For An Immune Boost, Get Into Nature

I am lucky to have spent the long weekend in Wellfleet, in a cottage in the woods with my children. So I was overjoyed to read Anahad O'Connor's "Really" column yesterday detailing the immune boost researchers have identified in people who have spent time outdoors around trees and nature.

In a series of studies, scientists found that when people swap their concrete confines for a few hours in more natural surroundings — forests, parks and other places with plenty of trees — they experience increased immune function.

Stress reduction is one factor. But scientists also chalk it up to phytoncides, the airborne chemicals that plants emit to protect them from rotting and insects and which also seem to benefit humans.

In Japan, the popular practice of visiting a nature park for its therapeutic effect is called "forest bathing," O'Connor says, noting that one Japanese study found that "being among plants produced lower concentrations of cortisol, lower pulse rate, and lower blood pressure."

A number of other studies have shown that visiting parks and forests seems to raise levels of white blood cells, including one in 2007 in which men who took two-hour walks in a forest over two days had a 50-percent spike in levels of natural killer cells. And another found an increase in white blood cells that lasted a week in women exposed to phytoncides in forest air.