Crash Course in Blood Pressure

Updated 7/27/2014

Elevated blood pressure is a common health issue today. Almost a third of U.S. adults have high blood pressure – perhaps you or someone in your family does? High blood pressure isn’t necessarily something you can feel, but it increases the risk of serious conditions such as strokes and heart attacks.

The good news is that you can improve your blood pressure by way of simple lifestyle changes.

The usual treatment for elevated blood pressure today is medication. This is often reasonable. But what if you could achieve perfect blood pressure without pills or side-effects – with improved health and weight as welcome side-bonuses, instead?

The truth is that high blood pressure was extremely rare as recently as a few hundred years ago. Something in today’s environment is giving more and more people high blood pressure. What is it?

Contents

1. What is blood pressure? 2. How is blood pressure measured?

3. What’s a “good” blood pressure?

4. What’s a high blood pressure?

5. Who needs blood pressure medication?

6. Causes of blood pressure

7. Five ways to lower your blood pressure

8. Blood pressure medication

9. Measuring blood pressure at home

10. Further reading and studies

What is blood pressure?

Blood pressure is exactly what it sounds like: the pressure in your blood vessels. With a normal amount of blood, a healthy heart and healthy, elastic blood vessels, you’ll experience a normal blood pressure.

Low blood pressure can make you feel dizzy, especially right when you stand up from having been seated. This is usually harmless and can be the result of dehydration or salt deficiency.

Mildly or moderately elevated blood pressure will rarely give obvious symptoms (a light headache might occur sometimes). A very high blood pressure can give severe headaches, fatigue and nausea. High blood pressure is the result of an increased amount of liquid and salt in the blood, and also of the blood vessel walls being thicker and harder than normal.

As high blood pressure often goes unnoticed, it’s common for people to live with it unawares for some time. As it’s a risk factor, it may be wise to check your blood pressure every few years, even if you’re feeling healthy in general. This advice is especially directed towards people who are middle-aged or older, as high blood pressure is more common with age.

A markedly raised blood pressure leads, in the long term, to an increased risk of heart disease and stroke. The higher your blood pressure, the higher the risk. High blood pressure is often treated medically to reduce health risks; however, you can also lower your blood pressure with lifestyle changes (see below).

High blood pressure is known among doctors as hypertension, a word used frequently on this page.

How is blood pressure measured?

Blood pressure is usually measured by wrapping an inflatable cuff around your upper arm and pumping it up. The cuff pressure which stops the blood flow to your arm is then measured, and this is equal to the pressure in your blood vessels.

Blood pressure readings consist of two numbers, for example 120/80.

The first number is the peak pressure (when the heart contracts, “systolic” pressure). This is the highest pressure in your blood vessels.

The second number is the minimum pressure, taken when the heart relaxes (“diastolic” pressure).

To get your blood pressure checked, you can get in touch with your GP/medical specialist. You can also get it checked at many pharmacies. Another option is to buy   your own blood pressure meter – they are reliable and easy to use at home, whenever you want.

What’s a “good” blood pressure?

If you’re healthy, and not currently on any blood pressure medication, a lower-than-average blood pressure shouldn’t be anything to worry about.

An ideal, healthy blood pressure is not over 120/80. This is what young, healthy and lean people have.

Most people in the Western world, however, have a higher blood pressure than this. An elevated blood pressure is common in middle-aged people and older, especially in those who are overweight.

Between 120-140 systolic pressure and 80-90 diastolic pressure is considered a precursor to hypertension. This is nothing that needs to be treated in otherwise healthy people, but may mean that there is room for improved health by lifestyle changes.

Indigenous populations not eating a Western diet tend to have excellent blood pressure, even at old ages. We can learn and be inspired from them.

What’s a high blood pressure?

A reading of over 140/90, measured at at least three separate occasions, is considered elevated blood pressure. Temporarily having a slightly elevated blood pressure (when under stress, for example) is not dangerous.

As blood pressure tends to vary somewhat from day to day, it’s recommended to only diagnose someone with high blood pressure if they have given a repeatedly high reading. If the average of either of the readings (either the systolic or diastolic) is higher than the norm, it will be considered an elevated blood pressure. That is, an average of 150/85 or 135/100 over readings on several occassions will be considered too high.

Almost every third adult in the U.S. has elevated blood pressure, according to the CDC (Centers for Disease Control and Prevention) and the ASH (American Society of Hypertension).

