1988 · Wytock et al. — All Yogurts Are Not Created Equal
Super-Abstract
Not all yogurt brands are equally effective at helping lactose-intolerant people digest lactose — the key variable is the lactase activity of the bacterial cultures used. In eight lactose-malabsorbing subjects, breath hydrogen testing revealed that Dannon and Royal Maid yogurts significantly improved lactose absorption compared to plain lactose, while Borden yogurt did not. (The American Journal of Clinical Nutrition, 1988.)
Commentary
This study uses the breath hydrogen (H₂) test — a well-established diagnostic technique — to measure lactose malabsorption. When lactose is not absorbed in the small intestine, it reaches the colon where bacteria ferment it and produce H₂ gas; this H₂ is exhaled and measured in breath samples. Higher breath H₂ = more malabsorption; lower H₂ = better digestion. The paper's finding is that yogurt from different brands varies substantially in its capacity to reduce malabsorption symptoms because their bacterial cultures have different lactase activities. This is a gastroenterology and nutrition study; hydrogen appears only as the diagnostic measurement signal, not as a therapeutic agent. Notable limitation: no correlation between breath H₂ levels and gastrointestinal symptoms was found — suggesting symptom scores are not reliable proxies for absorption status.
Key quotes
- „The cumulative breath H2 and the area under the discontinuous curve of breath-H2 concentration decreased relative to lactose results after ingestion of Dannon and Royal Maid but not after Bordon yogurt.“ — the main finding: two brands improved lactose absorption, one did not
- „no correlation of symptoms with the degree of carbohydrate malabsorption was demonstrated.“ — important null finding: symptoms do not reliably track malabsorption
- „We conclude that the lactase activity of yogurt cultures varies among brands.“ — the practical conclusion
Our assessment
Important note on scope: This is a gastrointestinal diagnostic study using breath H₂ as a measurement tool. H₂ is the biomarker for fermentation, not the therapeutic agent. The study provides useful gastroenterology and nutrition data on yogurt brands and lactose malabsorption. The null finding on symptom correlation is clinically important. No H₂ therapy relevance: this paper does not study H₂ administration as a health intervention. Limitations: very small n (8 subjects); only 3 yogurt brands tested; no randomisation or blinding described; single-centre design.
Study design
- Type: crossover dietary challenge study · n: 8 lactose-malabsorbing subjects · H₂ use: end-alveolar breath H₂ as diagnostic biomarker for lactose malabsorption — not therapeutic H₂
- Result: Dannon and Royal Maid yogurt reduced breath H₂ vs. plain lactose (improved absorption); Borden yogurt did not; no correlation between breath H₂ and GI symptoms · H₂ therapy relevance: none
Abstract
Because of autodigestion of lactose by its endogenous bacteria, the lactose in yogurt is better absorbed than other sources of lactose in lactase-deficient subjects. To investigate possible differences among brands of yogurt in this autodigesting capacity, we challenged eight lactose-malabsorbing subjects with 20 g oral lactose and three different brands of yogurt (Borden, Dannon, and Royal Maid). As a quantitative measure of carbohydrate absorption, end-alveolar breath samples were collected for 8 h and assayed for hydrogen gas. Symptoms were scored by questionnaire every 30 min for 8 h. The cumulative breath H2 and the area under the discontinuous curve of breath-H2 concentration decreased relative to lactose results after ingestion of Dannon and Royal Maid but not after Bordon yogurt. no correlation of symptoms with the degree of carbohydrate malabsorption was demonstrated. We conclude that the lactase activity of yogurt cultures varies among brands.
Source & links
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