Combined effects of vitamin D and cumulative dietary risk score on fatty liver and mortality in vulnerable individuals: a prospective analysis from the UK Biobank.

Frailty is a global public health issue associated with multiple adverse outcomes in later years, however, studies have shown exercise, diet, and vitamin D supplements can help reverse frailty. There is a lack of further risk stratification and evidence for secondary interventions in populations that have undergone primary prevention. This was a prospective cohort study involving 53106 physically active vulnerable individuals from the UK Biobank. We combined vitamin D with cumulative dietary risk scores to evaluate its predictive value. Correlation and predictive power were assessed using restricted cubic spline (RCS) analysis, corrected Cox models, stratified analysis, Kaplan-Meier analysis, and Harrell's c-index. During 12.7 years of follow-up, there were 870, 1317 new-onset metabolic dysfunction-associated fatty liver disease (MAFLD) and mortality. RCS analysis revealed a J-shaped negative or positive correlation in vitamin D and dietary risk score respectively. The hazard ratios (95% confidence interval) for MAFLD and mortality in the vitamin D deficiency and high dietary risk groups were 1.80 (1.45-2.24) and 1.99 (1.67-2.38), compared to those with no vitamin D deficiency and low dietary risk. Kaplan-Meier analysis suggested vulnerable individuals with vitamin D deficiency and a poor diet were at a higher risk of disease in the future. Further, separate analyses of vitamin D and dietary risk scores did not demonstrate better efficacy. The combination of vitamin D and dietary risk score offers a more effective method for assessing disease risk in vulnerable populations. This provides evidence for secondary guidance following exercise interventions, which is significant for older population.