A Beginner’s Guide to Blood Pressure

A Beginner’s Guide to Blood Pressure

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Thirty-three percent of adults in the U.S. have high blood pressure. Globally, that number jumps to 40%, but many people with the condition remain unaware or go untreated because there are no real signs or symptoms for high blood pressure. Most of us know that blood pressure is an important measurement of heart health, but what is it, and why does it matter?

By Elle Penner, MPH, RD, MyFitnessPal dietitian and nutrition editor
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What Is Blood Pressure?

Blood travels through the body via the circulatory system, a maze of blood vessels of varying sizes. It moves from the large arteries and veins that direct blood to and from the heart to tiny capillaries that reach the smallest and farthest parts of the body. Blood pressure rises with each heartbeat—as blood is pushed out of the heart into arteries—and falls when the heart relaxes between beats.

Why Is Blood Pressure Important?

Blood pressure directly affects the health of our blood vessels. Healthy blood vessels are strong and flexible, and can withstand the constant pressure of blood rushing throughout the body. Over time, chronic high blood pressure causes damage to healthy blood vessels, and unhealthy blood vessels put us at risk for certain health conditions like heart attacks, heart failure, stroke, kidney failure and more.

What Makes Blood Pressure Go Up and Down?
Short-term changes in blood pressure

As mentioned before, blood pressure rises with each heartbeat, and falls when the heart relaxes and refills between beats. Blood pressure fluctuates from minute to minute depending on factors like posture, hydration, activity level, the presence of stress or anxiety, and sleep. These moderate, short-term changes in blood pressure are normal and healthy. They’re simply the body’s way of making sure oxygenated blood gets where and it is needed.

Long-term changes in blood pressure: Other factors can influence long-term changes in blood pressure. Over time, high or low blood pressure can lead to and/or be indicative of bigger health problems, so these are important numbers to know.

Some factors that may cause chronically high blood pressure include age, race, family history, overweight or obesity, physical inactivity, smoking, poor diet (think: too much sodium, too little potassium), stress, high alcohol consumption and certain chronic conditions, such as kidney disease, sleep apnea and hypothyroidism.

Generally, low blood pressure is not a problem as long as symptoms (see Low Blood Pressure Basics below) are not present. Some circumstances may cause extended periods of low blood pressure though, including prolonged bed rest, pregnancy (especially during the first 24 weeks), heart or endocrine problems, low blood sugar, certain medications or combinations of medications, severe infection and nutritional deficiencies like anemia.

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To help keep blood vessels and tissues healthy, blood pressure should normally remain within a certain range, which is why it’s important to know your numbers, and follow them over time.

When you visit the doctor and your blood pressure is measured, the nurse usually rattles off two numbers. Here’s what each number means:

Systolic
The first number (also the higher of the two) measures the pressure in the arteries when the heart contracts, squeezing freshly oxygenated blood into the arteries. Having a high systolic measurement is a major risk factor for cardiovascular disease for those over 50 years old.

Diastolic
The second number (also the lower of the two) measures the pressure in the arteries between heartbeats while the heart rests and refills between beats.

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Blood Pressure Categories

Below is a table to help you understand the different blood pressure ranges, and what category you fall into. One high reading does not mean you have high blood pressure. Before a diagnosis is made, your doctor will want to compare several readings over time and/or have you monitor your own blood pressure at home. If, after several readings, your blood pressure readings fall into two different categories, your correct range is the higher one. Note: Ranges may be lower for children and adolescents, thus the ranges below apply only to adults age 20 and above.

BLOOD PRESSURE CATEGORIES
Systolic (in mmHg) AND/OR Diastolic (in mmHg) Category
Below 120 AND Below 80 Normal blood pressure
Between 120-139 OR Between 80-89 Pre-high blood pressure (prehypertension)
Between 140-159 (or 150-159 if age 60 and above) OR Between 90-99 Stage 1 High Blood Pressure
Above 160 OR Above 100 Stage 2 High Blood Pressure
Higher than 180 OR Higher than 110 Hypertensive Crisis (emergency care needed)
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No matter what category you fall into, both doctors and dietitians will recommend maintaining or adopting a healthy lifestyle that includes regular physical activity and a nutritious, balanced diet (see Lower High Blood Pressure, below). Those with Stage 1 or Stage 2 may require medication to help reduce blood pressure if lifestyle changes are not enough.

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Those who fall into Stage 1 or Stage 2 Hypertension have high blood pressure.

Causes

Blood pressure tends to increase as we age, though the exact causes are not known. Several factors may play a role in its development though, including:

  • age
  • race
  • smoking
  • family history
  • being overweight or obese
  • too much sodium (and too little potassium, calcium and magnesium) in the diet
  • stress
  • consuming more than 1-2 alcoholic drinks per day
  • chronic health conditions like kidney disease and thyroid disfunction

Symptoms

Most people with high blood pressure will have no signs or symptoms. Rarely, some with early-stage hypertension might experience a dull headache, dizziness or a nosebleed, but again, these symptoms are rare as they are typically overlooked or attributed to other causes if and when they do occur.

