Does acidity cause cancer?
Being a complementary medicine student/researcher with a previous background in biomedical sciences, I often hear things that make my scientific mind cringe. I consider myself very open-minded, and I do recognize the problems with the scientific method, but I also see many scientific studies and theories being misinterpreted, removed from context, and misused out here in the “common” world.
Among the things that grab my particular attention, probably due to my background studies on cancer metabolism, is the acidity and cancer topic.
This usually revolves around ideas such as “cancer cells are acidic”, “acidic diets cause cancer”, “cancer develops because the blood is too acidic”, and so on, which you probably have heard/read at least 100 times. These ideas then generated movements like the “alkaline diet”, one of its associated assumptions being that organisms that are too “acidic” are more likely to develop pathologies (in this article I will refer only cancer specifically), while making the body more “alkaline” through diet (and sometimes other methods) might help prevent or treat disease.
I am not really an expert in terms of alkaline diets, but my scientific radar always turns on when hearing terms like “pH”, “cancer”, “acidic”, “alkaline”, so I decided to present some research on the subject, in light of the current scientific thought.
It’s very clear that our diet (among other factors) has a profound effect on our health and can help prevent diseases like cancer, but there is currently no solid evidence supporting that it’s due to changes in pH.
So let’s take a look at some basic concepts first. I’ll keep it brief, and as simple as I can.
What is pH? How is it measured? What is an acid?
Speaking of things like “acidic” and “alkaline”, it’s important to know that those terms need to be understood within the reference system that supports them: the pH scale.
The very definitions of “acidic” and “alkaline” are related to the behavior of substances during chemical reactions in solutions. Therefore, “acids” are substances that can donate H+ ions (hydrogen ions) during a chemical reaction. This is the Bronsted-Lowry definition, which is one among several. A base (or alkali), on the other hand, is a substance that receives those H+ ions.
“pH” means “potential of hydrogen”, and is essentially a value on a logarithmic scale, calculated using a standard formula. This value directly depends on the concentration of hydrogen ions in a solution. See this graph:
This graph shows us that, the more hydrogen ions are in a solution (which makes the solution more concentrated in terms of those ions), the lower its pH value. This means that the acidic solutions have higher H+ concentrations and therefore lower pH.
And so scientists arranged a simple system to reference these variations: the pH scale. It allows us to classify substances in a solution, based on their pH values.
The values inside the pH scale range from 0 to 14:
- Substances with pH=7 are considered neutral (an example is pure water);
- With pH levels above 7 they’re considered alkaline;
- When the pH levels are below 7, those are acidic substances.
The closer pH levels are to 0, the “stronger” are the acids. An example of a strong acid is hydrochloric acid, which is in our stomachs. On the other hand, “weak” acids have pH levels closer to 7, like for example acetic acid, which is the component of vinegar.
But how do we know the pH value of something? Usually, the pH levels of a solution are measured through the electric potential generated by the activity of its hydrogen ions. This method uses a piece of equipment called “pH meter”, and is the most reliable and precise.
We can also use pH indicators (also called “acid-base indicators”) to evaluate the nature of a solution, but that’s a less precise and less reliable method. These are chemical reactants that change their color according to the H+ concentrations. The pH paper strips, frequently used to measure urine pH, are a good example of this method.
What does it mean to have an “acidic” body?
The first thing we need to have in mind is that “acidic” and “alkaline” are relative terms. The fact that a certain degree of acidity may be “good” or “bad” in a given body part, is not meant to be indiscriminately extendable to all of the body. And this is simply because different body parts have different pH levels. Trust me, you WANT certain parts of your body to be acidic. Stomach and vagina, for example.
So, when you hear someone say “your body can’t be acidic”, just remember to ask — Which part? — How acidic?, and I promise things will start to make a lot more sense.
Our metabolism is constantly generating waste products, which can either be acidic or alkaline. To balance this, we have ways of disposing of those products, and controlling the pH changes, preventing the waste’s existence from tipping the pH scale excessively over to one side or the other. Life exists because there’s a relative, dynamic, balance, constantly moving and shifting, which controls several different factors; pH levels are only one among several.
But when our bodies can’t keep those factors in check, unbalances and problems arise. In this particular case, excess acidity or alkalinity.
