Have you ever heard about the acidic or alkaline nature of urine?
Probably you know that your urine is acidic in nature.
If you have ever noticed your routine urine analysis report, you must have seen the word ‘acidic’ or ‘alkaline’ in the report.
You might have got the term “pH of urine”. But what do you think about it? Is there any relationship between urine pH and urinary tract infection? Acidic or alkaline, which one is good to prevent UTI? Does it affect the efficacy of antibiotics used for treating UTI?
In this article, we will try to find the answer to those questions.
Before going to the main point, we will discuss in brief the acidity and alkalinity of the urine and the pH of urine first. Then we will talk about the effect of urinary pH on UTI and its treatment, the target pH to prevent UTI, etc.
The topic is a bit complex and controversial. Please read carefully with patience. Be assured that you will easily understand it.
What is the pH of urine?
At first, let’s talk about the pH scale first.
You will get this term frequently when we discuss acidity and alkalinity.
To be simple, pH is the measurement of the acidity or alkalinity of any fluid.
It is calculated as the negative logarithm of hydrogen ion concentration.
The more the concentration of hydrogen in a fluid, the more acidic it is.
The ph scale ranges from 0 to 14. The lower the value, the higher the acidity is.
And as the value increases, the acidity decreases. pH 7.0 is the neutral pH and after that, it becomes alkaline. The pH of pure water is 7.0 which is neutral. Like all other body fluids, the urine has a pH value too. The normal value of urine ph is around 6. That means, it is slightly acidic in nature. But, any pH value between 4.5- 8.0 is considered normal depending on diet and physical activity.
The pH value of urine changes frequently depending on a lot of factors. That means the acidity or alkalinity of your urine is not constant.
One of the functions of your kidney is to maintain the acid-base balance of the body. If the acid load of the body increases, your body tries to balance it by excreting acidic substances via the kidney.
So the pH of urine decreases and it becomes acidic. And the opposite actions take place in alkalosis leading to the production of alkaline urine.
If you understand this mechanism, you will understand the cause of variations in urine pH. The pH of urine is dependent on the time of day, the prandial state, diet, health status, and medications.
Urinary pH exhibits a diurnal variation with decreased pH values at night and in the early morning (most acidic towards midnight) followed by increasing pH values upon awakening.
Urine tends to become alkaline immediately after a meal because of a phenomenon known as the alkaline tide and gradually becomes acidic between meals.
These are the physiological causes of variations in urinary pH. But there are some diseases or pathological causes which may bring change in pH.
We are not going to discuss everything in this article. We will just discuss the effect of urinary pH on the incidence and treatment of UTI.
Does urinary pH have an effect on UTI?
It is really a debated topic. Acidity or alkalinity, which one is good to prevent UTI?
The answer is not straightforward. There are controversial opinions from scholars and there are different kinds of hypotheses.
According to some experts, the acidic pH of the urine helps to prevent urinary tract infection. Because, the growth of many bacteria, including Escherichia coli, is inhibited in acidic medium.
As Escherichia coli is the principal organism to cause UTI in adults, acidic urine plays a major role in preventing UTI.
And some studies show that urinary tract infection is more common in people with alkaline urine. It is found more in cases of diabetic patients.
A study with diabetic patients shows that the alkalinity of urine increases with the duration of diabetes mellitus. The patients with long-standing diabetes mellitus excrete alkaline urine and are more prone to UTI.
But some other studies show that alkaline urine may help to reduce burning sensation and help to flush out the organism.
Why is this debate taking place?
Because different bacteria prefer different kinds of environments to grow.
Those bacteria who prefer an acidic environment, will not grow fast in alkaline urine. And those bacteria which grow in alkaline media, will not cause a severe infection in acidic urine. And most of the UTI is caused by Escherichiacoli which prefers an alkaline medium.
Does urinary pH change during UTI?
Yes, like many other diseases, urinary tract infections may lead to a change in pH.
It is found that during UTI the pH is raised in many patients. That means it becomes alkaline.
It is caused by different factors like bacterial metabolism, inflammatory reaction, etc. You may think that this will promote further infection. In one sense, you are right. But there are some other facts too.
The alkaline pH helps many antibiotics to work efficiently which will be discussed later. But, this finding is not consistent. In many patients, the urinary pH is found mildly acidic or near neutral.
Actually, the production of urine is a complex process and the nature of urine depends on body physiology, diet, exercise, and coexisting conditions.
So, the change of urinary ph differs from person to person. That’s why no consistent data regarding pH change during UTI is found.
Does urinary pH affect the defence mechanism of the body against UTI?
Yes, recent studies suggest that the pH of urine affects the defence mechanism of the body against UTI.
Traditionally it was thought that, the more acidic the urine, the more the inhibition of bacterial growth. But modern studies proved something different.
A study was done at Washington University in St. Louis to investigate the immune mechanism against UTI. They found that the cells in the urinary tract secrete an antimicrobial protein called siderocalin(SCN) during UTI.
The siderocalin or SCN inhibits bacterial proliferation in the urine.
The study was done to evaluate the influence of pH on the antimicrobial effectiveness of SCN. It was found that in less acidic urine, closer to neutral Ph(around 6.0), SCN has stronger activity than more acidic urine.
And the SCN activity gradually declines if the urinary pH shifts to either direction.
That means if the urinary pH is more than 7.0, or far less than 6.0, the SCN activity worsens. Please note this point. It will help you to understand the answer to the key question of this article.
Is there any relationship between urinary pH and antibiotic efficacy?
This is another important point to be discussed.
We all are familiar with antibiotics used for treating urinary tract infections.
The effect of many antibiotics is pH-dependent. Some groups of antibiotic work best in acidic urine, and some shows optimal efficacy in alkaline urine.
