Really the conclusion of that paper, that people are not vitamin D deficient, ought to be that people are sunlight deficient. This is why studies that involve supplementation of vitamin D frequently show no effect. Vitamin D is only one of many many ways in which light affects biology.
The paragraph near the end about babies needing fortified milk because breast milk is insufficient in vitamin D is laughable. It seems pretty obvious that babies are one of the most, if not the most, sunlight deficient demographics.
The paragraph near the end about babies needing fortified milk because breast milk is insufficient in vitamin D is laughable. It seems pretty obvious that babies are one of the most, if not the most, sunlight deficient demographics.