The alkaline diet may support health by limiting processed foods and promoting more whole foods. However, it doesn’t help fight disease by affecting your body’s pH levels.

The alkaline diet is based on the idea that replacing acid-forming foods with alkaline foods can improve your health.

Proponents of this diet even claim that it can help fight serious diseases like cancer.

This article examines the science behind the alkaline diet.

The alkaline diet, also known as the acid-alkaline or alkaline ash diet, claims that eating certain foods can alter the pH of your body.

Metabolism is like a chemical reaction converting food into energy and leaving behind an “ash” residue known as metabolic waste.

This waste consists of acidic, neutral, or alkaline ash. Proponents of this diet argue that the acidity of the ash affects your body’s acidity.

Alkaline ash is thought to protect you from illness, while acidic ash can make you vulnerable. By choosing more alkaline foods, you may be able to “alkalize” your body and improve your health.

Food components that leave acidic ash include protein, phosphate, and sulfur, while alkaline components include calcium, magnesium, and potassium.

Certain food groups are considered acidic, alkaline, or neutral:

  • Acidic: meat, poultry, fish, dairy, eggs, grains, alcohol
  • Neutral: natural fats, milk, starches, sugars
  • Alkaline: fruits, nuts, legumes, vegetables

According to proponents of the alkaline diet, the metabolic waste — or ash — left from the burning of foods can directly affect the acidity or alkalinity of your body.

PH is a measurement of how acidic or alkaline something is.

The pH value ranges from 0–14:

  • Acidic: 0.0–6.9
  • Neutral: 7.0
  • Alkaline (or basic): 7.1–14.0

Many proponents of the alkaline diet suggest that people monitor the pH of their urine to ensure that it’s alkaline (over 7) and not acidic (below 7).

However, it’s important to note that pH varies greatly within your body. While some parts are acidic, others are alkaline — there’s no set level.

Your stomach is loaded with hydrochloric acid, giving it a pH of about 1.5–2.0, which is highly acidic. This acidity is necessary to break down food.

On the other hand, human blood is always slightly alkaline, with a pH of 7.35–7.45. When your blood pH falls out of the normal range, it can be fatal if left untreated.

However, this only happens during certain disease states, such as ketoacidosis caused by diabetes, starvation, or alcohol intake.


The pH value measures a substance’s acidity or alkalinity. For example, stomach acid is highly acidic, while blood is slightly alkaline.

The pH of your blood needs to remain constant for you to stay healthy, and your body has several effective ways to regulate it.

Food won’t usually cause a major change in the pH of your blood. However, food can change the pH value of your urine — though the effect is somewhat variable.

Excreting acids in your urine is one of the main ways your body regulates its blood pH.

For example, if you eat a large steak, your urine will become more acidic afterward as your body gets rid of the metabolic waste.

Therefore, urine pH is a poor indicator of overall body pH and general health. It can also be influenced by factors other than your diet.


Your body tightly regulates blood pH levels. In healthy people, diet doesn’t significantly affect blood pH, but it can change urine pH.

Osteoporosis is a progressive bone disease characterized by a decrease in bone mineral content. It’s particularly common among postmenopausal women and can drastically increase your chance of fractures.

The alkaline diet theory claims that to maintain a constant blood pH, your body takes alkaline minerals from bones to buffer acids from acid-forming foods. This is called the “acid-ash hypothesis of osteoporosis,” and implies that acid-forming foods can cause bone mineral density loss.

However, this theory ignores the function of your kidneys and your lungs. The blood can contain different acids, which are either “metabolic” (fixed) or “respiratory” (volatile).

Fixed acids are excreted in the urine, whereas volatile acids are excreted by the lungs. One volatile acid is carbonic acid, which is formed by the lungs as part of your breathing process. This increases the acidity of your blood.

The kidneys, meanwhile, are reabsorbing bicarbonate, which comes from the carbonic acid in the blood. This entire process resists change to the pH to allow you to stay in the necessary pH range for life.

The acid-ash hypothesis also overlooks the role of collagen loss in osteoporosis. Ironically, low levels of orthosilicic acid and vitamin C in your diet are strongly linked to such collagen loss.

Keep in mind that recent scientific evidence suggests no link between dietary acid and bone health. In fact, a high protein, acid-forming diet may be linked to better bone health due to increased calcium retention and activation of IGF-1 hormone.


Research does not support the theory that acid-forming diets harm your bones. Protein, an acidic nutrient, even seems to be beneficial.

In the past, comprehensive reviews on the relationship between diet-induced acidosis — or increased blood acidity caused by diet — and cancer concluded that there is no direct link.

Newer research suggests that there might be a link between the acid in food and cancer.

However, this research does not reflect blood acidity. It is also unclear if dietary acid load definitively causes cancer. In fact, experiments have also successfully grown cancer cells in an alkaline environment.

And while tumors grow faster in acidic environments, the tumors create this acidity themselves. It’s not the acidic environment that creates cancer cells, but cancer cells that create the acidic environment.


There’s no link between an acid-forming diet and cancer. Cancer cells also grow in alkaline environments.

Examining the acid-alkaline theory from both an evolutionary and scientific perspective reveals discrepancies.

One study estimated that 87% of pre-agricultural humans ate alkaline diets which formed the central argument behind the modern alkaline diet.

Keep in mind that our remote ancestors lived in vastly different climates with access to diverse foods. In fact, acid-forming diets were more common as people moved further north of the equator, away from the tropics.


Current studies suggest that about half of ancestral diets were acid-forming, especially among people who lived far from the equator.

What are the top 10 alkaline foods?

The primary alkaline food categories are vegetables, fruit, nuts, and legumes. 10 examples include:

  • beets
  • broccoli
  • mushrooms
  • peas
  • tomato
  • apple
  • cherries
  • pineapple
  • almonds
  • pumpkin seeds

What is the fastest way to Alkalize your body?

There’s no fast way to alkalize your body, nor is there conclusive evidence that this is necessary. Your body’s pH levels are tightly controlled, and food doesn’t affect blood pH very much. It may have some impact on urine pH.

The alkaline diet is healthy due to its focus on whole and unprocessed foods. However, claims that it boosts health by altering pH levels are not supported by reliable studies.

A low protein version may benefit those with chronic kidney disease, but no evidence suggests it has an effect on pH levels.