Zinc bioaccessibility of foodstuffs after in vitro study in children with illnesses

Childhood is a life stage particularly sensitive to malnutrition, including obesity, celiac disease, and food allergies. Zn is an essential element in development, metabolism, and the regulation of inflammatory processes and oxidative stress.

Zn bioaccessibility (Zn-BA), an indicator of the fraction of Zn available for intestinal absorption, is commonly evaluated through in vitro digestion models. This study applied a novel in vitro digestion-fermentation method to assess Zn-BA in various raw and cooked foods using fecal inocula from children with gluten-related disorders (GRD-CH), obesity (OB-CH), and allergy/intolerance to cow's milk protein (AICM-CH).

The results showed that Zn bioaccessibility in the large intestine (Zn-BALI) values were significantly lower in these clinical groups compared to healthy children (P < 0.001). Mean Zn-BALI values in the large intestine of all foods in GRD-CH are significantly higher (34.7 ± 28.8%) than those determined in OB-CH (29.6 ± 30.1%) and AICM-CH (26.7 ± 30.4%) (P < 0.001). For allergic children, Zn-BALI in animal foods was significantly lower than in plant foods and in both plant and animal foods in the other children's groups (P < 0.05). Zn-BALI in animal foods cooked in liquid media (frying/boiling) was significantly higher than when cooked with hot air (roasting/grilling).

In children, the studied diseases diminished the Zn-BALI, which could negatively affect their appropriate long-term development. In sick children, the higher Zn-BALI in celiac children is probably related to differences in gut microbiota composition, as well as to different metabolites and ligands obtained by the fermentation processes, a fact that should be addressed in future studies.