Symptoms of dangerously high blood pressure (systolic greater than 180 mmHg or diastolic greater than 110 mmHg) include severe headaches, anxiety, nosebleeds and shortness of breath; seek immediate medical attention in this case.

Risks

Research has shown that, in some age groups, cardiovascular disease risk doubles for each increment of 20/10 mmHg of blood pressure, starting as low as 115/75 mmHg. Over time, high blood pressure can stretch arteries beyond their healthy limit and increase the workload on the circulatory system. High blood pressure can also cause damage that can then create numerous problems. Below are the major risks and what causes them.

Weakening & Scarring of Blood Vessels

Stretched-out blood vessels are more prone to rupture and can lead to problems like aneurysms and strokes. High blood pressure can cause tiny tears in blood vessel walls, leaving behind scar tissue in arteries and veins. The scar tissue and inflammation make the vessel more prone to plaque buildup.

Plaque Buildup

The tiny tears, scar tissue and inflammation in damaged blood vessels act like nets that catch tiny particles passing by like blood cells and cholesterol, often referred to as plaque. As plaque grows over time, it can severely restrict or cut off blood flow, causing major damage to tissues and organs. (When this happens in the heart, it is called a heart attack.) At the same time, pressure builds throughout the rest of the circulatory system and forces the heart to work harder—this can cause pieces of plaque to break off and possibly lead to a stroke.

Greater Risk of Blood Clots

Blood trapped from plaque buildup is more likely to form clots that can also narrow or completely block blood vessels, greatly increasing someone’s risk for heart attack or stroke.

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No matter what your numbers are, the benefits of adopting a healthy lifestyle go far beyond just improving blood pressure. If your blood pressure falls within the pre-high blood pressure (prehypertension) range, lifestyle changes might be enough to normalize it, and/or prevent your blood pressure from getting higher. For those with Stage 1 or Stage 2 high blood pressure, medications are generally prescribed in combination with healthy lifestyle changes, the most common of which are summarized below.

Lifestyle Changes

Eat a healthy diet. Foods that are low in sodium and high in potassium, calcium and magnesium are great for blood pressure. Incorporate more fruits, vegetables, reduced-fat milk and yogurt to get more of these important nutrients. Cut back on processed and fast foods; this will slash a significant amount of sodium, which should be around 2,300 milligrams per day.

Stop smoking. In addition to causing general cardiovascular problems, like the buildup of plaque in arteries, smoking tobacco temporarily increases blood pressure, which stays elevated for some time after finishing a cigarette.

Aim for a healthy weight. If you’re overweight, losing as few as 10 pounds can reduce blood pressure, and will also reduce strain on the heart.

Moderate alcohol intake. Limit consumption of alcoholic beverages to 1-2 drinks per day for men, one drink per day for women.

Exercise regularly. To lower your blood pressure, shoot for 40 minutes of moderate to vigorous physical activity at least 3-4 times per week (break it up into 10-minute intervals if you need to) and strength train at least two days per week.

Medications

If lifestyle changes aren’t enough to bring down your blood pressure, your doctor may prescribe one or more medications to help you manage it. There are an overwhelming number of blood pressure medications on the market, but fear not, your doctor will recommend the one(s) most appropriate for you. Below is a summary of how five common blood pressure medications work:

  • Diuretics help the body get rid of excess fluid and sodium (which retains fluid) to help reduce blood pressure. Diuretics are often used in combination with other blood pressure medications.
  • Beta-blockers reduce the heart’s rate, workload and output of blood, which lowers blood pressure.
  • ACE Inhibitors help the body produce less angiotensin, a chemical that causes arteries to narrow. Less angiotensin helps blood vessels relax, which then lowers blood pressure.
  • Angiotensin receptor blockers curb the effects of angiotensin—this means blood vessels remain relaxed and open, thus reducing blood pressure.
  • Calcium channel blockers prevent calcium from entering muscle cells in the heart and arteries, resulting in a less forceful contraction. They also relax narrowed blood vessels and reduce heart rate which, in turn, lowers blood pressure.
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Causes

It’s not uncommon for a healthy adult to have blood pressure readings around 85/55 mmHg, what medical professionals might refer to as low-normal. If your blood pressure is normally higher or if you are experiencing any symptoms like those listed below, your low pressure may have an underlying cause like prolonged bed rest, pregnancy (especially during the first 24 weeks), heart or endocrine problems, low blood sugar, certain medications or combinations of medications, severe infection or nutritional deficiencies like anemia.

Symptoms

While 85/55 mmHg might seem too low, low blood pressure is usually only concerning if it causes noticeable signs and symptoms, including:

  • dizziness or lightheadedness
  • fainting
  • dehydration and/or unusual thirst
  • lack of concentration
  • nausea
  • blurred vision
  • cold and clammy skin
  • paleness
  • fast and shallow breathing
  • fatigue

As long as no symptoms are present, low blood pressure is generally not a problem.

 

For more from our friends at MyFitnessPal, check out the full article on their blog here.

Susie Felber

Susie is a writer, comedian, and producer who has worked in TV, film, theater, radio, video games, and online. As the daughter of a hard-working M.D., she's had a lifelong interest in health and is currently on a personal mission to "walk the walk" and get her writer's body in better shape.
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