institute of the McGill University Health Centre in Canada looked at 27,000 people from various backgrounds — European, South Asian, Chinese, Latin American and Arab. All of them had the 9p21 genetic variant, which increases the risk of heart disease. Those who ate a diet heavy in raw vegetables and fruit deleted the effects of the gene defect. They had a heart attack risk equivalent to people without the genetic marker.

At first blush the study, which was published on Tuesday in PLoS Medicine, seems to repeat what we already knew: a diet rich in fruit and vegetables is good for your heart. But it's also evidence that you can't always blame your genes for the sorry state of your health. What you shove in your face matters.

It's also fodder for a nascent and quickly growing field called epigenetics, which is the study of environmental effects that can change the way your genes are expressed — i.e. changes in your genes not caused by the underlying DNA sequence. It explains why identical twins can be different. "Epi" is Greek for above or over.

Researchers have more work to do before they can prove that the lowered heart attack risk in this study is epigenetic — they didn't look for that specifically. But James Engert, one of the authors of the study, wouldn't be surprised if that's at least in part what's happening.

"We expect epigenetics to mediate situations where a person's primary DNA sequence does not change, yet the outcome changes," Engert said. "We think the environment causes it and epigenetics can mediate that."

Michael Skinner, a professor at the School of Biological Sciences at Washington State University also suspects that's the case.

"Likely epigenetics will have an important role in the molecular level effects observed," Skinner said. "This is a great genetic association study and link to nutrition."

Also on deck for future studies: how long must one maintain a veggie-rich diet to silence the heart attack gene? Starting now couldn't hurt. [PLoS Medicine]

Image credit:Photocrea/Shutterstock