Low Carb High Fat - Ketogenic

Vitamin C Overuse Can Worsen Oxalate Load: Vitamin C metabolizes into oxalic acid, so excessive vitamin C intake—particularly intravenous high-dose therapy—can exacerbate oxalate crystal formation in tissues and veins, causing fibrosis and vascular damage. This is a caution against indiscriminate use of vitamin C supplements without considering oxalate toxicity risks.

I was mildly horrified to learn of this because I was given high doses of vitamin C as a child to "bolster my immune system."

I also recently learned that sugar reduces the body's ability to uptake vitamin C, and the body is also able to recycle vitamin C quite efficiently, so there is no need to supplement vitamin C since you only need a small amount from your diet.