Center for Alaska Native Health Research, Institute of Arctic Biology, Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, AK, USA.
Washington Health Research Institute, Kaiser Permanente, Seattle, WA, USA.
J Nutr. 2022 Sep 6;152(9):2031-2038. doi: 10.1093/jn/nxac101.
The natural abundance nitrogen stable isotope ratio (NIR) of whole tissue correlates with animal protein intakes, including meat and fish. Amino acid (AA) NIRs (NIRAAs) are more variable than the whole-tissue NIRs and may thus better differentiate among foods.
We evaluated whether NIRAAs were associated with intakes of fish and meat and whether these dietary associations were larger than with whole-tissue NIRs.
Men were recruited at the National Institute of Diabetes and Digestive and Kidney Diseases in Phoenix, Arizona, and randomly assigned to one of eight 12-wk inpatient dietary interventions, which varied the presence/absence of fish, meat, and sugar-sweetened beverages (SSBs) in all possible combinations. Fasting blood was drawn pre- and postintervention and plasma and RBC NIRAAs (free and protein-bound) were measured as secondary outcomes in 32 participants. Multivariable regression was used to determine responses of postintervention NIRAAs to dietary variables, and logistic regression was used to calculate receiver operating characteristic AUCs.
Most plasma NIRAAs increased with fish and meat intakes, but to a greater extent with fish intake. The largest increase in response to fish intake was plasma NIRLeucine (β = 2.19, SE = 0.26). The NIRThreonine decreased with both fish and meat intakes. Fewer RBC NIRAAs increased with fish intake, and only RBC NIRProline increased with meat intake. No plasma or RBC NIRAA responded to SSB intake. We identified fish intake with a high degree of accuracy using plasma NIRLeucine (corrected AUC, cAUC = 0.96) and NIRGlutamic acid/glutamine (cAUC = 0.93), and meat intake to a lower degree using plasma NIRProline (cAUC = 0.80) and RBC NIRProline (cAUC = 0.85).
Plasma and RBC NIRAAs were associated with fish and meat intakes but were not superior to whole-tissue stable isotope biomarkers in identifying these intakes in a US diet. This trial is registered at www.clinicaltrials.gov as NCT01237093.
全组织氮稳定同位素比值（NIR）与动物蛋白摄入量相关，包括肉和鱼。氨基酸（AA）NIR（NIRAAs）比全组织 NIR 更具变异性，因此可以更好地区分食物。
我们评估 NIRAAs 是否与鱼类和肉类的摄入量有关，以及这些饮食关联是否大于全组织 NIRs。
在亚利桑那州凤凰城的美国国立糖尿病、消化和肾脏疾病研究所招募男性，并将他们随机分配到八项为期 12 周的住院饮食干预之一中，这些干预在所有可能的组合中都不同地包含鱼类、肉类和含糖饮料（SSBs）。在干预前后采集空腹血样，并测量 32 名参与者的血浆和 RBC NIRAAs（游离和蛋白结合）作为次要结果。多元回归用于确定干预后 NIRAAs 对饮食变量的反应，逻辑回归用于计算接收器操作特征 AUC。
大多数血浆 NIRAAs 随鱼和肉摄入量增加而增加，但随鱼摄入量增加更为明显。对鱼类摄入量的反应最大的是血浆 NIRLeucine（β=2.19，SE=0.26）。NIRThreonine 随鱼和肉摄入量的增加而减少。较少的 RBC NIRAAs 随鱼类摄入量增加，只有 RBC NIRProline 随肉类摄入量增加。没有血浆或 RBC NIRAA 对 SSB 摄入量有反应。我们使用血浆 NIRLeucine（校正 AUC，cAUC=0.96）和 NIRGlutamic acid/glutamine（cAUC=0.93）以较高的准确性识别鱼类摄入量，并使用血浆 NIRProline（cAUC=0.80）和 RBC NIRProline（cAUC=0.85）以较低的准确性识别肉类摄入量。
血浆和 RBC NIRAAs 与鱼类和肉类摄入量相关，但在识别美国饮食中的这些摄入量方面并不优于全组织稳定同位素生物标志物。本试验在 www.clinicaltrials.gov 注册，编号为 NCT01237093。
