Toxicity is defined by serum levels, and is at around 100 ng/mL. My last labs put me at 39 ng/mL, and I've been taking vitamin D for years. Under 30 is consider

Toxicity is defined by serum levels, and is at around 100 ng/mL. My last labs put me at 39 ng/mL, and I've been taking vitamin D for years. Under 30 is considered insufficient, under 20 is deficient. I mean, yeah, sure, don't chug bottles of the stuff without measuring for years on end, but you have to take a lot to hit toxicity levels. And periodic bloodwork to keep an eye on numerous metrics is a generally good idea anyhow.