Hey, Kevin Drum. A better common denominator than lead poisoning.

Scientific American:

The push to prevent skin cancer may have come with unintended consequences—impaired brain function because of a deficiency of vitamin D. The “sunshine vitamin” is synthesized in our skin when we are exposed to direct sunlight, but sunblock impedes this process. And although vitamin D is well known for promoting bone health and regulating vital calcium levels—hence its addition to milk—it does more than that. Scientists have now linked this fat-soluble nutrient’s hormonelike activity to a number of functions throughout the body, including the workings of the brain.



“We know there are receptors for vitamin D throughout the central nervous system and in the hippocampus,” said Robert J. Przybelski, a doctor and research scientist at the University of Wisconsin School of Medicine and Public Health. “We also know vitamin D activates and deactivates enzymes in the brain and the cerebrospinal fluid that are involved in neurotransmitter synthesis and nerve growth.” In addition, animal and laboratory studies suggest vitamin D protects neurons and reduces inflammation.