Fasting and postprandial ghrelin changes in older and younger volunteers

Little evidence is available on how both forms of ghrelin change during the aging process. Most of the earlier studies measured only total ghrelin levels and mainly in the fasting state. This study aimed to assess periprandial changes of acylated and deacylated ghrelin (AG, DAG) in volunteers aged ≥65 and <65 years and to establish an association between both forms of ghrelin and nutritional status in older volunteers.

Venous blood for serum AG and DAG assays were collected in sixty volunteers after an overnight fast and two hours after the consumption of a standard 300 kcal-mixed meal. In those aged 65 years or more nutritional status was assessed.

Levels of DAG and AG were lower in older compared to younger volunteers in the fasting state as well as postprandial. DAG levels after a meal decreased in older, but not in younger subjects. However, significantly higher levels of postprandial AG were found in subjects with a risk of malnutrition and those with reduced appetite in comparison to well-nourished ones. Interestingly, elderly subjects with the lowest insulin and BMI had the lowest fasting AG levels and subjects with too high BMI and hyperinsulinemia presented also the highest fasting AG levels.

In older subjects, levels of both forms of ghrelin were lower and differential postprandial AG and DAG responses were observed when compared to younger subjects.