Are Blueberries Good For Diabetes?

Are Blueberries Good for Diabetes?
Are Blueberries Good for Diabetes?

Over the past few days we’ve been examing blueberry health benefits. Today, I’m asking – are blueberries good for diabetes?

With the Center for Disease Control reporting that more than 10 percent of US adults are diabetic, and 35 percent of those 18 and older are pre-diabetic, diabetes among Americans has reached a crisis level. 

Think about it! We are fast approaching one-half  (currently 45 percent) of Americans 18 and older living with prediabetes or diabetes. 

Insulin resistance (poor response to insulin stimulation) indicates both prediabetes and type 2 diabetes. Insulin resistance makes it harder for the glucose in our food to enter our cells and be converted into energy.

We know that a whole-foods, plant-based diet is good for diabetes. But are its individual ingredients helpful by themselves? 

For instance, are blueberries good for diabetes? 

A Harvard study sought to determine whether certain fruits or fruit juices had different impacts on diabetes.  The researchers looked at three studies with data from 187,382 US health care professionals followed from the mid-1980s to around 2008.

Over that time, 12,198 (6.5 percent) of the participants developed type 2 diabetes. Those who consumed a variety of whole fruits had a  lower risk of the disease, but some fruits reduced the risk more than others.

Starting with the bad news, the study found a strong association between fruit juice consumption and increased diabetes occurrence. Among fruits, only cantaloupe had a small correlation with higher risk.

blueberries good for diabetes
Are blueberries good for diabetes?

On the positive side, fruits with a beneficial impact on diabetes risk (ranked from least to most helpful) were:

  1. Strawberries
  2. Oranges
  3. Peaches, plums, and apricots
  4. Grapefruit
  5. Apples and pears
  6. Prunes
  7. Grapes and raisins 

But where are blueberries?

Are Blueberries Good for Diabetes? Harvard Answers!

Absolutely yes! In the Harvard study’s category of fruits most associated with lower incidents of type 2 diabetes, blueberries claimed the top spot! 

What happened if people replaced fruit juice with whole food ingredients? The risk of type 2 diabetes dropped dramatically.

The researchers analyzed how much replacing three servings of fruit juice a week with an equivalent amount of whole fruit would lower the pre-diabetes risk. The average reductions?  

Are Blueberries Good for Diabetes? - Eating oranges reduces diabetes risk. Drinking them raises it.
Eating oranges reduces diabetes risk. Drinking them raises it.
  • Total whole fruits: 7 percent
  • Oranges: 8 percent
  • Peaches, plums, and apricots: 11 percent
  • Grapefruit: 12 percent
  • Bananas:13 percent
  • Apples and pears: 14 percent
  • Prunes: 18 percent
  • Grapes and raisins: 19 percent

Blueberries: 33 percent!

How consistent were these findings? According to the researchers, “Most of these associations were quite consistent among three cohorts.”  

How Are Blueberries Good for Diabetes? Anthocyanins!

The other posts in this week’s blueberry series have emphasized the berries’ high anthocyanin content. To determine if this specific compound accounted for the berries impact on diabetes, the Harvard researchers  examined five flavonoid subtypes: 

  • flavonols 
  • flavones 
  • flavanones 
  • flavan-3-ols 

and anthocyanins.

Amazingly, they found that more than one monthly, but less than two weekly, servings of anthocyanin-rich foods, “particularly blueberries,” reduced incidences of type 2 diabetes by 23 percent. 

Other substantial studies support their findings. A 2016 systematic review and meta-analysis published in the European Journal of Clinical Nutrition examined the associations between anthocyanins or berry fruits and the risk of type 2 diabetes. 

This research connected anthocyanin intake with a 15-percent reduction in type 22 diabetes risk. For berry fruits, including blueberries, the reduction climbed to 18 percent (a 20-percent increase over anthocyanins in general).

Are Blueberries Good for Diabetes? - Eating this many blueberries a day can lower type-2 diabetes risk 5 percent!
Eating this many blueberries a day can lower type-2 diabetes risk 5 percent!

They found a further dose-associated response to both anthocyanins and berries. Every 17 grams (about 1.5  tablespoons) of daily berry intake reduced type 2 diabetes risk by 5 percent.

More is better – that’s about 15 small blueberries a day!

Finally, a  study published in the British Journal of Nutrition showed even more impressive results: it connected greater anthocyanin consumption with a 32-percent drop in the risk of type 2 diabetes!

Are blueberries good for diabetes? 

The evidence is strong that blueberries are much more than merely “good” for diabetes. They are clearly one of the best foods we can eat if we want to avoid what’s become a crisis-level disease! 

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