Inadequate Niacin Intake Disrupts Growth and Retinol Homeostasis Resulting in Higher Liver and Lower Serum Retinol Concentrations in Male Rats

• Published in: The Journal of nutrition Vol. 153; no. 8; pp. 2263 - 2273
• Main Authors: Titcomb, Tyler J., Fathi, Fariba, Kaeppler, Mikayla S., Beatriz Sandoval Cates, Sofía, Falco Cobra, Paulo, Markley, John L., Gregory, Jesse F., Tanumihardjo, Sherry A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.08.2023; American Institute of Nutrition; American Society for Nutrition
• Subjects: Acclimation; Acclimatization; Adenine; Animals; Body weight; Diet; High performance liquid chromatography; Homeostasis; Humans; Intestine; Liquid chromatography; Liver; Liver - metabolism; Male; Males; Metabolism; Metabolites; NAD; Niacin; Nicotinamide; Nicotinamide adenine dinucleotide; Nicotinic acid; NMR; Nuclear magnetic resonance; nutrient interactions; Nutrient Physiology, Metabolism, and Nutrient-Nutrient Interactions; pyridoxal-P; Rats; Rats, Sprague-Dawley; Retinoids; Small intestine; Tryptophan; Vitamin A; Vitamin A Deficiency; Vitamin B; Vitamin deficiency; nutrient interactions; pyridoxal-P; MN; vitamin A; DSS; niacin; small intestine; DN; VA; AN; NAD(P)
• ISSN: 0022-3166; 1541-6100; 1541-6100
• DOI: 10.1016/j.tjnut.2023.06.026

Niacin-derived nicotinamide adenine dinucleotide is an essential cofactor for many dehydrogenase enzymes involved in vitamin A (VA) metabolism. Several countries with high prevalence of VA deficiency rely on maize, a poor source of available niacin, as a dietary staple. This study evaluated the interaction of dietary niacin on VA homeostasis using male Sprague-Dawley rats, aged 21 d (baseline body weight 88.3 ± 6.6 g). After 1 wk of acclimation, baseline samples were collected (n = 4). Remaining rats (n = 54) were split into 9 groups to receive low tryptophan, VA-deficient feed with 3 different amounts of niacin (0, 15, or 30 mg/kg) and 3 different oral VA doses (50, 350, or 3500 nmol/d) in a 3 × 3 design. After 4 wk, the study was terminated. Serum, livers, and small intestine were analyzed for retinoids using high-performance liquid chromatography. Niacin and metabolites were evaluated with nuclear magnetic resonance. Plasma pyridoxal-P (PLP) was measured with high-performance liquid chromatography. Niacin intake correlated with serum retinol concentrations (r = 0.853, P < 0.001). For rats receiving the highest VA dose, liver retinol concentrations were lower in the 30-mg/kg niacin group (5.39 ± 0.27 μmol/g) than those in the 0-mg/kg and 15-mg/kg groups (9.18 ± 0.62 and 8.75 ± 0.07 μmol/g, respectively; P ≤ 0.05 for both). This phenomenon also occurred in the lower VA doses (P ≤ 0.05 for all). Growth and tissue weight at endline were associated with niacin intake (P ≤ 0.001 for all). Plasma PLP correlated with estimated niacin intake (r = 0.814, P < 0.001). Optimal niacin intake is associated with lower liver VA and higher serum retinol and plasma PLP concentrations. The extent to which vitamin B intake affects VA homeostasis requires further investigation to determine if the effects are maintained in humans.