Hypertension (High Blood Pressure) and Yoga: An Overview

by Baxter

On these hallowed blog pages, we have previously addressed several conditions that involve our cardiovascular system (heart and blood vessels), such as arrhythmias, strokes, hypotension and hypertension (also referred to as High Blood Pressure and Hypertension, or HTN). We even have at least six posts that at least mention HTN. However, due to the large percentage of adults who will develop HTN over the course of their lifetimes, I thought it worth revisiting. In 1999-2002, 28.6% of the U.S. population had hypertension. And this number seems to be on the rise. Plus, there is yet another study that demonstrates yoga’s beneficial effect on lowering blood pressure in those with mild to moderate hypertension! (For background information about what blood pressure is, see So, what is blood pressure, anyway?)

Why all the hype about HTN or high blood pressure, anyway?  Well, if you have HTN, you are at an increased risk of developing other more serious health problems, including heart attacks, strokes, rupture of your largest blood vessel (the aorta), chronic kidney disease, congestive heart failure, decreased blood supply to your legs, and problems with your vision. Some people develop HTN secondary to the presence of some other health condition that leads to high blood pressure, such as chronic kidney disease (hey, wasn’t that just mentioned?!), diseases of the adrenal and parathyroid glands (part of our endocrine system), pregnancy, and medications such as birth control pills, diet pills, some cold meds, just to mention a few. 

And some people are at a higher risk of developing HTN, if any of the following factors are present for you: obesity, chronic stress and anxiety, excessive alcohol consumption, excessive salt in diet, family history of HTN, diabetes, smokers, and African American ancestry. Part of the frustration for people who are diagnosed with HTN is that they often don’t have any really noticeable symptoms. I can’t tell you how many times I diagnosed a patient in my family practice with high blood pressure when they came in for a routine annual exam with no real complaints, or were in the office for some unrelated complaint, like a cold or headaches. This is why HTN is often referred to as the “silent killer,” as you may not know you have it until one of its complications like stroke or heart attack strike you.

Complexity in Nature by Brad Gibson

It’s been known now for at least 40 years that yoga practices can help lower blood pressure in people with HTN, starting back in the 60s and 70s with the work of Herbert Benson, MD, a cardiologist who used a particular kind of yogic meditation popular at the time (TM or transcendental meditation) to help lower the blood pressure in his patients who were not responding as expected to the newest medications of that era. Since then, other studies have shown similar results, including the newest study from the University of Pennsylvania, Philadelphia, still in progress, which is following 120 patients with mild to moderate elevations in their blood pressure. Already, with 58 people completing the study so far, there is small but significant decreases in blood pressure readings in the yoga group. This could be of greatest importance to patients who are labeled with “pre-hypertension,” where the blood pressure readings fall between 120/80 and 140/90.  This group of people is at much higher risk of going on to develop full HTN and is at higher risk than the general population of serious situations such as stroke and heart attack. However, if treated with yoga, they could drop their numbers low enough to avoid the need for medications to do the job.  In previous posts, Nina and Shari have talked about kinds of asana practices that have been shown to lower blood pressure, such as forward bends and certain inversions, as well as the effect on the baroreceptors that monitor and influence blood pressure moment by moment.  See Blood Pressure: Talking About Baroreceptors and Yoga and Just in Time for the Holidays: Inverted Poses.

As to how you might incorporate yoga practices into your efforts to lower your own rising blood pressure, you would likely want to add it to a broader approach to treatment, instead of substituting yoga for medications, for instance. Usually, a combination of aerobic activity, dietary changes, appropriate salt restriction, stopping tobacco use, lowering stress, and achieving an optimal body weight are the first line actions recommended when you are diagnosed with HTN. As we have shown before, yoga can help with many of those goals, such as weight management and stress, as well as improving will power, which could help with establishing all of those changes suggested from your usual dietary and lifestyle habits. But, independent of that, as this newest study again points out, yoga helps lower blood pressure on its own. It can do it via a balanced asana practice, via meditation practices and via breathing techniques. It is, of course, frustrating for those of us familiar with this data, that mainstream medicine has not embraced this cost-effective modality to any significant degree. If it were a pill, I suppose, it would be a no-brainer. 

