While salt levels in your blood stream are one mechanism that affects your blood pressure, it is not alone.
Here's a quick primer on high blood pressure and its common causes.
It all starts with your heart and your arterial blood vessels. HTN is affected by how your heart is pumping, how much it is pumping, and what it is pumping against. So if your arteries, which are the blood vessels your heart pushes blood through to get it to your organs, are narrowed because of arteriosclerosis or spasm, your pressure goes up. If your blood volume is increased because of water retention, your pressure also goes up.
Blood pressure is also affected by neurological systems called the autonomic system, which is controlled by the brain. Although it's role is not perfectly understood regarding its contribution to HTN, it is known that the system can raise and lower your blood pressure by sending signals to blood vessels to narrow or dilate. This system is also called the "fight or flight" system because it controls your body's reaction to external factors.
Your kidneys are believed to play a major role in HTN. First, kidneys regulate fluid balances in your body by controlling how much fluid and salt is excreted to maintain a good circulating fluid volume. If you ingest more salt, the kidneys are suppose to excrete more salt to keep the balance.
The kidneys also release a hormone and enzyme called renin, which perhaps plays a very significant role in fluid maintenance and blood vessel control as part of the renin-angiotensin-aldosterone axis. This axis is the body's system that ultimately controls one of the kidney's main functions--to excrete excess sodium and potassium. The amount of two elements in your body affects how much water the body retains. This axis also controls the flexibility of blood vessels walls and has the ability to narrow the blood vessel when beneficial to the body. Obviously, if the system malfunctions and blood vessels narrow inappropriately, this can cause HTN.
HTN is deadly to your body because of the extra strain it puts on your always pumping heart to work harder. This can lead to the growth of heart-muscle, which is not a good thing. As the heart works harder, it can grow larger and actually become flabby and dysfunctional. Untreated, this often leads to heart failure and eventual death.
So when a doctor confronts HTN, the first instinct, if not rule, is to lower it with medication(s) to prevent any damage. There are many types of medications to treat HTN, including diuretics which simply cause the kidneys to excrete more fluid, calcium channel blockers,beta-blockers, vaso-dilators etc. Unfortunately, many doctors do not effectively address many of the root causes of the rising blood pressure such as stress, eating the wrong foods and avoiding the right ones, weight gain, etc. This brings to mind one of my favorite childhood anecdotes.
My father drove an old car and one day a red light went on in the dashboard. We drove to a gas station and my father asked if they could address the problem. They said sure, we can "disconnect the red light." It seems that when it comes to high blood pressure, doctors often disconnect the red light with medication rather than address why the red light went on in the first place.
This morning, I received an email from a website called REALAGE.com. The website is now owned by sharecare.com, which is partially owned by Dr. Oz (yes, him again). Clicking on the link and probing around the website, I found an article titled Reduce High Blood Pressure with Yogurt. The article claims that yogurt and low fat dairy can reduce high blood pressure. To quote the article, "In a recent study, a diet that was rich in low-fat dairy seemed to help curb the risk of high blood pressure by as much as 31 percent."
Wow, that sounds pretty good, but it couldn't be more misleading. I previously blogged about that study (Want Milk?, Friday April 20, 2012, http://mdprevent.blogspot.com/2012/04/want-milk.html). It showed that compared to eating dairy with a higher fat content, there was a decrease in blood pressure by eating low-fat dairy. The study did not look at how low fat dairy compared to no-fat dairy and no dairy altogether. Telling you something is the lesser of two evils without telling you what it is compared against I believe is misleading.
I guess by now, you may not be surprised that health information provided by anything connected to Dr. Oz may be misleading. If you want to lower your blood pressure, learn what foods to eat and which to avoid, and most importantly get the right type of exercise, a good night's rest, and manage your stress effectively. All of these affect blood pressure. Either way, always consult a doctor if you have high blood pressure, rather than a website or TV show that may be misleading. Accurate information allows you to make informed choices. Isn't that what you want?