But now some scientists say they know exactly how much of the good stuff we should be eating.
According to a new study led by Imperial College London, eating 10 servings — or a little over 28 ounces — of fruits and veggies every day could significantly lower the risk of many serious health problems and even early death.
As an article on the study notes, one serving, or about 2.8 ounces, of fruit "equals approximately one small banana, apple, pear or large mandarin." For vegetables, the article says, "Three heaped tablespoons of cooked vegetables such as spinach, peas, broccoli or cauliflower count as a portion."
That might seem like a lot — the World Health Organization recommends consuming about half that.
But researchers found a link between doubling WHO's recommendation and a 24 percent reduced risk of heart disease, a 33 percent reduced risk of stroke and a 31 percent reduction in premature death.
The study's lead author said in a statement, "It is clear from this work that a high intake of fruit and vegetables hold tremendous health benefits, and we should try to increase their intake in our diet."
Now, not all fruits and vegetables are created equal.
Researchers say apples, citrus fruits and leafy green veggies are best when it comes to preventing heart disease and stroke.
And to reduce the risk of cancer, they recommend chowing down on green and yellow vegetables, like spinach, carrots and peppers.