The alkaline diet delusion

What if I told you that all it takes to lose weight, boost energy and prevent diseases like arthritis, osteoporosis and cancer is to eat the right foods to keep the pH of your body in the alkaline zone? Well, if I were prepared to throw out every bit of scientific knowledge that I have on how the human body works to buffer against acidity and alkalinity then sure, I could tell you that. But I’m not. Instead, in this blog post, I’m going to investigate those wild health claims made by the celebrity-endorsed alkaline diet and explain why it is pseudoscience squared.

The alkaline diet and all things related to ‘alkalinising’ your body has been a trend that has bubbled away for decades and shows no signs of abating. It seems any Insta influencer who isn’t promoting the merits of alkalising your body just isn’t healthing hard enough.

The modern popularity of the diet can be traced back to best-selling books from the early 2000s written by Robert O. Young – an American naturopathic practitioner. The most well-known was titled The pH Miracle which has sold more than four million copies worldwide.

Foods to eat and avoid because….pH

Alkaline diets are promoted as a magical cure-all to treat or prevent cancer, heart disease, low energy levels, and a whole host of other illnesses. The premise behind the whole alkaline trend is related to something called the acid-ash hypothesis.

It goes like this: when we eat certain foods like meat, poultry, cheese, fish, eggs, and grains, a type of metabolic waste residue which is called an ‘ash’ is produced.  This metabolic waste can be alkaline, neutral, or acidic. Now, this isn’t quite the same as the ash you get after a fire, but the analogy is useful. Think of metabolism as like a fire that converts food to energy.

The type of ash produced is determined by the balance of acid-forming components in a food (such as phosphate and sulphur), and alkali-forming compounds such as calcium, magnesium and potassium. And it is the acidic waste that has launched the whole crazy idea of alkaline diets because eating acid-forming foods makes your blood acidic and….disease!

Where to start. As with any extreme diet, there is always a kernel of truth behind it. It is true that different types of foods produce different types of metabolic by-products. Alkaline ash is produced by most fruits and vegetables, nuts and legumes. More neutral foods include most types of dietary fats. And the evil acid-forming foods are meat, poultry, fish, dairy, eggs, grains and alcohol.

Summary of the alkaline diet: it is plant foods for the win (except grains, because they’ll kill you🤦‍♂️) and cut out most animal foods. There’s your alkaline diet.

Following the pH diet is just a recipe for a vegetarian diet with a lot less highly processed foods. And if before you were eating unhealthy, but are now focussed on a new dietary paradigm of ‘alkalising your body’, then is it any wonder that you could start to feel better? It has nothing to do with acid or alkaline foods, but just a list of food rules that the diet makes you stick to. But I’m getting ahead of myself.

pH for dummies

Time to circle back for a bit of pH basics. pH is, of course, a measure of acidity or alkalinity. The pH scale ranges from 1 to 14 with 1 being strongly acidic, 14 being strongly alkaline, and 7 neutral. Anything below 7 is acidic, and anything above 7 is alkaline (also known as basic).

Your stomach acid (and also battery acid) has a pH of about 1. Meat is about 3. Coffee is a 5. Most fruits and vegetables fall in the pH 8 to 10 range. While drain cleaner has a pH of 14. I guess Draino would count as a health tonic supplement in the alkaline diet world then?

Advocates of the alkaline diet claim that since the normal pH of the blood is slightly alkaline and kept in a very tightly controlled range of 7.35 to 7.45 then you should eat alkaline foods and shun acidic foods to keep it there.

Here’s the thing: if food could make an impact on blood pH in either an acidic or alkaline direction, then it would be life-threatening. A blood pH below 7.35 is called acidosis. Above 7.45 and it is alkalosis. Both are medical emergencies which can result in death.

For almost every healthy person on the planet, the body keeps blood pH in a very tight range thanks to the coordinated actions of the lungs, kidneys and liver. But anyone who has studied physiology would know this sort of basic stuff. Those promoting an alkaline diet are not in that group.

Food though can change the pH of the urine and that’s one of the regulatory mechanisms the body uses to buffer against too much acidity or alkalinity. Urine though is contained in the bladder so does not affect the pH of any other part of your body.

