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I have read that eating more alkaline foods and changing your pH balance reduces stress and anxiety.

For example, see Eat a Lemon, Feel Less Stressed:

Stephanie McClellan, MD, and Beth Hamilton, MD, the authors of So Stressed, The Ultimate Stress-Relief Plan for Women, say that when the body is stressed on a cellular level it becomes acidic. So to counter that and even out your pH levels -- which makes your body better able to absorb nutrients and expel toxins -- you'll need to eat alkaline foods and avoid acidic ones.

Is there any research to support this?

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I just took a quick look at the link you provided, and it is one of those "half-smart" claims that begins with misinterpretation of known phenomena and a few correct facts but quickly diverges into pseudoscience and bizzarre inaccuracies by taking unfounded leaps of faulty logic which may still sound correct to an average reader without an in-depth knowledge of acid-base regulation in the human body.

The first thing I noticed was that this claim is a watered-down version of the same woo that hawked ionized water, the pH Miracle Living, the acid/alkaline theory of disease, the Hay diet, and a host of other already debunked alkaline diets, including a similar one that was touted by Edgar Cayce.

I began chewing a lemon (which has an acidic pH of about 3) as I read the article and researched the book a little, however I find myself no less annoyed by the same old woo under a new name. Again.

But here goes...

The first major way to shoot down this claim down is that "body pH" is not a term. Different systems in the body have different pH ranges which are considered normal.

  • Cerebrospinal fluid as a range of 7-7.2
  • Bile has a range of 7-7.7
  • Urine has a range of 4.5-8
  • The eye has a range of 7-7.3
  • Stomach acid has a range of 1-3
  • Blood has a range of 7.35-7.45

These values are not set in stone, the pH of body systems are always fluctuating in relationship to one another to keep the balance.

The second is the bizzarre statement they make that the lemon is alkaline. They seem to justify this assertion by claiming that when eaten, the body will make it alkaline through digestion. This is true. However, this is a normal part of the digestive process for anything, whether it be lemon or beer-battered unicorn. Once in the instestines, a lemon will not be more or less alkaline than anything else.

If anyone's still interested...

Acid-base balance in the human body is an extremely complex system. This is mainly because it is affected by just about everything you do. However it is well-studied and well-understood.

The pH scale is a measure of hydrogen(H+) and hydroxide ions(OH-). It is a logarithmic scale ranging from about 0 to 14.

The pH of human blood generally ranges from 7.35-7.45 and deviation from this range will result in either acidosis or alkalosis, depending on which way you go (it's a complex topic, don't split hairs with my generalizing please). These are serious medical conditions which can result in death if uncorrected. Because of that fact, the body's balance is maintained by a complex and extremely effective system of chemical and physiological mediators which protect from any rapid change in pH.

The greatest way to change the pH of the blood in a healthy person for a short time is via the respiratory system. This is because in the venous blood CO2 comes into contact with carbonic anhydrase which converts it to carbonic acid for the lungs to exhale. In fact the lungs expell about 30L a day. This is why hyperventilation can make one feel giddy and dizzy, and deep breathing can have a variety of effects. However these changes are limited, short-lived and cannot be linked to what this article is claiming. Eating a lemon, or even a truck full of them won't even come close to matching this simple, well-understood physiological respone. This is because of the way the digestive system works.

IF YOU WANT TO EXPERIENCE WHAT HAPPENS WHEN YOU CHANGE YOUR BLOOD PH, HOLD YOUR BREATH.

The stomach of a healthy person contains mucous, hydrochloric acid and pepsinogen. It has a pH of about 1-3. Gastric acid is secreted for digestion and its pH drops as a result of this. After a heavy meal, the blood pH will increase proportionally to this, particularly in parts of the circulatory system supplying the digestive system, this is sometimes called the alkaline tide. The change is determined by the amout of food eaten and amount of acid produced, not the acidity of the food eaten. But again, this is well known and understood physiological response and is not the claim made by the article.

However, this is not the end. The food is acidified in the stomach, and it becomes a material called chyme with a pH of about 2.0 regardless of what was in it.This chyme is then alkalinized when the duodenum secretes hormones which cause the gall baldder to release bile. It also stimulates release of enzymes from the pancreas which raise the pH of the chyme to about 7 so it can be absorbed by the intestines.

There have been other claims that when the body takes in to much protein in a meal, the amino acids become organic acids and acidify the blood. Calcium released from the bones neutralizes this process, which has been theorized to lead to osteoporosis. But again, the body steals calcium from the bones all the time for a variety of reasons, and this is not the claim made.

Regardless of where your lunch lies on the pH scale, it is rendered meaningless by these processes, and the only thing it may change the pH of is your urine. This is completely irrelevant, because if your urine is coming into contact with your bloodstream you have serious problems unrelated to your diet.

To quote Homer Simpson "Blue M&M, red M&M, they all wind up the same color in the end".

  • +1 for being willing to read through my insanely long ramble about homeostatic regulatory mechanisms. Thankfully, I stopped myself before I got into the Krebs cycle and started boring people to death... – Monkey Tuesday Mar 29 '11 at 1:59
  • nice reply to all the nonsense – user1719 Apr 8 '11 at 19:57
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    Some say unicorns don't exist. They used to, until someone invented beer batter. – horatio Apr 8 '11 at 21:12
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    "if your urine is coming into contact with your bloodstream you have serious problems unrelated to your diet" - ayup – Russell Steen Jun 17 '11 at 14:28

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