Potassium Against Hypertension

My father had high blood pressure and, in addition to medication, his doctor advised him to limit his salt intake, which he did – at least in terms of his diet. But a favorite family summer activity when I was growing up was snorkeling in the Florida Keys.

Now, we weren’t just floating around on the surface, we were diving down to catch tropical fish for our aquariums and catching lobster for dinner. If you’ve ever done any of that sort of snorkeling, you know that you swallow a LOT of very salty water! Compared to the amount you might get from diet, it was a massive amount of sodium he was taking in on those snorkeling trips! But snorkeling didn’t seem to increase Dad’s blood pressure – in fact, it usually lowered it slightly. Of course, the physical exercise and stress-reduction from snorkeling no doubt was a big part of that effect, but seawater has a lot more than just sodium in it. I have to wonder if some of those other components might have also participated in the positive effects snorkeling had on my father’s blood pressure.

One potentially significant factor is potassium. Although it’s not nearly as plentiful in seawater as sodium, there’s still a considerable amount, and again, we were swallowing quite a bit of seawater on our snorkeling adventures.

But why would potassium lower blood pressure? There’s actually multiple mechanisms for this.

Potassium “softens” the cells lining the walls of blood vessels, making them more pliable. It also stimulates increased nitric oxide, which relaxes the smooth muscle walls of the blood vessels and allows them to open up more. So, while sodium increases blood volume by pulling more fluid into the blood stream (which increases blood pressure) potassium essentially increases the size of the “pipes” carrying the blood, thereby reducing the pressure.

Potassium also stimulates the release of hormones that increase the excretion of sodium by the kidneys, so it not only reduces the blood pressure increasing effects of sodium, it actually reduces the amount of sodium in the blood as well.

In fact, one of the mechanisms by which exercise is thought to help lower blood pressure is that muscle contraction pushes potassium out of the muscle cells into the bloodstream.

By itself, the effects of increased potassium intake on blood pressure is relatively mild – about a 5 point drop in those diagnosed with hypertension. Combined with exercise, stress-management, and other interventions, the effects on blood pressure would likely be greater.

But even a small reduction in blood pressure has a big impact on stroke risk. In particular, I’m talking about hemorrhagic stroke – in which blood vessels rupture (as opposed to ischemic stroke associated with plaques narrowing blood vessels). Normalizing potassium levels in those deficient has been shown to reduce stroke risk by about 24%.

There are a couple of precautions to keep in mind if you’re trying to increase your potassium levels. First, there’s not a good reason to increase potassium intake if you’re not actually deficient in it, and taking too much can create problems. So, if you go the supplement route, be careful to stick to the recommended dosage indicated on the bottle.

If you have any loss of kidney function, supplementing with potassium is not recommended, unless done with careful medical supervision, as it will increase the workload of the kidneys in excreting sodium and may also throw your sodium-potassium balance off.

You’re unlikely to overdose on potassium from foods, so simply increasing potassium-rich foods in the diet is a safer way to go than supplements (although supplements are quite safe if your kidney function is normal and you stick to the recommended dosage). Among the potassium rich foods are bananas (of course), avocados, leafy greens such as spinach, apricots, almonds, and salmon.

Until next time…

George F. Best, D.C.