What if I told you that all it takes to lose weight, boost energy and prevent diseases like arthritis, osteoporosis and cancer was 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 of how the human body works to buffer against acidity and alkalinity then sure, I could tell you that. But I’m not. Instead, in today’s podcast, 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 going away. It seems any Insta influencer who isn’t promoting the merits of alkalising your body just isn’t healthing hard enough.

Alkaline diets have been 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 which underlies this diet. It goes like this: when we eat certain foods like meat, poultry, cheese, fish, eggs, and grains, ash is produced in the body. The type of ash is determined by the relative content of acid-forming components in a food such as phosphate and sulphur, and alkali-forming compounds such as calcium, magnesium, and potassium.

Now, this isn’t quite like the ash you get after a fire, but the analogy is useful. Think of metabolism as like a fire that converts food to energy. And within all the chemical reactions going on, there is some residue leftover called metabolic waste. And this metabolic waste can be alkaline, neutral or acidic. And it is that acidic waste that has launched the whole crazy idea of alkaline diets because eating acid foods makes your blood more acid and….disease!

Where to start….As with any crazy diet, there is always a kernel of truth behind it. And it is true that different types of foods produce different types of metabolic by-products. Alkaline ash is produced by fruits, vegetables nuts and legumes. Neutral foods are more natural fats. And the evil acidic foods are meat, poultry, fish, dairy, eggs, grains, and alcohol.

Now if you’ve been alert, you probably can already see that based on the broad definition of what constitutes an acid food and what is an alkaline food, then following this sort of diet means you eat essentially a vegetarian diet with a likely a lot less highly processed foods in it. And if before you were eating fairly 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? Nothing at all do with acid or alkaline foods, but just a list of food rules that the diet makes you stick to. But I’m ahead of myself.

Back to pH and why this diet is total cray. 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, a grapefruit about 3 and black coffee a 5 or 6. While on the other end, seawater is about pH 8 and liquid 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 diet claim that since the normal pH of the blood is slightly alkaline at just above 7, then you should eat alkaline foods and shun acidic foods to keep it there. Here’s the thing: if food could really make an impact on blood pH in either an acidic OR alkaline direction, it would be life-threatening. A blood pH below 7.35 is called acidosis and above 7.45 it is alkalosis and both are medical emergencies which can result in death. The body keeps blood pH in a VERY tight range thanks to the coordinated actions of the lungs and kidney. But anyone who has studied physiology would know this sort of basic stuff. Those promoting 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, along with respiration. 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. That’s all because our natural acid-base regulatory mechanisms don’t need a special diet to work so any effect of food on blood pH is minimal and transient.

There is the argument that those pushing alkaline diets sometimes come up with when they actually look at a physiology textbook and acknowledge that acidic foods don't change blood pH, that they instead deflect this to the stress acidic foods place on the body from the need to buffer the pH against the acidity by 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 just doesn't hold pH 7 neutral water. Yes, that's a great theory which 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.

So even though the hypothesis holds that higher intakes of protein and phosphate are acidifying and therefore detrimental to bone health, what happens when you look at the research that diets high in these nutrients have a positive effect on calcium metabolism and markers for bone health.

And all this focus on blood pH pushed by alkaline diets ignores the one simple observation: pH differs all 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 salivary amylase that helps with starch breakdown. While a lower pH in the colon from bacterial fermentation is linked to favourable changes in disease risk profile. 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 just covered here is pretty basic chemistry and physiology – some of it high school level. Yet those pushing these scam diets either ignore it in the rush to sell you their diet program and alkalinised water or are completely ignorant to it. I don’t know about you, but if you’re going to bang on about pH chemistry and acid-base physiology it kinda would be expected that you’ve studied it – not just read it off a blog.

Now, there are some serious diseases that have actual acid-base imbalances. 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 grainy piece of bread. And let’s mention here that there are a whole bunch of diseases that are based on alkalosis from adrenal disease to even overuse of antacids but those pushing alkaline diets are pretty quiet on that front.

Cancer

Cancer is one of the diseases clearly linked to an acid diet – at least according to those pushing an alkaline diet. It comes from the observation that cancer cells grow better in an acidic environment so an alkaline diet can change the environment of the body to treat cancer. However, it is actually 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 too can any of the other cells in your body. And all of 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. 

Summary

An alkaline diet 'works' because it gives a person a selective 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 from your diet to make a positive change to your diet and life. The alkaline diet follows in the footsteps of what I consider the most whacky diet of all time: that being the Eat Right for Your Blood Type diet that also gives a long list of foods to eat and avoid purely based on your ABO blood type. I prefer to believe in the benefits of eating healthy without the need to fill someone’s brain with pseudoscientific nonsense.

So that’s it for today’s show. You can find the show notes either in the app you’re listening to this podcast on if it supports it, or else head over to my webpage www.thinkingnutrition.com.au and click on the podcast section to find this episode to read the show notes.

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I’m Tim Crowe and you’ve been listening to Thinking Nutrition.