So, while an alkaline diet may change the pH level in the urine, it has not been shown to cause a sustained change in blood pH levels. We even have a controlled dietary trial investigating this very issue which found that acid-forming or alkaline-forming dietary changes could alter blood pH by a tiny 0.014 units, while the urine pH increased by 1.02 units.

Be thankful that your natural acid-base regulatory mechanisms don’t need a special diet to do their job.

There are though some serious diseases that have real acid-base imbalances at their core. Acidosis can happen with illnesses such as cancer, respiratory disease, severe diarrhoea, excessive alcohol use, hypoglycaemia and kidney failure to name a few. But all these conditions have underlying medical causes. They are not caused because you ate a piece of grainy bread for lunch.

Does cancer love acid?

Cancer is one of the diseases clearly linked to an acidic diet – at least according to those advocating an alkaline diet. It comes from the observation that cancer cells in a laboratory grow better in an acidic environment. So, follow an alkaline diet to change the pH environment of the body and….cancer cured.

The reality here is that it is the rapid growth of cancer cells that creates an acidic environment associated with cancer; the acidic environment does not create cancer. And yes, indeed, cancer cells can’t live in an overly alkaline environment, but neither can any of the other cells in your body. And this is theoretical anyway as it comes from laboratory studies of cancer cells grown in a petri dish so does not represent the complex nature of how tumours behave in the human body.

Tying yourself in knots to make sense of it all

There is an alternative explanation for how an alkaline diet ‘works’ sometimes given by those pushing the diets when they read a physiology textbook and acknowledge that acidic foods don’t change blood pH.

It goes like this. The stress acidic foods place on the body from the need to buffer the pH results in the body pulling out alkaline-rich minerals like calcium, phosphorus and magnesium from the bones, teeth and organs to buffer against the extra acid load.

They say this leads to osteoporosis and fatigue, and compromises our immune system, making us vulnerable to viruses and disease. That claim doesn’t hold pH 7 neutral water.

Yes, that’s a great theory that if you want to apply to ‘acidic foods’ will apply equally to ‘alkaline foods’ so an all-alkaline diet would be just as harmful and ‘stressful’ from the need of the body to buffer the pH back into the tight range of 7.35-7.45.

And there is also the ‘inconvenient truth’ that when you go looking for a significant bone loss of minerals in response to acid-forming diets, you can’t see it which was the finding of this meta-analysis and this one too.

So even though the alkaline hypothesis tells us that higher consumption of protein, animal foods and phosphate are acidifying (and thus detrimental to bone health), what you actually find in the research studies is that diets high in these nutrients have a positive effect on calcium metabolism and markers for bone health.

More to pH than the blood

All this focus on blood pH pushed by alkaline diets ignores this one simple observation: pH differs throughout different body compartments.

You want a very acidic stomach to help with good digestion. While your mouth salvia is slightly acidic at about pH 6 which is optimal for starting the process of starch breakdown. At the same time, a lower pH in the colon from bacterial fermentation is linked to favourable changes in the risk of colon cancer. Then there is your skin which has a pH of about 5. Just what on earth is an alkaline diet trying to achieve by just targeting the blood?

All I’ve covered here is pretty basic chemistry and physiology; most of it high school level. Yet those pushing alkaline diets either ignore it in the rush to sell you their diet program and alkalised water or are completely ignorant of it. I don’t know about you, but if you’re going to bang on about pH chemistry and acid-base physiology in support of a diet it kind of would be expected that you’ve studied it – not read it off a blog.

What it all means

An alkaline diet ‘works’ because it gives a person a very selective and restrictive list of foods to eat and avoid which means lots of fruits and vegetables and less highly processed food. That’s it.

You don’t have to believe in the crazy that is the alkaline diet, spend money on alkalinised water and needlessly cut out otherwise healthy foods like grains to make a positive change to your diet and life. I prefer to believe in the benefits of eating healthy by selecting from a wide variety of foods without the need to fill someone’s brain with pseudoscientific nonsense.