And for those interested in developing a home practice for hypertension, due to the multiple factors that could influence your unique situation, I highly recommend you work one-on-one with an experienced yoga instructor to create the optimal practice for you. Yoga for high blood pressure? You bet!  

Blood Pressure: Talking about Baroreceptors and Yoga

by Shari and Nina 

Nina: Yesterday, Baxter gave us a little background on blood pressure (see So, what is blood pressure, anyway?). I thought today you could talk a bit more about the relationship between blood pressure and yoga.

Shari: First some more background! Of particular importance is the effect of our baroreceptors on blood pressure. Baroreceptors are stretch receptors that found in the major arteries, and they are activated when our arteries are over- or under-pressured by blood flow. This in turn changes our heart rate and arterial diameters. Baroreceptors are found abundantly in the carotid sinuses, the carotid arteries of the neck and the aortic arch of the heart.

Carotid Sinuses (Carotid Arteries of the Neck)

Aortic Arch of the Heart

When there is an increase in arterial pressure because of increased blood flow, vasodilation occurs and the heart rate will then drop. This causes a decrease in cardiac contraction and in turn causes a decrease in blood pressure.

Nina: For all of us overstressed folks, decreasing blood pressure is a good thing. And I’m betting yoga can help with this....

Shari: Absolutely. Research has shown that both forward bends and inversions affect the cardiac baroreceptors, ultimately causing a decrease in blood pressure and heart rate! Inversions and forward bends also increase baroreceptor sensitivity toward the fluid dynamic changes. So both forward bends and supported inversions are both recommended for reducing blood pressure.

Nina: That explains why both forward bends and supported inversions are considered calming poses. I certainly use both in my home practice for stress reduction. Do you have any favorite poses for lowering blood pressure?

Shari: I like supported Setubanda Sarvangasana (Bridge pose, with straight legs), perhaps with a head wrap. I also like Viparita Karani (Legs Up the Wall pose) with a head wrap. When the going gets rough, these are my “comfort poses.”

Nina: I also love Legs Up the Wall pose. And supported Child's pose is a good example of a forward bend that is very comforting—just thinking about it makes me relax. And we’ll definitely have to talk about the head wrap sometime soon!

So, what is blood pressure, anyway?

by Baxter

If you read yoga magazines or read online articles about yoga and your health, you often come across a warning to avoid this or modify that yoga asana if you suffer from high blood pressure or hypertension another term used for high blood pressure). But it turns out that there are a lot of differing opinions about how and what to change about a typical yoga practice if you have hypertension (HTN), and not a great deal of agreement on the best approach to take. However, before we get into that, I thought it would be helpful to discuss what blood pressure is, and how it is determined, as well as why HTN needs to be addressed either via lifestyle changes or medical intervention.

So, what is blood pressure? Well, it is a measurement we take—usually in your upper arm via a blood pressure cuff—that measures the pressure in the arteries of your arm. When you are sitting or standing with your arms at your sides, the place where blood pressure reading is taken is in line with your heart and its main artery, the thoracic aorta. Now we are measuring the pressure downstream in an artery in the arm, but it seems to correlate well with the pressures inside the heart and aorta. The top number of a blood pressure reading, called the systolic blood pressure, is the amount of pressure the blood in your arteries is exerting on the elastic, stretchy walls of the artery when the heart is at its maximum point of contraction. On average, it runs around 120mmHg’s of mercury in a normal healthy person. The bottom number, called the diastolic blood pressure, is the pressure at the time the heart is most relaxed between beats and is filling with more blood coming in from the body and lungs. A healthy average for that number is 80.  So, if your blood pressure, on average over the course of the day, is at 120/80 or below, it is said to be in the normal range.

Arctic Moon by Michele Macartney-Filgate

Via observations and studies, if your blood pressure averages 140/90 or above over the course of the day, you are said to have high blood pressure or hypertension. If you fall between 120/80 and 140/90, you are now said to have a condition called “pre-hypertension,” a no man’s land where it seems you are at a greater risk of developing HTN over time. More on HTN and why it’s important later.

