Want to cure cancer, obesity, and never feel tired or hungry again? Ummmmm YES PLEASE! Well a quick Google search will tell you that the alkaline diet is your ticket. Reduce acidity in your body, i.e. become more basic, and you prevent illness. Sign me up right? Hold up there cowboy, don’t get too excited just yet. Let me break the theory of the alkaline diet down for you to make you not necessarily reconsider the foods they recommend, but the reason you’re choosing to eat them.
Reason 1: the pH of the foods we eat will influence the pH of our waste, not our blood.
Welcome to your gastrointestinal tract. You put food in your mouth, swallow and it passes down your oesophagus into your stomach. Boom – it gets hit with a wave of acid. Remember that time you spewed until you couldn’t spew any more and you were left with that awful acidic taste in your mouth and throat? Gastric acid. Acid produced in the stomach. Key word: acid. Gastric acid is secreted by the stomach to break down proteins to amino acids so we can later absorb them. We need it, and it’s there regardless of what food we eat.
Continue the gastrointestinal journey and your food passes through to the small intestine. Here, the food mixed with the gastric juice will trigger the release of bicarbonate by the pancreas to neutralise the acid, because the intestines don’t like the burn.
I could go on and on (and make my year 9 science teacher super proud) but moral of the story is that our body runs a tight ship. We release acids and bases where required to tightly control the pH of food mixtures as they travel through our body. The pH of our blood is so tightly controlled that on a scale of 0-14, the blood sits between 7.35 and 7.45. It’s been scientifically proven that what you eat does not affect that.
Alkaline cheerleaders suggest checking the pH of your urine before you start the diet, and again after to prove that it makes a difference. They’re spot on here, it does make a difference. The food we eat doesn’t significantly alter the pH of any of our important tissues, but it can influence the pH of our waste output. Urine is waste. Measuring the pH of your waste is like assuming that what is in your rubbish bin is what you have in your fridge. I don’t know about you but I wouldn’t be caught dead eating those totally stanky eggwhites that I thought I’d use but totally forgot about. Waste: we get rid of it for a reason.
Reason 2: Cancer grows in alkaline environments too.
As cancer dietitians, we often get asked if the alkaline diet can cure or prevent cancer. The short answer: sadly, no. Boy do we wish it were that simple.
Comprehensive reviews have been conducted and no direct link has been found between diet-induced acidosis and cancer. The theory behind this claim stems from the concept that cancer only grows in acidic environments. Therefore, make everything alkaline and you’re good as gold.
Rejection, your honour!
As we learnt before, food pH does not influence blood pH. Normal body tissue has a slightly alkaline pH of 7.4, meaning that, if this theory were correct, cancer wouldn’t grow in any of these tissues. Cancer cells can grow in alkaline environments too. Whilst it is accurate to say that tumours grow more aggressively in acidic environments, the tumours actually cause this acidity themselves. Cancer cells can’t thrive in an overly alkaline environment, but neither can any of the other cells in our body.
I’ve killed the vibe, I know.
Reason 3: Let’s talk muscle.
Topic change. Lean body mass! Everyone’s friend for health, strength and metabolism.
In the eyes of the alkaline gang, protein is an acidic nutrient. The metabolism of amino acids produce hydrogen ions. The alkaline diet recommends reducing animal proteins including meat, chicken, fish, eggs and dairy. While we’re all for increasing our intake of plant- based proteins (such as nuts, seeds and legumes), we’re also aware of the nutritional value of foods such as oily fish, eggs and dairy.
Reason 4: Sorry, what am I allowed to eat?
If you ask someone basic what’s on their ‘do not eat’ list and they’ll hit you with something like this:
- Wholegrains (oats, barley, spelt), pasta, rice
- Dairy products
- Walnuts and peanuts
- Oranges (but not lemons…)
- High salt foods
- Deli meats
Quite a restrictive list you got there guys. You’d want to hope all that chatter about reducing hunger hormones is accurate because I’m hungry from all the energy it took to simply read that list. Disclaimer: the hunger hormone chatter is not backed by science (we’ll get to that later).
Now this oranges and lemon thing has got me stumped. The pH of a lemon is 2. The pH of orange is a round 4. Both acidic, and by pH, oranges more alkaline than lemons. Yet lemons are considered ‘alkaline’ and oranges not. Go figure.
Seriously though…we tried to go figure…and didn’t get very far (not through lack of trying!). Now you may be wondering how a highly acidic fruit could have an ‘alkalising’ effect on the body. Proponents of the alkaline diet spin something about the ratio of minerals vs sugar impacting the “internal” alkalising effect, many reporting that sugar is acidic (my year 9 science teacher told me that sugar tends not to release hydrogen or hydroxide ions when dissolved in water…i.e. sugar cannot materially alter the pH level of a solution). Another big objection, your honour.
Some alkaline charts don’t bother with the mumbo jumbo and just leave oranges on their list. We wonder if maybe these particular basics just didn’t want to face the wrath of all the disease-free 90 year plus Mediterraneans who have been eating an orange a day all their life.
Now don’t get us wrong. There’s a lot of things about the foods on the alkaline diet “yes” list that we love. Plenty of veggies, fruit and limited processed foods. But please don’t hate on walnuts. We don’t like that talk. We’re also not so thrilled about the lack of evidence behind how they came up with their ‘naughty’ and ‘nice’ list. Yoghurt and kefir (on the naughty list), for example, are valuable sources of probiotics that pimp our gut microbiome. And wholegrains (also naughty) help to feed these probiotic bacteria. Please let them stay.
Reason 5: You’re only losing weight because there’s hardly anything on your ‘can eat’ list. And I’ll reluctantly make a bet that you’ll end up putting it back on again.
They’ll tell you your weight loss is related to balancing levels of the hunger-suppressing hormone leptin, but there’s a lack of science to support this. On the flip side, diets rich in fish and wholegrains have been scientifically associated with improved leptin sensitivity. But they’re on the naughty list. Get your story straight basics! You’re contradictions are confusing us!
One area where the selection of ‘alkaline’ foods might be useful in health is in kidney disease. Our kidneys are organs that filter our blood to get rid of wastes in the form of urine. Some studies suggest that if someone already has renal failure, an alkaline-type diet may help to reduce the stress on the kidneys filtering process and slow the progression of this disease. This makes sense given the kidneys are dealing with the waste. If you have a kidney condition or renal failure, talk to an Accredited Practising Dietitian about reducing the pressure on your precious filters!
The moral of the story
The reality is there’s no significant evidence to suggest that what we eat can manipulate our whole body pH, and nor would we want to. Even miniscule changes to our body’s pH are life threatening. When our regulatory systems don’t work to maintain this, such as in kidney disease or pulmonary dysfunction, our body relies on dialysis machines or ventilators to keep our acid-base levels balanced. To suggest that eating loads of broccoli is enough to alter this is a little bit unfair (and unsafe!) to the individuals challenged with these life-threatening conditions.
Don’t believe everything you read or are told. Venture back to year 9 science and, pardon the pun, go back to basics. If things don’t add up or you’re struggling to make sense of it all, chat to us – we’re scientifically trained to cut through the mumbo jumbo and dish up the facts.
While we love the foods on the basic ‘nice’ list, we also like many that aren’t. Don’t restrict without reason, and don’t be basic.
- Alkaline diets”. American Institute for Cancer Research. http://www.aicr.org/patients-survivors/healthy-or-harmful/alkaline-diets.html
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