If you have flirted at all with any of the welter of different diets that have littered the American landscape since at least the 19th century, you have probably heard someone say that as a rule, our bodies are too acidic. That most people are in a chronic state of acidosis. And that this condition causes all kinds of diseases -- or at the very least helps promote them.
You might also have heard that you should be consuming foods in certain combinations, and that unless you do so they won’t digest properly and will putrify in the grimmest fashion imaginable RIGHT THERE in your digestive tract. You may think that you should be testing the pH of your saliva and your urine regularly with testing strips and tweaking your diet accordingly depending on the results. You may even have read about the “acid alkaline balance diet” and are now consequently terrified of ever putting another donut into your mouth ever again. (For a while, anyway.) And so forth.
Let’s look at this acid-alkaline thing a little more closely. First of all, what are we even talking about? Well, acidity is measured by the pH scale. “pH” stands for “power of hydrogen” and it is the decimal logarithm of the reciprocal of the hydrogen ion activity in an aqueous solution. I’m sorry, that wasn't clear? Does this help?
No? Can’t imagine why not.
Never mind that. You know what acidity is already. A little bit of it tastes sour like lemon juice, and a lot of it will burn the heck out of you. Basically, the concentration of hydrogen ions in a solution is what makes something acidic or not, and that is what is measured by the pH scale. Because of the above math, the scale runs from 0 to 14. In the middle of that range we find 7, which is neutral and is the pH of water. The 0 end is super acidic. The 14 end is super alkaline, which is like bleach and isn’t any healthier for you than the acid end.
We are made up mostly of water, so body chemistry is water based. Our overall pH is between 7.35 and 7.45, slightly on the alkaline side. And as long as we don't stray from this tight range, the umpteen chemical pathways that make up our metabolism function smoothly.
Monitoring and keeping your body pH between 7.35 and 7.45 is a lot of work, and your body (mainly the lungs and kidneys) works very hard at it. This is because if your pH gets even a smidgen out of that zone it starts to fall to pieces. Well, not literally, not like in zombie movies (not even the good ones) but you get what I mean. Start dumping a lot of extra hydrogen ions into places where there is delicate chemistry happening and everything goes haywire.
pH is maintained so rigorously and in such a narrow range that to talk about someone being chronically acidic or in acidosis is terribly inaccurate unless they are very ill. Saliva normally varies considerably in pH depending on, among other things, which part of your mouth the testing strip was contacting. Urine is a dumping ground for your kidneys -- if it's in there, your body is getting rid of it. Neither of those fluids reflects the state of your internal environment pH-wise. Because of all this, Science has airily hand-waved away the acid-alkaline thing from the very beginning.
However, just because you have a weak theory does not mean that you can dismiss the practice it supports. People have been doing the right things for the wrong reasons ever since we first crawled out of the ocean to get a little more elbow room, and traditions of healthy living may be one of the best examples there is of this. The fundamental practice of acid-alkaline balance is essentially to eat more fruits and vegetables (alkaline) and less meat, sugar and white flour (acidic). Also to drink more water to help the kidneys out. And sometimes to get more sleep, more exercise, and more sunshine. It's nice that Science has caught up to these things, which 'health nuts" have done for a very long time.
Certainly at this stage in the evolution of conventional medicine, which is the third leading cause of death in the United States (I may have mentioned that before), automatically getting on one’s high horse in the face of any health practice that is not obviously detrimental is probably a big mistake. So if you consider yourself a scientist, what do you do with a practice that is clearly not harmful and that a lot of people swear by? How about -- actually investigate it, and see if it does anything of what it claims to?
And this is what has happened. Somebody (actually several somebodies) finally decided that they would try to see if there might really be a baby in all the bathwater of acid-alkaline balance theory. Especially whether the recommended changes in diet 1) might change people's basic body chemistry in some fashion, and/or 2) might be beneficial.
One of these studies has found that people eating a high-acid diet (in this case, meaning a lot of meat) had a bigger risk of chronic kidney disease than those who ate a lot more fruits and vegetables. Another study found that patients with chronic kidney disease had a three times greater risk of progressing to kidney failure if they ate a high-acid diet. And when they measured the kidney’s metabolic by-products, they could see clearly that the people with the low DAL ("dietary acid load") were demanding less of their kidneys.
Continuing in this vein, a high DAL appears to increase the chance of insulin resistance appearing in healthy people. And a high DAL increases the likelihood that people with type 2 diabetes will develop metabolic syndrome.
Finally, WebMD states that "there's some early evidence that a diet low in acid-producing foods like animal protein (such as meat and cheese) and bread, and high in fruits and veggies could help prevent kidney stones, keep bones and muscles strong, improve heart health and brain function, reduce low back pain, and lower risk for colon cancer and type 2 diabetes." Impressive.
So this is what it looks like to me. Meat, cheese and grains do tip your body towards being acidic. But that doesn’t mean that your body turns into a bubbling froth of yellow-colored toxic waste every time you eat a cheese omelet. It suggests that your kidneys in particular aren’t thrilled by having to cope with too much acid-forming food, even if you are healthy. It also suggests that a high-acid diet is rougher on your body, especially said kidneys, than a low-acid diet. None of this means that acid diets actually make people acid. But the food you eat seems to make a difference as to how hard your kidneys have to work -- and no matter how healthy you are, they don't like having to cope with a lot of acid-forming food.
What we see is that eating a lot less meat and a lot more fruits and vegetables is correlated with improved health. In itself that isn't news, but the actual measurements of metabolic byproducts done in at least some of these studies lend a little credibility to the idea that one way eating more meat damages the body is by forcing the kidneys to deal with undesirable amounts of acid.
So. If you are habitually eating more than the recommended amounts of meat and dairy (which would be about two servings per day of each), this is one more reason not to do so. I'll even go so far as to say that if you eat a lot of meat and cheese and aren't going to cut back, that it wouldn't hurt to emphasize the most alkaline foods in your diet a bit (especially onions, asparagus, cauliflower and broccoli, greens, and lemons and limes).
And I would take away two other things from this.
One is, just because something sounds weird, or if it is said by a weird person, does NOT automatically mean that there isn't something to it.
The other is that we should eat more fruits and vegetables. But we already knew THAT.