As an example, the effect of erythromycin is limited to Enterococcus bacteria in acidic urine. But when used in alkaline urine, its efficacy extends to gram-negative bacilli (a group of bacteria species) like E. coli.
One of the most commonly used antibiotics against UTI is the cephalosporin group(e.g cefuroxime, ceftriaxone, etc).
It shows optimal antimicrobial effect in acidic urine with pH 5-6. But when the urine becomes more alkaline having pH more than 6.0, the efficacy is decreased.
Among other antibiotics the fluoroquinolones (e.g. ciprofloxacin), co-trimoxazole, azithromycin all functions optimally at alkaline pH.
Whereas the tetracyclines, nitrofurantoin, and many of the β-lactams(e.g. cefuroxime) exhibit their highest activity under more acidic conditions.
On the other hand, Sulfamethoxazole, oxacillin, amoxicillin, and clavulanic acid, vancomycin, imipenem, and clindamycin are largely unaffected by pH. That means they work irrespective of urinary pH.
This phenomenon is very important to choose the best antibiotic for you. Because, if the antimicrobial effect is reduced by pH, the treatment may fail. This may also increase antimicrobial resistance.
Usually, in mild UTI, neither you nor your doctor will bother about urinary pH before selecting the antibiotic. And that is not commonly required to do. But in complicated UTI or recurrent UTI, it should not be forgotten.
What should be the target pH to prevent UTI?
Now, you have got some information about the relationship of urinary pH and UTI.
What do you think now? Should we try to change our urinary pH to prevent UTI? Which one is better? Should we try to maintain an acidic pH? Or, should we try to make the urine alkaline?
Lots of debate exist there.
you already have read the merits and demerits of both acidic and alkaline pH.
It is suggested that you shouldn’t do anything to change pH unless required.
Just think a little, your body systems work in a way that equilibrium is maintained everywhere. So, what happens in a healthy body in physiological conditions, shouldn’t be interfered.
Usually, our body maintains a slightly acidic pH of urine( pH around 6.0).
You have already noticed that the siderocalin or SCN works best in this pH.
This is the best pH range of urine and it should be maintained.
Too much acidic urine may lead to stone formation in kidneys. And too much alkaline urine may promote bacterial growth.
So our target pH should be around 6.0 in a healthy status. However, in a diseased condition, we may need to alter the pH by medication for treatment purposes.
Does the alkalinization of urine help to cure UTI?
You probably have noticed that doctors often prescribe drugs like potassium citrate to reduce the acidity of urine.
You may have listened to the advice to take citrus foods like lemon, orange, etc during UTI.
These fruits also reduce the acidity of urine. (You may be astonished knowing that those acidic fruits do alkalinization of urine. But it is true and proved in scientific research.)
However, you may ask why this is done? Why we are trying to make the urine more alkaline when it is clear from the previous discussion that slightly acidic pH is better to prevent UTI?
This is done mainly to improve UTI symptoms.
There is no reliable study that shows that urine becomes more acidic during UTI. Rather, the urine may be neutral or alkaline during UTI in some cases.
So, we take alkalinizing foods and drugs not to neutralize the excessive acidity of the urine. We are just making the urine more alkaline.
Actually, the presence of bacterial end products and inflammatory reactions during UTI increases the activity of the bladder.
So, the patients suffer from urgency, frequency of urination, burning sensation, etc. And it is found that alkalinization of urine reduces the severity of these symptoms to a great extent.
But it can’t kill the invading organisms and antibiotics are required to cure the infection.
Note: there are opinions that contradict what is said in this last segment especially about the urinary alkalinization topic, both groups of opinions have evidence so it’s up to the reader to decide, you can see the different opinions in this article.
How do you know if your urine is acidic?
Well, you must observe the color of your urine if it’s dark yellow or somewhat near dark yellow then it means that the urine is acidic, also it means that you need to drink more water because the yellow to dark yellow color of the urine means 2 things:
1. the urine is acidic
2. you are somewhat dehydrated so you need to drink more water these two conditions make the best conditions for the formation of kidney stones and salts.
So, by just simply drinking normal water, it will hydrate the urine and will make the color of the urine transparent to pale yellow (which is the optimal color for the urine) and also will decrease the acidity of the urine.
So, unless if you made a urinalysis test and the result showed that your urine was very acidic then you will need to drink alkaline water otherwise you will be O.K. with regular water.
By giving the person who suffers from more than normal acidic urine by giving him alkaline water (basic water) or a urine alkalinizing agent ( the alkaline water eventually makes the urine alkaline in other words basic, so does the alkalinizing agent) you will make the urine return back to its normal ph also you will increase his hydration and thereby you will decrease the probability of him getting a kidney stone or salts and also a UTI.
How do you know if your urine is alkaline or basic?
If you notice that the color of your urine is somewhat bluish-green or greenish-blue or something like that then your urine is alkaline or basic.
The normal ph of the urine ranges from 5.5 to 7.5, normally the urine is slightly acidic and there is no problem with that, the problem is when the urine becomes too acidic and that is what we advise you to be cautious from.
But, having a urine ph like 6.5 or 6 is nothing that you need to worry about, of course, the urine is still acidic at that ph but it’s within the normal range for every human being.
So, the key messages from the article are:
1. Your urine is slightly acidic in healthy status( having pH around 6.0) which is optimum for the body,s defence mechanism. So, it should be maintained to prevent UTI.
2. The pH of urine may affect the antimicrobial activity of the antibiotics used for treating UTI. So it should be considered when selecting antibiotics, especially in complicated cases.
3. Alkalinization of urine does not cure infections but helps to reduce UTI symptoms.