The Alkaline Diet

The Alkaline Diet

What is the alkaline diet?

It is a diet that suggests that acidic foods should be replaced with alkaline food to improve health and prevent or cure certain diseases like osteoporosis and even cancer.
It is sometimes called the acidic-alkaline diet or alkaline ash diet. It claims that the foods you eat can alter the pH of your blood.

How does an alkaline diet work?

When food is digested and metabolised, it leaves behind an ash residue. This ash residue can either be acidic or alkaline or neutral. The alkaline diet proposes that this ash can directly affect the acidity of the body. Therefor acidic food causes an acidic body and alkaline food causes an alkaline state in the body.

Acid ash it thought to increase the risk for various diseases and alkaline ash is believed to be protective.

Certain food groups are considered acidic, alkaline or neutral:
» Acidic: Grains, meat, chicken, fish, eggs, dairy and alcohol.
» Neutral: Natural fats, starches and sugars.
» Alkaline: Fruits, vegetables, nuts and legumes.

Regular pH levels in the body

pH is a value of acidity or alkalinity. A pH between 0 and 7 is acidic; 7 is neutral and 7-14 is alkaline. pH varies largely in the body: some parts are acidic and others are alkaline. The pH of the stomach for instance is between 2 and 3.5. This is required for digesting food.
The pH of blood is always slightly alkaline at 7.35 to 7.45. If the pH of blood falls outside this pH, it is a serious condition that could lead to death. This might happen due to certain disease conditions, and has nothing to do with the foods you eat.

 

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Bottom line

The PH of blood is tightly controlled, and if it would change, one would not survive. People saying that they are very acidic or have acidic blood are misguided.

Your body has mechanisms in place to control the pH of blood, which is called the Acid-base Homeostasis. Buffer systems that work in cellular fluid and the bloodstream, keep pH constant. Our kidneys are fundamental to removing acids and regulating body pH. The kidneys produce bicarbonate ions that neutralize acids in the blood, a sustainable process which enables the body to tightly regulate blood pH. Our lungs are also involved in controlling blood pH. When bicarbonate ions from the kidneys bind to acids in the blood, they form carbon dioxide (which we eliminate through breathing out) and water (which we eliminate through urinating).

As for a link between osteoporosis and blood pH, observational studies have found no relationship between dietary acid and bone density or fracture risk. There is not even a relationship between urine pH and bone health.

Current research shows that there is absolutely no link between an acid forming diet and cancer. Cancer cells also grow in alkaline environments.

Food can however definitely change the pH value of urine. But urine pH is actually a very poor indicator of overall body pH and general health. It can be influenced by many factors other than diet.

The alkaline diet can get some credit for encouraging the inclusion of unprocessed foods, fruits, vegetables and healthy plant foods, which has nothing to do with alkalinity or acidity.

Sources:
1.    The kidney and acid base regulation; Adv Physiol Educ 33: 275-281, 2009
2.    The Alkaline Diet: Is There Evidence That an Alkaline pH Diet Benefits Health? Gerry K. Schwalfenberg. Journal of Environmental and Public Health, Volume 2012
3.    pH and acid excretion do not predict bone fractures or the loss of bone mineral density: a prospective cohort study. Fenton et al. BMC Musculoskeletal Disorders 2010, 11:88 http://www.biomedcentral.com/1471-2474/11/88.
4.    Examining the relationship between diet-induced acidosis and cancer. Ian Forrest Roby. Nutrition & Metabolism 2012, 9:72. http://www.nutritionandmetabolism.com/content/9/1/72 .
5.    Nutritional disturbance in acid-base balance and osteoporosis: a hypothesis that disregards the essential homeostatic role of the kidney. Jean-Philippe Bonjour. British Journal of Nutrition (2013), 110, 1168-1177
6.    Authority nutrition: evidence based nutrition. www.authoritynutrition.com

Claudine Ryan, Registered Dietitian, RD (SA)

Written by : Claudine Ryan, Registered Dietitian, RD (SA)

Claudine Ryan holds a Bachelor of Science degree in Dietetics and is registered with the Health Professions Council of South Africa. Claudine is passionate about people and their health, and enjoys helping others to optimise their health and manage their chronic lifestyle related diseases through sound nutritional therapy and practical advice.