Two major studies have confirmed the importance of vitamin D to support a range of bodily functions, offsetting cancer and heart disease. But the studies also question the efficacy of taking vitamin D in supplement form. Known as the “sunshine nutrient,” most of the vitamin D we require is produced photochemically in the skin, and the best way to stock up is to spend time outdoors. But while we may be short on sunlight, today’s humans are overdosing on artificial light and risking depression, obesity and heart disease. Basically, we’re trapped between a light and a dark place.