Postprandial regulatory mechanisms in old age

Contact persons: Catrin Herpich, Prof. Dr. Kristina Norman

Although nutrition plays an important role in health in old age, the postprandial response - i.e. the reaction of the metabolism to a meal - in older adults has so far been insufficiently investigated. There are several indications that the postprandial response of older people differs from that of younger people. For example, it has been shown that muscle protein synthesis after a meal is reduced in older people. Furthermore, differences in the production of appetite-stimulating and inhibiting hormones after a meal were found in young adults compared to older adults. This leads, for example, to prolonged post-meal satiety in older people. Research into postprandial metabolic regulation in older adults thus contributes to our understanding of age-associated changes in digestion and metabolism.

An important regulator of metabolism is the fibroblast growth factor 21 (FGF21) produced in the liver. Due to its versatile functionality, FGF21 is also known as the longevity hormone. FGF21 is produced in animal models after a short period of fasting to regulate glucose and fat metabolism. Due to these properties, FGF21-like drugs have already been developed and their use is currently being tested in the treatment of e.g. type 2 diabetes or fatty liver.

Data on the association between fasting and FGF21 concentrations in human studies are, however, controversial. In a pilot study we found significantly higher FGF21 serum concentrations in old people compared to a young control group. The significance of these increased serum concentrations in older people has so far not been clarified. However, higher FGF21 levels in the mouse model are associated with reduced bone mineral density and loss of lean body mass.

In the POST study, we were able to show that postprandial response was significantly different in older study participants (Herpich et al. 2021). The dynamics following carbohydrates showed an age-associated rise after the initial decline while younger participants remained stable. The dynamics in the old was shown to be partly the result of the increased postprandial glucose levels in the old.

In order to better understand the role of postprandial response for health in old age, we want to further investigate the postprandial response of inflammatory and other metabolic parameters (blood lipids, hunger and satiety hormones) to test meals varying in macronutrient content in older compared to younger adults.