Associations between food consumption patterns and saliva composition: Specificities of eating difficulties children

Identifying objective markers of diet would be beneficial to research fields such as nutritional epidemiology. As a preliminary study on the validity of using saliva for this purpose, and in order to explore the relationship between saliva and diet, we focused on clearly contrasted groups of children: children with eating difficulties (ED) receiving at least 50% of their energy intake through artificial nutrition vs healthy controls (C). Saliva of ED and C children was analyzed by various methods (targeted biochemical analyses, 2-D electrophoresis coupled to MS, ¹H NMR) and their diet was characterized using food frequency questionnaires, considering 148 food items grouped into 13 categories. Complete datasets were obtained for 16 ED and 16 C subjects (median age 4.7y and 5.0y, respectively) and the statistical link between salivary and dietary characteristics was studied by Multiple Factor Analysis (MFA). Overall, ED children showed as expected lower consumption frequency scores and higher food selectivity. The two groups of children differed in "diet/saliva" associations. Some distinctive salivary variables were common to both groups of children. For example, carbonic anhydrase 6 and the consumption frequency of biscuits & sweets and drinks were positively associated with the MFA axis 1 in C children, but oppositely associated in ED children. Specifically for ED children, abundant salivary proteins (cystatins, amylase, amylase fragments) and some metabolites (amino acids, galactose, lactate) correlated with axis 1, together with the consumption frequency of sauces & seasonings, bread & cereal products, ready-to-eat meals, fish, biscuits & sweets, drinks and potatoes. Specifically for C children, several proteins (serum albumin, haptoglobin, Igκ, apolipoprotein A-1, α-1 antitrypsin) correlated with axis 1, together with the consumption frequency of biscuits & sweets, milk & dairy products, drinks, fruit, meat and vegetables. This study demonstrates that the qualitative aspect of diet is linked to saliva composition, and that the associations between dietary consumption and salivary composition differ between groups of subjects with contrasted diets.