PREDIMED was a randomized controlled trial whose design was so sound — and whose results were judged so important — as to merit publication in the New England Journal of Medicine , one of the top three medical journals in the world.  The PREDIMED physicians recruited 7447 Spanish men and women who did not have actual cardiovascular disease, but who were at high risk of heart attack or stroke because of things like overweight and obesity, high blood pressure, high cholesterol, and diabetes. In the balanced-but-random way of the best clinical trials, subjects allocated to groups that would be counseled to follow one of three diets.
In Ayurvedic medicine, sunshine is supposed to be good for a person's circulation, which I've found usually means it also thins the blood. As noted above, other Ayurvedic remedies for improving circulation, such as cinnamon and ginger, have actually been proven in modern medical studies to be natural blood thinners. As such, it would be logical to consider the possibility that if Ayurvedic medicine scholars were correct about the spices thinning the blood, they may have been right about sunshine, too.