This article was originally published in the June 2018 Edition of NHD Magazine. The alkaline diet is one of my favourite fad diets to debunk, so it was interesting taking a deeper dive into the history and evidence related to this diet, I hope you like it too!

The alkaline diet is also known as: the alkaline ash or the acid-alkaline diet. This diet promotes replacing so-called ‘acid forming foods’ with ‘alkaline forming foods’ in order to promote better health by altering the pH of our blood.

This proposed mechanism is of course flawed, as the processes of homeostasis and digestion (including the acidic pH of our stomach) maintains the pH of our blood between about 7.35 and 7.45 regardless of the type of food eaten, which keeps us healthy and avoids the harmful effects of alkalosis or acidosis¹. 

This article examines how the alkaline diet emerged and gained popularity, as well as the current evidence base related to this.

The Development of the Alkaline Diet:

Early Research into the Acid/Ash Content of Food

In the 1850’s the French physiologist Claude Bernard (who is also known for discovering glycogen and the role of pancreatic juice) conducted experiments in which rabbits were fed boiled beef in place of their usual plant-based diet.

In response to this, the rabbits were observed to develop acidic urine in contrast to their usual alkaline urine^2-3. This phenomenon was later explained due to the metabolism of methionine and cysteine found in meat, which produces sulphuric acid and in turn causes more acidic urine⁴.

In the early 20th century our understanding of acid-base disorders was evolving further; for example in 1908 the Henderson–Hasselbalch equation was developed, which is used to calculate the pH of a buffer solution⁵.

It also became possible to determine in a laboratory setting whether the ‘ash’ content of a food was acid, alkaline or neutral^6-7.

This experiment is conducted by heating the food along with oxidising agents until the water and organic matter is removed and then analysing the mineral content of the remaining ash⁸.

Acid-forming minerals include: chlorine, phosphorus, and sulphur; whereas calcium, magnesium, potassium, and sodium are alkaline-forming minerals (also referred to as base-forming minerals)⁸.

Table adapted from page 6 of “Foods & Nutrition Encyclopedia – 2nd Edition”⁸

Alkaline Diet Theories Emerge

In the early 20th century, theories about how these acid and alkaline forming foods can affect health were also cropping up.

The Report of the Committee on Nutritional Problems of the American Public Health Association for 1935-1936 highlighted that: “elaborate menus are offered for ‘alkali-forming’ meals, and systems of dieting which can be had by purchasing their books or enlisting their services and special courses”⁷.

Another article published in the American Journal of Public Health that year also reported that: “one widely publicised system of diet is based on the erroneous theory that proteins and starches, and fruits and starches should not be mixed in any one meal. As a reason for this perverted idea, it is declared that protein digestion takes place in the acid contents of the stomach, while starch can be digested only in the alkaline intestine, and that carbohydrates encounter some sort of baleful interference when associated with protein in the stomach”⁶.

The Committee on Nutritional Problems reported: “There is no evidence that a preponderantly acid diet is injurious. That the body reaction remains practically unaltered even when a wide range of amount of acid or base is ingested has been pointed out by Henderson.”⁷.

This report also highlighted that acidosis only occurs in response to certain medical conditions such as: diabetes, kidney disease and metabolic disorders⁷.

So it was known by academics and medical professionals at the time that the acid/ash content of food does not significantly impact the pH of our blood – as a healthy body maintains homeostasis via our buffer, respiratory and renal systems⁶.  

The Modern Alkaline Diet

The alkaline diet reared its head again in the 1990’s in conjunction with the rise in popularity of low-carb diets.

In 1992 “One Sickness, One Disease, One Treatment” by Robert O Young was published which warns about “over-acidification of the blood and then tissues due to an acidic lifestyle and diet”.

Robert O Young, who has been referred to as ‘father of the alkaline diet’, has published numerous other books on similar topics, including “the pH Miracle” which was first released in 2002 and has sold more than four million copies worldwide⁹.

The pH Miracle advises “striking the optimum 80/20 balance between an alkaline and acidic environment provided by eating certain foods” including low carb options, a “liquid detox”, drinking water, taking specific supplements and of course eating mainly “alkaline foods”¹⁰.

