According to http://www.vitaminsinamerica.com/news/vitamin_d.htm, “it is estimated that for each 5% of skin surface exposed, approximately 435 IU of Vitamin D can be manufactured. The process requires that the oil on the skin remain intact for awhile after exposure to the sun.  For instance, life guards and farmers, who don’t go shower immediately after sweating in the sun, have the highest serum Vitamin D levels. Try to keep the oil on your skin for at least several hours after sun exposure.”

Don’t be afraid to get sweaty in the sun. And don’t rush to take that shower. Your body is busy producing vitamin D, the sunshine vitamin.

The benefits if vitamin D are numerous : healthy teeth, stronger bones, regulating immune defense system, improve cognitive functions, help maintain healthier body weight, and protect from radiation damage.

But only to smart causes. The power couple is interested exclusively in “impact giving.”

They, for example, plan to fund a comprehensive experiment on what causes obesity. There is much more to know about how the body processes food. A study like this could lead to effective advice not just on obesity but also on other dietary issues; it could improve well-being for virtually everybody.

Along with obesity, they also want to dig into criminal justice and pension reform.

The Arnolds want to give their money to projects that will contribute to the wider depository of human knowledge. Causes have to show a scientific approach to prove that the projects have a high probability of working.

The Arnolds have been criticized for not giving to more immediate (non-experimental) causes. Their public donations focus on public policy problems that create “moral inefficiencies”. They want to help society by making it smarter.

According to The Chronicle of Philanthropy, last year, at $423 million give this far, they are the third-highest givers in the country.

Some philanthropers give money to maintain an image. Some give money to help organizations that helped them. And some, like the Arnolds, give money to actually improve society. The fact that the Arnolds think about the causes they’re supporting in terms of scientific inquiry, implementation, and impact rather than just randomly writing checks indicates that they care both deeply and smartly.