A new study published in the journal Food Research International by researchers from Jiangnan University found that soy milk may be digested more efficiently than cow’s milk, with higher levels of fat and protein breakdown observed during simulated digestion.
The study looked at commercial soy- and cow-based milk products with similar compositions and structures, allowing researchers to compare how each behaved during the gastric and intestinal phases of digestion. The findings suggest that differences in protein composition and structure can play a major role in how these products are broken down and how nutrients become available to the body.
During the gastric phase, soy milk showed a lipolysis degree of 47%, higher than cow milk, while proteolysis was similar between the two at 15%. In the intestinal phase, soy milk again showed stronger results, reaching 90% lipolysis and 87% proteolysis. According to the study, this indicates that soy milk underwent more extensive fat and protein hydrolysis than cow milk during digestion.
Researchers also found that soybean products generally had higher fatty acid bioaccessibility, due largely to major differences between soybean oil and cow milk fat. The study says these contrasting fatty acid profiles led to clear differences in how nutrients became available during digestion.
Vitamin D results were more mixed. The researchers found that vitamin D had slightly higher gastrointestinal stability in soy milk than in cow milk, 52% compared to 50%. However, vitamin D bioaccessibility was the same for both at 50%.
The study also tracked lipid droplet behavior throughout digestion and found that changing microstructures likely influenced digestion kinetics as well. Researchers said the findings provide “an overview of digestive behaviors of plant- and animal-based milks and creams,” and may help support the development of future mixed plant-based milk products.
