Specialised lab testing is not available for the assessment of stomach acid levels. Although a simple observational screening method sometimes used in clinical practice involves beetroot ingestion. 

Beetroot contains a natural red pigment known as betalain, which is responsible for its vibrant colour. In some individuals, a pink or red tint may be observed in the urine or stool after consuming beetroot. This phenomenon, known as beeturia, occurs in an estimated approximate of 14% of the population, and can provide insight into gastric acidity.

To perform this screening, consume approximately half a cup of fresh beetroot juice, ideally on an empty stomach. Over the following 24 hours, observe whether a red or pink hue appears in the urine or stool. The absence or presence of pigment offers an indication of stomach acid status.

This method relates to the chemical stability of betalain. Research shows that betalain remains colour stable within a pH range of approximately 3 to 7, with optimal stability around pH 5 to 6. However, at a highly acidic pH of approximately 1.5 to 2, which reflects typical healthy gastric acid levels, betalain undergoes chemical conversion into a yellow compound known as neobetanin. 

In individuals with adequate stomach acid, this conversion reduces the likelihood of visible red pigment appearing in the stool or urine. Conversely, when stomach acid levels are lower and gastric pH is higher, betalain is less readily converted and remains red, becoming detectable after digestion and absorption.

Repeat this assessment on a fortnightly basis to monitor relative changes suggestive of sufficient acid levels or hypochlorhydria over time

Urine and faecal