The Science of Yoga: The Risks and the Rewards

by William J Broad

  In all, the scientists locked volunteers into the samadhi pit eleven times. Nothing like it had ever been done before. The results tore a hole in yoga’s legacy of miraculous claims.

  Today the ashram has a slightly dilapidated air, walls crumbling here and there amid dense foliage. But the pit is frozen in time, bright and spotless and ready for any new volunteer who might appear. It is part museum, part open challenge.

  “We’re still ready to do this,” said Makrand Gore, a senior researcher at the ashram. He opened the pit’s door while describing its past. The tidy den, well lit and brightly painted, did in fact seem ready to admit a new volunteer. A bundle of wires hung down from its ceiling, awaiting a miracle worker.

  Gore’s boss, T. K. Bera, a small man with a muscular presence, joined the tour. He said the ashram had looked hard for siddhis over the decades but had found no miracles—none, try as it might.

  “People say yoga is black magic,” Bera remarked. “But what we’ve found is that it gives the power to live on a reduced metabolism. That’s all. It’s not magic.”

  Popular yoga made no explicit acknowledgment of the pit demythologizing but continued to shed the old emphasis on magic and eroticism. The trend culminated with Iyengar.

  His 1965 book, Light on Yoga, quickly became the how-to bible of Hatha yoga. Around the globe, it sold more than a million copies, confirming the field’s export potential. In his preface, Iyengar poked fun at credulous people who asked if “I can drink acid, chew glass, walk through fire, make myself invisible or perform other magical acts.” Instead, he described his objective as portraying yoga “in the new light of our own era.”

  Iyengar made no mention of Gune, Bagchi, the humiliation of his own guru, Krishnamacharya, or the coaching of his scientific tutor, Gokhale. He simply infused his book with the new sensibility.

  For every posture, he noted a number of invisible health effects, often using medical terms. An example was the Locust, or Salabhasana. The student lay facedown and lifted the head, chest, and legs as high as possible. Iyengar said the pose “relieves pain in the sacral and lumbar regions” while benefiting “the bladder and the prostate gland.”

  Locust, Salabhasana

  So too he praised the Headstand. Its upending of the body “makes healthy pure blood flow through the brain cells” and “ensures a proper blood supply to the pituitary and pineal glands.” Iyengar never said anything about research or clinical trials or the possibility of placebo effects. Instead, he piled on the medical terms and laid out the health benefits, giving his book a feeling of scientific authority while avoiding the messy issue of evidence. It was light with no explanation of its origin.

  More aggressively, Iyengar claimed a wide array of cures and therapeutic benefits, again with no reference to supporting evidence other than “experiences with my pupils.” His book used the word “cure” dozens of times. At the book’s end, he laid out a master list of “Curative Asanas” for nearly one hundred ailments and diseases. They included arthritis, asthma, back pain, bronchitis, diabetes, dysentery, epilepsy, heart disease, insomnia, migraine headaches, polio, pneumonia, sciatica, sterility, tonsillitis, ulcers, and varicose veins.

  The subliminal message was perhaps the most important of all. Nearly six hundred photographs showed Iyengar bending his supple body into all kinds of loops and curls, twists and knots. Here was an accomplished body builder whose appearance bore no hint of yoga’s past. He displayed no ashes or amulets, no matted hair or beard. Ages of decay had given way to a new kind of yogi.

  The agenda no longer featured sex. Even so, it still made a few appearances, often with a therapeutic spin. For instance, Iyengar put impotence on his list of curable ailments.

  More important, at the very end of his book—in the final pages of a section called “Hints and Cautions,” buried in a discussion of advanced practices, couched in language more evocative than explicit—he made a sudden disclosure. Even sanitized yoga, it turned out, retained a considerable measure of its old fire.

  Iyengar spoke of “sexual retentive power” and suggested that the discipline could fan the smoldering embers of human sexuality into a tempestuous blaze. If the yogi gave in, he said, “dormant desires are aroused and become lethal.”