Let’s go back to the concept of blood pressure for a few more moments. Your blood pressure is not a constant figure, but changes as your physical, mental and emotional activities change. It often goes up during exercise, stressful situations, and emotionally charged interactions, as well as varying with your body position of reclining, sitting or standing. It must vary dynamically to accommodate our changing situations throughout the day. Maintaining the proper blood pressure for our changing needs is a complex system that involves many of the body’s systems, including hormones, brain activity, and specialized receptors for pressure in the some of the biggest arteries in the body, called baroreceptors. As these various components of the blood pressure regulation interact, they result in dynamic fluid changes within the blood vessels and heart, via changing the blood flow in the vessels, the heart rate and the intensity of the contraction of the heart itself. Other organs also get involved, such as the kidneys, which are asked to help lower blood pressure at times by filtering out more water from the blood to decrease the overall amount of fluid in the system. Other parts of our nervous system can also influence the blood pressure readings. Your autonomic nervous system, composed of the two opposing and balancing parts, the sympathetic (Flight, Fight or Freeze response) and the parasympathetic (Rest and Digest response), can either increase or decrease your blood pressure, depending on how activated they are.

A few more thoughts on the general topic of blood pressure. Although we have defined the situation where blood pressure is elevated above the normal level and is considered potentially dangerous if left untreated, the opposite situation can also exist. That is, your blood pressure can be lower than normal, and this situation is called hypotension. Highly trained runners, especially long distance runners, can have blood pressures that average 100/60 or even lower and feel no worse for the wear. However, in other situations, hypotension can create symptoms that indicate it is not a normal adaptation to good aerobic fitness, such as lightheadedness, dizziness on standing and fainting. So next time, we will look at the conditions of hypertension and hypotension in more detail, and begin to discuss how yoga could fit into plan for better health for these students. Special thanks today to both Shari Ser and PubMed for their insights on blood pressure, as well as all my teachers back at UC College of Medicine in Ohio!

Health markers varying inexplicably? Do some detective work with HCE

John was overweight, out of shape, and experiencing fatigue. What did he do? He removed foods rich in refined carbohydrates and sugars from his diet. He also ditched industrial seed oils and started exercising. He used HealthCorrelator for Excel (HCE) to keep track of several health-related numbers over time (see figure below).

Over the period of time covered in the dataset, health markers steadily improved. For example, John’s HDL cholesterol went from a little under 40 mg/dl to just under 70; see chart below, one of many generated by HCE.

However, John’s blood pressure varied strangely during that time, as you can see on the chart below showing the variation of systolic blood pressure (SBP) against time. What could have been the reason for that? Salt intake is an unlikely culprit, as we’ve seen before.

As it turns out, John knew that heart rate could influence blood pressure somewhat, and he also knew that his doctor’s office measured his heart rate regularly. So he got the data from his doctor's office. When he entered heart rate as a column into HCE, the reason for his blood pressure swings became clear, as you can see on the figure below.

On the left part of the figure above are the correlations between SBP and each of the other health-related variables John measured, which HCE lists in order of strength. Heart rate shows up at the top, with a high 0.946 correlation with SBP. On the right part of the figure is the chart of SBP against heart rate.

As you can see, John's heart rate, measured at the doctor's office, varied from 61 to 90 bpm. Given that, John decided to measure his resting heart rate. John’s resting heart rate, measured after waking up using a simple wrist watch, was 61 bpm.

Mystery solved! John’s blood pressure fluctuations were benign, and caused by fluctuations in heart rate.

If John's SBP had been greater than 140, which did not happen, this could be seen as an unusual example of irregular white coat hypertension.

If you are interested, this YouTube video clip discusses in more detail the case above, from HCE’s use perspective. It shows how the heart rate column was added to the dataset in HCE, how the software generated correlations and graphs, and how they were interpreted.

Reference

Kock, N. (2010). HealthCorrelator for Excel 1.0 User Manual. Laredo, Texas: ScriptWarp Systems.

The low modern potassium-to-sodium ratio: Big problem or much ado about nothing?

It has been argued that the diets of our Paleolithic ancestors had on average a much higher potassium-to-sodium ratio than modern diets (see, e.g., Cordain, 2002).

This much lower modern ratio is believed by some to be the cause of a number of health problems, including: high blood pressure, stroke, heart disease, memory decline, osteoporosis, asthma, ulcers, stomach cancer, kidney stones, and cataracts.

But, is this really the case?

The potassium-to-sodium ratio in ancient and modern times

According to some estimates, our Paleolithic ancestors’ daily consumption was on average about 11,000 mg of potassium and about 700 mg of sodium (salt). That yields a potassium-to-sodium ratio of about 16. Today’s ratio in industrialized countries is estimated to be around 0.6.