Values between 140/90 and 160/100 are considered as slightly elevated blood pressure. Over 160/100 is said to be moderately elevated.

Over 180/110 is a severely elevated blood pressure.

The calculated difference between the systolic and diastolic pressures is also of interest. If the difference is large (e.g. 170/85), it could be the sign of stiff arteries – often caused by heart disease. This means the blood vessels can’t dilate enough when the heart sends out a pulse, which forces the blood pressure to increase. (The walls can’t expand, so the pressure rises when the heart tries to pump the blood through.)

White lab coats cause high blood pressure

Many people find that their blood pressure increases because of subconscious stress from confrontation with medical institutions and the staff working there. This is usually called “white coat hypertension”, that is, elevated blood pressure levels from just seeing the white lab coats doctors wear.

This is a common problem: a full 10-15% of people diagnosed with high blood pressure after measurements taken at a hospital or medical facility, later find that measurements taken in their own home or averaged over 24 hours are normal.

If you’re one of the people with “white coat hypertension”, you have approximately the same risk of heart disease as other people with normal blood pressure. People with “white coat hypertension” don’t need blood pressure-lowering medication – but they often get it unnecessarily!

If you suspect a stress-related elevation in your blood pressure, you can borrow blood pressure meters from your medical facility, strap them on for 24 hours to register blood pressure several times an hour. You could also buy your own blood pressure meter to check up on yourself at home.

When should hypertension be medicated?

If your blood pressure is severely elevated (over 160 systolic or over 100 in diastolic), medication is wise. If you have other risk factors for heart disease (like smoking, diabetes or obesity), medication may be recommended even for a slight elevation in blood pressure (over 140/90).

There is no evidence that medication improves the health of otherwise healthy people with mildly elevated blood pressure (140-159 systolic and/or 90-99 diastolic). This means it’s unclear whether it’s worth risking the side effects of the medication if all you have is a slight elevation.

Diabetics often have lower recommendations for blood pressure, the maximum normal value being seen as 130/80-85. However, it’s questionable whether it’s a good idea to medicate your blood pressure levels down to those values. Diabetics can probably stick to approximately the same upper limit as people with heart disease: 140/90 (according to new studies and expert comments, as well as the latest recommendations from the American Diabetes Association, ADA).

To summarize, the following are approximate limits for the levels of blood pressure at which medication becomes appropriate:

Otherwise healthy individuals: Over 160/100 Diabetics/people with heart disease: Over 140/90

With that said, smaller elevations in blood pressure could be suggestive of a need of some lifestyle changes in order to improve health and decrease the risk of diseases.

Reasons for high blood pressure

There are several rare causes of high blood pressure (such as kidney or adrenal disorders). If there’s reason to suspect  such disorders are the cause of hypertension, the appropriate measures should be decided by medical professionals.

However, the overwhelmingly more common type of elevated blood pressure is the kind that doesn’t have a clear cause, so-called primary hypertension. In these cases it’s often part of what’s called “metabolic syndrome”, also known as the disease of the Western world: 

 

The above health problems are grouped together because they so often appear as a cluster of symptoms in one individual. People with elevated blood pressure often carry extra weight around their belly, and they’re also likely to be in the risk zone for high blood sugar and type 2 diabetes.

The good news is: if you can get to the root and cause of this, you can often improve all these markers with one simple lifestyle change.

The common cause

Metabolic syndrome is typically caused by eating more carbohydrate than the body can handle. This primarily true for high-glycemic carbs that are quickly digested, such as white flour and pure sugar. Depending on how sensitive you are, you might be experiencing the same symptoms from more complex, lower GI carbs.

Carbohydrate starts getting broken down into simple sugars as soon as it arrives in your stomach (for example, starch in bread and pasta becomes glucose) which raises your blood sugar the moment it’s taken up by the bloodstream. The body then produces more of the hormone insulin, in order to take care of this blood sugar.

Insulin is the main fat-storing hormone in the body, and too much insulin can therefore lead to overweight in the long run. In large amounts, this can also disturb the cholesterol metabolism in your body. What’s more, it can also affect your blood pressure.

High insulin and high blood pressure

Raised insulin levels seem to lead to the accumulation of fluid and salt in the body. This increases blood pressure. In addition, high levels of insulin can thicken the tissue around blood vessels (the so-called smooth muscle), which also may contribute to an elevated blood pressure.

