Interdepartmental Graduate Program in Nutritional Sciences, Department of Nutritional Sciences, University of Wisconsin-Madison, Wisconsin, United States.
Department of Biochemistry, University of Wisconsin-Madison, Wisconsin, United States.
J Nutr. 2023 Aug;153(8):2263-2273. doi: 10.1016/j.tjnut.2023.06.026. Epub 2023 Jun 22.
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.
烟酰胺腺嘌呤二核苷酸（NAD）是维生素 A（VA）代谢中许多参与的脱氢酶的必需辅助因子。一些 VA 缺乏症高发的国家以玉米作为主食，而玉米中烟酸的生物利用度较低。
本研究使用 21 日龄雄性 Sprague-Dawley 大鼠（基线体重 88.3±6.6 g）评估了膳食烟酸对 VA 体内平衡的影响。
适应 1 周后，采集基线样本（n=4）。其余大鼠（n=54）分为 9 组，接受低色氨酸、VA 缺乏饲料，并添加 0、15 或 30 mg/kg 的烟酸和 50、350 或 3500 nmol/d 的 3 种不同的口服 VA 剂量，采用 3×3 设计。4 周后，研究结束。使用高效液相色谱法分析血清、肝脏和小肠中的类视黄醇。使用核磁共振评估烟酸及其代谢物。使用高效液相色谱法测量血浆吡哆醛-P（PLP）。
烟酸摄入量与血清视黄醇浓度呈正相关（r=0.853，P＜0.001）。对于接受最高 VA 剂量的大鼠，30 mg/kg 烟酸组的肝脏视黄醇浓度（5.39±0.27 μmol/g）低于 0 和 15 mg/kg 烟酸组（分别为 9.18±0.62 和 8.75±0.07 μmol/g；均 P≤0.05）。这种现象在较低的 VA 剂量下也存在（均 P≤0.05）。终点时的生长和组织重量与烟酸摄入量相关（均 P≤0.001）。血浆 PLP 与估计的烟酸摄入量呈正相关（r=0.814，P＜0.001）。
最佳烟酸摄入量与较低的肝脏 VA 和较高的血清视黄醇和血浆 PLP 浓度相关。维生素 B 摄入量对 VA 体内平衡的影响程度需要进一步研究，以确定这些影响在人类中是否持续存在。
