New blood pressure research finally worth its salt

Nearly one-third (31%) of American adults have high blood pressure. And according to the CDC, more than half of the people who have high blood pressure do not have it under control. Of course, the CDC serves as the Pentagon in the government’s war on salt. So maybe it’s time they realized they’ve been fighting the wrong war for 40 years?

But if the government really thinks salt is an important culprit, why not help figure out how to apply it to individuals, instead of blanket, mass-market mis-directives?

As you know, salt is not the answer for the majority of Americans who have high blood pressure (see my Daily Dispatch from 6/23/2012, titled “The great salt scam”).

The real problem is stress. However, sometimes stress and salt do go hand-in-hand when it comes to blood pressure. You see, some people do respond to stress by retaining extra salt. In these instances, preventing salt from being excreted by the kidneys, and thus retaining it in the blood, can cause the body to retain water in the blood circulation, raising blood pressure.

In general, only one in five white people respond to stress by retaining salt.  However, one in three black people respond to stress by retaining salt. And unfortunately many African Americans are exposed to more sources of stress. Not to mention more foods with higher salt content, in light of often restricted food choices. In fact, as early as the 1970’s in the American Journal of Public Health, researchers actually presented elevated blood pressure levels among blacks as an index of the stress they are under.

But long before this clinical proof, poet, playwright, and activist Langston Hughes noted this connection in his work. In the 1920’s, he wrote: “In the quarter of the Negro; Pressure of the blood is slightly higher; Where black shadows move like shadows; Cut from shadows, cut from shade.” Even Hughes recognized stress as the protagonist, at least for most people.

But as I have pointed out before, statistics like these do nothing to help individual patients. As hypertension researcher Gregory Harshfield at the Georgia Prevention Institute put it, “Salt sensitivity is a great concept but it’s never been implemented into the clinical arena.”

But researchers have finally come up with something helpful for determining whether individual patients retain salt—a simple urine test.

Researchers at the Georgia Regent University’s Institute of Public and Preventive Health found that when some subjects experienced stress, their urine showed high levels of sodium indicating more salt in the body. This knowledge allowed the doctors to pinpoint which patients should go on restrictive, low-salt diets. And they could leave the other patients alone about their salt intake.

But if you do happen to be one of the minority of people who retain salt this way, there are also other measures you can take to keep your blood pressure in check.

Harshfield’s studies, funded by the National Institutes of Health, show that people who retain excess sodium respond well to drugs called angiotensin receptor blockers, or ARBs. (Some commonly prescribed ARBs include candesartan, eprosartan, and irbesartan.)

As the name suggests, these drugs act by blocking receptors for an enzyme called angiotensin. This enzyme causes blood vessels to constrict, thereby raising blood pressure. Studies have shown angiotensin also promotes sodium retention directly. And, to make matters worse, it also increases levels of the hormone aldosterone, which enhances sodium and water retention by the kidney. But ARBs offset these effects and reduce blood vessel constriction.

Harshfield and his colleagues also made one other interesting discovery. They noted that people who retain sodium are still able to get rid of excess potassium.  Normally sodium and potassium are excreted at the same time to maintain healthy fluid balance.  Keeping levels of both sodium and potassium balanced, both within cells, and in the extra-cellular fluids and blood, is a key component of homeostasis. But the only way this balance can really happen is when cells make their own water through the process of cellular respiration. If you excrete too much potassium without excreting the same amount of sodium, it throws off the balance.

Preliminary research by Harshfield and his colleagues shows that potassium supplementation may help patients maintain a healthier sodium level following exposure to stress. There are also many good dietary sources of potassium such as citrus fruits, bananas, and healthy meats.

So, if you’re worried about salt, get your urine tested. Find out if you’re prone to excess salt retention. If so, by all means, keep an eye on your salt intake. Work closely with your doctor to keep your blood pressure under control. Even if that means taking a safe and effective drug (such as an ARB). And make sure you’re eating plenty of potassium-rich foods. After all, when you eat a banana you could actually be making a monkey out of CDC’s “war on salt.”


1. “Simple steps may identify patients that hold onto excess sodium,” Science Daily ( 9/12/2013