Eating less carbohyrate has repeatedly been shown to decrease insulin levels and also blood pressure. Perhaps this is because a low-carbohydrate diet also tends to discourage the body from accumulating fluids, and increases the elimination of salt via urine.

Lifestyle changes for a healthier blood pressure

There are several possible lifestyle changes you can make to lower your blood pressure. I’ll go through five of them below. The first one is, in my experience, the most important. It eliminates the most common cause of high blood pressure:

1. Cure the Western disease

An elevated blood pressure is often the product of so-called metabolic syndrome, especially in people with some excess weight. This means you can accomplish great benefits to your health by reducing your intake of (bad) carbohydrates.

Multiple studies on low-carbohydrate diets show improved blood pressure and more improvements than on other diets. As a bonus, a low-carbohydrate diet also usually leads to weight loss and improved blood sugar levels:

Review of low-carb vs high-carb diets The low-carbohydrate diet beats low-fat AND medication (A Randomized Trial of a Low-

Carbohydrate Diet vs Orlistat Plus a Low-Fat Diet for Weight Loss)

This does not only work in scientific studies but also in real life. Many patients and readers of mine have tried it with positive results.

2. To salt or not to salt

Eating less salt may lower your blood pressure a little. Research has shown that this effect is, however, minimal in the long term: an average of only 1 mmHg reduction was recorded.

We lack contemporary evidence that less salt in our food will affect the risk of heart disease or death. This was shown in a recent meta-study of all research on the subject. It’s unclear whether you will become healthier by eating less salt or not. Nobody knows.

Much of the salt we ingest comes from fast food, ready-made meals, bread and soft drinks – things to avoid when on a low-carbohydrate diet. This will lower your salt intake automatically. Furthermore, the hormonal effects of LCHF make it easier for the body to dispose of excess salt through urine; this can explain the slight lowering of blood pressure.

In summary, the demonising of salt is exaggerated. At any rate, if you stick to a low carb diet, you should be able to enjoy salt in moderation with a clear conscience.

3. Avoid other things which increase blood pressure

Blood pressure can be lowered simply by avoiding the things that drive it up. Here are the most common causes of elevated blood pressure:

Common painkillers (so-called non-steroidal anti-inflammatory drugs, NSAID), can increase your blood pressure by inhibiting the production of salt in your kidneys. This includes over-the-counter pills such as Ipren, Ibumetin, Ibuprofen, Diklofenak and Naproxen as well as the prescription drug Celebra. Painkillers with the active substance paracetamol are better for your blood pressure.

Cortisone pills, such as Prednisolon

Birth control pills (for some people)

Coffee (caffeine)

Alcohol in large amounts

Nicotine (smoking, other forms of tobacco) can give short-lived rises in blood pressure of 15-20 units

Drugs such as amphetamine and cocaine

Licorice in large amounts

This doesn’t mean it’s imperative to abstain from coffee or alcohol completely; however, if you are a big “user” it may be wise to decrease your intake. On the other hand, it’s always a good idea to completely stop smoking: kicking a smoking habit is excellent for your health in general, not just your blood pressure.

4. Exercise!

Regular exercise has been shown to somewhat lower blood pressure. And, if nothing else, at least you’ll be burning carbohydrate and therefore increasing your carb tolerance.

5. Avoid deficiency of omega 3 fats or vitamin D

Studies indicate that omega 3 fats may lower blood pressure somewhat (especially the systolic blood pressure value). More on omega 3.

One study shows the lowering of blood pressure by about 4 units systolic and 3 units diastolic by administration of vitamin D supplements in deficient people (common during the winter half-year). More on vitamin D.

Follow up your blood pressure

Following up a decrease in blood pressure is most easily done at your local medical centre or with the DIY instruments.

Blood pressure medication

At levels of blood pressure which are at least moderately elevated (>160/100), such as those induced by heart disease, medication may be appropriate. Keeping in line with the lifestyle suggestions above is still a good idea, though – they may help ensure that you don’t need to take more medication than necessary for your treatment.

Blood pressure-lowering medication tends to primarily reduce the risk of the having a stroke, heart failure or damage to the kidneys caused by elevated blood pressure.

There are many good options when it comes to such medication. Examples are ACE (angiotensin-converting-enzyme) inhibitors or AII-blockers (angiotensin II receptor blockers) such as Enalapril or Losartan. If this kind of medication doesn’t give the desired effect, you might have to add other medication such as so-called calcium antagonists (e.g. Felodipin) or a mild diuretic (can be found as a combined pill with Enalapril and Losartan).

