Does liver damage explain the inverse association between vitamin D status and mortality?

Area of Science:

• Biochemistry
• Epidemiology
• Public Health

Background:

• Observational studies indicate a correlation between vitamin D deficiency and increased all-cause mortality.
• Vitamin D deficiency is prevalent in individuals with liver diseases.
• The potential role of liver damage in the vitamin D-mortality relationship requires further investigation.

Purpose of the Study:

• To investigate whether liver damage, indicated by elevated liver enzymes, explains the inverse association between vitamin D status and all-cause mortality.
• To examine the relationship between vitamin D levels, liver enzyme levels, and mortality risk in a general population sample.

Main Methods:

• A cohort of 2649 individuals was studied, with data collected between 1993-1994.
• Serum 25-hydroxyvitamin D and liver enzyme levels were measured.
• All-cause mortality data were tracked until July 2011, with a median follow-up of 17.0 years.

Main Results:

• Higher vitamin D levels were associated with a reduced risk of all-cause mortality.
• This association remained significant even after adjusting for liver enzyme levels (HR, 0.96 per 10 nmol/L increase in vitamin D).
• The findings did not support the hypothesis that liver enzymes mediate the relationship between vitamin D and mortality.

Conclusions:

• The study did not find evidence that liver damage, as measured by liver enzymes, explains the link between low vitamin D status and mortality.
• The inverse association between vitamin D and mortality appears independent of liver enzyme levels in the general population.