Just for the sake of illustration, let us compare a healthy Paleolithic diet food, walnuts, with a modern industrialized food that many believe to be quite healthy, whole-wheat bread. The table below (click on it to enlarge) compares these two foods in terms of protein, carbohydrate, fat, vitamin, and mineral content.

Walnuts have a potassium-to-sodium ratio of about 205. The whole-wheat bread’s ratio is about 0.5; much lower, and close to the overall ratio estimated for industrialized countries mentioned above.

At the same time, walnuts provide a better nutritional value than whole-wheat bread, including a good amount of omega-3 fatty acids (2.5 g; of α-linolenic acid, or ALA). However, walnuts have a fairly high omega-6 fat content.

Also, many diabetics experience elevated blood glucose levels in response to whole-wheat bread, in spite of its glycemic index being supposedly lower than that of white bread. Walnuts do not seem to cause this type of problem, even though several people are allergic to walnuts (and other tree nuts).

Health effects of the potassium-to-sodium ratio

So, the potassium-to-sodium ratio appears to have been much higher among our Paleolithic ancestors than today. It is important to stress that, even though this is a possibility, we do not know this for sure. Animals go to great lengths to find salt licks, and then consume plenty of sodium in them. Our ancestors could have done that too. Also, we know that sodium deficiency can be deadly to both animals and humans.

As for the many negative health effects of a low potassium-to-sodium ratio in modern humans, we have reasons to be somewhat skeptical. One has to wonder if the studies that are out there do not conflate the effects of this ratio with those of other factors, such as smoking, heavy alcohol consumption, or consumption of industrialized high carb foods (e.g., cereals, pasta, refined sugars).

Another possible confounding factor is potassium deficiency, not the potassium-to-sodium ratio. Potassium deficiency, like other deficiencies of essential minerals, including sodium deficiency, is associated with serious health problems.

If potassium is deficient in one’s diet, it is also likely that the potassium-to-sodium ratio will be low, unless the diet is also equally deficient in sodium.

Let us take a look at a study by Ikeda et al. (1986), which included data from 49 regions in Japan, a country known for high consumption of sodium.

This study found a significant association between the potassium-to-sodium ratio and overall mortality and heart disease, but only among men, and not among women.

One wonders, based on this, whether another uncontrolled factor, or factors, might have biased the results. Examples are smoking and heavy alcohol consumption, which could have been higher among men than women. Another is chronic stress, which could also have been higher among men than women.

The researchers report that they found no association between the potassium-to-sodium ratio and mortality due to diabetes, liver disease, or tuberculosis. This ameliorates the problem somewhat, but does not rule out the biasing effect of other factors.

It would have been better if the researchers had controlled for the combined effect of covariates (such as smoking, alcohol consumption etc.) in their analysis; which they did not.

Moreover, the study found no association between the potassium-to-sodium ratio and blood pressure. This is a red flag, because many of the diseases said to be caused by a low potassium-to-sodium ratio are assumed to be mediated by or at least associated with high blood pressure.

Regarding the possible confounding effect of industrialized high carb foods consumption, it seems that many of these foods have a low potassium-to-sodium ratio, as the example of whole-wheat bread above shows. Thus, some of the health problems assigned to the low potassium-to-sodium ratio may have actually been caused by heavy consumption of industrialized high carb foods.

It is also possible that the problem is with the combination of a low potassium-to-sodium ratio and industrialized high carb foods consumption.

At the time the study was conducted, Japan was somewhat westernized, which is why industrialized high carb foods consumption might have been a factor. The US strongly influenced the Japanese after World War II, as it helped rebuild Japan’s economy.

In conclusion, the jury is still out there regarding whether the low modern potassium-to-sodium ratio is a big problem or much ado about nothing.

References:

Cordain, L. (2002). The Paleo Diet: Lose weight and get healthy by eating the food you were designed to eat. New York, NY: Wiley.

Ikeda, M., Kasahara, M., Koizumi, A., and Watanabe, T. (1986). Correlation of cerebrovascular disease standardized mortality ratios with dietary sodium and the sodium/potassium ratio among the Japanese population. Preventive Medicine, 15(1), 46-59.