Diet, pH

Related Terms

Acid-alkaline diet, acid-base disorder, acid-base hypothesis, acid-forming, acid waste, alkali therapy, alkaline, alkaline diet, alkaline water, anion gap, anion gap acidosis, anions, basic, diet, hydrogen, pH balance, pH level, pH range.
Not included in this review: Metabolic acidosis.

Background

The pH diet is based on the idea that a person should consume foods that are slightly alkaline, because the body's normal pH is slightly alkaline. Advocates claim that consuming a diet high in acidic foods, such as animal protein, sugar, caffeine, and processed foods, may disrupt the pH of the bloodstream, and increase a person's likelihood of developing chronic or degenerative diseases.
Salads, fresh vegetables, healthy nuts and oils are recommended while fatty meats, cheeses, sweets, chocolates, alcohol and tobacco are not recommended. Foods that are acidic include sugar, caffeine, wheat, saturated fats, processed foods, carbonated beverages, peanuts, pasta and white rice.
The normal pH range of the bloodstream is between 7.36 and 7.44. However, the food ratio for the diet is roughly 75 - 70% alkaline foods and 20 - 25% acidic foods.
Advocates believe that the pH level of the body's internal fluids affects every living cell in the body. They believe that, as a result, over-acidification of the body from over consumption of certain foods may lead to chronic disease, such as cancer, heart disease, obesity, weight problems, allergies, fatigue and premature aging as well as problems with the nervous system, cardiovascular system and muscles. Other physical problems that are thought to result from over acidity include lack of energy, conjunctivitis, sensitive gums, agitation, dental caries, diarrhea, colitis, dry skin, itches, red and irritated skin, leg cramps, osteoporosis, rheumatism, arthritis, sciatica, and tendonitis.
According to pH diet theory, when an alkaline environment is maintained in the body, metabolic, enzymatic, immunologic, and repair mechanisms function at their best. The acid forming metabolic of stress and inflammation and of high fat and high protein foods can be adequately and effectively neutralized only when sufficient mineral-buffering reserves are present, which can be found in a diet that is predominantly alkaline-forming.
The pH diet is used by athletes in the hopes of improving recovery time after competitions.

Theory / Evidence

pH is the measure of the activity and potency of hydrogen ions in a substance. The scale used to measure pH is broken down into two categories: acid and alkaline (basic). pH is the symbol for the logarithm of the reciprocal of the hydrogen ion concentration. A solution with a pH of 7.0 is neutral, over 7.0 is alkaline, and under 7.0 is acidic.
The pH diet or alkaline diet focuses on maintaining an alkaline environment in the body. In a normal state, the human body is slightly alkaline in all areas with the exception of the digestive tract and the urinary tract. When the body is fighting an illness or under stress, the body usually takes on more acidic properties.
Body balance, in terms of acid-alkaline state, is a pH of 7.450 for blood in the arteries, and 7.350 for blood in the veins. Acid-alkaline equivalence is a pH of 7.000. Thus, a healthy body means a pH that is slightly alkaline. This means there are more buffering mineral receptors for electrons than acid-forming electron donors.
Proponents of the pH diet have noted that in some extreme cases, the build up of acidic elements is so great that it may destroy neighboring healthy cells. It is believed that healthy cells must maintain a slightly alkaline pH level. Some cells change their makeup in order to survive in an acidic environment; however, if these cells are successful at surviving in the immediate future, they may become cancerous in the long term. Some individuals believe that cancer cells are acidic while healthy cells are alkaline. Therefore, if the cancerous tumors are completely removed by surgery, the chances that a new tumor will reappear in the same area increase if a person continues to eat an acidic diet.
One purported way to test the body's pH is to use pH strips and test the urine. This will allow for the monitoring of pH changes. The ideal pH of this diet is around 7.4 or 7.5.
Although there has been extensive laboratory research investigating cellular changes in response to pH changes, there have been no available clinical trials to determine if the pH diet or alkaline diet is effective in treating any health related conditions. People that have tried the diet claim that it works but the true effects of the diet are still under investigation.
Several human trials have investigated the relationship between alkaline diets, protein and bone disorders, however, none of the trials have drawn any definitive conclusions. For instance, one cohort study investigated the basic effects (derived from magnesium, potassium, fruit, vegetables) and acid effects (protein) on bone mineral density in an elderly population. Magnesium, potassium, fruit, vegetable, and protein intakes were significantly associated with bone mineral density at baseline and among men, with less bone loss over four years. But, the role of protein appears to be complex and the authors did not reach any definitive conclusions regarding acid-alkaline diets.
In another study using elderly women, bone mineral density was not significantly associated with the ratio of animal to vegetable protein intake. Women with a high ratio had a higher rate of bone loss at the femoral neck than did those with a low ratio (p=0.02) and a greater risk of hip fracture (relative risk = 3.7, p=0.04). These associations were unaffected by adjustment for age, weight, estrogen use, tobacco use, exercise, total calcium intake, and total protein intake. This suggests that an increase in vegetable protein intake and a decrease in animal protein intake may decrease bone loss and the risk of hip fracture. Conformation is necessary by other prospective studies and randomized trials.

Author information

This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

Bibliography

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Diet

In general, people who follow the pH diet consume 75-80% alkaline foods and 20-25% acidic foods. Many of the foods eaten in this diet are raw fruits and vegetables, because they are generally alkaline in the body. Further, these foods hold many vitamins and minerals, as well as phytochemicals.
Individuals who choose to follow the pH diet are generally recommended to consume eight ounces of water every two hours.
Acidic foods do not have to be totally avoided during the pH diet. However, their consumption needs to be moderated to about 20% of daily food intake. These acidic foods include dairy, white flour, poultry, beef, coffee and eggs. Anything high in proteins may create an acidic state in the body.
The general idea behind the pH diet is to eat 75-80% alkaline foods and 20-25% acidic foods. The majority of the diet consists of raw fruits and vegetables because they are alkaline in nature. Also emphasized is the consumption of large amounts of water in an attempt to keep the body hydrated.
Advocates of the diet recommend soaking mildly acidic foods, such as whole grains and legumes, before cooking them. Chewing the complex carbohydrates, such as grains, vegetables, and legumes, mixes them with saliva, which is a very alkaline fluid. This begins the digestive process. Drinking while eating is thought to stop the digestive process from beginning in the mouth, because saliva does not come into as much contact with the foods.