Berries 101: Small Fruits, Powerful Benefits

Note: this is a short launch draft. It's being expanded into a full guide, and every figure in it gets read back against the source before that happens.

Berries get more health-halo marketing than almost any other food, which is a shame, because the real story is decent and doesn't need the halo.

What's in them

The pigments that make blueberries blue and blackberries black are anthocyanins, a family of polyphenols. Darker berries carry more. Blackcurrants, blackberries, blueberries and black raspberries sit near the top; strawberries and red raspberries carry less anthocyanin but bring other polyphenols, mainly ellagitannins. Cranberries are their own case, with proanthocyanidins doing most of the work.

Per 100 grams, anthocyanin content runs from a few dozen milligrams in strawberries to several hundred in blackcurrants and wild blueberries. Cultivated blueberries sit in the middle. Frozen berries hold most of their polyphenols, which matters because frozen is what most of us actually buy in February.

What the evidence looks like

The strongest human data is observational. A large analysis from the Nurses' Health Study II, published in Circulation in 2013, found that women who ate the most anthocyanin-rich foods, mostly blueberries and strawberries, had a lower rate of heart attacks over 18 years than women who ate the least, even after adjusting for the usual confounders. That's an association, not a trial. People who eat a lot of berries differ from people who don't in ways a questionnaire can't fully capture.

The short trials that exist are small and mostly measure things like blood vessel function over hours or weeks. They're encouraging and they're not the same as an outcome.

How to eat them without making it a project

About a cup a day is what the observational studies call "high intake", and it's an easy amount to hit. A handful on oatmeal, a bag of frozen blueberries kept for smoothies, or just a bowl after dinner. I'd pick whatever you'll actually eat over whatever has the highest number in a table. The best berry is the one that doesn't go moldy in your fridge.