Dangerous Myths: The Alkaline Diet

If you have spent any time at all on the Internet or watching TV in the past few years, you will have heard of the alkaline diet. Proponents of the fad have claimed it not only works wonders to shed a few extra pounds, but also will cure cancer that “western” medicine can’t treat. If you have too much faith in the human condition to believe me, check it out. Unsurprisingly, proponents of this idea also happen to be in the business of making a lot of money selling “alkaline” treatments to the terminally ill. In a well-reported case exposed by BBC earlier this year, the family of a dying Royal Army officer ended up paying over $77000 to one such “alternative doctor” for “alkaline treatments”. Typing “bicarb treat” onto Google prompts immediately to a much-fabled Cure For Cancer (and bizarrely doesn’t mention the one thing bicarb does help with  – indigestion).


The idea behind “alkaline therapy” is that “cancer is acidic” and thrives in an acidic environment (which means it needs its surroundings to be a a very low pH). Therefore, in order to kill it we need to increase the pH of the body (thus making it more alkaline). If the body becomes alkaline, cancer cells will eventually die off, curing the patient. In order to make the body more acidic, patients need to follow an “alkaline diet” composed almost exclusively of “alkaline foods”.


Let’s go in order and work out each problem the scientific community has with this idea.

1 – Cancer is acidic

This is a fascinating case of an urban myth with a very clear origin story. Cancer cells usually switch their metabolism from aerobic to anaerobic respiration, often because they they are too far away from a blood vessel to get the oxygen they need. One of they byproducts of anaerobic respiration is lactic acid , which is the same substance produced in your muscles when you work out for a sustained period of time. If you would like a more in-depth discussion on this switch, check out my previous post. This means that the environment around cancer cells is more acidic. It does not, however, mean that taking away the acid will make the cancer go away. Acidity is a characteristic, not a necessity, of cancer cells.

2 – By making the body becomes alkaline, cancer cells will eventually die off

Human beings are wondrous machines. For example, human blood will only range in pH between 7.35 and 7.45. In case you are not familiar with pH scales, rest assured this is a very, very small interval. In fact, it is so small that for all intents and purposes the pH of the blood is essentially a fixed and stable number. If the pH drops under 7.35, you get very very sick with a condition called acidosis. If your blood pH drops under 6.8, you die. If the pH of your blood raises above 7.45 (and therefore your body becomes alkaline as the “alternative doctors” will have you believe) you also get very very sick from a condition known as alkalosis. In fact – you guessed it – if your blood pH goes up by more than 0.4 points reaching 7.8 you also die. Of alkalosis. Which is a life-threatening condition.

If all this talk of your blood pH swerving and you dying has made you nervous, relax. Your body has got this under control. You lungs, following a wonderful mechanism called the LeChatelier principle, will regulate your blood pH with exceptional precision. If your blood gets too acidic, they will make it more alkaline. If it gets too alkaline, they will make it more acidic. No matter what you do, unless your organs are failing you cannot change the pH of your body. 

3 – Eating an alkaline diet will make your body more alkaline

As well as the physical impossibility of changing the blood pH, there is a second snag in the plan of introducing alkaline foods in the human body. After you chew your “alkaline” foods – like a tasty cucumber/carrot combo – you swallow it and it ends up the stomach. The pH of the stomach ranges between 1.5 and 3.5. In other words, it is very acidic. If you’ve ever had really bad food poisoning or gastric flu and you’ve dry-heaved for a while you will have felt it – that awful burning sensation at the back of your throat. Being dropped into a big pool of acid, the pH of the food also drops down like any third-grade chemistry experiment will demonstrate.

4 – “Alkaline” foods are actually alkaline

The foods that are labelled as “alkaline” on the “alkaline food chart” are not – in fact – alkaline. The right”most alkaline foods” include lemon – which is stuffed full of citric acid and whose measured pH is around 2 (which is very acidic) and vinegar – which is literally acetic acid and has a pH of around 2.5. If you have ever eaten a kiwi fruit (or a lemon, or a grapefruit) with a small cut in your mouth you know that’s acidic. 

Does this mean you shouldn’t eat a diet full of green vegetables and fruit and with less alcohol, popcorn and cream cheese? Of course not. The “alkaline” chart seems to have put all the healthy food on the “alkaline” side and all the stuff that’s bad for you on the other. You should eat lots of fruit and vegetables as part of a balanced diet with and get plenty of rest, water and exercise. If you are looking to lose weight, eating platefuls of cabbage and carrots and cutting out all the cheese and processed meat is definitely going to help, because cabbage and carrots have few calories and sugar and plenty of fiber.  That’s not “the alkaline diet”, that’s common sense. And it has nothing, nothing to do with curing cancer. Selling false promises to brave cancer patients who are going through the fight of their lives does not make it so.



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