Whole Fruits, Fruit Juice and Type 2 Diabetes Risk

I recently read the findings of a study conducted by researchers at the Harvard School of Public Health, (ref 1) and due to the health implications I thought it would be valuable to share this information with our readers. Fruit is packed with heart-healthy fiber, vitamins and antioxidants, making it a natural go-to for healthy breakfasts and lunch boxes worldwide.


But for optimum health, experts say that  it is  important to eat fruits in moderation and in their whole form, not as juice.

According to researchers at the Harvard School of Public Health, eating whole fruits can lower the risk of developing type 2 diabetes, while juicing them can significantly increase that risk.

Researchers studied data gathered over a 25-year period, and found that people who ate at least two weekly servings of whole fruits – especially the powerhouse trio blueberries, apples and grapes - reduced their risk for type 2 diabetes by more than 20 percent compared to those who ate less.

A closer look

The study also found that people who drank fruit juice once or twice a day hiked their risk of type 2 by more than 20 percent. Trading at least three of those glasses of juice for the fruit itself reduced that risk by about 7 percent, researchers said.

While experts have long suggested that consuming more raw, whole fruit may help prevent many chronic diseases, the link between fruit consumption and type 2 diabetes hasn't been crystal clear, researchers said. This study, however, solidifies the benefits of at least certain fruits, though more detailed studies are needed to determine if fiber, antioxidants or some other factors may play a role.

While the glycemic index - a measurement that determines how quickly a food is turned into glucose and sent into the blood stream to be used as energy - did not seems to factor into the research regarding whole fruits (most of which are on the low end of the scale), experts said, the glycemic index might have had a role in the relationship between juice consumption and elevated risk, since juices offer less fiber and are quickly turned into energy.

Another key point to mention, which these researchers did not, is that whole fruits, as beneficial as they are, should be eaten in moderation. That’s because in comparison with veggies for example, they:

  • Are higher in simple carbs which may cause blood sugar imbalances
  • Don’t contain much protein which helps to preserve muscle mass, and keeps you fuller longer
  • Are high in fructose which may lead to increased blood lipid levels and to visceral adipose fat.

Why these three fruits?

Not only are blueberries, apples and grapes on the low end of the glycemic index, previous research may provide clues to the connection between the three key fruits and a reduced risk of diabetes.

Because blueberries are one of the most antioxidant-rich foods available, they could help reduce inflammation, which has been linked to type 2, while fighting free radicals and protecting against cell damage. According to WebMD.com, one cup of blueberries also has almost 15 percent of a day’s fiber and a quarter of the recommended dose of Vitamin C.

Apples are packed with soluble fiber, which means the sugars in the fruit are released into the bloodstream slowly, providing a steady flow of energy that keeps you feeling full while keeping blood sugar levels steady. They also offer pectin, which may help to promote a healthy cholesterol profile.

Grapes offer the phytonutrient resveratrol, which has been linked to a healthier metabolic rate among other benefits.

The following links related to the HSPM study may be of interest:

1. Harvard School of Public Medicine study

2 Food Navigator article

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