Yoga and Cardiovascular Disease

FACT: Approximately 1 million people will die from heart disease this year.

According to The American Heart Association, cardiovascular disease (CVD) is the leading cause of death and disability in the United States and other industrialized nations. A growing number of developing countries are also suffering from this killer disease. Therefore, it’s impossible to overstate the clearly pressing clinical and economic significance of CVD. It leads to premature death, loss of employment, income, and quality of life. Fortunately, advances in technology have often provided a lifeline to those stricken with cardiovascular disease.

But amidst all the modern technology lies an ancient approach to combating this deadly disorder as well as complications caused by living overweight. It’s non-invasive, inexpensive, and suitable for practically anyone. This ancient, time-tested method is now more popular than ever – approximately 15 million people in the USA alone practice it. What is it?

Yoga.

Yoga and Cardiovascular Disease

Kim E. Innes, MSPH, PhD from the Center for the Study of Complementary and Alternative Therapies conducted a systematic review  of published literature regarding the effects of yoga on specific anthropometric (body measurement) and physiologic indices of cardiovascular disease. This comprehensive study underscored the need for effective primary prevention efforts targeted at common risk factors.

Among these risk factors are those associated with the insulin resistance syndrome or IRS. IRS, also referred to as the metabolic syndrome, is a combination of metabolic disorders that increase the risk of developing cardiovascular disease. Prominent features of IRS include insulin resistance, atherogenic dyslipidemia (lipid abnormalities), glucose intolerance, high blood pressure, and visceral adiposity, or common “belly fat”.

In addition to metabolic disorders, there are psychosocial factors that play a huge role in the development of both IRS and CVD. Most everyone has had experience with a “Type A” personality – those with character traits that lead to a high stress response to their environment. Generally speaking, psychosocial factors are those that affect a person both socially and psychologically. And there is a strong correlation between these factors and CVD.

It’s because of these facts that mind-body therapies such as yoga may have considerable potential with regards to the prevention and treatment of CVD. Yoga is an ancient mind-body discipline that has been used extensively in India for the management of chronic insulin resistant conditions. So the question is why shouldn’t yoga have equally positive results in the U.S. as well?

As it turns out, it does.

Yoga originated in India over 4000 years ago. In recent decades the practice of yoga has enjoyed rising popularity in Western industrialized countries. The most widely practiced forms are Hatha (or forceful) yoga, Raja (or classical) yoga, and Mantra yoga. Mantra yoga emphasizes the use of specific sounds or chants with the purpose of bringing about mental and spiritual transformation.

Both Hatha and Raja yoga emphasize specific postures (asanas), breath control (pranayama), concentration, and meditation. In the Western world, Hatha yoga is the most commonly practiced.

The advantages of yoga run broad and deep. In the United States specifically, yoga is practiced to alleviate stress, improve health, and increase fitness. What makes it so attractive is the fact that yoga is economical, has no significant side effects, yet the lifestyle benefits are substantial. It’s safe, easy to learn and even the elderly or disabled can practice yoga.

But most importantly, there is growing evidence that suggests that yoga may reduce IRS related risk factors for CVD and may actually improve the prognosis of those suffering from cardiovascular disease. However, systematic review to support this evidence has been lacking.

But that’s all changed now. The study conducted by Innes critically reviews the published scientific literature regarding the effects of yoga on IRS-related indices of CVD risks. This article explains the methodology employed in the review, the substantial results, and the eye-opening conclusion.

Methodology

The first step was a systematic examination of the mounting evidence. A thorough research of published medical literature was conducted, focusing on English language articles published after 1970 and original studies specifically evaluating the effects of yoga on cardiovascular disease. These original studies reported outcome data and evaluated the effects of yoga intervention on the following:

1.Measures of insulin resistance
2.Lipid profiles
3.Weight loss and composition
4.Blood pressure and oxidative stress
5.Markers of sympathetic activation and cardiovagal function

Randomized controlled trials (RCTs) were included if they met specific criteria. An RCT is a type of scientific experiment that involves the random allocation of different treatments to subjects.