In medical terms, an excess of body acidity is called “acidosis”, while excess alkalinity is called “alkalosis”.
In short, we can say that acidosis happens when our metabolism generates excessively acidic products, and/or when the acidic products of our metabolism accumulate in the organs and tissues, causing damage.
Acidosis can be derived from different causes and processes, and so it has two different general classifications:
- Metabolic acidosis
- Respiratory acidosis
Metabolic acidosis happens when the acidic products accumulate (for example, if the kidneys can’t efficiently eliminate them through urine), or if we somehow lose the bases needed to balance the pH (like in severe diarrhea).
Respiratory acidosis happens when we can’t breathe properly, and the carbon dioxide isn’t eliminated by the lungs and starts accumulating (like in cases of chronic obstructive pulmonary disease).
Both alkalosis and acidosis are extreme situations, occurring as a result of severe conditions. For every other situation of pH fluctuation (which happens daily, by the way), the body has mechanisms to constantly balance the pH, thus preventing pH shifts from damaging tissues and organs.
How does the human body balance pH?
The body has several ways of keeping its pH within certain ranges, depending on the body area. This is necessary because both acids and bases can cause severe damage to tissues. Being able to keep our bodies functioning properly would be unthinkable if every piece of food we ate, every breath of air, every internal chemical reaction, significantly altered our pH at every minute. Life would be impossible to sustain. It’s required that the body keeps its internal balance at every instant, not letting every single external factor affect us. We call this pH homeostasis.
Maintaining bodily pH requires a constant, dynamic balance between the amounts of acids and bases, which are adjusted by the body at every moment.
There are several bodily mechanisms associated with pH maintenance scattered around the tissues and organs. Some rely on what we call buffer systems. These systems are capable of maintaining pH within relatively constant ranges, regardless of what happens in the surrounding environment, and even if external acids or bases are added to the mix (within certain limits, of course). One very well-known buffer system exists in the blood and, since blood pH is a very hot topic when it comes to acidity and cancer, let’s take a quick look at how that works.
The blood pH
The most important mechanism in maintaining blood pH is the carbonic acid-bicarbonate buffer system.
It’s a dynamic system composed of the water that’s in the blood plasma, and certain molecules/ions that are dissolved in it: carbon dioxide, carbonic acid (a weak acid), and bicarbonate (a base).
Its chemical representation is something like this:
So, in short:
- Some part of the carbon dioxide that is generated in the cells’ metabolism goes to the blood and dissolves in the water.
- This combination originates carbonic acid.
- Carbonic acid dissociates into hydrogen and bicarbonate.
- The double arrows (↔) indicate that the reactions are reversible, i. e., they can occur in one direction or the other, depending on the components that are lacking or are in excess, until it’s all completely balanced.
This is a system that is constantly, dynamically, moving.
So, when acid enters the bloodstream, this buffer system will provide bases to neutralize the acid. If a base gets in, the reaction will occur in the opposite way, with acids neutralizing the base. Therefore, the relative quantities of acids and bases in the blood can vary, depending on whether it’s necessary to neutralize acid or base excess, but keeping the blood pH always within a very tight range (usually around 7.4).
The balance of this buffer system, which will in turn balance the blood pH, is maintained through different mechanisms. Here I will give two examples:
- Our breathing, which controls the levels of carbon dioxide in the blood;
- Our kidneys, which can regulate the amounts of acid expelled in the urine and the reabsorption of bicarbonate ions to the bloodstream.
Both these mechanisms will move the balance of the system, as we saw in the equation before. These aren’t the only intervenients in the process, which is extremely complex, but are two good examples for showing how all bodily functions are interconnected. The balance of this buffer system moves according to the environmental conditions, but without letting the environment have too much influence over the blood pH, thus avoiding sudden and violent changes.
Now, besides the blood pH, usually another highly discussed topic is the cell pH.
pH inside the cells
And now it’s time to present a very important fact… (drumroll please)… no cell can survive if it’s too acidic or too alkaline. Both these types of environments lead to protein denaturation and destruction of biomolecules. This will essentially deregulate the entire cell metabolism until the cell dies.
Usually, a cell can keep its pH in balance, just like the blood and the other tissues. This is due to the existence of buffer systems, certain proteins, and mechanisms, which control the number of hydrogen ions present inside the cell.
