Breathing your way to better blood pressure
Hypertension. Sixty-seven million Americans have been diagnosed with the condition, more commonly known as high blood pressure.
Before they hit age 50, hypertension is less common in women than in men. The female hormone estrogen likely serves as a kind of protection. But after 50, women’s rates of hypertension go up. That increases the risk of heart disease. And heart disease kills more women than anything else.
That’s how it went for Susan Evans. Her blood pressure changed with age.
“It was always 110/70, 120/80...perfectly fine blood pressure,” Evans said. “But it was beginning to creep up. I was like, hmm...not good.”
Evans is a nurse, and she tries hard to stay healthy with diet and exercise. She didn’t want medication. Later, she saw a flyer at the gym. That led her to a clinical trial set up by researchers at UC San Francisco’s Osher Center for Integrative Medicine.
“They told me I would listen to a woman named Terre on the tape, and she would introduce the idea of meditation to me. And while I was listening, they would test my breathing and my blood pressure,” said Evans.
The Osher researchers wanted to know: could mindfulness meditation lower the risk for hypertension in women like Evans? That is, women who were past menopause, with blood pressure that wasn’t terrible, but not great either.
Through mindfulness Evans would learn to watch her mind and her breath. If it worked, a decrease in blood pressure would lower her risk for things like heart attacks and strokes.
“Most medications have side effects,” said Margaret Chesney, lead investigator of the clinical trial and director of the Osher Center. What we’re trying to do, she said, is help people avoid the point where their physicians have to make those decisions.
Chesney and her husband, who is also a scientist, designed the clinical trial. They’re part of a growing number of researchers who are exploring the benefits of mindfulness. The two stand out in that crowd because they’re not devoted, true believing meditators. Instead, you could say their marriage got them here. A marriage that fused separate interests — in basic science and the relatively new field of integrative medicine, which takes a holistic approach to health care.
“I grew up in a household where there was great attention to diet and exercise and these kinds of things,” Chesney said.
In other words, a balanced approach to health, which has been Chesney’s focus for years. Back in the 80s, she was already testing ways to treat hypertension in more natural ways.
“And we did get effects on hypertension, but it wasn’t what everyone had hoped,” said Chesney. “It was not as effective as an inexpensive drugs and so the medications for hypertension really became very popular.”
Chesney is pragmatic and moved on in her career. Then in 2002, she married David Anderson, a scientist who had spent his entire career in basic research, obsessively studying hypertension. When he first started out scientists still hotly debated the cause.
“I was amazed to find that the cause of high blood pressure was actually unknown,” said Anderson.
He became like a detective following clue after clue. There are likely several mechanisms by which hypertension occurs. But after many years and many experiments, he pinpointed breathing as a possible culprit and cure for some people. The tip-off came from an observation about carbon dioxide.
“We observed that under some conditions levels of carbon dioxide increased above normal levels and that’s when blood pressure began to rise,” said Anderson. “And so we thought we were onto something there. And to our surprise, this was more true in women than in men.”
What was happening? Remember, we breathe in oxygen and exhale CO2. But if you hold your breath, carbon dioxide stays in your blood and the levels go up.
Chesney says women in particular may respond to stress by holding their breath. For example, in the movie Superman, you can hear Lois Lane catch her breath when he swoops her up into the air for the first time.
“Everything is so finely tuned,” Chesney said.
She explains. You hold your breath and CO2 goes up. When your CO2 goes up, your blood becomes more acidic. When your blood becomes more acidic, the kidney senses it.
“The kidneys pick up this through the blood, and realizes, this isn’t ideal,” Chesney said.
Normally, the kidneys are acting as a filter. They remove excess sodium, or salt, and we end up peeing it out. But when you hold your breath, the kidneys will start holding onto sodium to restore acid-base balance, she said.
That starts a whole other sequence of events. More fluid enters the blood vessels. For some people, it’s no big deal. The blood vessels expand. But for others, the blood vessels can’t adjust. And that’s when blood pressure starts to go up.
“This is, I would say, my theory,” said Anderson. “It is not proven to the satisfaction of everyone on earth because there are many competing hypotheses, but it seems to have been incorporated into, most of it into the current consensus of how things work.”
This is where it helps to have a partner who believes in you, and is also another scientist.
“Once you join lives with somebody else, it influences the direction your work takes if you interact with her about that work,” Anderson said.
When a grant opportunity came up, Anderson and Chesney decided to merge their interests. She had become intrigued by treatments like ayurveda, acupuncture and meditation that fell outside mainstream Western medicine. The couple designed two studies. The study on mindfulness meditation is one. They’re also testing a biofeedback monitor that beeps whenever it detects that you exhale high levels of CO2, i.e. if you’re holding your breath. The results aren’t published yet, but Chesney and Anderson say both studies look promising.
Susan Evans says the study is working for her. We’re at her San Francisco apartment staring at a piece of paper stuck to her front door. In black is written the word, “breathe.” It’s supposed to be a reminder.
“Sometimes I look at it as I go out the door and remember to breath and to be more calm or meditative, but sometimes I just rush out the door because the bus is coming,” Evans said.
Even so, Evans’ blood pressure is down. She doesn’t feel any different, but it’s still a relief. Plus, she enjoys the meditation.
As for Anderson, he’s about to retire. It’s gratifying that what is likely his final experiment may offer a treatment option for a condition that has been his life’s work. It took a lot of persistence, but also a partnership with his wife Margaret Chesney to get here.
“What am I doing now wouldn’t be here without her,” said Anderson. “How much more can I say than that?”