The short answer: Sodium bicarbonate can help people with chronic kidney disease (CKD) who develop metabolic acidosis, a condition in which the blood contains too much acid or too little bicarbonate. It works by providing bicarbonate, which helps neutralize excess acid.
However, the claim that sodium bicarbonate definitively slows CKD progression is stronger than the current evidence supports. Some studies have suggested slower loss of kidney function, but larger and placebo-controlled trials have produced mixed results. Current KDIGO guidance therefore supports considering treatment for clinically important acidosis while emphasizing careful monitoring rather than treating bicarbonate as a proven kidney-preserving drug. (KDIGO)
What is metabolic acidosis in CKD?
Your kidneys help maintain the body’s acid-base balance. They remove acid generated by normal metabolism and help maintain an adequate level of bicarbonate, an important chemical buffer that neutralizes acid.
As kidney function declines, the kidneys may become less able to remove acid and maintain bicarbonate levels.
This can lead to metabolic acidosis.
A blood test commonly reports bicarbonate as serum bicarbonate or, on many chemistry panels, as CO2. These measurements are related but are not literally the same thing.
Metabolic acidosis becomes more common as CKD becomes more advanced, particularly in later stages. However, one low bicarbonate result does not automatically prove chronic metabolic acidosis. Diarrhea, certain medications, acute illness, laboratory variation, and other conditions can also lower bicarbonate.
Why does excess acid matter?
Persistent metabolic acidosis has been associated with several problems, including:
- Muscle loss and protein breakdown
- Reduced nutritional status
- Changes in bone and mineral metabolism
- Abnormal potassium levels in some situations
- Potentially faster CKD progression
There is an important distinction here: many of these relationships come from observational research, so an association does not prove that acidosis itself causes every outcome.
KDIGO notes that the biological rationale is strong, but the evidence that treating acidosis actually prevents kidney failure remains uncertain. (KDIGO)
How does sodium bicarbonate work?
Sodium bicarbonate is an alkali, meaning it can counteract acid.
When taken orally, bicarbonate increases the body’s available bicarbonate buffer. This can raise a low serum bicarbonate concentration toward the normal range.
In simple terms:
CKD → reduced acid removal → bicarbonate may fall → metabolic acidosis → sodium bicarbonate supplies alkali → bicarbonate can rise and acid-base balance can improve.
The goal is not to make the blood excessively alkaline. Treatment should bring bicarbonate toward the normal range, not above it.
Does sodium bicarbonate slow CKD progression?
This is where the title needs some qualification.
Earlier clinical trials, including the UBI study, suggested that treating metabolic acidosis with sodium bicarbonate might reduce CKD progression and improve clinical outcomes. (PubMed)
But subsequent evidence has been less convincing.
The 2024 KDIGO CKD guideline reviewed randomized trials and noted that placebo-controlled evidence has not confirmed an important reduction in the risk of kidney failure with oral sodium bicarbonate. The guideline therefore issued a practice point rather than a strong graded recommendation for treatment. (KDIGO)
So the most accurate conclusion is:
Sodium bicarbonate is an established way to correct clinically important metabolic acidosis, but it should not be described as a proven medication that reliably slows CKD progression in every patient.
Correcting acidosis may have benefits beyond kidney function, but the extent to which it prevents kidney failure remains an active area of research.
When might treatment be considered?
KDIGO 2024 advises considering pharmacological treatment, with or without dietary intervention, when CKD is associated with acidosis that has potential clinical consequences. It gives serum bicarbonate below 18 mmol/L in adults as an example of clinically important acidosis. (KDIGO)
This does not mean that everyone with a bicarbonate below a particular number automatically needs sodium bicarbonate.
Doctors may consider:
- Whether the low result is persistent
- The degree of reduction
- Kidney function and CKD stage
- Blood pressure
- Fluid status
- Sodium intake
- Potassium level
- Other illnesses
- Medications
- Possible causes of the low bicarbonate
A mildly abnormal result may require confirmation and evaluation rather than immediate treatment.
Why sodium content matters
Sodium bicarbonate contains sodium.
