Researchers at Arizona State University have introduced a new mathematical framework called the Digestion, Absorption, and Microbial Metabolism (DAMM) model, aimed at understanding how gut bacteria influence food's caloric value. Led by graduate researcher Taylor Davis and collaborating with the Biodesign Center for Health Through Microbiomes and the AdventHealth Translational Research Institute, the team's findings were published in PLOS One in May 2026.
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The DAMM model analyzes dietary energy across three key stages: the initial gross energy from macronutrients, the absorption of energy in the small intestine, and the colonic fermentation where bacteria break down remaining food residues into absorbable or excretable compounds.
Rosa Krajmalnik-Brown, the senior author, stated that digestion is a collaboration between humans and trillions of microbes. The model offers crucial insights into how these microbes impact human health and energy balance, emphasizing the significance of diet in supporting gut microbial health.
In a controlled clinical trial involving healthy adults, the team tested the model by comparing participants on a fiber-rich diet to those on a low-fiber Western diet. Results indicated that individuals consuming the Western diet absorbed an average of 116 more calories daily than those on the fiber-rich diet, despite both groups feeling equally full. The study showed that while approximately 85% of total usable energy is absorbed in the small intestine, gut bacteria in the large intestine extract the remaining 15%.
The trial highlighted that fermentation of unabsorbed fiber by gut bacteria produces short-chain fatty acids (SCFAs), which contributed about 140 calories daily, or around 7.4% of total energy intake. Even with increased SCFA production from a high-fiber diet, net caloric absorption was lower overall.
The adaptability of the DAMM model allows it to evolve as new data emerges regarding host-microbe interactions. Beyond improving nutritional calculations, the model is intended to assist scientists in studying metabolic disorders such as obesity and diabetes. In the future, healthcare providers might utilize this framework to create personalized nutrition plans based on how an individual's gut microbiome interacts with different foods.
Source: Davis, T.L. et al. “Modeling the microbial contribution to human energy balance using the Digestion, Absorption, and Microbial Metabolism (DAMM) model.” PLOS One (2026).