Foods which are considered “highly alkaline” include¹¹:

• “pH 9.5 water drinks” and “green drinks”
• Salt
• Avocado
• Broccoli
• Cabbage
• Celery
• Kale
• Spinach
• Tomato

Foods which are considered “highly acidic” include¹¹:

• Alcohol
• Coffee and black tea
• Miso
• Dried fruit
• Honey
• Jam
• Eggs and dairy products
• Beef
• Pork
• Chicken
• Farmed fish and shellfish
• White rice
• Artificial sweeteners  

There are numerous products related to the alkaline diet including: supplements, alkaline water, ‘water ionisers’, books and videos¹².

The popularity of the alkaline diet has also been boosted by endorsement from celebrities such as: Gwyneth Paltrow, Kirsten Dunst and Jennifer Aniston.

This was also very popular with a number of ‘wellness gurus’ and bloggers, although many have now turned away from this diet as it has become much more controversial.  

For example, in January 2017 it made worldwide news when a 27-year-old British woman with terminal breast cancer called Naima Houder-Mohammed “paid thousands of dollars for [Robert O Young’s] alkaline treatment, which consisted mainly of intravenous infusions of baking soda”⁹. Naima sadly passed-away a few months after receiving this ‘treatment’.  

Furthermore, in June 2017 Robert O Young was jailed for 5 months “after admitting that he illegally treated patients at his luxury Valley Center ranch without any medical or scientific training”¹³. Robert O Young was also previously convicted for practicing medicine without a license¹³.

Examining the Evidence-base:

Cancer

One of the most worrying health claims related to the alkaline diet is that it can be used as a cancer treatment^14-15.

This idea is based on studies which have found that cancer cells thrive in an acidic environment in vitro^16-17.

However, a recent systematic review concluded that: “promotion of alkaline diet and alkaline water to the public for cancer prevention or treatment is not justified” due to a lack of actual research¹⁷.

Bone Health

Arguments in relation to bone health are also common among alkaline diet supporters.

The theory is that a high ‘acidic load’ causes minerals such as calcium to leach from our bones to counteract an acidic blood pH.

But systematic review data has not found a causal relationship between dietary acid load and osteoporosis and there is “no evidence that an alkaline diet is protective of bone health”^{14, 18}. Furthermore, in April 2017 the National Osteoporosis Society (NOS) released a statement which associated increased bone fracture rates in young people with diets which exclude dairy (such as clean eating and the alkaline diet)¹⁹.

Heart & Metabolic Health

Some low quality studies have found an association between the modern Western diet (which has a high ‘acid load’) and an increase risk of cardiovascular disease and diabetes^{14, 20}.

However, this ‘acid load’ is based on the food the modern Western diet contains, rather than the effect of these foods in our body, so it is too simplistic to assume that it is purely the ‘acid load’ which affects disease risk.

As the alkaline diet is low in carbohydrates, this style of eating may be effective for some people with type two diabetes²¹. However, there appears to be no evidence from systematic reviews or randomised controlled trials that following an alkaline diet or altering the dietary ‘acid load’ can prevent or cure type 2 diabetes¹⁴.

In fact in  October 2017 the UK Advertising Standards Authority (ASA) actually banned an advertisement for ‘ADrop’ which claimed that “ionised alkaline water [is] a natural way to improve your circulation” in the context of treating Diabetes²².

Similarly, certain characteristics of the alkaline diet may be effective for some people in terms of weight management, as the low carbohydrate content and high level of plants can lead to a calorie reduction. But there doesn’t appear to be any experimental evidence to test whether an ‘acidic dietary load’ directly affects obesity¹⁴.

Other Conditions & Risks

Although the alkaline diet is promoted as being a treatment for depression, yeast overgrowth and cellulite – there is no good evidence to support this¹⁴.

Certain human studies have identified specific risks associated with ‘alkaline water’ including: reduced gallbladder emptying, inhibited gastric secretion and even toxic reactions¹⁷.

As with all diets which exclude food groups, there is also a risk of nutritional deficiency, as the alkaline diet can be low in: protein, calcium, iron and calories. This restrictive diet can also promote an unhealthy relationship with food. 

Conclusion:

Theories about the alkaline diet have been in circulation for more than 100 years, but there is still no good evidence that reducing the ‘acidic load’ of our diet has any direct health benefits.

Although there may be some positive side-effects of this diet in certain contexts (as this promotes a plant-based diet which is low in sugar and alcohol).

