Is Baking Soda (Bicarbonate) Good for Your Kidneys?

Healthy kidneys excrete the acid produced by normal protein metabolism. In CKD this capacity falls, and acid accumulates in the blood (metabolic acidosis). It is one of the commonest complications of CKD stages 3b–5 — around 1 in 4 patients have serum bicarbonate persistently below 22 mmol/L.

Metabolic acidosis is associated with:

• Muscle wasting and weakness
• Bone loss (the body buffers acid with bone calcium)
• Worse cardiovascular outcomes
• Possibly faster CKD progression (mixed evidence)
• Hyperkalaemia (acid promotes potassium movement out of cells)

Correcting it is standard care. The question is how — and that's where the kitchen baking soda confusion starts.

• de Brito-Ashurst trial (2009, UK, 134 patients): oral sodium bicarbonate slowed CKD progression and reduced dialysis starts. This caused widespread enthusiasm for routine bicarbonate.

• UBI study (2019, Italy): similar findings — bicarbonate slowed eGFR decline.

• BiCARB trial (2020, UK, 300 older CKD patients): no significant difference in physical function or eGFR between bicarbonate and placebo at 2 years. Cooled the enthusiasm.

• KDIGO 2024 guidance: 'We suggest oral alkali in patients with CKD with serum bicarbonate < 18 mmol/L', and to consider in those between 18 and 22 mmol/L. This is a weaker recommendation than older guidelines.

The current honest position: correct acidosis when it's there, don't expect dramatic slowing of CKD, and don't take bicarbonate routinely without confirmed low blood bicarbonate.

Sodium bicarbonate is chemically the same molecule whether it's in a Sainsbury's tin or a pharmacy bottle. The difference is dose, presentation and how easy it is to overdose:

• Prescription sodium bicarbonate tablets: typically 500 mg or 600 mg per tablet. A common dose is 1 g three times a day = 3 g/day, giving ~ 820 mg sodium/day.
• Kitchen baking soda: ~ 4.6 g per teaspoon = ~ 1260 mg sodium per teaspoon. The 'pinch in a glass of water' that people see on TikTok delivers an unpredictable but often very large dose.

For a CKD patient with hypertension (most of them), adding 1–3 g of sodium daily on top of dietary salt is a recipe for raised blood pressure, ankle/lung swelling and breathlessness. There are case reports of:

• Severe metabolic alkalosis from overuse
• Hypokalaemia (alkalosis shifts potassium into cells)
• Acute fluid overload with hospitalisation
• Gastric rupture (rare but documented) from rapid CO2 release

Typical UK pathway:

• Routine CKD blood test shows persistent bicarbonate < 22 mmol/L (sometimes < 18 mmol/L using stricter criteria).
• Your renal team prescribes sodium bicarbonate tablets — often 500 mg–1 g three times a day.
• Blood is rechecked at 4–8 weeks; dose titrated.
• Blood pressure and fluid status are monitored — if BP rises or swelling develops, the dose may be reduced or another alkali (e.g. potassium citrate, calcium carbonate) considered.

Alternatives: increasing alkali-forming foods (fruit and vegetables) can help — though potassium must be balanced. The DASH-Sodium and PLANT-CKD studies suggest plant-based diets help correct acidosis without sodium load. Newer specific medications (veverimer) exist but are not routinely available on the NHS.

• Don't self-medicate with kitchen baking soda for kidney disease.
• If you have CKD stage 3b or worse, ask your renal team about serum bicarbonate at your next blood test.
• If you're prescribed sodium bicarbonate tablets, take them as directed; tell your team if you notice ankle swelling or worsening BP.
• For occasional indigestion: short-term, low-dose antacids (calcium carbonate, e.g. Rennie) are preferable to baking soda water — but if heartburn is a regular issue, see your GP.
• Don't take baking soda with any prescription medication without checking — it can change the absorption of several drugs (e.g. iron, some antibiotics, ketoconazole).
• Avoid the 'TikTok baking soda kidney detox' trend completely.