Observed Effects of Yoga on Core Indices of the IRS

70 eligible studies were revealed with a majority (63%) of the identified studies published between 1990 and 2004.

51 published studies investigated the potential influence of yoga on insulin resistance, lipid profiles, weight loss and composition, and blood pressure. A detailed discussion of each follows.

Markers of Insulin Resistance

13 studies evaluated the effects of yoga on markers of insulin resistance. Insulin normally enables cells to take up and utilize the blood glucose from the blood stream. Insulin resistance, however, is a condition in which cells display “resistance” to insulin by failing to take up and utilize glucose for energy and metabolism.

• Most studies showed a significant improvement in insulin resistance following the practice of yoga. In these cases, yoga was practiced anywhere from 40 days to 12 months and incorporated yoga asanas, or positions.
   
• 7 of the 8 uncontrolled studies of healthy young adults, patients with type 2 diabetes, or hypertensions reported significant improvement.
   
• Controlled studies of healthy young adults reported reductions in fasting glucose.
   
• In a small RCT of diabetic British adults, a decline in both fasting glucose and glycohemoglobin was noted. Glycohemoglobin is a form of hemoglobin that is formed when hemoglobin is exposed to high levels of glucose – a condition common in diabetic patients.

Overall, yoga practice was associated with 5.4% to 33.4% reduction in fasting glucose, 24.5% to 27.0% reductions in postprandial (after a meal) glucose, and 13.3% to 27.3 % reduction in glycohemoglobin.

Lipid Profiles

More good news is that 14 studies revealed that yoga may improve lipid profiles. Vyas and colleagues determined that Raja yoga meditation had reduced cholesterol and triglyceride levels relative to those with no yoga experience. These studies included investigations of both healthy adults and patients with hypertension and coronary artery disease.

• Cholesterol and low-density lipoprotein (LDL), or “bad cholesterol” was reduced.
   
• Good cholesterol (HDL) levels were increased.

Yoga practice was associated with a 5.8% to 25.2% decrease in total cholesterol, 22% to 28.5% reduction in triglycerides and a 12.8% to 26.0% reduction in LDL.

Weight Loss and Body Composition

In the 34 years between 1970 and 2004, 18 clinical trials in six countries analyzed yoga’s effect on the anthropometric indices of CVD risk. What that means for weight loss is certainly significant.

• Improvement in weight loss and body composition after yoga-based intervention for 4 weeks to 12 months was evidenced in 6 of the 8 uncontrolled clinical trials and 3 or the 4 nonrandomized controlled studies.
   
• The studies included healthy populations as well as those with hypertension and/or other CVD risk factors, CAD, or diabetes.

Yoga practice was associated with a 1.5% to 13.6% reduction in body weight. All studies used interventions incorporating yoga asanas.

For those of us struggling to lose unwanted pounds, this is especially good news. Even though there are certainly many weight loss options available - you can even count calories online for free - the many other benefits of yoga make it an excellent choice for your overall health.

Blood Pressure

Blood pressure is the most extensively studied endpoint with respect to the effect of yoga as an intervention measure.

• 37 studies were identified and over 75% report improvement. Those practicing Raja yoga meditation had reduced diastolic blood pressure compared with those who did not engage in meditation.
   
• 28 studies reported a beneficial effect of yoga on blood pressure change.
   
• 9 non-randomized studies of healthy adults and those with hypertension and/or CAD showed a decrease in blood pressure due to yoga.
   
• 11 RCTs of healthy adults demonstrated significant declines in blood pressure.

These positive findings came from yoga-based programs that ranged in duration from 30 days to 6 months.

Observed Effects of Yoga on Oxidative Stress

What is oxidative stress?

Your body constantly reacts with oxygen as you breathe and your cells produce energy. As a consequence of this activity, highly reactive molecules are produced known as free radicals.

