The alkaline diet is a popular diet based on the theory that certain foods affect your body’s pH levels or acid-base balance.

Proponents of the diet claim it can rid the body of various diseases, including cancer.

However, you may wonder whether there are any merits to these claims.

This article explains the theory behind the alkaline diet and whether you should try it.

The theory behind the alkaline diet

The alkaline diet is centered around the idea that eating a diet high in acid-forming foods disrupts your body’s natural pH level.

The pH value is a measure of how acidic or alkaline something is.

The pH scale runs from 0 to 14, with 0 representing the most acidic, 14 representing the most alkaline, and 7 representing neutral.

The pH of your blood is slightly alkaline, tightly controlled between 7.35 and 7.45 (1).

However, the body’s pH varies considerably from one organ to the next.

The stomach contains hydrochloric acid, giving it an acidic pH of 1.35 to 3.5. This helps aid digestion and protect the body from microorganisms that may cause infection.

And the skin has a slightly acidic pH between 4 and 6.5 to protect against infection from bacteria, viruses, and other infectious agents.

On the other hand, the inner surface of the stomach is more alkaline to protect its lining from hydrochloric acid.

Still, proponents of the alkaline diet like Dr. Sebi claim the body is optimally healthy when it is in an alkaline state and that you can rid the body of disease by avoiding acid-forming foods and emphasizing more alkaline-based foods.

Fruits, vegetables, and low-phosphorus beverages — including wine and mineral soda waters — are base- or alkaline-forming. Whereas grains, meats, dairy, and phosphorus-containing beverages — including diet and regular soda — are acid-forming.

However, the body regulates blood pH independent of diet.

Food indeed can change the pH value of urine — and why proponents of the diet suggest that followers of the diet monitor the pH of their urine using testing strips to ensure it’s alkaline (2).

But urine tends to vary in pH from acidic to alkaline throughout the day. Therefore, urine pH is a poor indicator of body pH and overall health.

Alkaline diet claims

Proponents of the alkaline diet claim it can treat cancer, osteoporosis, and kidney disease.

Cancer

The most commonly cited — and unfortunately the most dangerous — claim about the alkaline diet is that it can cure cancer.

Proponents of the diet claim that because cancer grows in an acidic environment, an alkaline diet can prevent the growth of cancer cells and even eliminate existing cells.

But this idea is flawed for several reasons.

First and foremost, food cannot influence the pH of the blood (1).

The pH of the blood is tightly controlled between 7.35 and 7.45 — anything outside of this narrow range is potentially life-threatening.

Secondly, cancer can survive and grow in an alkaline environment.

The normal pH of the blood is 7.4, which is slightly alkaline, and in many studies, cancer cells are grown in an alkaline environment, similar to that of human blood (3).

Indeed, cancer cells grow better in an acidic environment, but once cancer develops, it creates an acidic environment through the upregulation of metabolic processes and decreased circulation (4).

Therefore, it’s not the acidic environment that causes cancer, but cancer that causes the acidic environment.

Cancer is a grim diagnosis and people with the condition are easily manipulated to try anything that may serve as a cure, especially if previous treatments haven’t been effective.

Unfortunately, people have capitalized on this vulnerability and have recommended the diet in replace of traditional cancer treatments for financial gain.

For example, Robert O. Young, the father of the alkaline diet, advised a young woman who was dying from breast cancer to pay him more than $77,000 for his alkaline treatment, which consisted of baking soda infusions.

After about three months of these treatments, the woman’s condition worsened and she later died.

This is just one story of dozens where people — usually with no medical background or formal training, such as Dr. Sebi — have prescribed or recommended the diet as a cancer treatment for financial gain.

Osteoporosis

When food is digested and absorbed, it presents itself to the kidneys as either acid-forming or base-forming.

Food components that are acid-forming include sulfate, chloride, phosphate, and organic acids. Base-forming food components include sodium, potassium, calcium, and magnesium.

The hypothesis is that a diet high in acid-forming foods causes the body to release calcium — an alkaline mineral — from the bones to help neutralize the excess acid.

Most of the calcium is then lost through the urine. This is then thought to lead to weaker bones and increase one’s risk for osteoporosis.

But urinary calcium losses are not a direct measure of osteoporosis or bone health, for that matter (5).

Instead, many regulatory factors help compensate for any loss of urinary calcium.

For example, a high-protein diet — which is acid-forming — increases urinary calcium losses, but protein-rich foods are also high in phosphates, which decrease the loss of calcium from the urine, increasing its retention by your body (6).

Therefore, any potential urinary calcium losses are negated by the phosphates in protein-rich foods.

To this point, a high-protein diet is actually associated with improved bone health, not worse (7).

Chronic kidney disease

The kidneys play a key role in maintaining your body’s acid-base balance by adjusting the amounts of acid and alkaline substances that are reabsorbed and secreted from the urine (8).

This process is impaired in people with unhealthy kidneys — such as those with chronic kidney disease.

Consequently, the kidneys cannot efficiently remove acid from the body, causing a condition known as metabolic acidosis.

Metabolic acidosis occurs when the blood pH becomes acidic. It can cause various health problems and increase the progression of chronic kidney disease.

As such, it has been suggested that the alkaline diet may prevent or slow the progression of kidney disease by reducing the acid load on the kidneys.

Indeed, exchanging acid-forming animal-based proteins for plant-based proteins like beans and peas may reduce acid production and be beneficial for those with chronic kidney disease.

However, current guidelines state there is insufficient evidence to recommend alkalizing plant proteins over their acid-forming animal-based counterparts for slowing kidney function decline (9).

Even if the opposite were true, people with chronic kidney disease may need to limit foods that the alkaline diet emphasizes like fruits and vegetables to prevent high potassium levels.

Should you try it?

It’s important to understand what the alkaline diet can and can’t do for you.

There is no evidence to support the alkaline diet for treating or preventing cancer, osteoporosis, or chronic kidney disease.

However, the diet is rich in fruits and vegetables, which people don’t consume enough of.

Diets rich in fruits and vegetables have been linked with a lower risk of developing heart disease, diabetes, and certain types of cancer, including colorectal and breast cancer (10).

The benefits of increasing your intake of fruits and vegetables aren’t related to their alkalizing properties but due to their high concentrations of fiber and polyphenols, which are plant-based compounds that have potent antioxidant, anti-inflammatory, and anti-cancer effects.

Beyond the diet’s emphasis on fruits and vegetables, there are no evidence-based health benefits of the alkaline diet.

Because the diet restricts animal-based proteins, the alkaline diet likely lacks several key nutrients such as vitamin B12, calcium, iron, and zinc.

Animal-based proteins, especially meats and seafood, are also rich in nutrients like creatine, carnitine, and omega-3 fatty acids, which offer a range of health benefits related to muscle, heart, and brain function.

In either case, the alkaline diet continues to be popular among those looking to achieve better health, despite its lack of evidence.

The bottom line

The alkaline diet is based on the idea that specific foods affect the body’s pH. It claims to cure and prevent a variety of health alignments, such as cancer, osteoporosis, and chronic kidney disease.

These claims, however, are not supported by research and make assumptions that go against what has long been known about how the body works.

If you wish to try the alkaline diet, understand that it cannot treat the conditions for which it’s claimed to and it likely lacks key vitamins, minerals, and other nutrients.


Gavin Van De Walle, MS, RD, LN
Gavin Van De Walle, MS, RD, LN

Gavin Van De Walle holds a master's degree in human nutrition and bioenergetics. He is a registered dietitian who aims to arm the public with evidence-based nutrition recommendations so they can make their own educated and informed health decisions.