Sunday, June 23, 2013

The pH Myth?

This is my response to Chris Kresser's blog post, The pH Myth.

Hi Chris, Yes, I agree the body “tightly regulates the pH of our blood” and yes, blood pH will consistently remain close to 7.4 unless a person is critically ill. But this does not mean that people don’t develop chronic low-grade metabolic acidosis and that this condition contributes to poor health. In fact, this catabolic condition is much more common than most realize. I also agree with you that there is no correlation between urine pH, metabolic acidosis, bone mineral density or fracture risk. I don’t think that there are many people out there who disagree with this..at least those who understand the pathophysiology of osteoporosis. But this does not mean that testing urine pH is bogus or that it has no place in the clinical setting. Testing urine pH can be extremely helpful especially for promoting patient compliance to a healthy high fruit and vegetable diet.
All patients are metabolically different and the causes of bone loss are complex—acid-base balance is only one aspect of osteoporosis. I describe osteoporosis as a collision between immunological dysfunction and the body’s energy regulatory mechanisms. This collision is then influenced by hormonal, mechanical, neuronal, and transcriptional regulatory arms of bone remodeling—and all of this is embedded in a pH and temperature sensitive environment.
If you notice, I mention body pH as only one part of the equation. For strong bones, an individual’s immune system must be in balance, their hormones effective, and their nerve flow optimal for osteoclasts and osteoblasts in bone remodeling to remain coupled. Immerse all of these factors in a suboptimal pH (or a system that struggles to maintain this pH) and it just may not function as well. Does this mean that an acidic pH will give a person osteoporosis? No. Does it mean that a diet high in acidic foods will cause bone loss….well, no, not directly. But it does mean that it may have a detrimental effect on the function of the “whole-body” and if a person’s immune system or hormone system or digestive tract is in any way compromised then in all probability pH and his or her dietary choices will create a greater impact on bone health.
I don’t think anyone would disagree that chronic systemic low-grade metabolic acidosis is destructive to bone and to health in general. The problem arises when advocates of the acid-ash hypothesis begin to oversimplify things by suggesting that we choose foods based on acidity or alkalinity and that this will determine the density of our bones. This creates a skewed view of what is healthy to eat and what is not. There are many “acidic” foods that are healthy. In fact certain amino acids from protein with their additional carboxyl groups are helpful for eliminating acids from the body. Adequate protein intake is important not only for building strong muscles but also for building bone matrix and for important blood buffering properties.
Testing first morning urine pH is not meant to determine if a person is alkaline or acidic. It is simply a tool to help monitor a person’s acid/alkaline contribution of food and how their body metabolizes it. If they eat a lot of greens with alkaline salts then urine alkalinity will increase. If they eat lots of meat, cheese, and ice cream, their urine will become more acidic. It isn’t that his or her blood pH is changing but rather by seeing this measurement in living color (pH strips) they are encouraged to eat the things that will provide them with the substrate (minerals, etc.) that their body will need to regulate pH.
I don’t believe that the acid-ash hypothesis is meant to refute the importance of buffering bicarbonate ions and the roll the kidneys and lungs play in regulating body pH. It only states that acid-ash intake is fundamentally important to health and the development of disease. Unfortunately, kidney dysfunction, even when mild, can reduce the body’s ability to eliminate acid. Any decrease in kidney function or any increase in metabolic acidosis for what ever reason (inflammation, stress, etc.) can have far reaching detrimental effects: elevated blood pressure, insulin resistance, and osteoporosis, to mention just a few. Encouraging a diet high in alkalinizing potassium salts, magnesium and sodium (not sodium chloride) from fruits and vegetables (and when necessary adding supplemental potassium salts) will ensure an effective potassium and sodium-rich bone membrane (another important buffering strategy developed by the body for maintaining normal body pH) as well as other numerous beneficial health effects. I explain this in more depth in my book The Whole-Body Approach to Osteoporosis but I hope this adds a bit to the discussion.
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