Why Harvard doctors are seeking out this natural remedy for themselves

BOSTON — Susan Abookire, an internist and professor at Harvard Medical School, had a cure for all that ailed me. But I was going to have a difficult time getting her prescription filled at CVS.

“Imagine that your body has roots,” she advised me, “and notice the roots. Watch them as they tunnel down from your body, through your legs and your torso down into the earth. Your roots are mingling with other roots in the earth. Imagine your roots have eyes and wonder what they might see.”

I was imagining my root-eyes struggling to see anything through all that dirt — but the doctor was not done with her instructions.

“Find a being. The being might be a tree or rock,” she told me. “Greet it as you would a friend. … You might want to introduce yourself. You may want to share something with that being.”

I was participating, somewhat skeptically, in a forest bathing session Abookire was leading at Harvard’s Arnold Arboretum for seven young doctors. It’s part of resident training at Harvard-affiliated Brigham and Women’s Hospital, which is looking for ways to reduce stress and burnout within the profession. Abookire also trains health care professionals nationwide to be “forest therapists,” a program accredited by Mass General Brigham that promotes nature as a form of medicine.

Abookire conducts a tea ceremony for medical residents. (Dana Milbank/The Washington Post)

Before I looked into forest bathing, I feared it might be another goofy wellness fad like Gwyneth Paltrow’s jade eggs and Tucker Carlson’s genital tanning. But here was a doctor from a top medical school, with the support of one of the top residency programs, guiding some of the brightest young medical minds into the woods.

So I did what the doctor ordered. I introduced myself to a mushroom.

“We’re standing here breathing in the atmosphere of the forest,” she told the residents, who had showed up in their scrubs, some carrying stethoscopes. She explained that just by standing among the trees, we were inhaling essential tree oils called phytoncides and aromatic plant compounds called terpenes. “There’s several studies now showing that inhaling phytoncides boosts our immune system, and specifically our natural killer-cell numbers and activities go up,” she said. “And there are a lot of studies going on — NIH, others, many in vitro and some in vivo — showing how terpenes are cytotoxic and anti-tumorigenic, they’re neuroprotective, et cetera.”

Breathing in tree scents fights infection, prevents cancer and protects against dementia? Deep underground, the eyes in my roots opened wide with delight.

A medical resident reads a scroll during the forest bathing exercise. (Dana Milbank/The Washington Post)

Medical residents “breathing in the atmosphere of the forest.” (Dana Milbank/The Washington Post)

Qing Li, a professor at Japan’s Nippon Medical School and a prolific researcher of forest bathing, believes the key is the phytoncides that trees emit, which he has found to boost immune function and anticancer proteins.

The many benefits of forest bathing — reduced depression and stress, better pulmonary and cardiovascular health — can be achieved even in city parks. But, he told me, “the larger the trees, the higher the tree density, and the larger the forest area, the greater the effects of forest bathing.” More phytoncides and more terpenes, more benefit.

He also believes we profit from inhaling negative ions (found in abundance near waterfalls) as well as a microorganism found in the soil, Mycobacterium vaccae.

Li’s method of forest bathing, and the Japanese method of shinrin-yoku generally, is far less structured than the style commonly practiced in the U.S. He recommends spending two to four hours in the forest walking at a slow pace (about ¾ of a mile per hour) and paying attention to your senses, while also taking time for yoga, tai chi, deep breathing or reading. He counsels removing shoes, dipping toes in water and standing barefoot for 20 minutes to feel “grounded.” The Japanese like to end the session by bathing in hot springs.

Li reports that the immune benefits of a two-night camping trip in the forest can last for a month. If you don’t have time for all that, you can also inhale phytoncides at home by using diffusers that disperse cedar and other essential oils.

Clifford’s version of forest bathing, a sequence of “invitations” proposed by the guide, is, by comparison, highly ritualized. That stems from his background in meditation. But even he allowed that an unstructured approach will suffice. “Just find a place you enjoy in nature and … go out there and enjoy yourself,” Clifford counseled. Sometimes he forest-bathes just by sitting in a folding chair by a lake. “It doesn’t need to be any more complicated than that.”