A Ginger bug starter ferments wild yeast and Lactobacillus. The University of California, Davis highlights fermented ginger drinks as rich in probiotics. Mix grated ginger, sugar, and water for 5 days to make the starter, then ferment any fruit juice with it for a fizzy gut-friendly soda.
(Disclaimer: This content is for educational purposes only and does not replace professional medical advice. Consult your doctor or a registered dietitian before starting probiotic-rich foods if you have gut disorders, weakened immunity, or chronic illnesses.)