  It was like a doctor suddenly informing a patient that the current course of treatment had serious, previously undisclosed side effects. And it got worse. Iyengar proceeded to spell out the ultimate stakes, making his belated admission in the middle of a very large paragraph. In my edition, the disclosure comes on page 438.

  Yoga, Iyengar warned, could transport the practitioner “to the cross-roads of his destiny.” One path led to the divine, he said, and the other to “the enjoyment of worldly pleasures.”

  In its fundamentals, the transformation of yoga was now complete. It had gone from the calling of supermen to the pursuit of common men—and increasingly of common women. It no longer belonged to mystic loners but to humanity. Its home was no longer India but the world. Its mode of instruction was public rather than private. To a growing degree, its practitioners no longer reveled in skulls and ashes but exercise mats and gym clothes. Enthusiasts by the millions ignored the old mysticism for the new ambitions of health and fitness. If yoga still harbored some of its old eroticism, that aspect of the discipline typically got ignored and downplayed, often to the point of invisibility.

  In short, yoga had gone from an ancient obsession with transcendence of the body to a modern crusade for a new kind of physicality.

  Of the ironies that come to light in a review of yoga’s modernization, one of the greatest is how its health agenda—begun by Paul, seized on by Hindu nationalists, developed as an export item, marketed with bold pretense, championed globally as the ultimate life enhancer—turned out to produce a wealth of real benefits. The posturing in some respects proved to be fortuitously accurate. The evidence grows richer every few days, as suggested by PubMed’s posting of new reports on yoga at the rate of more than one hundred a year.

  A large body of research derives from the kinds of metabolic slowdowns that Paul began to identify a century and a half ago. For instance, scientists have found that physiological slowing from yoga can reduce stress, the heart rate, and blood pressure, helping to boost immunity and prevent diseases. In 2009, investigators at the University of Pennsylvania reported that twenty-six people who did Iyengar yoga for three months succeeded in reducing hypertension and its precursors. That is important because hypertension, or high blood pressure, is associated with an increased risk of stroke, cardiovascular disease, and kidney disease. Strange as it seems, the deathlike trance of the Punjab yogi ultimately threw light on healthy living. It turns out that several of the miracles—if false in terms of otherworldly feats—nonetheless reflect a real ability of yogis to accomplish lesser manipulations of the body that produce a range of health benefits. Take the heart. Bagchi may have shattered Yogananda’s claims about full stoppage. But decades of investigations have shown that yoga can produce heart repercussions that work powerfully on behalf of cardiovascular health, a potentially vital issue of civic welfare since heart disease is the leading cause of death in the industrialized world. The studies range from anecdotal to rigorous. But their large number—dozens conducted everywhere from India and Japan to Europe and the United States—argue persuasively that yoga works remarkably well. It has been found to lower such cardiovascular risk factors as high blood pressure, blood sugar, cholesterol, and levels of fibrinogen, a protein involved in blood clotting. It has also reduced signs of atherosclerosis—an underlying factor in heart disease that arises when cholesterol and other fatty deposits begin to clog the arteries. Finally, it has been found to raise levels of antioxidants in the bloodstream and to lower oxidative stress, a euphemism for highly reactive species of oxygen that wreak havoc with cellular machinery.

  More important, scientists have found that the lowered risk factors translate into medical benefits. Clinical studies have shown that patients who do y
oga have fewer hospital visits, less need for drug therapy, and a smaller number of serious coronary events ranging from heart attacks to death. Analysts at the University of Virginia reviewed seventy of the studies and concluded in 2005 that yoga shows promise as a “safe and cost-effective intervention” for improving cardiovascular health.

  A different field of research shows that yoga can counteract the forces of aging—another area rife with miraculous claims, as when the Hatha Yoga Pradipika spoke of eliminating wrinkles and gray hair.

  Consider a 2011 study. It looked at elderly women who took up yoga and found their balance much improved. That’s significant. For seniors, falls are the leading cause of death by injury.

