The Alkaline Diet: Evidence and Myth Review


The alkaline diet, also known as the alkaline ash diet, gained its popularity due to the promotion by celebrities that follow it. It advocates removing all acidic foods and replacing them with alkaline food to help improve one’s health and fight various chronic diseases such as cancer. Proponents of this diet reason that some foods such as processed foods, wheat, meat, and refined sugar produce acidity in the body, which causes health problems. Therefore, they conclude that eating alkaline foods can protect your body against the inversion of these diseases.

What is an alkaline diet?

The alkaline diet is based on the unproven hypothesis that following a diet rich in fruits and vegetables with limited protein can promote alkalinity in the body and help you change the body’s pH. The theory also advocates for drinking certain alkaline beverages to reduce the body’s acid levels and reduce weight. The pH scale ranges from 0-14, with seven as neutral, meaning that below seven are regarded as acidic and above seven is alkaline. The alkaline diet school of thought ascertains that consuming alkaline foods will result in alkaline metabolic ash or waste left in the body after digestion. The reason that this waste can affect the body’s acidic or alkaline depending on the food you ate. The acidic ash contributes to illness, while alkaline ash protects against health problems.

Food elements contributing to acidic ash include phosphate, protein, and sulfur, whereas alkaline elements include potassium, calcium, and magnesium. Below is a category of food groups classified as acidic, alkaline, and neutral

Acidic foods include meat, fish, eggs, poultry, alcohol, and grains

Neutral foods are starches, natural fats, and natural sugars

Alkaline foods- legumes, fruits, vegetables, and nuts.

Understanding the pH levels in your body

The pH measures how acidic or basic something from a range of 0-14, with figures above seven indicating alkalinity and below seven is acidic. Proponents of an alkaline diet monitor their Urine pH to know whether their body is alkaline or not. However, such a direct measurement is not true since various parts of the body may have different pH levels. For instance, the stomach is full of hydrochloric acid with a pH of 2-3.5, which helps digestion, nutrient absorption, and killing off germs. On the other hand, the human blood has a pH of between 7.36-7.44, slightly alkaline, and a drastic fall from this range can prove fatal if not treated. A dangerous change in the blood’s pH is very rare in situations of ketoacidosis brought about by diabetes, too much alcohol intake, or starvation.

Can alkaline food affect the body’s pH level?

As already noted, the blood’s pH level needs to remain within the normal range, failure of which one can quickly die if left untreated. Because the body’s pH is critical for your health and life, the body often has a mechanism to keep it in balance through a process called acid-base homeostasis. The blood pH for normal people rarely changes, albeit with tiny fluctuations but within the normal range. Therefore, food neither makes the blood more acidic nor can it make it alkaline.

However, food can alter the pH of one’s urine since the body regulates the blood’s pH through it. For instance, if one eats a lot of meat, their urine several hours later will be more acidic, indicating that the body is removing metabolic waste from the system. Therefore, urine pH can not correctly determine the body’s acidic level and general health.

Acidic foods and cancer

The proponents of an alkaline diet often associate alkaline food and cancer prevention. The reason that cancer cells can not grow in an alkaline environment. However, several studies found no link between acidity induced by diet and cancer. The findings show that diet does not significantly affect the blood pH value. Besides, cancer cells do not necessarily need an acidic environment to grow, so even if food were to make the body acidic, there is no relation with cancer.  Studies show that the normal body tissues often attacked by cancer are slightly alkaline, having a pH of 7.4. Probably the argument of acidity causes cancer growth came from the observation that tumors hasten growth in an acidic environment. However, it is noteworthy that tumors are the ones that make these environments acidic. In other words, an acidic environment does not create cancer; rather, it is cancer cells that promote the creation of an acidic environment.

Alkaline foods and osteoporosis

Osteoporosis is a degenerative bone disease associated with a decreased bone strength due to its reduced mineral content. Postmenopausal women often complain about this problem which can escalate to bone fractures. The champions of the alkaline ash diet argue that consuming alkaline food will provide alkaline components, such as calcium, to counteract the acid from western foods. The theory called acid-ash osteoporosis argues that acid-forming foods contribute to the loss of bone mineral density. However, this theory does not consider the functions of the kidney, which is charged with removing acids from the body to balance pH levels.

The body, through the kidney, produces bicarbonate ions which are then used to neutralize acids in the blood, thus keeping the body’s pH at par. The body’s respiratory system also plays an important role in stabilizing the blood’s pH. When bicarbonate ions combine with the acid in the blood, carbon dioxide is formed, which the body flushes out through breathing and urine. The theory also overlooks osteoporosis’s main cause, which is the loss of collagen protein from the bone. Interestingly, reduced collagen is linked to low levels of ascorbic acid and orthosilicic acid found in one’s diet. Additionally, clinical trials have found that acidic foods did not negatively affect calcium production and absorption in the body. Acid-forming foods could improve bone health by facilitating calcium retention.

The bottom line

The alkaline diet is a healthy diet that can result in weight loss since it emphasizes the taking of vegetables and fruit, food components known for their high fiber and nutrients. However, the claim that this diet can make the body more alkaline and help fight cancer has neither scientific backing nor support by any human study. On the contrary, studies establish that there is no link between cancer and acid-forming foods.  The theory that an alkaline ash diet can help fight osteoporosis is also not founded on any study. Some studies even suggest that several acid-forming foods can enhance bone health.

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