Too Much Fruit?

Many popular commentators suggest that we limit fruit intake to two pieces of fruit a day due to the fructose content. However, there is a big difference between consuming fructose in fruit and consuming fructose added to foods in products such as high-fructose corn syrup.

Dr. Bruce Bistrian, a professor at Harvard Medical School explains in a the role of fruit in a Harvard newsletter, Rethinking fructose in your diet. 1

But don’t reject a food just because it contains fructose. Fructose is naturally found in fruits. Fruits are not harmful and are even beneficial in almost any amount. Fruits contain lots of fiber. The fructose is bound to the fiber, which slows its absorption. Even more important fruits and vegetables contain many other essential nutrients, such as bioflavonoids.

The newsletter concludes with the following advice:

Bottom line: Look for added sugar on food labels and limit your intake. The American Heart Association recommends no more than 100 calories, or 6 teaspoons, of sugar per day for women, and 150 calories, or 9 teaspoons, of sugar per day for men.

However, this recommendation is incorrect by 6 teaspoons of sugar a day for women and 9 teaspoons of sugar a day for men.

David Jenkins (the originator of the Glycemic Index) and colleagues compared three diets over a two week period.2

  • high vegetable diet: leafy and low-calorie vegetables with an emphasis on leafy vegetables and pods, fruits, and nuts with 20 servings of fruit and 40 servings vegetables
  • high starch diet: whole-grain cereals, legumes, low-fat dairy products, olives, and olive oil and 11 servings per day of fresh fruit and vegetables
  • low saturated fat diet: low-fiber starchy foods, skim milk dairy products, olive, and safflower oils, together with 5 servings per day of fruit

The 20 servings of fruit on the high vegetable diet could easily contain more than 200g of fructose – equivalent to about 6 cans of cola.

There were no ill effects on any of the diets. The average body weight, total cholesterol and LDL cholesterol were reduced on all three diets with the greatest reduction in cholesterol occurring in the high-vegetable diet.


  1. Harvard Medical School (2013) Rethinking fructose in your diet.
  2. Jenkins, D. J. A. et al. (2001) Effect of a very-high-fiber vegetable, fruit, and nut diet on serum lipids and colonic function. Metabolism. 50 (4), 494–503.

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