What is Products of Protein Breakdown (Total)? High and low values | Lab results explained

Products of Protein Breakdown, which includes isovalerate, valerate and isobutyrate are produced by bacterial fermentation of proteinaceous material (polypeptides and amino acids) in the distal colon.

Products of Protein Breakdown (Total) is a set of markers of undigested protein reaching the colon [L]:

– Isovalerate

– Valerate

– Isobutyrate

It is derived from bacterial fermentation of protein in the distal colon.

Normal protein digestion and absorption is relatively complete in the stomach and small intestine.

Lower values:

May indicate:

– decreased protein intake

– imbalanced bacterial levels,

– or intestinal inflammation.

Higher values:

Increased fecal Products of Protein Breakdown may be due to:

– Underlying gastrointestinal conditions such as exocrine pancreatic insufficiency (maldigestion)

– Bacterial overgrowth of the small intestine

– Excessive delivery of protein to the colon, (ex: hypochlorhydria)

– Insufficient pancreatic proteases

– Excessive protein intake

– Increased colonic protein due to a GI bleed, excess mucus, bacterial overgrowth

May indicate protein maldigestion and malabsorption resulting in colonic protein fermentation, and/or excessive delivery of protein to the colon.

Assess for and treat root causes of insufficient protein digestion:

– Hypochlorhydria: Assess for/reduce use of acid-blocking medications (as clinically indicated). Consider addition of betaine HCl (=stomach acid hydrochloric acid). Please discuss with your doctor.

– Pancreatic exocrine insufficiency: Evaluate fecal PE1 and support with PERT (=Pancreatic enzyme replacement therapy). Please discuss with your doctor.

Assess for excessive delivery of protein to the colon:

– High-protein diet?

– Bacterial overgrowth?

– GI irritation/inflammation, bleeding?

Review, evaluate, and treat any abnormal inflammatory biomarkers and/or infection.

If these other biomarkers are also elevated, it is suggested to perform a SIBO breath test:


– n-butyrate

– Fecal fat (total)

– Methanobrevibacter smithii


– Protein origin of the volatile fatty acids isobutyrate and isovalerate in human stool. [L]


The information on is NOT intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice.

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