High blood pressure is one of the most common medical conditions humans face. An estimated 75 million Americans have it. High blood pressure is a topic of intense discussion in the medical world. One example of this is the fact that the definition of what hypertension is was recently changed. We review the way the body maintains a normal blood pressure, ideas behind what causes high blood pressure and what situations can cause it in people who don’t have it.
How does normal blood pressure work?
The blood pressure inside our arteries and veins keeps us conscious and alive. Blood pressure is the result of the pumping of the heart, the squeezing and relaxing of the arteries and veins and the amount of blood inside the body. To maintain constant blood pressure at all times, the body has a fine-tuned system that can adapt quickly to any challenge. The system is constantly adjusting itself to changes in our activity, the effect of gravity, diet, outside temperature and even changes in our emotions. Many different parts make up this complex machine, including organs like the heart, brain and kidneys; hormones like aldosterone and epinephrine; and the arteries and veins. There are sensors in the arteries of our neck that constantly monitor the blood pressure, cells in our brain that measure how much salt there is in our blood, and special filters in our kidneys that can remove water from our body depending on what is needed. Depending on the situation, some parts may crank up their functions while others relax. This miracle of engineering has evolved over millions of years and works so well that most of us never notice it.
Causes of high blood pressure
To understand what causes high blood pressure, you can think of three different categories.
Things you do, take, eat or drink
Essential High Blood Pressure
Medical conditions that cause high blood pressure
Identifying the cause of high blood pressure is very important, because the way we treat the problem depends on it. It is often necessary to take the time and effort to identify the cause of the problem, because all not all hypertension gets treated the same way. Finding the right treatment for your high blood pressure will help you reduce the need for medication and the risks of their side effects.
High blood pressure that is caused by things you do, take, eat or drink
The first cause of hypertension is the easiest to explain: there are things that cause blood pressure to go up in most people, even in those who do not have the medical condition called hypertension. By removing these things you can potentially lower blood pressure without the need for medication. The things that cause high blood pressure are as following:
The fact that alcohol causes high blood pressure is well known. How exactly alcohol raises blood pressure is complicated. Its effect on blood pressure depends on the amount of alcohol a person drinks and the time of the day the alcohol is drunk. The effect on blood pressure also varies depending on ethnicity.
Non-steroidal anti-inflammatory drugs (known as NSAIDs) are commonly used for treatment of pain, arthritis and fever amongst others. People who take NSAIDs regularly have a higher chance of being diagnosed with hypertension and being prescribed medication to treat it. Also, for people already on blood pressure medication, regular use of NSIDS can cause a blood pressure that is more difficult to control. Why this happens is complicated and is likely the result of the effect NSAIDs have on the kidney.
Medications and substances that stimulate the nervous system are well known to raise blood pressure in a variety of ways including raising the heart rate and causing blood vessels to clamp down. Examples of this type of substances include medications used to treat attention deficit disorders like prescribed amphetamines, herbal supplements like Ma Huang (also known as ephedra) and so-called “recreational” drugs like cocaine.
Long term use of estrogen containing contraceptives can cause hypertension. The effect can be delayed as far as 6 years after starting them. Developing high blood pressure as a result of contraceptives is more likely if you are older and taking them, have been pregnant in the past, have kidney disease or are obese; how exactly this happens is still under investigation.
Steroids like Prednisone
Prednisone and other steroids are mainstays in the treatment of conditions like asthma. These medications cause salt (and therefore water) retention the body. This in turns causes blood pressure to rise. Any person in need of long-term use of steroids should have their blood pressure monitored closely.
Does coffee raise blood pressure?
The correct answer to this very common question is yes, but the details here matter. The increase in blood pressure that coffee causes usually happens soon after drinking it and is very short lived. Most people that drink coffee are not affected by this. Drinking coffee throughout the day in large quantities should be reduced in a person with new high blood pressure as it could help improve this condition.