But there are also significant risks to consider related to this diet, including potential nutritional deficiency and spreading harmful messages about using the alkaline diet to treat serious medical conditions.

References:

1. 1. Lewis et al. (2014) “Medical-Surgical Nursing 10th Edition – chapter 16 fluid electolyte and acid-base imbalances” https://books.google.co.jp/books?id=f-MCDQAAQBAJ&pg=PA287&lpg=PA287&dq=maintains+pH+between+7.35+and+7.45&source=bl&ots=KKQGuUIsOK&sig=Lfqu6LdG-rtrdKtRnsBaJ4qSCRk&hl=en&sa=X&ved=0ahUKEwiz-YnauLHZAhUEwrwKHU7cDbs4ChDoAQhTMAc#v=onepage&q=maintains%20pH%20between%207.35%20and%207.45&f=false
   2. Bernard (1857) “An Introduction into the Study of Experimental Medicine”
   3. Bernard (1859) “Lecons sur les proprietes physiologiques et les alterations pathologiques des liquides del’organisme”
   4. Gennari et al. (1982) “Determinants of plasma bicarbonate concentration and hydrogen ion balance” (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4421511/)
   5. Arunachalam & Woywodt (2010) “Turbid urine and beef-eating rabbits: Claude Bernard (1813–78)” (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4421511/)
   6. Tobey (1936) “The Question of Acid and Alkali Forming Foods” (http://ajph.aphapublications.org/doi/pdf/10.2105/AJPH.26.11.1113)
   7. Committee on Nutritional Problems (1936) “Food Fallacies and Nutritional Quackery” (http://ajph.aphapublications.org/doi/pdf/10.2105/AJPH.26.3_Suppl.58)
   8. “Foods & Nutrition Encyclopedia, 2nd Edition – acid foods and alkaline foods” (https://books.google.co.jp/books?id=o3UD2iL4sAAC&pg=PA41&lpg=PA41&dq=ash+residue+of+food&source=bl&ots=SxSaTiJQKC&sig=Xkbej3NpKbyhOfpGNK39-1aphZs&hl=en&sa=X&ved=0ahUKEwiljsLxvbHZAhUEurwKHQlSAHoQ6AEIowEwEQ#v=onepage&q=acid%20foods%20and%20alkaline%20foods&f=false)
   9. http://www.bbc.com/news/magazine-38650739 [accessed February 2018]
   10. Young RO (2002) “The pH miracle”. New York: Warner Books, 2002
   11. https://www.phmiracleliving.com/t-food-chart.aspx [accessed February 2018]
   12. https://www.phmiracleliving.com/t-Microscopist-List.aspx [accessed February 2018]
   13. http://www.sandiegouniontribune.com/communities/north-county/sd-no-phmiracle-sentence-20170628-story.html [accessed February 2018]
   14. PEN “Diet Composition – Alkaline Diet” [accessed via: http://www.pennutrition.com/KnowledgePathway.aspx?kpid=17944&trid=18054&trcatid=42]
   15. https://www.phmiracleliving.com/t-approach.aspx [accessed February 2018]
   16. Robey (2012) “Examining the relationship between diet-induced acidosis and cancer” (https://nutritionandmetabolism.biomedcentral.com/articles/10.1186/1743-7075-9-72)
   17. Fenton & Huang (2017) “Systematic review of the association between dietary acid load, alkaline water and cancer” (http://bmjopen.bmj.com/content/6/6/e010438)
   18. Fenton et al. (2011) “Causal assessment of dietary acid load and bone disease: a systematic review & meta-analysis applying Hill’s epidemiologic criteria for causality” (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3114717/)
   19. http://www.independent.co.uk/news/health/clean-eating-trend-broken-bones-norm-future-experts-warn-national-osteoporosis-society-dairy-gluten-a7680041.html [accessed February 2018]
   20. Khan et al. (2016) “Association between dietary acid load and the risk of cardiovascular disease: nationwide surveys (KNHANES 2008–2011)” (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5002186/)
   21. https://www.diabetes.org.uk/professionals/position-statements-reports/food-nutrition-lifestyle/low-carb-diets-for-people-with-diabetes [accessed February 2018]
   22. https://www.asa.org.uk/rulings/b-life-ltd-a17-382805.html [accessed February 2018]