Metabolic and Diagnostic Perspectives on Secondary Lactose Intolerance in Infants Through Fecal Lactose Measurement and Gut Microbiome Analysis

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Secondary lactose intolerance (SLI) in infants is prevalent in China, primarily due to secondary lactase deficiency from mucosal damage.
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Infants with SLI show higher residual fecal lactose and lactate levels, alongside reduced fecal short-chain fatty acids, indicating incomplete lactose digestion.
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Microbiota profiling in SLI infants reveals significant depletion of Bacteroidetes and certain Firmicutes, indicating structural dysbiosis.
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In vitro fermentation assays demonstrate reduced acid and SCFA production in SLI samples, while lactate and gas production are significantly elevated.
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Residual fecal lactose may serve as a non-invasive indicator of SLI, providing insights into microbiota and metabolic features associated with the condition.

Frontiers In Immunology

by Jian Kuang, Mengmei Zhang, Xiangyu Bian, Xin Wang, Xiaoqiong Li, Qingbin Wu, Jinjun Li
April 21, 2026

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