  The spine is another target. Yoga has long claimed that all the bending and stretching will make the backbone youthful. Science has examined such declarations and found that yoga can, in fact, counteract the deterioration of the disks that lie between the vertebrae.

  The watery cushions act as pivot points and shock absorbers so that the vertebrae can move smoothly, letting the body go through its regular bending and rotating. The disks of adults have no blood supply of their own but instead rely on nearby vessels to nourish them. With normal aging, the already limited supply of blood diminishes still further and the disks gradually dry out and become thinner. As a result, the trunk shortens and a person shrinks in size. The thinning of the disks can result in a number of nerve conditions and severe pain.

  In 2011, the idea that yoga can slow such deterioration received support when physicians in Taiwan reported on a study of thirty-six people. Half had taught Hatha yoga for at least a decade, and the other half were judged to have exhibited good health. The two groups showed no statistical difference by age or sex. The physicians then scanned all the spines and carefully inspected the disks for signs of damage. The results, the team wrote, showed that the yoga teachers had “significantly less” degenerative disease than the control group.

  Why? The physicians suggested that spinal flexing may have caused more nutrients to diffuse into the disks. Another possibility, they wrote, was that the repeated tension and compression of the disks stimulated the production of growth factors that limited aging.

  The frontiers of biomedical science turn out to hold many clues to prospective health benefits. The new understandings reveal potential—if unproven—rewards for practitioners even if the word “yoga” never appears in the text or title of a scientific paper.

  One surprise centers on the vagus, often portrayed as the most important nerve in the body. It travels from the brainstem to the torso, where it radiates out to the lungs, heart, stomach, liver, spleen, colon, and other parts of the abdomen. The word vagus shares etymological roots with “vagrant” and “vagabond,” denoting how it wanders through the body.

  The nerve’s action is central to the regulation and slowing of the human heartbeat, and thus has played important roles in ostensible miracles going back to the days of the Punjab yogi. But the new research focuses on what turns out to be an even more fundamental talent of the nerve—the regulation of the immune system, in theory offering protection against a number of serious illnesses.

  The body’s immune response is typically portrayed as white blood cells battling foreign invaders, and the immune and nervous systems as distinct entities—like oil and water, never mixing. The itinerant nerve would thus seem to have nothing whatsoever to do with the body’s defense mechanisms.

  Kevin J. Tracey found otherwise. In 2002, the immunologist at the North Shore University Hospital on Long Island, New York, reported that the vagus wields remarkable control over the body’s immune system, playing major roles, for instance, in fighting inflammation.

  That may sound unimportant. But a number of deadly conditions arise from the body’s overreaction to infection or its threat. For instance, the whole body can swing into an inflammatory state known as sepsis, a quiet killer that in the United States takes more than two hundred thousand lives each year. Other disorders include lupus (an autoimmune disease), pancreatitis (a chronic inflammation of the pancreas), and rheumatoid arthritis (a chronic inflammation of the joints). Scientists are working hard on anti-inflammatory therapies.

  Tracey initially focused on drugs meant to excite the vagus. But the more he learned of yoga and other Eastern disciplines, the more interested he became in their potential as natural agents to fight inflammation and its debilitating effects. In 2006, he discussed the topic at a conference held under the auspices of the Dalai Lama, the Tibetan spiritual leader who has long shown an interest in Western science.

  Tracey’s ideas won support in 2011 when Indian scientists under the leadership of Shirley Telles—one of yoga’s most prolific investigators—reported that doing intensive practice for a week can ease trauma from rheumatoid arthritis, the painful disorder of the joints. It afflicts millions of people. The study looked at sixty-four patients, ranging in age from twenty to seventy. The yoga included flexing poses and slow breathing, which stimulates the vagus. Measurements at the beginning and end of the week showed drops in rheumatoid factor—an indicator in the bloodstream of the disease—as well as improvements in the ability of practitioners to get out of bed, dress, walk, eat, and grip objects.

