The hunt for the Holy Grail of nutrition has given us a lot of scientifically bunk theories–witness the current hysteria over wheat, gluten, and carbohydrates in general–and, as you’ll soon see, the “alkaline diet” theory is just another lame duck that needs to sit down and shut up.
While I wish we could optimize our health and protect ourselves against disease by simply using food to create an “alkaline environment” in our bodies, the evidence is clear–it’s just not that simple.
Ironically, there’s nothing wrong with eating the plant-based foods advocated by alkaline dieters–in fact it’s quite healthy to include these foods in your diet–but the evidence shows that they’re badly mistaken about how the body processes foods in general, and how this affects various physiological functions.
So, let’s start with what the alkaline diet is all about, and then we’ll look at where it falls apart.
Table of Contents
The first thing to understand to grok the alkaline diet theory is pH.
In chemistry, pH is a measure of the acidity of a solution. A pH of less than 7 is said to be “acidic” while a pH greater than 7 is “basic” or “alkaline,” and the more acidic a substance, the more it can react with other substances and cause chemical changes.
Alkaline diet proponents split up foods into three categories:
- “Acidic” foods: basically all sources of good protein–meat, poultry, fish, dairy, eggs–and grains.
- “Neutral” foods: fats, sugars, and starches.
- “Alkaline” foods: plant-based foods like fruit, nuts, legumes, and vegetables.
And the alkaline diet story goes like this:
When you eat foods, the metabolic byproducts (called “ash”) have pH values. Some are acidic (a pH score lower than 7) and some are alkaline (a score higher than 7), and–we’re told–the more foods you eat with acidic ash, the more acidic your entire body becomes.
An acidic body, alkaline dieters claim, is basically a mound of shit to the flies of disease, and all kinds of horrors can fester and grow, ranging from osteoporosis to diabetes to cancer.
Eat a bunch of acidic foods, they say, and you’re poking the wasp’s nest of disease and dysfunction. Eat a bunch of alkaline foods, however, and you’re bulletproofing your body against the modern onslaught of superbugs, mutant foods, and hazardous chemical.
The pitch is neat, and ironically the “alkaline” style of eating is rather healthy, but like the Paleo craze, the Emperor of Alkalinity is without clothes…
Let’s not waste time toying with our captive–let’s just chop off his head. (I’m a merciful tyrant.)
The biggest problem with the alkaline diet theory is the fact that the foods you eat simply can’t cause large or lasting changes in the pH value of your blood.
We’re lucky this is the case, too. Life on earth requires a tightly controlled pH of about 7.4 in and around cells and living organisms, and a dramatic change toward alkalinity or acidity means certain death.
Unless you have kidney disease, your blood is going to remain at a comfortable pH of about 7.35 regardless of what you eat for dinner. Ironically, this was demonstrated in research stretching all the way back to the 1930s, but the cockroach of the food-blood-pH myth just won’t die.
One of the reasons it’s still scurrying around in Food Babe’s swimming pool of gold coins, however, has to do with how food affects the pH of our urine.
You see, it’s true that the metabolism of food produces alkaline and acidic byproducts, and that “acidic” foods produce acidic byproducts whereas “alkaline” foods produce the alkaline variety. We can’t detect this in our blood, however–we can see it in our urine.
This is why alkaline dieters keep a stash of pH test strips on hand to divine their metabolic horoscope (my pee says it’s gonna be a good day!), but it’s all for naught: the pH of our urine isn’t a reliable index of our blood pH or our health…
A bale of spinach will make your pee more alkaline than a big ol’ bronto burger, and seeing that change on the pee strip can be gratifying–an immediate change for the better, you think.
The flaw, however, is that research shows that the pH level of our urine simply isn’t a reliable indicator of the pH of our blood or of our overall health and susceptibility to disease.
You see, the physiological mechanism alkaline dieters don’t know about or simply don’t get is the role of the kidneys in the regulation of blood pH, and how they’re specially equipped to deal with the “acidic ash” resulting from the metabolism of certain foods.
Here’s how it works:
When you eat “acidic foods,” the low-pH byproducts are quickly neutralized by bicarbonate ions in the blood. This process produces carbon dioxide, which is exhaled through the lungs, and salts, which are disposed of by the kidneys. Part of this disposal process includes the production of new bicarbonate ions to go back into the blood, and thus, the body is able to sustain the entire cycle.
Some people claim that the kidneys alone can’t handle this process and that the body must pull minerals from the bones to neutralize acidic ash, thus increasing the risk of osteoporosis, but this has been disproven by several studies.
Ironically, as researchers from the University of Calgary noted, increasing protein intake (which increases the “acid load”) has been shown to improve, not impair, bone health, including animal protein, which is the most acidic of all foods.
Alkaline dieters often claim that they’re taking a page from the dietary book of our ancient hunter-gatherers, whose societies were virtually free of many of our modern diseases.
They’ll often back up their claims with a study that concluded that 87% of pre-agricultural humans ate an alkaline diet, but newer research has amended this number and estimates that about 50% of our ancient hunter-gatherer ancestors ate more acid-forming than alkaline-forming foods, mainly due to high reliance on animal-based foods.
This more balanced estimation makes more sense when we consider that our ancestors had to survive in a variety of climates, which dictated the types of foods they had access to. Research shows that the further north of the equator people lived, the less access they had to fruits and vegetables, and thus, the more acidic their diets were.
As I said in the beginning of this article, the alkaline diet suffers from the same malfunction as the Paleo diet: its recommendations are healthy, but its foundations are flawed and its dogmatic stances against certain foods unjustified.
You absolutely should include plenty of alkaline-forming foods in your diet, including fruits, vegetables, nuts, and legumes, as they’re great sources of vitamins and minerals, fiber, and other nutrients, but you also should include plenty of acid-forming proteins as well, as they are high-quality sources of amino acids needed to sustain life.
The bottom line is the healthful aspects of alkaline dieting boil down to its emphasis on eating nutritious, unprocessed foods, which is sound dietary advice, not on the manipulation of blood pH levels, which is a myth.