[randomstudent]

> Apparently at the current moment the best is to keep your PH value in the body neutral. It's particularly important to prevent "acidity"

If you're talking about a neutral pH as in pH = 7.0 (the usual accepted definition of neutral), these claims are contradictory. The pH of the human blood is usually between 7.35 and 7.45. This is usually way less acicic than the neutral pH of 7.0. Furthermore, a pH of 7 is usually associated with very serious disease (and yes, it is causal: if you inject/ingest enough acid to make the pH drop to 7.0 you're in pretty bad shape, especially because it means the regulatory mechanisms aren't working as they should). I don't know who that "professional nutritionist" is, but this sounds like crackpot-level science.

Also, to the best of my knowledge, it's extremely hard to change the blood's pH with diet... The body has a multi-layered system specifically dedicated to keeping the pH in the normal range (7.35-7.45), and that's independent of what you eat. Maybe you're mistaking it for changing the urine's pH, which is much easier to do, and can be achieved through diet alone. Unfortunately, changing the urine's pH doesn't seem to achieve much beyond preventing some inds of kidney stones...

[beggi]

I second the fact that this is crackpot-level science - you can basically only change the acidity of your urine with dietary modifications - not your blood. Btw changing the PH value of your body thing is endorsed by various charlatans for all kinds of stuff - from curing the flu to cancer.

[andy_ppp]

Hmmm, a brief search reveals this; https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3195546/

I'm not really equipped to review, but it does make some interesting points that while the body strongly maintains blood PH of between 7.35 and 7.45 the mechanisms of doing this can cause more stress on other systems in the body depending on your diet. It's also interesting that we used to have pre agriculture a 10:1 rather than a 1:3 K:Na balance.

Anyway, the article is an interesting read - maybe supply some counter evidence that Alkaline diets have zero supporting evidence.

[randomstudent]

The K:Na balance is very interesting, especially because pre-agriculture societies usually have very low levels of hypertension, and this is probably the cause. Na+ and K+ balance does have something to do with acid-base regulation, because of urinary excretion of HCO3- and H+, but the benefits of a low sodium diet seem to be related to hypertension and not to acid-base regulation.

I haven't read the study, and I don't want to claim that Alkaline diets have zero supporting evidence. I just wanted to argue against the claim that your pH is "too acidic" or "too alkaline" or whatever. Any potential benefits of an alkaline diet are surely independent of the pH variation they induce, because the variation will be close to 0 in any case, if your body's working properly. The stress hypothesis is interesting (I'm not saying it's even remotely correct! only that it's an interesting twist on the crackpot claims I've heard elsewhere), but you'll never be able to gauge how stressed your regulation mechanisms are just by measuring the blood's pH. You'll have to find some upstream biomarker that measures "stress" directly.

[randomstudent]

My very cursory analysis, after skimming the article follows. First, the article in general is quite misleading. It's written in a language that a layman would understand, but in a way that causes such layman to misunderstand some crucial points. I don't know if this is on purpose, or if the author is just honestly trying to address a complex topic and failing.

- Part 1. Background

> Life on earth depends on appropriate pH levels in and around living organisms and cells.

I take issue with this sentence. This is obviously true, as life must carefully control the concentrations of some substances inside and outside the cell. However, this makes it seem like pH is uniquely special. This is not true: pH is merely a measure of the concentration of hydrogen ions in a solution. If this is meant to address the layman, as it's supposed to, such clarification is important. In fact, I think many of the myths around pH would be better addressed by making the pH concept taboo, and talking instead of "the concentration of H+ ions in solution".

> As a comparison, in the past 100 years with increasing industrialization, the pH of the ocean has dropped from 8.2 to 8.1 because of increasing CO2 deposition.

This is very important for the bisphere as a whole, but useless to understand the impact of pH changes in the body. I don't understand the reason for this section.

> This results in a diet that may induce metabolic acidosis which is mismatched to the genetically determined nutritional requirements

No. This is not true. Such diet may wreck your kidneys due to hypertension, and the kidney damage will give you metabolic acidosis. The diet itself will not give you metabolic acidosis, as long as your lungs and kidneys are fine. This is written in a very misleading way.

> With aging, there is a gradual loss of renal acid-base regulatory function and a resultant increase in diet-induced metabolic acidosis while on the modern diet

Now we're talking. I don' know if this is exactly true, but at least it makes sense.

- Part 2. The Role of pH in Various Cells, Organs, and Membranes

None of the mechanisms described here have anything to do with the systemic blood pH. The author doesn't say it, and he should. This section adds confusion and very little understanding

- 3. Chronic Acidosis and Bone Disease

This section is a little confusing. Many studies, little understanding.

The interesting part is this:

> There is evidence that in healthy humans the increased sodium in the diet can predict the degree of hyperchloremic metabolic acidosis when consuming a net acid producing diet

The study this is taken from has does have some regressions that advance this point, but the correlation is so weak I'm not sure we should take the results at face value.

- 4. Alkaline Diets and Musce

> Conditions such as chronic renal failure that result in chronic metabolic acidosis result in accelerated breakdown in skeletal muscle [40]. Correction of acidosis may preserve muscle mass in conditions where muscle wasting is common such as diabetic ketosis, trauma, sepsis, chronic obstructive lung disease, and renal failure

While you can manipulate the pH f patines with no functioning kidneys by giving them tablets with NaHCO3 (an alkali), you should never, ever extrapolate this to the diet of healthy people. Even in patients with kidney failure, doctors don't try to correct the pH with diet alone.

- 5. Alkaline Supplementation and Growth Hormone

> It has long been known that severe forms of metabolic acidosis in children, such as renal tubular acidosis,

No, no, no... Again, don't extrapolate from serious kidney diseases to healthy subjects.

- 7. Alkalinity and Chemotherapy

Some drugs work better with low pH and some work better with high pH. Again, you won't change the pH with diet, so this is useless to a discussion of Alkaline diet

> It has been suggested that inducing metabolic alkalosis may be useful in enhancing some treatment regimes by using sodium bicarbonate, carbicab, and furosemide

As you can see, even when you cant to induce alkalosis, you sue actual drugs, and not dietary changes (one of these drugs, furosemide, works by manipulation kidney function, it's not merely an alkali concentrate).

The discussion and conclusion say that the evidence is weak for lots of things. The only stroong part is the K/Na ratio. If the Alkali diet does this, then its benefits have nothing to do with blood alkalinization per se.