Alkaline diet
Encyclopedia
The Alkaline diet is a diet based on the scientifically unsupported theory that certain foods, when consumed, leave an alkaline residue, or ash
. Minerals containing elements like calcium
, iron
, magnesium
, zinc
, copper
, are said to be the principal components of the ash. A food is thus classified as alkaline, acid or neutral according to the pH
of the solution created with its ash in water. Proponents suggest adhering to an alkaline diet might prevent cancer
, fatigue, obesity
, allergies, as well as increase bone health.
One of the most famous proponents of the alkaline diet is Robert Young, who has come under scrutiny from the National Council Against Health Fraud. Others who have promulgated alkaline-acid diets include Edgar Cayce
, D. C. Jarvis
, and Herman Aihara. A similar theory, called the Hay diet, was developed by the American physician William Howard Hay
in the 1920s. A later theory, called nutripathy, was developed by another American, Gary A. Martin, in the 1970s.
and other low-sugar fruits, vegetables, tubers, nuts
, and legumes and avoiding grains
, dairy
, meat
, sugar
, alcohol
, caffeine
and fungi. Such a diet is alleged to help to maintain the balance of the slight alkalinity of blood without stressing the body's regulators of acid-base homeostasis
.
to either elicit a sustained change in blood pH levels, or provide the clinical benefits as alleged by its proponents. In addition, the mechanisms by which an alkaline diet would produce the alleged benefits are vague, unknown, or nonfactual. As a result, it is not widely accepted by the mainstream medical or scientific community, and is often thought of as a pseudo-science. It is listed on the medical watchdog site Quackwatch
.
Opponents of the alkaline diet usually point out that the pH of the human bloodstream is tightly regulated by homeostatic mechanisms between 7.35 and 7.45, and that a blood pH above 7.45 (more alkaline) results in a harmful condition known as alkalosis
, often causing hypokalemia
and hypocalcemia. In addition, most of the studies which are alleged to show benefits produced by an alkaline diet are in fact reporting a neutralisation the effects of acidosis
(a medical condition where blood pH falls below 7.35), or theorising based on a holistic approach to human health, or interpreting in vitro
results with little or no relevance to the human body in vivo
.
Meta-analyses
of studies that have looked at the effect of the alkaline diet on bone
health have found no indication that it has any use in preventing osteoporosis
, nor evidence that it produces any beneficial effects on bone health whatsoever.
Ash (analytical chemistry)
In analytical chemistry, ashing is the process of mineralization for preconcentration of trace substances prior to chemical analysis. Ash is the name given to all non-aqueous residue that remains after a sample is burned, and consist mostly of metal oxides....
. Minerals containing elements like calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
, iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
, magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...
, zinc
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
, copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
, are said to be the principal components of the ash. A food is thus classified as alkaline, acid or neutral according to the pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
of the solution created with its ash in water. Proponents suggest adhering to an alkaline diet might prevent cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
, fatigue, obesity
Obesity
Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have an adverse effect on health, leading to reduced life expectancy and/or increased health problems...
, allergies, as well as increase bone health.
One of the most famous proponents of the alkaline diet is Robert Young, who has come under scrutiny from the National Council Against Health Fraud. Others who have promulgated alkaline-acid diets include Edgar Cayce
Edgar Cayce
Edgar Cayce was an American psychic who allegedly had the ability to give answers to questions on subjects such as healing or Atlantis while in a hypnotic trance...
, D. C. Jarvis
D. C. Jarvis
DeForest Clinton Jarvis was an American physician from Vermont. He is best known for his writings on the subject of folk medicine. He recommended a mixture of whole apple cider vinegar and honey that have variously been called switchel or honegar, as a health tonic...
, and Herman Aihara. A similar theory, called the Hay diet, was developed by the American physician William Howard Hay
William Howard Hay
William Howard Hay, MD was a New York doctor, author, lecturer, and founder of The East Aurora Sun and Diet Sanatorium.A traditional physician for the first 16 years of his career, this New York doctor introduced the world to food combining, ran a successful sanatorium for many years , and was a...
in the 1920s. A later theory, called nutripathy, was developed by another American, Gary A. Martin, in the 1970s.
Foods
In general, the alkaline diet involves eating certain fresh citrusCitrus
Citrus is a common term and genus of flowering plants in the rue family, Rutaceae. Citrus is believed to have originated in the part of Southeast Asia bordered by Northeastern India, Myanmar and the Yunnan province of China...
and other low-sugar fruits, vegetables, tubers, nuts
Nut (fruit)
A nut is a hard-shelled fruit of some plants having an indehiscent seed. While a wide variety of dried seeds and fruits are called nuts in English, only a certain number of them are considered by biologists to be true nuts...
