BP and Special K+ - Dr. Roe's Poisoned Foods Part 4
Poster: Daniel Roe @ Sun Jul 19, 2009 5:03 pm
The PhD who taught us nutrition at our medical school was this old skinny vegetarian guy who, after three decades of teaching, still had a modicum of enthusiasm for professing, but none left for research. On the rare occasions he did update his lectures, he'd do it by just adding an addendum to his PowerPoints stating the exact opposite of what he'd just spent 45 minutes talking about. Through no fault of his own, he taught us the folly of thinking you know everything, and the skepticism required when dealing with statistics and studies.
One thing that always did strike me as extremely solid, however, is the role of potassium in diet. After going through a list of foods that were high in potassium, I could see right away one immutable fact: If you are American, you are almost certainly potassium deficient.
At the time, I was new to biochemistry working hard to get through it, but I kept this thought in my head until my physiology teacher finally taught me what potassium does.
Special K+ Makes Kidneys Happy
The most important function of the kidney is to regulate electrolytes (for reasons I'll get to later). A close second, however, is management of blood pressure (BP). Without adequate blood pressure, your tissues run out of oxygen and nutrients, and then die.
The kidney produces urine at a roughly constant rate 24 hours a day. 20% of blood volume that goes through the kidney ends up in urine. This ends up being about 34 gallons of urine per day.
You may saying "Listen idiot, you need to learn some math. 34 gallons would weigh 280 pounds. Converting to metric, that's about 1,400 milli-Oprahs a day. I'd have to drink like 70 Mountain Dew big-gulps to keep up with that!"
The reason why you don't end up peeing out all that liquid is because the kidney reabsorbs what it wants to keep. The nutrients it chooses to reabsorb with that water depend on the hormone levels in your blood that tell your kidney what to do (there are many).
The problem with this kind of biological machine is that it's not very exact when it comes to blood pressure.
The kidney manages blood pressure in part by regulating the total amount of urine excreted. One of the mechanisms it uses to do this is by actively pumping sodium into the urine. The higher salinity of the urine will draw water from the body through osmosis. More water in urine means less water in the blood.
The reverse is also true: The more sodium you have in your blood, the less urine you will pee. This is why high-salt diets cause high blood pressure.
One such pump is actually a molecular machine (enzyme) that exchanges a single potassium ion (K+) for a single sodium ion (Na+)--one at a time. This sounds ineffective, but it when you consider that there are millions of these things each moving faster than a migrant worker at an AFLCIO meeting, you realize that it is more than adequate.
The problem with this particular pump is that the urine has to have an equal amount of potassium to the amount of sodium you want pump into the urine (and remember, the more sodium you pee out, the more water comes with it, and therefore the lower your blood pressure is).
You see where I'm going with this?
Being as how you need potassium to reduce your blood pressure, if you're potassium deficient like most Americans, you're going to have higher blood pressure.
So Should I Eat More Potassium or Less Sodium?
The Unrealistic Dick™ answer is "both." However, the more useful answer could actually be potassium!
In a study done of blacks (who are less tolerant of sodium than whites), it was found that higher potassium diets lowered blood pressure better than restricting sodium in the diet.
Potassium is also highly effective at lowering blood pressure in whites, but it's inconclusive how much.
What about asians? I'm not sure. You guys can use google as well as I can though.
Obviously reducing your sodium is a smart thing to do, so don't totally overlook it. Nor should you think you can get away with eating more of Mr Ed's salt-lick just because you're eating more bananas. Though technically you can, it's incredibly tough to gauge your salt and potassium levels without a blood test (remember what I said about BP not being exact?)
Great! So I'll Just Take a Potassium Pill Then!
"No you fucking wont, asshole!" -- Food and Drug Administration
The problem with taking too much potassium is that having too much potassium in your blood will upset the electrical system of every cell in your body... This includes your heart. High potassium in your blood will literally cause your heart to short-out and start misfiring.
Ahh, now you know why electrolyte balance is the most important thing the kidney maintains: Your heart wont pump right without it.
So why does the FDA say you can't have it in multivitamins? The simple answer is that Americans are, for the most part, damnable idiots that can't be trusted.
People overdose on vitamins all the time, and it so happens that taking too much potassium will kill you in just a few minutes. Compare this with taking too much vitamin A, which takes weeks or months to die of.
So what the hell do I eat then?
Luckily, high potassium foods are usually quite good for you. In general, we're talking about high fiber foods, green vegetables, and certain fruit.
Also, there is no risk of overdosing on potassium from eating it in foods unless you have certain medical conditions.
Here's a list of some really good ones that are easy to throw into just about any diet:
- Melons (especially cantaloupe and watermelon)
- Beans (baked, kidney, soy, lima, pinto, refried, white, garbanzo,)
So become a vegetarian, then?
God damn it, NO!
Okay maybe that was an overreaction. Some of my best friends are vegetarians, I swear!
Really, all you need to do is eat more veggies. As you can see from the above list, staples of the vegetarian diet are very high in potassium. That, combined with the way meats are usually seasoned (read: bacon) is why vegetarians usually have lower blood pressure.
With just a few, albeit painful, changes to your carnivorous lifestyle, you may be able to avoid being stuck on a blood pressure pill. The best part is, changes in blood pressure can be seen within a few days. Electrolyte consideration in diet and weight loss is curative for hypertension in the majority of those who have it.
Addendum on black licorice: For those who don't know, black licorice is a disgusting candy eaten by home-schooled children, old ladies, and goths. Black licorice has a chemical that acts similar to a certain salt-regulating hormone (aldosterone) and can decrease blood potassium levels. It is for this reason that you should NOT eat large amounts of black licorice. The level of the chemical varies in each batch, and too much can kill you. This became news a few years ago because people lady died after eating nearly a half pound of it per day. Can you guess her symptoms?: High blood pressure and muscle (including heart muscle) weakness.
Update: black licorice addendum needed to be corrected, as it was backwards: It is certainly not a diuretic, but a pressor.
Keywords: Potassium Blood Pressure Sodium Dieting Health Food
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|Bio: Daniel Roe
Daniel is Medical Resident from the southwest US. Prior to medicine, he worked in IT as a consultant, programmer, web designer/developer, and technician.
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