I am often asked for clarity on this issue of the acid-alkaline diet. There is a whole “diet industry sub-culture” grown up around the acid-alkali thing, and there are a lot of companies selling supplements and products designed to help you ‘get alkaline’.
This keeps coming up, and I keep meaning to write about it, so I thought I’d address it properly, once and for all.
I’ll keep this as short and non-scientific as I can, I hope that helps keep things clear and simple.
We hear all this talk of “You eat the wrong foods and your body will be too acidic.” The people promoting this stuff say that your body will be too acidic, they promote dark field microscopy, suggesting that you should pay hundreds of pounds for a ‘live blood test’ and they often will say they can see acid in your blood. They tell you this leads to everything from osteoporosis to diabetes to heart disease and cancer, and they often say the cause is eating animal products, meat and dairy.
These people need to define ‘your body’ when they say “your body will be too acidic.”
What bit of your body do they mean?
Your digestive system, the entire system, is acidic by default, from the entrance to your stomach right through to your anus. It needs to be acidic in order to foster the growth of healthy gut bacteria. Your stomach uses hydrochloric acid to break down your food, it’s just about one of the strongest forms of acid found naturally occurring anywhere on the planet. If your stomach was alkaline you would not be able to break down food properly (especially proteins); if your intestines were alkaline you would not be able to grow the enzymes (enzymes are a type of protein) that are required to complete digestion and pass the nutrients through your gut wall. So your entire digestive system, the largest energy-using system in your body, is acidic and needs to remain that way in order to be healthy.
Bones? They are alkaline, they are your body’s calcium deposits, you cannot make them acidic. If you had acidic bones you would find yourself in hospital with all kinds of problems going on.
Muscles? You cannot make them more acid or alkaline. Lactic acid builds up during hard exercise and then clears, this is completely normal.
Organs? Heart, brain, skin? If you tried to change the pH of your organs you would very probably die!
The only parts of your body which can change pH are the fluids. Obviously, blood is the most important and voluminous fluid in your body. (Everything is made of water, mostly, including your blood.) The pH of your blood is tightly controlled by a process called acid-base homeostasis. Your arterial blood (blood flowing away from the lungs, rich in oxygen) must be between pH 7.35 and pH 7.45. If it deviates from that by even 0.2, you’ll be dead in about 48 hours. So when these guys who sell dark field microscopy tell us “You can see the acid in your blood” and all this – they are talking garbage.
So controlling the “acidity in your body” really comes down to understanding the processes involved in regulating blood pH. If your blood becomes too acidic, you have a condition called acidosis and you will be very sick and hospitalized immediately.
When we eat, the food is chewed in our mouths, crushed and swallowed. In our stomachs, it is further crushed and squashed and mashed up with hydrochloric acid. It moves out of the stomach into the duodenum, where bile salts are injected in, reducing the acidity considerably, then the pancreas does it’s funky stuff, spraying in insulin and other compounds. This mashed up, still quite acidic food then moves into the small intestine, then the lower intestine for slow absorption of the nutrients. As the nutrients pass through the gut wall, they are broken down into what is essentially glucose molecules, which are then taken by the blood to the liver, which is a bit like the ‘Royal Mail Sorting Office of your body’, figuring out what everything is and filing it away or sending it off to where it needs to go, on a molecular level.
As glucose molecules pass through your kidneys they enter little capsules called glomerular capsules which help filter your blood to pass waste into urine for elimination. (I’m keeping this is simple as possible guys!! Honest!!) At this point, these little capsules can monitor and influence blood pH. These glomerular capsules can and do influence and control acid-base homeostasis. If the blood is showing signs of acidity, this is where base (bicarbonate) can be used to maintain the correct pH.
The kidneys control quite a few useful processes in your body. As well as controlling acid-base homeostasis, they also control the balance of calcium and magnesium in your body, and the kidneys help regulate a number of metabolic processes involving sodium and calcium, essential for muscular contractions. So the kidneys do play a role in managing calcium in your body - your kidneys regulate the amount of calcium in your urine and to some degree some functions of the kidneys are connected to calcium-density within your bones.
It’s this measure of calcium in the urine that has driven a lot of the acid-alkaline diet idea. The foods you eat have some effect on the amount of calcium in your urine, and the theory has been build around testing these calcium levels and suggesting that they are indicative of a loss of bone mineral density.
Extra science detail here…
Blood pH is different in venous blood (blood heading back to the lungs, via the heart) as this is more acidic, full of waste (carbon dioxide). Your lungs also help balance your blood pH, pulling in more oxygen when required. When you exercise hard, as your muscles work hard they produce lactic acid (that feeling when your muscles ‘burn’ as you approach exhaustion) and in order for your blood to clear this acid away, you need more oxygen. Once you ease up the exercise, your lungs will keep working hard, bringing in oxygen to supply the muscles (this is called oxygen debt) to clear that lactic acid.
