Thank you for the blog post! I live in New England and always had the winter blues, always just assumed it was because of the weather but never acted on it.

About a week ago, there was a reddit post claiming it's actually geographically impossible for anyone where I live to produce enough Vitamin D naturally from the sun alone, due to the shorter days and lower angles throughout the day. I had no idea.

Thank you! I relate; I live in Montréal, close to New England, with similar climate. The current UV Index for Montréal is... 0. And the current UV Index for Boston is... 0.6. (1.6 later today)

I can't find a rigorous academic source right now, but the top web results all say we need at least UV Index 3 for our skin to be able to make enough Vitamin D. I guess summer may work for us, in the Montreal/New England area, but other than that, yeah, you and I will need to get Vitamin D from diet and/or supplements. And fish is expensive, so supplements it is.