My son battles with constipation and this product was recommended. However, he has an allergy to yeast. Most citric acid is created using yeast. The ingredients list 'natural citric acid', does that mean yeast is not used to create the citric acid?

Oxy-Powder is excellent for addressing occasional constipation and cleansing the entire intestinal tract. We include natural citric acid (from tapioca vs. yeast) in the blend to help jumpstart the detoxification process.