Why are Blueberries Blue?

by Taylor Tibbs

Versión en Español

Photo of blueberries. Source: Daniel Hurst Photography / Getty Images.

I can think back to the hot summers of my childhood bickering with my cousins about who gets the coveted blue raspberry ice pop. Similarly, we would also debate over which jolly rancher flavor is the most superior, which while the answer is clearly watermelon, there are many in camp blue raspberry too. But if I stopped to think about it, what actually is a “blue raspberry”? Had I ever seen one? In the produce section of the typical grocery store, among the purply-pink raspberries and the succulent red strawberries, there is only ever one fruit that could be considered truly blue. If blue fruits are so rare, what is so special about the blueberry? Why are blueberries blue? 

Of the over 2,000 different kinds of edible fruit in the world, only 14 of them are blue. That’s less than 1%! Given those statistics, it’s no wonder that we see so few blue foods at the supermarket. But why are blue fruits so rare? Ultimately, it comes down to a (perhaps disappointing) fact that no fruit is actually blue, but rather a very deep and quite unique shade of purple. All fruits gain their color by the production of phytochemicals. Phytochemicals are molecules produced by plants to carry out various cellular functions, like photosynthesis, to gain energy. Interestingly, phytochemicals often also act as pigments or color dyes. It is due to these vibrant phytochemicals that “roses are red and violets are blue”. What makes blueberries so blue is actually their unique combination of phytochemicals, most notably anthocyanins. Anthocyanins are the culprit behind the gradient of reds and purples we see in fruits and vegetables – and blueberries have a lot of them. When certain combinations of anthocyanins are in high enough quantities, the resulting color is a deep robust purple, which to our eyes appears as blue. 

Illustration of blueberries and various anthocyanin chemical structures. Author’s own work.

In addition, anthocyanins aren’t just good for turning things blue. These same colorful phytochemicals are also cancer-fighting antioxidants. Antioxidants (small molecules and vitamins) are responsible for neutralizing free radicals in the body, which are unstable toxic molecules that can give rise to inflammation and cancer. Blueberries are jam-packed (pun intended) with antioxidants, which is why they are so good for you! 

The blueberry’s fetching blue color is also exactly what draws us to them. Blue is a rare color in nature, so when a plant produces blue-looking fruit, it is sure to be a headturner. This attractive quality persuades both us (and other animals) to eat the scrumptious berries packed full of healthy vitamins, minerals, and antioxidants. Then, once the animal eats the berries, they go in one end and out the other. And since animals often don’t stay in the same place for very long, they are ultimately helping the blueberry seeds to spread. So it’s a win-win scenario for both us and the blueberry. The blueberry provides us with a nutritious snack, while we help the earthbound blueberry bush spread its roots to far-off places. Tasty, healthy, and pretty. Blueberries really are the whole package!

While the blindingly out-of-this-world-blue “blue raspberry” may be confined to popsicles and the candy aisle, we can be sure that the blueberry, one of the world’s truest and bluest fruits, will never disappoint. Even if you’re more of a strawberry or banana fan, you would have to go blue in the face to refute the blueberry’s remarkable production of anthocyanins and antioxidants.

Edited by Olivia Steiner