That matters in CKD because excess sodium can contribute to:
- Higher blood pressure
- Fluid retention
- Swelling
- Worsening heart failure in susceptible people
Therefore, sodium bicarbonate is not simply a harmless alkalizing supplement.
KDIGO specifically recommends monitoring treatment to ensure that bicarbonate does not rise above the normal range and that treatment does not adversely affect blood pressure, potassium, or fluid status. (KDIGO)
People with heart failure, difficult-to-control hypertension, or significant fluid retention may require particularly careful monitoring.
What about potassium?
The relationship between acidosis and potassium is complex.
CKD itself can impair potassium excretion, increasing the risk of hyperkalemia, or high blood potassium. Certain medications can increase this risk further.
Correcting metabolic acidosis may sometimes affect potassium levels, but sodium bicarbonate should not be considered a general treatment for high potassium.
If your potassium is abnormal, the cause and severity need to be evaluated separately.
Should you take baking soda for CKD?
Do not self-treat CKD-related acidosis with kitchen baking soda.
Sodium bicarbonate used medically is the same active chemical as baking soda, but the appropriate amount and need for treatment depend on laboratory results and your overall health.
Taking excessive sodium bicarbonate can cause excessive alkalinity and increase sodium exposure. It can also interfere with management of blood pressure or fluid balance.
Prescription or clinician-directed treatment is preferable because bicarbonate levels and other relevant laboratory values can be monitored.
What should be monitored during treatment?
A clinician may monitor:
- Serum bicarbonate/CO2
- Creatinine and eGFR
- Potassium
- Sodium
- Blood pressure
- Weight and signs of fluid retention
- Other electrolytes when appropriate
The trend matters.
For example, a bicarbonate result of 19 mmol/L means something different when it is a new isolated finding versus a persistent decline from 24 to 21 to 19 over several months.
Likewise, a rising bicarbonate after treatment does not automatically mean the kidneys are healthier. It may simply indicate that the acid-base abnormality has been corrected.
Can diet help?
Dietary approaches can sometimes contribute to managing metabolic acidosis, particularly diets emphasizing more plant-based foods in appropriate patients.
However, there is no universal CKD diet.
Potassium, phosphorus, protein, sodium, diabetes, CKD stage, medications, and blood-test results all influence dietary recommendations.
A diet that is appropriate for one person with CKD may be inappropriate for another, particularly if hyperkalemia is present.
What should you do if your bicarbonate is low?
If a kidney panel shows a low bicarbonate or CO2:
- Look at the previous results to see whether the abnormality is persistent.
- Review the result with your clinician rather than interpreting it alone.
- Consider other possible causes of low bicarbonate, especially if the change is sudden.
- Review medications and supplements with your clinician.
- If treatment is prescribed, monitor bicarbonate, blood pressure, potassium, and fluid status as advised.
- Do not increase sodium bicarbonate on your own simply because the latest value remains low.
A low bicarbonate result can be important, but one abnormal laboratory value does not tell the entire story.
When does CKD-related acidosis need urgent attention?
Metabolic acidosis can become serious when severe, particularly during acute illness or acute kidney injury (AKI).
Seek urgent medical attention for symptoms such as:
- Severe or rapidly worsening shortness of breath
- Confusion or unusual drowsiness
- Fainting
- Severe weakness
- Persistent vomiting
- Very low urine output
- Severe dehydration or rapidly worsening illness
Severe acidosis is not managed the same way as routine outpatient CKD-related low bicarbonate and may require hospital-based evaluation.
Bottom line
Sodium bicarbonate can correct metabolic acidosis in people with CKD, but it is not proven to prevent kidney failure in everyone who takes it.
The strongest reason to use it is to correct clinically significant acidosis, while balancing the potential effects of its sodium content on blood pressure and fluid balance.
Current KDIGO guidance emphasizes individualized treatment and monitoring rather than a blanket rule to treat every mildly low bicarbonate result. (KDIGO)
The practical question is therefore not simply “Should I take sodium bicarbonate?” but:
“Is my low bicarbonate persistent and clinically significant, what is causing it, and would the benefits of alkali treatment outweigh the risks in my particular situation?”