True enough, sunlight is a great way to get vitamin D. I read that the normal range is 40-50 ng/ml in the blood, and 20 is terribly low. In my case my last blood test showed I was down to 6 ng/ml. Unfortunately there isn’t much sun in my part of the world right now so I have to take a liquid supplement daily for the present.
A lot of people are having low vit D because of years of campaigns to prevent melanoma [skin cancer], so people often use sunscreen creams to block UV rays, or to prevent burning. As a result many are not getting the vit D from the sun they need.
Bugs Bunny: "I speak softly, but I carry a big stick."
Yosemite Sam: "Oh yeah? Well I speak LOUD! and I carry a BIGGER stick! and I use it, too!" BAM!