If possible, avoid using beta blockers to treat blood pressure (this means pills like Atenolol, Metoprolol or Seloken). They are less effective and cause more side effects (such as decreased potency, fatigue and weight gain). These medicines can, however, be of use in cases of heart disease (such as angina).

Coming soon: More on blood pressure medication.

Measuring blood pressure at home

It’s easy to measure your blood pressure with an automatic blood pressure meter – if you do it right. There are, however, common sources of error which can lead to unreliable results.

In order to accurately measure blood pressure, two things are important: good equipment and the right measuring technique.

Equipment

The blood pressure meter should be high-quality, preferably a tested and certified type. It should measure the blood pressure at your upper arm (wrist measurements are less trustworthy). Here are two blood pressure meters I can recommend:

Omron M6 Comfort and Omron M2

The arm cuff needs to be the right size. If you have large upper arms and measure your blood pressure with cuffs for normal-sized arms, you’ll get disproportionately high values – sometimes as high as 20 units more than your actual blood pressure. In other words, it’s possible that the measurement might falsely indicate an elevated blood pressure.

If you’re unsure of your upper arm size, measure the circumference with measuring tape:

A circumference of roughly 8.5-12.5 inches will fit normal-sized cuffs (and Omron M2). Upper arms larger than this might need a cuff size of 8.5-16.5 inches (such as the one accompanying Omron M6 Comfort).

Measuring technique

Blood pressure is best measured when seated, as that’s the way it’s usually measured in the studies determining healthy values. Being systematic and conforming to measuring standards decreases the risk of over-medication following wrongful measurements.

For highest accuracy, blood pressure measurements should be performed like this:

1. In the half hour before measurement, refrain from exercise, tobacco use or eating.2. Rest at comfortable room temperature for 5-10 minutes before the measurement.

3. Expose your upper arm.

4. The cuff should be wrapped so that its lower edge is about 0.7 inches above the crook of your arm. The cuff should neither be too tight nor too loose – two fingers should just be able to fit underneath it.

5. Take a seat with a back rest and make sure your back and feet are at comfortable rest, do not cross your legs.

6. Rest your arm comfortably and position it so that your upper arm is at the same height as your

heart, by e.g. placing it on a table.

7. Relax and take the measurement.

8. Repeat the measurement at least once, with one minute’s pause in between. The average of two or more measurements should be noted.

Accurate results

As long as the measurement is conducted correctly, with certified blood pressure meter, you’ll be getting results just as accurate as you would at a medical clinic. In fact, in Sweden, an investigation has shown that medical practices sometimes wrongly take blood pressure measurements with the patient lying down – so you might even be getting more accurate results at home!

The difference between blood pressure sitting up and lying down

In Sweden, blood pressure is often wrongly measured at clinics with the subjects lying down. The differences tend to be small, however: when seated, the systolic blood pressure registers a little lower, and the diastolic a little higher. Trying this on myself, I noted readings of 116/73 averaged over several seated measurements and an average of 119/72 lying down.

Blood pressure measurements lying down can bring errors and the risk of overtreatment in some people, especially elders (in the case of “orthostatism”, i.e. blood pressure drop in sitting/standing).

Fluctuations during the day and year

Blood pressure is usually at its lowest in the morning, and rises slightly towards the afternoon and evening. It tends to be lower during the summer half-year and slightly higher during the winter.

Studies

Treatment of high blood pressure

Treating slightly elevated blood pressure (140-159 systolic, 90-99 diastolic) in otherwise heart-healthy patients does not necessarily result in health gains:

Diao D, et al. Pharmacotherapy for mild hypertension. Cochrane Database Syst Rev. 2012 Aug 15;8:CD006742.

Appropriate technique for blood pressure measurements

Overviews:

Williams JS, et a. Videos in clinical medicine. Blood-pressure measurement. N Engl J Med. 2009 Jan 29;360(5):e6.

Pickering TG, et al. Recommendations for blood pressure measurement in humans and experimental animals: Part 1: blood pressure measurement in humans: a statement for professionals from the Subcommittee of Professional and Public Education of the American Heart Association Council on High Blood Pressure Research. Hypertension. 2005 Jan;45(1):142-61.