In order to survive, human life requires a pH value of around 7.4 in the blood serum. In the context of the human diet, the pH levels and the net acid load has undergone many changes from the ‘hunting-gathering’ civilization to the present. Due to the agricultural revolution over the last 10,000 years and the industrial revolution over the last 200 years, the amount of potassium in diet has decreased in comparison to the amount of sodium. Similarly, the amount of chloride has increased, as compared to bicarbonates.

The alkaline diet is based on the premise that eating certain foods leaves behind an alkaline residue, called ash, in the body. Alkaline foods have a positive pH value. Eating a diet highly alkaline is said to have the following benefits:

• Prevents cancer
• Prevents osteoporosis
• Improves digestion
• Keeps allergies at bay
• Prevents fatigue
• Stops obesity

Some alkaline foods are green vegetables, avocado, seeds, legumes, stavia, and blackstrap molasses.

Today, many have diets with insufficient amounts of magnesium, potassium, and fiber in their foods. It is also seen that many foods contain high amounts of saturated fat, sodium, simple sugars, and chloride. This may cause metabolic acidosis that does not match with the body’s genetically determined nutritional requirements. With age, the renal acid-base regulatory function is lost and thus chances of metabolic acidosis are increased.

According to a study in the Journal of Clinical Densitometry, there is no scientific evidence that manipulation of diet in healthy subjects caused any change in blood pH or bicarbonates. The metabolic acidosis concept remains kind of hypothetical. Further, the study concludes that there is not enough evidence to support an association between a high-alkaline diet and bone health.

Gabe Mirkin, a medical practitioner in Maryland, states that dietary modifications cannot change the acidity of the body, with the exception of urine. All foods that leave the stomach are acidic. When there are too many organic acids in the blood, calcium from the bones neutralizes the acids and prevents any change in the pH value.

However, a review article in the Journal of Environmental and Public Health in 2012 states that there is some evidence that chronic low back pain can be relieved by supplementation with alkaline minerals. It also states that correcting metabolic acidosis in children with bicarbonate or potassium citrate enhances growth hormone in a significant manner and improves growth. The article also mentions that there is no scientific literature that proves the benefit of an alkaline diet for the prevention of cancer. Finally, it mentions that supplementing the diet of young people with sodium bicarbonate before strenuous exercise has shown to result in significantly less acidosis of the blood, as compared to those who did not.

Thus, alkaline diets result in a more alkaline urine pH and may lead to lower amounts of calcium in the urine. However, this may not be equivalent to the total calcium balance of the body, due to the presence of other buffers, such as phosphate. Though, such diets may be considered for the reduction of morbidity and mortality of chronic disease in an elderly population.