Listen to grandma and eat those greens!

According to the latest research grandma's advice about eating your greens was pretty sound.

A new study has in fact found that just one extra serving of fruit or vegetables a day may considerably reduce the risk of developing head and neck cancer.

Researchers at the National Cancer Institute conducted a large study of 500,000 American retirees and using a food frequency questionnaire, queried them about their diets.

They then tracked them over a five year period in order to establish and record all diagnoses of head and neck cancer.

Head and neck cancers are the sixth-leading cause of cancer-related death worldwide and are the cause of more than 350,000 deaths annually.

Many studies have suggested that diet plays a role in cancer and experts now say as many as two-thirds of all cancers come from lifestyle factors such as smoking, diet and lack of exercise.

The researchers found that tobacco and alcohol use increases the risk of head and neck cancers, which affect the mouth, nose, sinuses and throat.

They also found that eating six servings of fruit and vegetables per day per 1,000 calories cut the risk of head and neck cancer by 29 percent compared to eating one and a half servings.

The typical adult consumes around 2,000 calories a day.

Neal Freedman, Ph.D., cancer prevention fellow at the National Cancer Institute says just one serving of fruit or vegetables per 1,000 calories per day was associated with a 6 percent reduction in head and neck cancer risk.

According to Freedman, people who eat a lot of fruit also tend to eat a lot of vegetables, and vice versa and when examining fruit and vegetable intake simultaneously, the protective association with vegetables seemed to be stronger than the association with fruits.

Freedman says the study suggests that fruit and vegetable consumption may protect against head and neck cancer and adds support to current dietary recommendations to increase fruit and vegetable consumption.