Foods for the sexes: Differential digestibility of milk and plant-based drinks and proteins in healthy men or women

Aim:

Nutrition research is increasingly challenged to elucidate how consumer sex may affect the digestive fate of foods, particularly in an era of booming food innovations such as plant-based milk alternatives. This research explores how consumer biological sex affects the protein digestion of cow's milk (CM) compared to an oat milk alternative (OM) and concomitant protein isolates (i.e. isolated dairy proteins or oat proteins).

Methods:

This study utilized a recently developed in vitro digestion model that simulates digestion in males or females (Lajterer et al, 2022, Food Hydrocolloids). Various drinks and protein isolate suspensions were digested and digestive effluents analyzed using SDS-PAGE as well as dynamic and static light scattering techniques.

Results:

The study revealed notable differences in protein digestive trajectories between CM and OM, as well as between males and females. In CM digestion, caseins broke down efficiently in both sexes, while β-lactoglobulin showed higher persistence in females. On the contrary, OM proteins displayed greater persistence in males, suggesting less efficient digestion compared to CM. Zeta potential analysis highlighted CM's superior stability (-29 vs. -21-23 mV for OM) which could account for the observed digestive breakdown trajectories, but without explaining the noteworthy differences in the digestive proteolysis of the products between males and females. Interestingly, in males, CM gastric digestion exhibited greater stability compared to females (10 vs. 4.9 mV), indicating less interference with protein breakdown. Conversely, females demonstrated higher stability in OM digestion during the gastric phase, consistent with SDS-PAGE findings. Both CM and OM showed instability in the intestinal tract, suggesting potential aggregation and increased particle size, as supported by SLS data.

Conclusion:

This study emphasizes that sex-based differences in protein digestion may be an important consideration in the design of future foods. Notably, the findings herein suggest the potentially easier digestion of plant-based proteins from OM compared to CM, especially in females.