A common health claim made about green foods is they “alkalize” your body.  And it goes that alkalinity is key to your body detoxifying itself, fending off sickness, and maybe even fending off cancer.

None of that’s really true.

Crazy, right?  Bear with me.

The alkalinity story is a bastard child between legitimate science and ad hoc storytelling that makes it easier for companies to sell you overpriced bottled water.

It’s easy to read lots of articles about the correlation between your body’s pH and various health conditions, but the question that ought to be resting on your lips is:  “Who cares?”

Here’s the simple truth:  when it comes to physiology, alkalinity is a completely hollow  term.  By itself it means nothing.  It’s just a damn number.

Setting the Story Straight

I want to use this piece to slay three dragons:

1).  That you ought to eat with the goal of changing your body’s pH (itself a stupid term)

2).  That changing your eating habits is an effective way to change your blood’s pH (or a worthwhile goal)

3).  That changing alkalinity is the key to preventing cancer

Now to be fair, with each of these points there are worthwhile counter truths. I’m going to touch on them towards the end.  Diet can change blood pH somewhat which can affect metabolic stasis. The acidity of cancer cells helps propagate tumor growth. That’s important.  But the truth in these areas is subtle and lies outside the realm of what’s commonly thrown around.  What you have in its place is truth-iness.

Flawed Metaphors

The scientific reasoning behind an alkaline diet is halfway pregnant.  It anchors itself around the well established fact that blood pH tightly regulates itself around 7.4, which is slightly alkaline.  It’s very true that if it deviates much from that you’ve got serious problems.  Death is just around the corner.

But the same narrative completely ignores the other half of the high school chemistry lesson it draws on: buffers.  Buffers are substances that allow a solution to maintain a specific pH even in the presence of acidic or alkaline solutions being added to it.

Well, guess what? Your whole body is an interwoven buffering system!   And it buffers things six ways from sunday.  The saliva in your mouth acts as a buffer to keep your mouth slightly basic (alkaline).  Your stomach is buffered to maintain a highly acidic environment (the kind that’s supposed to be bad for you). Your intestine is buffered to keep things basic after it gets food from your stomach.  Your bones are one big buffering system designed to keep your blood’s pH in check.

There are even more (like your kidneys and the air you breath), but hopefully you get the idea.  By the time your food gets chewed, passed into your stomach, digested in your intestine, excreted into the blood, filtered through your kidneys and excreted, its pH has been twisted and turned so many times that its net effect on your body’s pH is almost meaningless.

Your body does this precisely because it wants the pH of your food to be as docile as possible.

Now it’s true that eating foods that consistently form acidic byproducts (like dairy, meat, and processed foods) can create stress over time.  You might get kidney stones or develop weak bones, but you need to keep in mind the following points:

• These effects are less draconian than the long term effects of insulin resistance, high blood pressure, and obesity.  Among others.
• Your body’s buffering systems are so tightly wound around certain pH levels that even modest changes in diet can halt these long term effects.
• Your body has such a byzantine network of buffering systems, enzyme pumps, and ionic regulators that it’s all but impossible to define a linear relationship between food eaten and blood pH.
• The importance of the acidity/alkaline effect is often disputed.  For instance it’s long been posited that excessive amounts of “acidic ash” causes your bones to weaken from excreting calcium carbonate. However, a meta-analysis published Journal of Bone and Mineral Research and found that while an acidic diet might increase the amount of calcium excretion, it doesn’t necessarily lead to higher risks of osteoporosis.

Here’s a useful analogy: eating food to increase your blood’s pH is like drinking cold water to cure your body of its fever.

Acidity and Cancer: Cause or Effect?

It’s often posited that acidity within the cell is the cause of cancer.  Not quite.  It’s an effect.  To see why, take a look at the following picture.  It depicts what’s going on inside a cancer cell:

I highlighted the most important part for you.  I don’t want to get too wonkish, but the circled pyruvate –> lactate conversion is extremely important.  A normal cell would never do that under normal conditions.  But cancer cells pre-emptively do it all the time as an adaptation to deprived oxygen.  It’s almost by definition what makes them cancerous.  (It’s called the Warburg Effect).

And lactate creates acid, which causes cancer cells to spew out protons…..which creates acidity.  Cause.  Effect.

Now at this point it’s important to back up a few steps.  Once the acid is there there’s a lot of interesting stuff you can do with it to change the face of the disease.  And yes, changing diet can help with that.  But it’s step 2 (or 3, 4, 5, etc), not 1.

Easily Measured, Poorly Understood

Now to be clear, none of this changes other diet advice one iota.  Raw greens, phytonutrients, high insulin sensitivity, and all that jazz.  But for the sake of simplicity cross this macro variable off your list of things to worry about.

The pH argument is enticing because it’s easily measured, is anchored around a common scientific principle, and reduces many problems to one variable.  But in the end it’s a case study in confirmation bias.  Just because you can observe something doesn’t mean you’ve learned something.

And without any additional context the pH of your blood, cytoplasm, gut, or kidneys is simply a digit and nothing else.

References

Van slyke, Donald, et. al. “Studies of Acidosis”

URL: http://www.jbc.org/content/30/2/289.full.pdf

Robey, Ian Forrest “Examining the relationship between diet-induced acidosis and cancer.”

URL: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3571898/

Chiche, Johanna, et. al. “Tumour hypoxia induces a metabolic shift causing acidosis: a common feature in cancer”

URL: http://onlinelibrary.wiley.com/doi/10.1111/j.1582-4934.2009.00994.x/abstract

Fenton, Tanis, et. al. “Meta-Analysis of the Effect of the Acid-Ash Hypothesis of Osteoporosis on Calcium Balance”

URL: http://onlinelibrary.wiley.com/doi/10.1359/jbmr.090515/full

Hsu, Peggy, et. al. “Cancer Cell Metabolism:Warburg and Beyond“

URL: http://sabatinilab.wi.mit.edu/Sabatini%20papers/Cancer_metab-Cell-2008.pdf

Kroemer, Guido, et. al. “Tumor Cell Metabolism: Cancer’s Achilles Heel”

URL: http://www.fundacion-barcelo.com.ar/oncologia-molecular/Bibliografia%20Complementaria%20sesion%201/Fernandez%20Piqueras%20-%20Genes%20supresores/Kroemer%20-%20Tumor%20Cell%20Metabolism.pdf

Remer, T. “Influence of Diet on Acid Base Balance”

URL: http://www.ncbi.nlm.nih.gov/pubmed/10923348