Why is soda harmful for patients with chronic kidney disease?

Why Soda is Harmful for Patients with Chronic Kidney Disease

Soda consumption, particularly sugar-sweetened colas, significantly increases the risk of CKD progression and should be completely avoided by patients with chronic kidney disease.

Primary Mechanisms of Harm

High Phosphoric Acid Content in Colas

• Cola beverages contain phosphoric acid that directly promotes kidney damage and urinary changes that accelerate kidney stone formation 1
• Consuming 2 or more colas per day increases the risk of chronic kidney disease by 2.3-fold (adjusted odds ratio = 2.3; 95% CI 1.4-3.7), with identical risk for both regular and artificially sweetened colas 1
• A systematic review confirms that sugar-sweetened soda consumption increases CKD risk by 58% (pooled RR 1.58; 95% CI 1.00-2.49) 2

Excessive Sodium Load

• Soda contributes to total dietary sodium intake, which directly contradicts the fundamental CKD management principle of sodium restriction to <2g/day (<90 mmol/day or <5g sodium chloride/day) 3, 4, 5
• The KDOQI 2020 guidelines explicitly recommend limiting sodium to <100 mmol/day (<2.3g/day) to reduce blood pressure and improve volume control in CKD patients 3
• Excess sodium intake worsens hypertension, increases proteinuria, and promotes volume overload—all of which accelerate kidney function decline 3

Simple Carbohydrates and Metabolic Consequences

• Sugar-sweetened beverages contain high-fructose corn syrup and simple carbohydrates that adversely affect lipoproteins, increase plasma triglycerides, and promote chronic conditions including diabetes, CKD progression, and obesity 3
• The American Heart Association/American College of Cardiology 2023 guidelines identify sugar-sweetened beverage consumption as directly associated with increased CVD events and all-cause mortality in secondary prevention populations 3
• Multiple healthy dietary components, including reduction in sugar-sweetened beverages, reduce all-cause death among patients with chronic disease 3

Metabolic Acidosis Contribution

Acid Load from Western Diet Pattern

• Soda consumption is part of the Western dietary pattern characterized by excess animal protein, cereals, and grains combined with low fruit and vegetable intake, creating an imbalance between nonvolatile acids and available alkali 3
• This imbalance leads to chronic low-grade metabolic acidosis that worsens as kidney function declines, accelerating kidney disease progression through multiple pathways including decreased nitric oxide production, increased endothelin-1 secretion, and stimulated angiotensin II production 3, 6, 7
• The acidosis from Western diet patterns (which includes soda) directly promotes interstitial sclerosis, renal fibrosis, and podocyte apoptosis 3

Displacement of Beneficial Foods

Reduced Fruit and Vegetable Intake

• Soda consumption typically displaces fruits and vegetables from the diet, which are critical for providing alkali (potassium citrate salts) to buffer nonvolatile acids 3
• Increasing fruit and vegetable intake (rather than consuming soda) significantly decreases systolic blood pressure, total body weight, net endogenous acid production, and urinary endothelin-1 excretion in CKD patients 3
• The Kidney International guideline recommends higher consumption of plant-based foods and lower consumption of ultraprocessed foods (which includes soda) 5

Fiber Deficiency

• Soda provides zero dietary fiber, and its consumption is associated with overall low fiber intake patterns 3
• Among adults with CKD, lower total fiber intake (<14.5 g/day) is associated with significantly increased mortality risk 3

Important Distinction: Cola vs. Non-Cola Beverages

A critical finding is that non-cola carbonated beverages were NOT associated with chronic kidney disease risk (OR 0.94; 95% CI 0.4-2.2), suggesting the phosphoric acid in colas is the primary culprit 1

Common Pitfall to Avoid

• Do not assume that artificially sweetened sodas are safe alternatives—they carry nearly identical risk as regular colas (adjusted OR 2.1; 95% CI 0.7-2.5 for artificially sweetened vs. 2.1; 95% CI 1.3-3.4 for regular) 1
• The meta-analysis showed artificially sweetened soda had a pooled RR of 1.33 (95% CI 0.82-2.15), which while not statistically significant, still trends toward harm 2

Clinical Bottom Line

Patients with CKD must eliminate all cola beverages (both regular and diet) from their diet due to phosphoric acid content, excessive sodium load, simple carbohydrate burden, contribution to metabolic acidosis, and displacement of beneficial plant-based foods 3, 5, 1, 2