Colorful fruits, green leafy vegetables and hearty, whole grains and legumes have long been touted as important for cancer prevention.

But Harvard nutrition specialist Doctor Walter Willett, who is the co-author of "Eat, Drink, and Weigh Less" says they just don't offer the big bang researchers once thought.

He says, " So far there really isn't any super food or super group of foods that's emerged for cancer prevention"

Doctor Willett says up to 35-percent of cancers in the U-S are due to nutritional factors, but most of those cases are related to obesity and inactivity, not a particular diet.

"We've known for years that obesity is strongly related to risk of heart disease and diabetes but even being minorly overweight is also a risk factor for many important cancers"

The American Cancer Society also says maintaining a healthy weight and being active are important for cancer prevention.

It recommends limiting intake of high fat foods and alcohol and choosing most foods from plant sources.

Doctor Willett advocates a low-calorie, balanced diet. -- a balance of healthy fats, healthy forms of carbohydrates, meaning whole grain, high fiber forms of carbohydrates, plenty of fruits and vegetables.

Doctor Willett says focusing on high quality food over quantity will go a long way toward good health.