  Investigators of the invisible are finding even deeper allures. They include an ultimate expression of good health—longevity.

  Few topics in yoga have produced more fog. The mythology goes back at least as far as Marco Polo, who first visited India around 1288 and reported that yogis could live for as long as two centuries. Today, yogis and yoga teachers routinely hail the practice as greatly prolonging life—though no study that I know of has examined that claim. What makes headlines are anecdotes. For instance, many authors point to the longevity of Krishnamacharya, who became a centenarian. So too his student Indra Devi, author of Forever Young, drew attention by living to be one hundred and two. Few yoga enthusiasts mention that pudgy Yogananda died of a heart attack before he was sixty.

  Despite the wishful thinking, a recent discovery suggests that yoga can indeed slow the biological clock. The finding centers on a long-standing riddle—why cells age, die, or in some cases defy the natural order of things to remain young. The answer involves the microscopic whorls of DNA that lie at the tips of the chromosomes, the central repositories of genetic information in the cells. Scientists have found that these DNA tips, known as telomeres, get shorter each time a cell divides and thus serve as a kind of internal clock that determines the cell’s allotted time in life. They have also discovered the secrets of telomere growth and youthfulness. The finding was considered so important that it won the 2009 Nobel Prize in Physiology or Medicine. To scientists, the story of the telomere suggested a more accurate way of measuring biological age than simply marking the passage of the years.

  As often happens in science, the discovery brought into sharp focus yet another question—why do the telomeres of some individuals hold up much better than others? In some cases, an eighty-year-old could have the long, youthful telomeres of a thirty-year-old. Why the variation?

  It turned out that a number of everyday conditions eroded the telomeres—a main one being chronic psychological stress. (Other factors include unhealthy diets and infections.) Happily, science also found that reducing stress could slow the biological clock. The slowdown was found to work even with subjects well into their middle and later years. Perhaps most intriguingly, given humanity’s long search for a fountain of youth, a few tentative studies suggested that short telomeres could be coaxed into growing long again, in effect turning back the biological clock.

  Enter yoga. Science over the decades has repeatedly shown yoga’s talent for undoing physical and mental stress, as we will discuss in chapter 3. Thus yoga, despite its checkered history on longevity claims, appears to be custom made for slowing the biological clock.

  Dean Ornish led the appraisal. A Harvard-trained physician known for his popular books, Ornish was a longtime devotee of yoga, having begun hi
s practice in the 1970s. Over the years, he developed and marketed a health plan that championed a combination of yoga, low-fat diets, whole foods, and relaxation techniques. Studies of his method became part of the evidence for yoga’s cardiovascular benefits. Now he turned his attention to the telomeres, in particular to a measure of their maintenance and building known as telomerase—an enzyme that adds DNA at the chromosome tips. He did so with colleagues from the University of California at San Francisco, including Elizabeth Blackburn, who was soon to share the Nobel Prize for her telomerase findings.

  The team looked at twenty-four men who took up the Ornish program. They ranged in age from fifty to eighty and did yoga for an hour a day, six days a week. The scientists assessed telomerase levels and other physical and psychological measures before the men began their overhaul and did so again at the conclusion of the three-month program. The results were unambiguous. The scientists found declines in cholesterol, blood pressure, and such indicators of emotional distress at disturbing thoughts. More important, they discovered that levels of telomerase shot up 30 percent.

  The team reported its findings in late 2008, proclaiming them a first. The eleven scientists said the findings had implications for cellular longevity, tissue renewal, disease prevention, and “increases in life span”—a holy grail of modern science.

  The Ornish inquiry was only a beginning, of course. Other investigators would have to zero in on yoga practitioners and do larger and more elaborate studies. But it was a start.

  As science over the decades succeeded in promoting health over the miraculous, some yogis nonetheless managed to cling tenaciously to the past and show a recurring fondness for discredited myths. Major gurus gave up wild declarations. But other authorities were often quick to embrace lesser miracles and trendy fictions.