Free radicals interact with other molecules within cells. This can cause oxidative damage to proteins, membranes and genes.

Yoga reduces oxidative stress by increasing antioxidants that fight free radicals and therefore it has a beneficial effect on your health.

Innes identified 5 eligible studies that investigated the influence of yoga on oxidative stress.

• All provide evidence that  yoga may actually reduce oxidative stress in healthy people as well as those with chronic IRS related disorders.
   
• Observed changes include increases in antioxidants and reduction in free radicals.

These studies offer compelling support that yoga has a beneficial influence on oxidative stress, which in turn leads to long-lasting health benefits.

Effect of Yoga on Cardio-Respiratory Function and the Vagus Nerve

Innes’ research identified a total 42 studies investigating the effects of yoga on cardiovagal function. The vagus nerve innervates the lungs and the heart. Specifically, it acts to lower the heart rate. Activation of the vagus nerve typically leads to a reduction in heart rate and blood pressure. Why is this important? Studies show that yoga stimulates the vagus nerve.

Key changes that take place due to the practice of yoga include…

• Significant reductions in respiratory and heart rate
• In cortisol concentrations
• In catecholamine levels
• In rennin activity
• In skin conductance
• And in cardiovascular response to stress.

Explanation of Terms

Cortisol is usually referred to as the “stress hormone” because it’s involved in response to stress and anxiety. It increases blood pressure and blood sugar and also reduces immune responses.

Catecholamines are “fight-or-flight” hormones that are released by the adrenal glands in response to stress. They are part of the sympathetic nervous system.

Renin is an enzyme that controls blood pressure. Low rennin levels lead to low blood pressure.

Skin conductance is a measure of stress response.

Studies conclude that yoga has a beneficial effect on baseline respiratory rate, baseline heart rate, and/or heart rate after exercise. Groups included in the study are healthy and hypertensive adults and healthy children.

Several studies suggest that yoga can improve the cardiovascular reaction to stress as well as recovery from stress. And with today’s hectic lifestyle, that is valuable information.

Yoga, Psychosocial Risk Factors for CVD, and Possible Underlying Mechanisms

As mentioned earlier, the psychosocial risk factors for CVD play a crucial role in the disease. Yoga is instrumental in relieving these risk factors. For example, yoga not only decreases the perceived stress but also how one reacts to stressors. Yoga enhances coping abilities, reduces symptoms of depression and anxiety, and also diminishes anger, tension, and fatigue.

Another important benefit is improved sleep in both healthy individuals as well as those that are chronically ill.

Even though the underlying mechanisms for the reputed effect of yoga on these risk factors isn’t totally understood, the changes most likely take place through 2 pathways.

First, by promoting feelings of well-being, yoga alleviates the damaging effects of stress. It also promotes positive effects on the neuroendocrine status, metabolism and inflammatory response.

Second, because yoga stimulates the vagus nerve, positive changes occur in the cardio-vagal function. Therefore, mood and energy also improves.

Summary and Conclusions

Because of the substantial amount of published research, the leading researcher in this study determined the data strongly suggests that the benefits of yoga are certainly noteworthy from a physical and psychological viewpoint. Core indices of the IRS improve – including glucose tolerance, insulin sensitivity, lipid profiles, anthropometric characteristics, and blood pressure. Cardiovagal function, factors often linked to IRS and CVD risk, is also enhanced by yoga.

In summary, anyone concerned about the risk of cardiovascular disease as well as overall health, including weight loss, owes it to himself or herself to try incorporating yoga into their lifestyle. You have nothing to lose and everything to gain.

Author Bio
Matthew Papaconstantinou, is a research assistant at Washington University School of Medicine. He has been twice awarded research grants by the American Heart Association to support his research on cardiovascular diseases. Matthew has a long held interest in researching treatments of obesity – a major risk factor for cardiovascular disease. On his website, which is devoted to people looking for weight loss diet plan reviews , he regularly publishes newsworthy content related to diet research. He also offers a coupon code for Medifast diet program.

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