Now, when we eat foods, the glucose molecules that pass through the gut wall and into our blood, are ferried off to various places where they are required to provide energy to various cells to do various tasks within our bodies. Once those glucose molecules reach those cells, they enter the cell, and complete a chemical reaction, and the cell produces energy to do whatever function that cell is designed to do. From that chemical reaction, there is a little waste.
Think of it the same as the engine in your car. Fuel goes in, it’s broken down into tiny amounts, which go into cylinders (where the pistons are) and there it is burnt, or turned into energy, but there is a little bit of waste, that comes out of the exhaust pipe. The acid-alkaline folks tell us that certain foods we have eaten leave a waste ‘ash’ that is acidic, and certain foods leave a waste ash that is alkaline. This is broadly true, and whether or not the ash is acidic or alkaline is largely determined by the mineral content of the food eaten, and this is is completely normal and your body handles it constantly all day long.
That waste has to be removed from your body, carried away, and so it enters the bodies transport system – your blood. That is then when the blood flows through the kidneys, to the glomerular capsules described above, and this is where blood pH is maintained.
So, the amount of this ‘acid ash’ we hear about really is determined by the mineral content of the foods you eat. A high protein diet (think, steak for breakfast and dinner every day) and a diet high in grains (it’s those grains again!) is likely to have the most net-acid-producing effect on the body. There is a lot more detail to it all than this, but I am trying to keep this as super-simple as I can.
Having read all this, we can understand how the acid-alkaline diet idea started, but the reality is that studies show that there is actually no evidence that a diet high in protein and grains, leads to a loss of bone mineral density. In fact, in complete contradiction, studies show that high protein diets can actually support bone mineral density.
Alkalizing diet - just another fad
In my personal opinion, the bit where the major promoters of ‘alkaline diets’ have gone wrong, is taking it too far in terms of minute details. When they start telling you not to eat a banana or an apple because it’s acid forming…they have gone too far.
- Bananas and apples are real, whole, fresh foods – compared to cigarettes, cola and a cream cake, you’ll be fine. Diet perfectionism be damned, it does more harm than good – Read more about diet perfectionism here: https://mothernaturesdiet.me/2013/09/18/avoiding-diet-perfectionism-and-the-trap-of-crippling-inaction/
- These folks have mainly done their research using a method called PRAL – which stands for Potential Renal Acid Load. Basically, they measure acidity and mineral content in your pee as a marker to what your glomerular function is up to. If your pee is acidic or too high in calcium, they assume your body is flushing a lot of acid waste out. But as far as I can tell, many of the PRAL studies these people quote were done between 1995 and 2000 and did not single out a million other factors than can affect the body flushing out waste – such as emotional stress, physical workload and loads more besides. There can be many factors affecting the mineral content in your urine
- PRAL is not an exact science. It’s not like they took 100 people and said “eat nothing but lemon’s for 1 week then we will test your pee”!!! Many foods leave detritus inside us for days, all sitting around washed in acid in our guts! I have written to several of the big name “alkaline diet” gurus in the Western world asking for more information, and not one has been prepared to explain to me the methodology of these lab tests. Some have written to me and privately rubbished PRAL as “fundamentally flawed research”
So in as brief a nutshell as I can, that’s what the acid-alkaline thing is all about.
Just stick to eating the Mother Nature’s Diet way. A sensible balanced diet, lots of fresh vegetables, some fruits, a balance of meat, oily fish and eggs, and a few nuts as snacks. Eat fresh whole foods, and you will be fine. My advice would be to ignore this silly “last 1% diet perfection” advice about “too many apples are acidic” – your only worry about too much fruit is the high sugar load, which might not help if you are trying to lose weight. Get the common sense scoop on fruit here. All vegetables are good for you, don’t pay too much attention to these folks and there “Acid-Alkaline” charts, that stuff is a distraction. Sure, some people will be intolerant to some plant foods, especially foods in the night shade family - such as tomatoes - but for most people, most vegetables are fine.
Don’t let these folks blind you with their sales and marketing ploys – they are telling you what’s wrong so you will buy their green superfood supplements…don’t get me started on that!!!!
In my personal opinion, most of the folks selling the green supplements are scare-mongering. If you live a healthy lifestyle, your body is amazing and will look after itself brilliantly. Mother Nature is so good at that stuff.
As always, questions and comments welcome, thanks all.
Stay healthy, stay happy.