Clinical trials in humans and population studies show that sugar added to foods increases risk for diabetes and heart attacks, while sugar in whole fruits does not (Mayo Clinic Proceedings, published online January 29, 2015). People who eat lots of fruits and vegetables are at reduced risk for heart attacks and are least likely to die prematurely (European Journal of Preventive Cardiology, 04/25/2015 and European Heart Journal, Sept 2014). An earlier review of several studies showed that heart attack risk is reduced by seven percent for each daily portion of fruit ( J. Nutr, October 2006;136 (10): 2588-2593). Another study showed that eating lots of fruits and vegetables is associated with a 46 percent reduction in diabetes in women (Preventive Medicine, Jan 2001;32(1):33-39).
Why Fruit is Healthful, Even Though it Contains Sugar
• Sugar in fruit is far less likely to cause a high rise in blood sugar than sugars added to drinks or foods.
• Fruits contain soluble and insoluble fiber that binds to the sugar while it is in your intestines, delaying absorption and blunting the rise in blood sugar levels.
• Fruits help people control weight by making them feel full earlier so they eat less. One apple contains 23 grams of sugar and is more filling than a 16-ounce bottle of cola that has 52 grams of sugar.
• The sugar in fruits is combined with antioxidants that help to block inflammation that damages cells.
• Fruits lower high blood pressure and blood sugar levels and reduce oxidative stress in diabetics (Complement Ther Clin Pract, 2013 May;19(2):97-100 and JAMA, May 19, 2015; 313(19)). On the other hand, sugar added to foods is associated with increased risk for high blood pressure (Open Heart, Jan, 2014;1(1)).
Why Sugar Added to Foods and Drinks is Unhealthful
Foods with added sugars cause a high rise in blood sugar, with sugared drinks causing the highest rises in blood sugar and a marked increase in risk for obesity, heart attacks, strokes, certain cancers and premature death (Int J Obes (Lond), 2008 Dec;32 Suppl 6:S28-34). The risk for diabetes is 11 times higher for each 150-kcal/person per day increase in sugar vs a similar increase in total calories (PLoS One, 2013;8:e57873). See Sugar Added Foods Increase Diabetes Risk. High rises in blood sugar cause sugar to stick to the outside membrane of cells and destroy the cells, so anything that causes blood sugar levels to rise too high after eating increases risk for diabetes and its consequences: blindness, deafness, heart attacks, strokes, dementia, impotence and so forth.
Avoid drinks with sugar except during vigorous exercise. Sugars are more damaging to your health in drinks than in solid foods because you get higher blood levels of sugar after drinking sugar than eating it. A teaspoon of sugar in coffee or a soft drink is more damaging than the same amount in a cookie or a piece of cake.
Fruit for Diabetics
If you are a diabetic and are taking medications, check with your doctor for recommendations on eating fruit and monitoring its effects on your blood sugar. We do not know the exact amount of fruit diabetics should eat, but we do know that omitting fruit from a diabetic's diet does not lower blood sugar or insulin levels.
• Try to replace most of the processed foods in your diet with foods in their natural state: fruits, vegetables, whole grains, beans, nuts and other seeds
• Avoid sugar in liquid forms, including fruit juices
• Restrict foods that have had sugars added to them