“Essential” high blood pressure
High blood pressure is defined today as an abnormal elevation in either systolic or diastolic blood pressure. Its definition has changed over time, as we continue to learn more about the consequences of high blood pressure in the body. High blood pressure is in fact is so widespread that for the majority of human history we thought of it as “essential” to our lives, and literally untreatable. Hence its name: “Essential” high blood pressure.
Why does “Essential High Blood Pressure” happen?
Modern humans exist in a very different environment than we evolved as cavemen. Human beings evolved in the plains and savannahs of Africa and now inhabit the whole planet, moving from hot to cold climates and across parallels of space. We evolved eating from nature and now cook everything, salting and processing our food for easy consumption.
As cavemen, we needed to be very fit to survive but now have machines that do a lot of our work for us. All of this has an impact on our finely tuned cardiovascular system, the machine whose purpose is to maintain our blood pressure. Essential hypertension happens to about 1 in 3 people; but why? A good way of understanding this is that certain humans have trouble adapting their highly evolved system to the conditions of the modern world.
Understanding survival is the key to understanding essential hypertension
Our ancestors evolved genes that helped them survive a huge number of incredible challenges among them starvation, temperature and drought. We learned how to change our behavior to adapt to new environments and so did our bodies evolved too. One of the ways the body learned how adapt was by enhancing parts of its cardiovascular system. Now that conditions are plenty, the adaptations that tended to make our cardiovascular system to “overcompensate” for the lack of something do not match our current environment. It is possible that one of the ways we fail to adapt to our new modern situation is by developing high blood pressure. A large number of genes that have evolved over centuries are responsible of this situation: genes that provided the humans who had them an advantage over others when dealing with harsh conditions. Some of these genes move forward and appear in the next generation, some genes don’t. Others only become a problem when we move from the environment we grew up in.
Modifying our environment
If we understand essential hypertension to be the result of a mismatch between the things we have to help us survive and our new rich environment, the then changing the environment you live in makes sense. Returning your body to a more “natural” situation that is similar to what we experienced in the past may offer a way to manage this condition and limit the need for medication. One way to do they is to step out and become active like your cavemen ancestors needed to be. A daily 30 minutes of walking can lower your blood pressure by an average of 5 mm of mercury.
Also, remember this, humans did not evolve in a situation where every day they filled themselves up with large quantities of food. Eating less will also help you approach the goal of behaving more “naturally”. And finally eating fresh foods you make, as opposed to preserved or or processed foods you buy already made its an important part of this plan too. By simply doing this you reduce the amount of salt your body takes in.
Medical conditions that cause hypertension
Obesity as a cause of hypertension
In general terms, medical conditions that cause hypertension are rare, with one formidable exception: obesity. Obesity, defined by a body mass index of over 30, is rampant. More than 1 out of every 3 American adults is obese. By some estimates obesity is responsible for 40 to 70% the cases of hypertension we see. The one good thing about this fact is that by getting rid of obesity we can actually get rid of hypertension. A person who sets out to lose weight can expect about 1 mm of mercury reduction in their blood pressure (for example 150/90 to 149/89) for each kilogram of weight they lose. This may not sound like much, but remember this: as pounds drop off, so will the need for blood pressure medication.
Expect about 1mm of mercury reduction in blood pressure (for example 150/90 to 149/89) for each kilogram of weight lost
Obstructive Sleep Apnea (O.S.A.) as a cause of hypertension
Another medical condition that stands out as “low hanging fruit”, that is well known to cause hypertension is obstructive sleep apnea (commonly referred as “O.S.A.”). The way obstructive sleep apnea causes hypertension is complicated but we know that as many as half the patients with O.S.A. have hypertension and many patients who have difficult to control hypertension probably have OSA. Long term treatment of O.S.A. has a important impact of blood pressure control, and has additional benefits to the heart apart from its blood pressure lowering effects. Of the other medical conditions that cause hypertension two more are worth mentioning as they make up a large percentage of blood pressure that is not considered “essential”. The first one is kidney disease and the other one is excessive and inappropriate production of aldosterone in the body.
Share this with a patient or friend.