, and legumes and avoiding grains
Food grain
thumb|150px|Barleythumb|150px|LentilGrains are small, hard, dry seeds harvested for human food or animal feed Agronomists also call the plants producing such seeds grains or grain crops....
, dairy
Dairy
A dairy is a business enterprise established for the harvesting of animal milk—mostly from cows or goats, but also from buffalo, sheep, horses or camels —for human consumption. A dairy is typically located on a dedicated dairy farm or section of a multi-purpose farm that is concerned...
, meat
Meat
Meat is animal flesh that is used as food. Most often, this means the skeletal muscle and associated fat and other tissues, but it may also describe other edible tissues such as organs and offal...
, sugar
Sugar
Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...
, alcohol
Alcohol
In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....
, caffeine
Caffeine
Caffeine is a bitter, white crystalline xanthine alkaloid that acts as a stimulant drug. Caffeine is found in varying quantities in the seeds, leaves, and fruit of some plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding on the plants...
and fungi. Such a diet is alleged to help to maintain the balance of the slight alkalinity of blood without stressing the body's regulators of acid-base homeostasis
Acid-base homeostasis
Acid–base homeostasis is the part of human homeostasis concerning the proper balance between acids and bases, in other words, the pH. The body is very sensitive to its pH level, so strong mechanisms exist to maintain it...
.
Criticism
Under normal circumstances, a selectively alkaline diet has not been shown in vivoIn vivo
In vivo is experimentation using a whole, living organism as opposed to a partial or dead organism, or an in vitro controlled environment. Animal testing and clinical trials are two forms of in vivo research...
to either elicit a sustained change in blood pH levels, or provide the clinical benefits as alleged by its proponents. In addition, the mechanisms by which an alkaline diet would produce the alleged benefits are vague, unknown, or nonfactual. As a result, it is not widely accepted by the mainstream medical or scientific community, and is often thought of as a pseudo-science. It is listed on the medical watchdog site Quackwatch
Quackwatch
Quackwatch is an American non-profit organization founded by Stephen Barrett with the stated aim being to "combat health-related frauds, myths, fads, fallacies, and misconduct" and with a primary focus on providing "quackery-related information that is difficult or impossible to get elsewhere."...
.
Opponents of the alkaline diet usually point out that the pH of the human bloodstream is tightly regulated by homeostatic mechanisms between 7.35 and 7.45, and that a blood pH above 7.45 (more alkaline) results in a harmful condition known as alkalosis
Alkalosis
Alkalosis refers to a condition reducing hydrogen ion concentration of arterial blood plasma . Generally, alkalosis is said to occur when pH of the blood exceeds 7.45. The opposite condition is acidosis .-Causes:...
, often causing hypokalemia
Hypokalemia
Hypokalemia or hypokalaemia , also hypopotassemia or hypopotassaemia , refers to the condition in which the concentration of potassium in the blood is low...
and hypocalcemia. In addition, most of the studies which are alleged to show benefits produced by an alkaline diet are in fact reporting a neutralisation the effects of acidosis
Acidosis
Acidosis is an increased acidity in the blood and other body tissue . If not further qualified, it usually refers to acidity of the blood plasma....
(a medical condition where blood pH falls below 7.35), or theorising based on a holistic approach to human health, or interpreting in vitro
In vitro
In vitro refers to studies in experimental biology that are conducted using components of an organism that have been isolated from their usual biological context in order to permit a more detailed or more convenient analysis than can be done with whole organisms. Colloquially, these experiments...
results with little or no relevance to the human body in vivo
In vivo
In vivo is experimentation using a whole, living organism as opposed to a partial or dead organism, or an in vitro controlled environment. Animal testing and clinical trials are two forms of in vivo research...
.
Meta-analyses
Meta-analysis
In statistics, a meta-analysis combines the results of several studies that address a set of related research hypotheses. In its simplest form, this is normally by identification of a common measure of effect size, for which a weighted average might be the output of a meta-analyses. Here the...
of studies that have looked at the effect of the alkaline diet on bone
Bone
Bones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue...
health have found no indication that it has any use in preventing osteoporosis
Osteoporosis
Osteoporosis is a disease of bones that leads to an increased risk of fracture. In osteoporosis the bone mineral density is reduced, bone microarchitecture is deteriorating, and the amount and variety of proteins in bone is altered...
, nor evidence that it produces any beneficial effects on bone health whatsoever.