Publication date: 16 October 2019
What is already known about this subject:
- Obesity and fatty liver disease are common and exercise whilst often effective in the short term has limited long term effects in the real world
- Impaired availability of iron for incorporation in haemoglobin or other metabolic processes is common in chronic diseases including obesity and can reduce the likelihood of being physically active
- This study aimed to determine whether fatty liver disease is associated with impaired physical activity and iron availability for metabolism and may represent a potential future therapeutic target to improve weight reduction and exercise treatment in nonalcoholic fatty liver disease (NAFLD).
What this study adds
- We analysed physical work capacity at heart rate 170 beats/minute, ultrasound-determined hepatic steatosis, iron studies, haematological and metabolic parameters in 450 Gen2 males and 371 Gen2 females at age 17 years participating in the Raine Study. Physical work capacity was markedly reduced in participants with nonalcoholic fatty liver disease compared with those participants who did not have nonalcoholic fatty liver disease. The red blood cell parameters mean cell volume, mean cell haemoglobin, and serum iron parameters transferrin saturation and serum iron levels all showed significant inverse correlations with increasing body mas index (BMI) in those with nonalcoholic fatty liver disease which were absent in those without. The red blood cell parameters both correlated with physical work capacity, irrespective of fatty liver disease status.
- In this well-defined cohort of adolescents, nonalcoholic fatty liver disease is independently associated with decreased cardiovascular fitness. Given the strong correlation between transferrin saturation and physical work capacity in the fatty liver disease cohort, reduced availability of iron may be a novel explanation for this finding.