Acidity and cancer: what’s the correlation?
The general idea that cancer development and progression are somehow related to acidic environments has been existing for a while now within the scientific community. Later it began to reach the general audience but was sometimes misinterpreted. The most invoked research in these “general audience” discussions, and which were also sometimes misinterpreted, is the one performed by Otto Warburg.
In 1931, Otto Warburg was awarded a Nobel prize for his studies on cellular respiration and the enzymes/mechanisms involved. In parallel studies, he also developed research on the metabolism of cancer cells, how the tumors evolve and progress, and which factors are involved in their survival. [This research was not the focus of his Nobel award… this is one example of a frequent misconception.]
The ‘Warburg Effect’, as it is known, tells us that cancer cells prefer using glucose (i.e., “sugar”) to generate energy, even if there’s enough oxygen available to perform cellular respiration. To this, we call ‘aerobic fermentation’ or ‘aerobic glycolysis’. “Normal” cells, on the other hand, prefer using oxygen since it’s a more efficient process.
And when glucose is used to produce energy, it’s usually through a process called ‘glycolysis’. One product that results from this metabolical pathway is lactic acid, or ‘lactate’. In normal circumstances, cells convert this lactic acid into pyruvate and carry on with the cellular respiration process, but cancer cells don’t. They just perform glycolysis, get the energy released from it, and get stuck with lactic acid, the end-product.
This and other reactions generate hydrogen ions and the lactic acid at incredible speeds, making the cells’ internal environment acidic. But, as no cell would survive like this, those products are exported outside the cells. This makes the environment surrounding the tumors… well, acidic.
This surrounding environment is thought to help cancer cells in many processes and survival mechanisms, such as evading the immune system, or weaken the surrounding tissues and allowing it to spread.
So, does this mean that cancer cells develop in acidic environments?
Well, not exactly. This suggests that acidic environments are the result of tumor development, not the cause of tumors.
In short, the evidence so far suggests that there’s indeed a correlation between acidity and cancer, and it seems of cause-and-effect. But the thing is, it’s not acidity that causes cancer… It’s cancer that causes acidity.
Studies of tumor pH have been performed extensively. This is a very complex system and there’s still much to study and discover, but I think it’s important we don’t fall for the “acidic — bad /alkaline — good” line of thinking.
For example, there are researchers who defend that acidity severely affects cancer cells and may, in fact, be a possible therapeutic approach in treating cancer. In fact, a study showed that inhibiting the mechanism that allows cancer cells to export lactic acid outside stops the tumor cells from growing and may lead to their deaths. On the other hand, other studies suggest that increasing alkalinity in tumor environments can affect their progression or improve the results of anti-cancer immunotherapy. But none of these methods presented here was extensively tested in humans yet, thus we’re still a bit far from being able to draw definite conclusions on any of the possible approaches.
In his studies, Warburg proposed that irreversible damage to the cellular respiration mechanism is responsible for leading these cells to use glucose to generate energy, even if there’s oxygen available, and that is ultimately the root of cancer development.
Meanwhile, hundreds of other studies on cancer were conducted after Warburg’s time, from many different perspectives and using different approaches. The current theories and observations suggest that DNA mutations and genetic alterations (which can be caused by several different factors) are most likely in the origin of the cell alterations, including those identified by Warburg, and cancer development.
In short, there are many things we know about the origin of cancer. And the most important is that it’s an intercorrelation of mechanisms, mutations, errors, changes, and other extremely complex alterations, in many different levels; not just one specific factor or alteration. If that were the case, cancer would be a lot easier to treat and cure.
Maintaining a healthy lifestyle and paying attention to the quality and the type of food we eat is certainly essential to naturally keep cancer at bay, and maybe even more important when fighting cancer. But it’s dangerous to assume certain alkaline methods can cure cancer, for example, when there’s no evidence for it, or that anything you eat can alter your blood pH to acidic and “give” you cancer. There’s currently plenty of research being conducted on these topics and absolutely none show any result of the sort.
It’s important to know how our bodies work and what the studies are really telling us. There’s still a lot we don’t know, and many of the things that we do know may change over and over. That is science. That is how knowledge is refined and consolidated. But to be able to receive new ideas, we must first understand the old ones.