It’s cheap, it’s sitting in your kitchen cupboard, and the internet is full of claims about it. But what actually happens inside your body — and is daily use a good idea?
What Baking Soda Does in the Body
Baking soda is sodium bicarbonate — a compound that acts as a buffer, neutralising acid. That’s why a spoonful in water has long been used as a quick antacid for indigestion. Bicarbonate isn’t foreign to your body; it’s something your blood already carries as part of its natural acid–base buffering system.
What’s important to understand is that your body regulates blood pH within an extremely narrow range, and it defends that range fiercely using the lungs and kidneys. You cannot meaningfully “alkalise your blood” by eating or drinking something — if you could, you’d be seriously ill. What baking soda can genuinely change is the acidity of your stomach and your urine, and, in specific medical situations, the bicarbonate level in your blood.
Why It’s Linked to Kidney Health
Your kidneys are the organs primarily responsible for excreting acid and keeping your acid–base balance steady. When kidney function declines significantly, that job gets harder, and acid can accumulate — a condition called metabolic acidosis. It’s common in advanced chronic kidney disease and is associated with muscle loss, bone problems, and faster decline in kidney function.
This is the origin of the internet claim. Because doctors do sometimes prescribe sodium bicarbonate to correct metabolic acidosis in kidney patients, the idea spread that anyone can take it daily to “protect” their kidneys. That leap doesn’t hold up.
What the Research Actually Shows
The evidence here is genuinely mixed, and it’s worth being honest about that. Some studies have been encouraging: a 2024 meta-analysis of 14 randomised controlled trials involving 2,037 patients found that sodium bicarbonate supplementation significantly improved kidney function as measured by eGFR in people with CKD and metabolic acidosis.
But other high-quality research has pointed the other way. The BiCARB trial concluded that in patients aged 60 and over with advanced CKD, 1.5 to 3 grams of oral bicarbonate per day produced no health benefits and may have been associated with net harms — and its authors noted that bicarbonate therapy carries real risks including worsening high blood pressure and fluid overload.
The crucial point running through all of it: these studies involve patients with diagnosed kidney disease and confirmed metabolic acidosis, given measured doses under medical supervision, with regular blood monitoring. None of it is evidence that a healthy person should take baking soda daily.
The Sodium Problem Most People Overlook
Here’s the number that matters most. Half a teaspoon of baking soda contains roughly 600 milligrams of sodium — about a quarter of the recommended daily maximum of 2,300mg, and closer to 40% of the 1,500mg ideal limit for people with high blood pressure. That’s on top of everything else you eat.
Taken every day, that added sodium load can raise blood pressure, promote fluid retention, and place extra strain on the heart. And since high blood pressure is itself one of the two leading causes of kidney disease worldwide, a daily “kidney remedy” that pushes your blood pressure up is working directly against the goal.
Other Risks of Daily Use
- Metabolic alkalosis: Too much bicarbonate can tip the body’s balance the other way, causing nausea, vomiting, muscle twitching, tingling, irritability, and in severe cases confusion or irregular heart rhythms
- Electrolyte disturbances: Bicarbonate can lower potassium and affect calcium levels, which matters greatly for heart and muscle function
- Rebound stomach acid: Regular antacid use can prompt the stomach to produce more acid over time
- Medication interactions: By raising stomach and urine pH, baking soda can alter how various drugs are absorbed and excreted — including some antibiotics, aspirin, and certain heart and psychiatric medications
- Acute overdose risk: Large amounts taken at once have caused serious harm, particularly on a full stomach
Who Should Definitely Avoid It
- Anyone with high blood pressure or heart failure
- People with kidney disease — unless specifically prescribed and monitored
- People with liver disease or fluid retention
- Those on diuretics, corticosteroids, or sodium-sensitive medications
- Pregnant women, and children, without medical advice
- Anyone on regular prescription medication, without checking for interactions first
What Your Kidneys Actually Benefit From
The unglamorous truth is that kidney health is protected far more by consistent basics than by any single remedy:
- Controlling blood pressure and blood sugar — diabetes and hypertension cause the majority of chronic kidney disease
- Staying properly hydrated with water through the day
- Reducing processed salt, which is a far bigger sodium source than most people realise
- Eating plenty of fruit and vegetables, which naturally lower dietary acid load without a sodium hit
- Being cautious with painkillers — frequent high-dose NSAIDs such as ibuprofen can damage kidneys over time
- Regular check-ups, since early kidney disease is silent and only shows up on blood and urine tests
A word on herbal alternatives: teas and supplements marketed as “kidney cleanses” — including parsley, nettle and dandelion — are not well supported by evidence, and some herbal products can actually harm the kidneys or interact with medications. If you have any kidney concern, discuss supplements with a doctor rather than assuming natural means safe.
The Bottom Line
Sodium bicarbonate is a legitimate medical treatment for a specific, diagnosed problem — metabolic acidosis in kidney disease — where doctors can measure your blood levels and adjust the dose. It is not a general daily supplement, and taking it “just in case” gives you a meaningful sodium load, a real risk of upsetting your electrolyte balance, and no proven benefit if your kidneys are healthy.
If you’re worried about your kidneys, the most useful thing you can do isn’t reaching for the cupboard — it’s asking your doctor for a simple blood and urine test. Simple doesn’t always mean safe.
