I will talk about raw materials used in popular, blueberry-based health food.
Bilberry (a wild blueberry species) is used in most blueberry-based health food as a raw material. The reason is that it contains more active ingredient anthocyanidin than blueberry. This active ingredient, anthocyanidin, is a blue pigment and also a kind of polyphenol. It has a very potent antioxidant effect. In its natural state, it exists in the form where sugar is attached to anthocyanidin, and this sugar-bound form is called anthocyanin.
Health foods always have to display ingredients, but they are rather vague in many cases and often confusing for consumers. For example, an indication of "Ingredient: Blueberry" on a blueberry-based health food can only mean that a blueberry cultivar was used as a raw material. Even if the label says "Ingredient: Bilberry", it does not tell whether it is of high quality. (Well, when ingredients are stated in such as manner, it is most likely that high quality ingredients are not used.)
To be detailed and easy-to-understand, "Ingredient: Bilberry (anthocyanidin content, 25% or higher)" should be OK. By the way, among raw materials currently available, those with the anthocyanidin content of 25% or higher are the best quality materials. There is nothing better than this.
Some state "Ingredient: Bilberry (anthocyanin content, 36% or higher)", although it means the same thing as the anthocyanidin content of 25% or higher. Because anthocyanin is the sugar-bound form of anthocyanidin as mentioned above, the value has increased by the amount of sugar attached. However, the content is exactly the same.