Can eating blueberries cause black stools?

In general, whether eating blueberries causes black stools depends on the amount consumed. If a large quantity of blueberries is eaten, black stools may occur; however, with normal consumption, black stools typically do not appear. The details are as follows:

Blueberries are rich in anthocyanins, which are blue-purple in color. After consuming a large amount of blueberries, these anthocyanins may be excreted along with food residues, causing the stool to turn black. This is a normal physiological phenomenon and does not require excessive concern.

For individuals who consume blueberries in normal amounts, moderate intake usually does not lead to noticeable changes in stool color, meaning black stools will not occur. This is because the body can effectively process and metabolize most of the ingested anthocyanins, leaving insufficient residue to significantly alter stool color.

It is advisable to eat blueberries in moderation, as they contain abundant fructose. Excessive consumption may affect blood sugar balance. Also, ensure that the blueberries are fresh.