Fourty-five days. That’s how long many of us in northern latitudes must wait before sunlight can help our bodies produce vitamin D again. Winter isn’t just about cold days and snow-covered streets—it’s a season when the sun, at least in its vitamin-generating form, disappears from our lives.
Even under a bright Vermont sky, my body probably won’t produce a single molecule of vitamin D in winter. From November through February, the sun sits too low in the sky to provide the UVB rays needed for vitamin D production across most of the United States. Only 15 states lie entirely below the 37th parallel, where sunlight remains strong enough year-round.
