I've read that vitamin C + fats might promote cancer, and that these fats remain in the stomach for quite a long time after a meal:
https://www.ncbi.nlm...pubmed/17785370
Vitamin C has been found to interfere with adaptations to exercise and interfere with beneficial pro-oxidant signaling, and it might interfere with the benefits of fasting or the benefits from other supplements (eg. resveratrol.) That said, I wouldn't mind finding a slot for an additional 250-1,000mg/d of ascorbic acid in my HFLC diet.
I usually eat in a 6-8hr window. Would I be best served having the Vitamin C upon waking, far before breakfast (with my coffee?), or with a high-fat meal inside my eating window, or right before bed?