According to statistics from the World Health Organization, low intake of fruits and vegetables is estimated to be the major factor behind 19 percent of gastrointestinal cancer cases and 31 percent of ischaemic heart disease in the world.
In their World Health Report -- a highly reputable summary of several facets of global health, including nutrition -- The World Health Organization specifies that "low fruit and vegetable intake is among the top 10 risk factors contributing to attributable mortality."
This 2002 Danish study published in Public Health Nutrition goes further into detail on this matter.
This is why I like to think of meeting your daily vegetable servings as a contribution to your nutritional retirement account!
The earlier you start and the more you contribute to it, the better off you are more likely to be in your later years.