Relationship Between Circulating FGF21 and Physiological and Lifestyle Characteristics, an Exploratory Study

Fibroblast growth factor 21 (FGF21) is a biomarker that has been linked to metabolic health. This study was conducted to examine the relationship between FGF21 and its purported upstream regulators and downstream targets in healthy humans. Male and female participants completed three study visits. During visit 1 anthropometrics were measured and a VO _2peak test was conducted on a stationary bike. During visits 2 and 3 resting metabolic rate, heart rate, and blood pressure were recorded and a blood sample was taken. Results from visits 2 and 3 were averaged before statistical analysis. Additionally, participants completed a food frequency questionnaire to detail typical diet over the previous month and had three days of measured physical activity and sleep. Moderate correlations between FGF21 and measured sleep ( r = 0.34, p = 0.05), saturated fat intake ( r = −0.37, p = 0.04), and blood urea nitrogen levels ( r = −0.47, p = 0.01) were observed. Additionally, greater intensities of daily physical activity were associated with lower FGF21 levels. Serum FGF21 levels may be influenced by lifestyle variables such as sleep and physical activity, diet, and other circulating biomarkers.