They may be tiny but this is what the NHS website has to say about them:
The Grandad of the superfood trend, this cute little North American fruit packs a powerful nutritional punch.
Blueberries are a good source of vitamin K. They also contain vitamin C, fibre, manganese and other antioxidants (notably anthocyanins)
Valued for its high levels of antioxidants, some nutritionists believe that if you make only one change to your diet, it should be to add blueberries.
I grew these myself. This year we’ve had our best blueberry harvest ever.