Dietary niacin may protect against death in NAFLD

Dietary niacin intake may benefit individuals with nonalcoholic fatty liver disease (NAFLD), with a study suggesting that a higher intake lowers the risk of mortality.

Data from the National Health and Nutrition Examination Survey (2003-2018) showed that daily niacin intake of ≥26.7 mg (highest tertile) vs ≤18.4 mg (lowest tertile) was associated with a 30-percent lower risk of all-cause mortality (hazard ratio [HR], 0.70, 95 percent confidence interval [CI], 0.50–0.96; p=0.03 for trend). [JAMA Netw Open 2024;7:e2354277]

There was no evidence of a link between higher dietary niacin intake and a decreased risk of death from cardiovascular disease (CVD; HR, 0.65, 95 percent CI, 0.35–1.20; p=0.16 for trend).

In subgroup analyses, participants with NAFLD with vitamin B₆ levels lower than 1.7 mg benefitted more from niacin, such that the third tertile of intake attenuated the risk of all-cause mortality by 74 percent compared with the first tertile of intake (HR, 0.26, 95 percent CI, 0.10–0.71; p=0.02).

Such finding, according to the investigators, is consistent with existing theories and has a sound biological basis. 

“Vitamin B₆ is required for the biosynthesis and metabolism of niacin, and low levels of vitamin B₆ reduce the conversion of tryptophan to niacin, making it even more important to increase dietary niacin intake,” they explained.

Meanwhile, higher niacin intake was more strongly associated with lower risk of mortality among patients with NAFLD without diabetes (HR, 0.58, 95 percent CI, 0.35–0.95) than among their counterparts who had diabetes (HR, 0.82, 95 percent CI, 0.50–1.35; p=0.04 for interaction).

The analysis included 4,315 participants with NAFLD (mean age 52.5 years, 55.0 percent men, 67.2 percent non-Hispanic White). Over a median follow-up of 8.8 years, 566 deaths were recorded, of which 197 were attributed to CVD.

Of the participants, 33.37 percent were in tertile 1 of dietary niacin intake (≤18.4 mg per day), 33.40 percent were in tertile 2 (18.5–26.6 mg per day), and 33.23 percent were in tertile 3 (≥26.7 mg per day). Participants in the higher vs lowest tertile of niacin intake were younger, more often male, had higher levels of education and family income, lower high-density lipoprotein cholesterol levels, and higher total energy intake, alanine aminotransferase, and aspartate aminotransferase levels.

Higher niacin intake might lower mortality risk through nicotinamide adenine dinucleotide (NAD)+ levels, according to the investigators.

NAD+ levels are often dysregulated in medical conditions such as cardiovascular disease, obesity, and neurodegenerative diseases, they pointed out. In such cases, consuming less than 20 mg of niacin daily is enough to cover the basic requirements for NAD+ synthesis in the body. [Metabolism 2022;126:154923; Pharmaceuticals 2020;13:247; Cell Metab 2018;27:529-547; Annu Rev Nutr 2008;28:115-130]