What causes urine to smell like cabbage?

Causes of Cabbage-Like Smell in Urine

The primary cause of cabbage-like smell in urine is the consumption of cruciferous vegetables or asparagus, which contain sulfur compounds that are metabolized and excreted in urine.

Dietary Causes

Asparagus Consumption

• Asparagus contains sulfurous compounds that produce a distinctive cabbage-like odor in urine after consumption 1
• This phenomenon involves both the production of specific metabolites and the ability to detect them
• Individual differences exist in both the production of these odorants and the perception of the odor
• The inability to smell the odor is associated with a specific genetic variation (single nucleotide polymorphism rs4481887) within a cluster of olfactory receptors 1

Cruciferous Vegetable Consumption

• Cruciferous vegetables (broccoli, Brussels sprouts, cabbage, etc.) contain compounds that are metabolized and excreted in urine, causing distinctive odors 2
• S-methyl-L-cysteine sulfoxide (SMCSO) and related metabolites have been identified as urinary biomarkers of cruciferous vegetable consumption 2
• These vegetables contain:
  • Glucosinolates that can be hydrolyzed by certain gut bacteria
  • Dietary fibers that can be fermented by various bacterial species 3
  • S-Methylmethionine, which can generate dimethyl sulfide with a cabbage-like odor 4

Metabolic Pathways

Sulfur Compound Metabolism

• Cruciferous vegetables contain varying amounts of S-Methylmethionine:
  • Celery: 176 mg/kg
  • Fresh tomatoes: 2.8 mg/kg 4
• These compounds are metabolized and excreted in urine, producing the characteristic odor
• The metabolism involves gut bacterial communities that are altered by cruciferous vegetable consumption 3

Individual Variation

• The bacterial community response to cruciferous vegetables is individual-specific 3
• Specific bacterial species involved in this metabolism include:
  • Eubacterium hallii
  • Phascolarctobacterium faecium
  • Burkholderiales species
  • Alistipes putredinis
  • Eggerthella species 3

Clinical Significance

Distinguishing from Pathological Causes

• Cabbage-like odor in urine is typically benign when associated with dietary intake
• It should be distinguished from other urinary odors that might indicate pathology:
  • Foul-smelling urine may indicate urinary tract infection with organisms like Escherichia coli, which is the most common cause of UTIs 5
  • Cloudy or smelly urine alone should not be interpreted as indications of symptomatic infection 5

Monitoring and Management

• No specific treatment is needed for diet-related urine odors
• If concerned about urinary symptoms beyond odor (dysuria, frequency, urgency), evaluation for UTI may be warranted 6
• Urine culture is recommended before starting antibiotics if a UTI is suspected 6

Practical Implications

• Patients can be reassured that cabbage-like odor in urine following consumption of cruciferous vegetables or asparagus is normal and benign
• The odor typically resolves as the compounds are cleared from the system
• If the odor persists without dietary explanation or is accompanied by other urinary symptoms, further evaluation may be warranted

In summary, cabbage-like smell in urine is most commonly a harmless consequence of dietary choices, particularly consumption of asparagus or cruciferous vegetables, and reflects normal metabolic processes rather than pathology.