天然存在的碳和氮稳定同位素比率[13C/12C(CIR)和15N/14N(NIR)]是有前景的膳食生物标志物。由于这些候选生物标志物具有较长的组织停留时间，需要进行长期喂养研究以进行评估。
我们的目标是评估血浆,红细胞,以及作为鱼类生物标志物的hairCIR和NIR，肉，和含糖饮料（SSB）的摄入量在12周的饮食干预。
32名男性（年龄46.2±10.5岁；BMI：27.2±4.0kg/m2）在凤凰城的国立糖尿病，消化和肾脏疾病研究所（NIDDK）接受了12周的住院饮食干预，亚利桑那.鱼的影响，肉，和SSB摄入量对CIR和NIR进行了平衡因子设计评估，每个摄入因子在2个水平(存在/不存在)的情况下，背景饮食(50%碳水化合物，30%脂肪,20%蛋白质)。从基线开始每两周采集空腹血样，在基线和干预后收集头发样本。采用多元回归分析数据。
当饮食包括肉类（β=0.89，95％CI：0.73,1.05）和SSB（β=0.48，95％CI：0.32，0.64）时，血浆干预后CIR升高。当饮食包括鱼类（β=0.85，95％CI：0.64，1.05）和肉类（β=0.61，95％CI：0.42，0.8）时，干预后血浆NIR升高。红细胞和头发的结果相似。干预后RBCCIR和NIR与基线有很强的相关性，这表明12周后干预饮食的周转不完全。同位素周转率的估计进一步证实了红细胞的不完全周转。
CIR与肉类和SSB有关，和更强烈的肉。NIR与鱼和肉有关，和鱼更强烈。总的来说,CIR和NIR区分了膳食鱼类和肉类，和较小程度的SSB，表明它们作为美国饮食中摄入的生物标志物的潜在效用。需要使这些生物标志物更具特异性的方法。该试验在clinicaltrials.gov注册为NCT01237093。
Naturally occurring carbon and nitrogen stable isotope ratios [13C/12C (CIR) and 15N/14N (NIR)] are promising dietary biomarkers. As these candidate biomarkers have long tissue residence times, long-term feeding studies are needed for their evaluation.
Our aim was to evaluate plasma, RBCs, and hair CIR and NIR as biomarkers of fish, meat, and sugar-sweetened beverage (SSB) intake in a 12-wk dietary intervention.
Thirty-two men (aged 46.2 ± 10.5 y; BMI: 27.2 ± 4.0 kg/m2) underwent a 12-wk inpatient dietary intervention at the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) in Phoenix, Arizona. The effects of fish, meat, and SSB intake on CIR and NIR were evaluated using a balanced factorial design, with each intake factor at 2 levels (present/absent) in a common, background diet (50% carbohydrate, 30% fat, 20% protein). Fasting blood samples were taken biweekly from baseline, and hair samples were collected at baseline and postintervention. Data were analyzed using multivariable regression.
The postintervention CIR of plasma was elevated when diets included meat (β = 0.89, 95% CI: 0.73,1.05) and SSBs (β = 0.48, 95% CI: 0.32, 0.64). The postintervention NIR of plasma was elevated when diets included fish (β = 0.85, 95% CI: 0.64, 1.05) and meat (β = 0.61, 95% CI: 0.42, 0.8). Results were similar for RBCs and hair. Postintervention RBC CIR and NIR had strong associations with baseline, suggesting that turnover to the intervention diets was incomplete after 12 wk. Estimates of isotopic turnover rate further confirmed incomplete turnover of RBCs.
CIR was associated with meat and SSBs, and more strongly with meat. NIR was associated with fish and meat, and more strongly with fish. Overall, CIR and NIR discriminated between dietary fish and meat, and to a lesser extent SSBs, indicating their potential utility as biomarkers of intake in US diets. Approaches to make these biomarkers more specific are needed. This
trial was registered at clinicaltrials.gov as NCT01237093.
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