" Supplements may hinder autophagy. When fasting for metabolic reasons (meaning insulin resistance–related conditions such as type 2 diabetes, obesity, PCOS, and nonalcoholic fatty liver disease), the effectiveness of supplements is questionable. Most vitamins are fat soluble, but if you’re not taking in fat they won’t be as effective. Probiotics are fine to continue taking while fasting. "

― Jason Fung , Life in the Fasting Lane: The Essential Guide to Making Intermittent Fasting Simple, Sustainable, and Enjoyable