Biomarkers related to oxidative stress and obesity among volunteers participated in the fasting program

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This study aimed to determine whether changes in the biomarkers related to oxidative stress (e.g. urinary malondialdehyde (MDA) and 1,N⁶-ethenodeoxyadenosine (εdA)) and obesity (e.g. plasma leptin) among volunteers in participated the fasting program in South Korea. The study subjects consisted of 57 individuals (54 women and 4 men; mean age 29, range 15 ∼ 48 years old) who participated the fasting program (average 7.3, range: 3 ∼ 11 days). All the participants did not take in any foods except water during the fasting program. Fifty seven paired urine samples and 32 paired blood samples were collected. Levels of urinary 1-hydroxypyrene glucuronide (1-OHPG), as internal dose marker of diet containing PAHs were measured by synchronous fluorescence spectroscopy. Plasma leptin levels, as biomarker of obesity were measured by radioimmunoassay (RIA). Urinary MDA and εdA levels, as oxidative stress biomarkers were measured by HPLC and immunoaffinity-HPLC-fluorescence detection, respectively. Information on demographic characteristics, smoking status, alcohol consumption, and others were collected using a self-administered questionnaire. Body weight loss (average 4.6 ± 1.9 kg) was significantly correlated with fasting duration (n=57, r=0.70, p<0.01). The plasma leptin levels after the fasting (6.41 ± 3.33 ng/ml) were significantly lower than before the fasting (8.00 ± 3.92 ng/ml) (p<0.01). Urinary MDA levels after the fasting (0.19 ± 0.12 mg/g creatinine) were also significantly lower than before the fasting (0.39 ± 0.30 mg/g creatinine) (p<0.01). Urinary 1-OHPG levels after the fasting (0.03 ± 0.03 μmol/mol creatinine) were significantly lower than before the fasting (0.05 ± 0.05 μmol/mol creatinine) among only non-smokers (n=36, p=0.05). Although levels of urinary εdA were lower in post-fasting (5.23 ± 2.62 fmol/μmol creatinine) than in pre-fasting (5.70 ± 3.32 fmol/μmol creatinine) non-smokers, these differences were not statistically significant. These results suggest that the fasting reduces biomarkers related to oxidative stress and obesity (e.g. urinary MDA, 1-OHPG and εdA, and plasma leptin).