> Sure enough, when he exposed volunteers to the equivalent of 30 minutes of summer sunlight without sunscreen, their nitric oxide levels went up and their blood pressure went down.
Sorry for challenging here, I don’t remember the actual study being linked, and it seems I’m now paywalled and can’t check myself: did he do the same experiment with folks wearing sunscreen? Did he control for relaxation effects? I’d expect both blood pressure to go down and nitric oxide to go up as folks relax, e.g. in a sunny garden or on a tanning bed.
Not sure the “causal connection” is fully established.
That is a causal connection.