Main Article Content
Evidence for potential effects of inorganic nitrate (NO3) on body weight is limited to inconsistent findings of animal experiments. In this systematic review and meta-analysis, we aimed to quantify the overall effect of inorganic NO3, administered via drinking water, on body weight gain in rats. We searched PubMed, Scopus, and Embase databases, and the reference lists of published papers. Experiments on male rats, reported data on body weight in NO3-treated animals and controls, were included for quality assessment, meta-analyses, subgroup analyses, and meta-regressions. Of 173 initially obtained studies, 11 were eligible to be included in the analyses, which covered the years 2004 to 2019 and included a total of 43 intervention (n=395) and 43 control (n=395) arms. Overall, the final body weights were significantly lower in the NO3-supplemented groups compared to controls (WMD= –16.8 g, 95 % CI= –27.38, –6.24; P=0.002). Doses of NO3 higher than the median (> 72.94 mg L-1 d-1) and longer NO3 exposure (> 8 weeks) resulted in greater mean differences (WMD= –31.92 g, 95 % CI= –52.90, –10.94 and WMD= –23.16 g, 95 % CI= –35.64, –10.68 g). After exclusion of experiments using high doses of NO3 (> 400 mg L-1 d-1), the overall mean differences in body weights between the groups decreased by approximately 37 % but remained statistically significant (WMD= –10.11 g, 95 % CI= –19.04, –1.19, P=0.026). Mean changes in body weight were affected by age, baseline values in body weight, and the duration of the studies. These preliminary experimental findings strongly support the hypothesis that NO3 can be considered as a natural anti-obesity agent.
This work is licensed under a Creative Commons Attribution 4.0 International License.
Authors who publish in this journal agree to the following terms:
- The authors keep the copyright and grant the journal the right of first publication under the terms of the Creative Commons Attribution license, CC BY 4.0. This licencse permits unrestricted use, distribution and reproduction in any medium, provided that the original work is properly cited.
- The use of general descriptive names, trade names, trademarks, and so forth in this publication, even if not specifically identified, does not imply that these names are not protected by the relevant laws and regulations.
- Because the advice and information in this journal are believed to be true and accurate at the time of publication, neither the authors, the editors, nor the publisher accept any legal responsibility for any errors or omissions presented in the publication. The publisher makes no guarantee, express or implied, with respect to the material contained herein.
- The authors can enter into additional contracts for the non-exclusive distribution of the journal's published version by citing the initial publication in this journal (e.g. publishing in an institutional repository or in a book).