Quantifying differences in bioavailability of different dietary proteins in older adults

Current protein recommendation and protein quality evaluation systems are typically representative for the general population of healthy young adults. However, it is known that the human body’s ability to digest proteins and absorb and utilize dietary amino acids is affected in older adults. We aim to quantify these differences in bioavailability, more specifically digestibility and metabolic availability, of different dietary proteins in older adults.

With the encouraged sustainable use of protein, special attention should be paid to the nutritive value of protein sources, particularly for groups in our society that are at risk of protein malnutrition. This entails not only consuming sufficient quantity of protein, but also paying attention to protein quality. Protein quality is influenced by the amino acid composition and bioavailability of a protein source.

Amino acid bioavailability upon aging

Up to now there is rather conflicting evidence on the effects of aging on the gastrointestinal tract and protein bioavailability. There are indications that chewing capacity, acid and enzyme secretions, gastric and small intestinal motility are diminished in older adults. These age-related adaptations can be readily applied to existing in vitro digestion models.  However, actual in vivo data are mostly dated and often measurements are performed in animals instead of humans.

This project

Therefore, we aim to investigate bioavailability of three dietary proteins in two different age groups. This project will make use of minimally invasive, stable isotopes to measure digestibility and metabolic availability. The dual tracer approach will be used to characterize amino acid digestibility of uniformly-labelled test proteins against that of a labelled reference. In a complementary manner, the indicator amino acid oxidation method will be used to determine metabolic availability of protein. These techniques will be applied in two separate clinical trials, that will include young healthy adults as well as a group of older adults.

This project is funded via the Top consortium for Knowledge and Innovation TKI AgriFood.