Bodily pH and general homeostasis
The pH in our body can vary considerably from one area to another with the highest acidity in the stomach (pH 1.35-3.5) to aid in digestion and protect against opportunistic microbial organisms. The skin is acidic enough (pH 4-6.5) to provide an acid coat as a protective barrier for the environment against microbial proliferation. There is a gradient from the external stratum corneum (pH 4) to the basal layer (pH 6.9). This is also seen in the vagina where a pH of less than 4.7 protects against microbial growth. The urine can have a pH varying from acid to alkaline depending on the need to balance the internal environment. Most of the normal urinary pH values are between 5.5-6.5; higher acid values come from urinary infections, either from bacteria or fungi.
When the pH and the net acid load in the human diet arrive, there has been a considerable change from the status of hunter to the present civilization. With the agricultural revolution (last 10,000 years) and even more recently with industrialization (last 200 years), there has been a decrease in potassium (K) compared to sodium (Na) and an increase in chloride compared to bicarbonate present in the diet. The relationship between potassium and sodium was reversed, K / Na was previously 10 to 1 while the modern diet has a ratio of 1 to 3. Compared to the pre-agricultural period, it is clear that agriculture today has a poor diet magnesium, potassium as well as fiber and rich in saturated fats, simple sugars and cooking salt. This results in a diet that can induce metabolic acidosis, which does not correspond to genetically determined nutritional requirements. However, this would turn into a manifestation of health problems or manifest illness.
pH, bone structure and brain functions
Calcium in the form of phosphates and carbonates represents a large reservoir of base in our body. In response to an acidic load such as the modern diet, these salts are released into the systemic circulation to determine pH homeostasis. It has been found that bicarbonate, which increases the alkalinity of a diet’s content, but not potassium can attenuate bone loss in healthy older adults. Bone minerals that are wasted in the urine may not have complete compensation through intestinal absorption, which is believed to lead to osteoporosis. There is online information that promotes an alkaline bone health diet and several searchable books. However, a recent systematic review of the literature, looking for evidence to support the alkaline diet for bone health, did not find any protective role of the food acid load in osteoporosis.
Another element of the modern diet is sodium excess in the diet. It is shown that in healthy humans the increase in sodium in the diet can predict the degree of hyperchloremic metabolic acidosis when an acidic diet is consumed. Furthermore, there is evidence that there are adverse effects of sodium chloride in the elderly population. A sodium-rich diet will aggravate the disordered induced bone and muscle loss during immobilization, increasing bone resorption and protein decay. Excess food proteins with high acidic renal load may reduce bone density if they are not buffered by ingesting supplements or alkali-rich foods. However, adequate proteins are necessary for the prevention of osteoporosis and sarcopenia; therefore, increasing the amount of fruit and vegetables may be necessary rather than reducing protein. A clear example is chronic renal failure, in which chronic metabolic acidosis results in an accelerated loss of skeletal muscle.
Acidosis correction can preserve muscle mass in conditions where muscle loss is common, such as diabetic ketosis, trauma, sepsis, chronic obstructive pulmonary disease and renal failure. It has long been known that severe forms of metabolic acidosis in children, such as renal tubular acidosis (congenital), are associated with low levels of growth hormone (GH) resulting in short stature. Correction of acidosis with bicarbonate or potassium citrate, significantly increases GH and improves growth. The use of enough potassium bicarbonate in the diet, to neutralize the daily acid load in post-menopausal women, resulted in a significant increase in the growth hormone and the resulting osteocalcin. Improving GH levels can improve quality of life, reduce cardiovascular risk factors, improve body composition and even improve cognition and memory, as recently reported (see here “Memory news: an unsuspected hormone, a hidden mediator “).
The components of the body are all connected: just a small factor such as the pH is enough for a grown man to become small.
- edited by Dr. Gianfrancesco Cormaci, PhD, specialist in Clinical Biochemistry.
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