Nonalcoholic fatty liver disease (NAFLD) is a global public health problem, with a dramatic increase in the number of deaths from NAFLD patients worldwide over the past 30 years. Cardiovascular disease (CVD) is the leading cause of death in patients with NAFLD, so it is particularly important to reduce the burden of disease and the risk of death from NAFLD. Niacin, also known as vitamin B3, is a precursor to the synthesis of nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), both of which play important roles in a variety of cellular metabolic reactions, energy metabolism, and redox reactions. Recently, studies have explored the association between dietary niacin intake and the risk of all-cause mortality and cardiovascular mortality in patients with NAFLD.
1. Research Methodology
Studies used United States National Health and Nutrition Examination Survey (2003-2018) data. A total of 4315 adults aged ≥ 20 years with NAFLD were included, and the subjects were divided into three groups according to niacin intake: low intake group (≤18.4mg/day), medium intake group (18.5~26.6mg/day) and high intake group (≥26.7mg/day). Three models were constructed. Model 1 did not adjust for any covariates. Model 2 adjusts for age and gender. Model 3 adjusted for race and ethnicity, education level, household income and poverty rates, smoking status, BMI, total energy intake, diabetes, hypertension, dyslipidemia, dietary supplement use, and the ratio of HDL cholesterol to total cholesterol. Risk ratios and 95% confidence intervals for all-cause and cardiovascular mortality were estimated using a weighted Cox proportional hazards model.
2. Findings
1. Niacin intake is associated with all-cause mortality and cardiovascular mortality
During follow-up, a total of 566 deaths were recorded, of which 197 were due to CVD. In model 1, the HR for all-cause mortality was 0.47 (95% CI, 0.36-0.63), P<0.001, compared with the low-niacin intake group. In model 3, after multivariate adjustment, the HR for all-cause mortality was 0.70 (95% CI, 0.50-0.96), P = 0.03, compared with the low-niacin intake group.
In model 1, the HR of CVD mortality in the niacin high intake group was 0.42 (95% CI, 0.22-0.83), P = 0.008. In model 3, the HR was 0.87 (95% CI, 0.63-1.21) in the medium intake group and 0.65 (95% CI, 0.35-1.20) in the high-intake group, P=0.16 (Table 1).
Table 1 Risk ratios of all-cause mortality and cardiovascular disease mortality in patients with NAFLD
The dose-response association between niacin intake and all-cause and CVD mortality is shown in Figure 1. There was no clear nonlinear association between niacin intake and all-cause mortality or CVD mortality.
Fig. 1 Relationship between niacin intake and all-cause mortality and cardiovascular mortality in patients with NAFLD
2. Stratification and sensitivity analysis
There is a significant interaction between dietary niacin intake and diabetes and the risk of all-cause mortality. In the diabetes subgroup, the HR for all-cause mortality was 0.82 (95% CI, 0.50-1.35) for patients in the high-intake group compared with the low-niacin intake group. In the diabetic subgroup, the HR for all-cause mortality was 0.58 (95% CI, 0.35-0.95) for patients in the high-intake group compared with the low-niacin intake group. However, no significant interaction was found between niacin intake and any other hierarchical variable and the risk of all-cause mortality (Table 2).
Table 2 Relationship between niacin intake and all-cause mortality in different subgroups of patients with NAFLD
3. Conclusions of the study
The results of this cohort study of adults with NAFLD in the United States suggest that higher niacin intake may be associated with a reduced risk of all-cause mortality in patients with NAFLD. Studies have not found that higher niacin intake is associated with a reduced risk of CVD death. The dose-response relationship between niacin intake and reduction of the risk of all-cause mortality and CVD mortality in patients with NAFLD requires further research to determine the optimal intake.
Bibliography:
Pan J, Zhou Y, Pang N, Yang L. Dietary Niacin Intake and Mortality Among Individuals With Nonalcoholic Fatty Liver Disease. JAMA Netw Open. 2024 Feb 5; 7(2):e2354277. doi: 10.1001/jamanetworkopen.2023.54277. PMID: 38300619; PMCID: PMC10835509.
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