by Connie Ray
Scrolling through your Facebook and Instagram feed, you might think yoga is just another avenue for the uber fit and flexible to show off their hot bods at the beach. But research has consistently shown yoga helps improve mood, reduce stress, and increase strength and flexibility.
There is also a growing field of evidence that yogic interventions can help treat and prevent chronic diseases. Published earlier in 2016 in the Journal of Diabetes Research, Innes and Selfe’s systematic review concluded that yoga may be beneficial for managing Type II Diabetes.
Type II Diabetes (DM2) is characterized by high blood glucose levels (hyperglycemia) and insulin resistance. It affects approximately 366 million people worldwide, a number which has doubled over the last 30 years. By 2030, this number is projected to reach 552 million.
In the United States, the CDC estimates that 29.1 million people suffer from DM2. In 2010, diabetes was the seventh leading cause of death in the US, and the number of cases is believed to be underreported. DM2 is the country’s single most costly chronic disease, accounting for at least 10% of all US healthcare costs ($245 billion annually).
Rather than an inherited disease like Type I Diabetes, DM2 is a preventable disease, and while certain factors like race, age, and genetic predisposition play a role in its prevalence, it is believed that over 90% of DM2 cases are attributable to lifestyle factors.
Lifestyle factors that increase risk of DM2 include physical inactivity, overnutrition, and obesity as the primary factors, with sleep impairment, chronic stress, and smoking as secondary contributing factors.
Yoga may be an ideal intervention for treating a multifactorial condition like DM2. Yoga is a mind-body approach to exercise, with roots in India over 4,000 years ago. The traditional practice of yoga incorporates 8 “pillars” or aspects of teaching, and the physical poses you see on Instagram, or “asanas” are only one of the 8. As yoga has become more prevalent in Western culture, it has branched into many different styles, including Bikram (hot yoga), Ashtanga (power yoga), Vinyasa (flow yoga), Iyengar (basic hatha yoga), Kundalini (awareness yoga), and restorative yoga. Most yoga styles incorporate physical poses (asanas), with breath practice (pranayama), focus (dharana), and meditation (dhyana).
Authors Innes and Selfe believe yoga’s mind-body approach suits it to a multifactorial lifestyle disease like DM2, and the results of their systematic review uphold their hypothesis. They analyzed 33 papers from 25 original controlled trials investigating the impact of yogic interventions on adults with DM2, and the results overwhelmingly demonstrated the benefits of a regular yoga practice on several health-related outcomes. Trials varied in duration and frequency of practice from 2-3 times a week to daily practice, spanning 6 weeks to over a year. In all cases, they compared results of the yogic intervention to “standard” DM2 care and in some cases, to a second control group subject to a standard exercise program.
Insulin Resistance: 22/24 relevant trials, or 92%, reported statistically and clinically significant improvement in at least one biomarker for insulin resistance (PPBG, insulin, and HbA1c).
Lipid Profiles: 15/16 relevant trials, or 94%, reported significant improvement in one or more lipid indices, including reduction in total cholesterol, LDL cholesterol, VLDL cholesterol, or triglycerides, and/or increases in HDL (“the good cholesterol”).
Body Weight & Composition: 8/9 relevant trials found significant improvement in at least one measure of body weight/composition, including weight, BMI, and waist-hip ratio, even in trials that compared a yoga intervention to standard care with regular exercise.
Blood Pressure: 3/5 relevant trials reported significant drops in both systolic and diastolic blood pressure compared to standard care and standard care with walking.
Oxidative Stress: 5/5 relevant trials indicated positive change in oxidative stress with the yoga intervention groups as measured by increased glutathione/Vitamin C serum levels, increases in superoxide dismutase levels, and reductions in malondialdehyde.
Mood & Sleep Impairment: 3/4 relevant trials reported significant improvements in quality of life, psychological well-being, symptoms of distress, and insomnia. One notable study of 41 adults practicing yoga nidra (yogic sleep) daily saw a decrease in insomnia prevalence from 43% to 5%.
Nervous System Function: 3/3 relevant trials reported improvement in cardiac autonomic function and reductions in heart and respiratory rate, all suggesting that yoga shifts the body’s nervous system from sympathetic to parasympathetic.
Pulmonary Function: 2/2 relevant trials reported improved pulmonary function (increased expiratory volume, forced vital capacity, peak flow rate, and maximum voluntary ventilation).
Medication Use: 3/3 relevant trials reported significant reductions in diabetes medication use in yoga intervention groups compared to standard care and comprehensive exercise programs. In one trial of 154 adults with DM2, there were 26-40% reductions in medication use at a 3-month follow-up.
“Overall, findings of these studies suggest that yoga-based practices may have significant beneficial effects on multiple factors important in DM2 management and prevention, including glycemic control, insulin resistance, lipid profiles, body composition, and blood pressure,” Innes and Selfe concluded.
Naturally, any systematic review has its limitations, and this one is no exception. Innes and Selfe found that several of the studies suffered from methodological problems or poor reporting, and the heterogeneity of study design, duration, and subject make it difficult to compare results across trials.
Yet even with its limitations, it is clear: yoga has obvious benefits in treating and managing DM2. As awareness of its benefits spreads, one would hope that more health practitioners will incorporate a yoga recommendation into their standard diabetes treatment plans.
Connie Ray is a first-year MNSP student at the Friedman School. She currently lives in Virginia, where she raises her two sons and teaches yoga.