Weight loss surgery remains the most effective treatment for severe obesity. During weight loss surgery, the stomach is made smaller, or the top portion is connected to the lower small intestine to bypass a section of intestine. While these changes may cause protein maldigestion, the few studies so far have not been able to confirm this. Older patients may be particularly vulnerable to protein malabsorption after weight loss surgery as they already have reduced absorption, lower protein intake, and loss of muscle mass can be expected. Therefore, in one of my AGePOP studies, I plan to investigate the degree of protein digestion in older patients after weight loss surgery.

I aim to measure protein digestion precisely using a new tracer technique termed dual-isotope digestibility. In a nutshell, isotopes are variations of the same atom with a slightly different weight. For example, 99% of nitrogen atoms have a weight of 14 u, while only 0.3% are heavier at 15 u. This Nitrogen 15 atom is a stable isotope which is non-radioactive and safe to use in research. Amounts of heavier and lighter nitrogen atoms can be measured using a mass-spectrometer. When patients consume food in which the proteins are enriched with heavy isotopes, isotope levels in the blood can be used to measure protein digestion. In practice this is much more complicated, hence my trip to Nashville!

The Isotope Tracers in Metabolic Research course was started more than twenty years ago and is truly one of a kind. Vanderbilt University in Tennessee hosts the course, while the National Institute of Health acts as the main sponsor.