Association between serum cotinine and α-Klotho levels among adults: Findings from the National Health and Nutrition Examination Survey 2007–2016

Abstract

INTRODUCTION Serum cotinine is a sensitive and specific marker of tobacco smoke exposure. α-Klotho is an anti-ageing molecule, which plays an important role in several diseases. We aimed to examine the association between smoke exposure indicated by the serum cotinine and α-Klotho levels, as previous reports regarding the level of α-Klotho in smokers have been inconsistent. METHODS This secondary dataset analysis included 9833 participants (aged 40–79 years; 47.0% females and 53.0% males) from the US National Health and Nutrition Examination Survey 2007–2016. Independent variables were serum cotinine level, age, sex, race, body mass index (BMI), and alcohol consumption. The outcome variable was serum α-Klotho level. Multiple linear regression analysis was used to examine the association between serum cotinine and α-Klotho levels. RESULTS The serum cotinine level was negatively associated with the α-Klotho level ( β = -0.107, 95% CI: -0.155 to -0.059, p<0.0001) after adjusting for age, BMI, sex, race, and alcohol consumption. The α-Klotho level in participants with cotinine ≥3 ng/mL decreased by 44.514 pg/mL (p<0.0001) compared to that in participants with cotinine <3 ng/mL. There is a non-linear relationship between serum cotinine and α-Klotho levels. The piecewise linear models indicated a significant threshold effect between serum cotinine and α-Klotho levels. On the left of the inflection point (cotinine <130 ng/mL), the serum cotinine level increased with decreased α-Klotho level ( β = -0.519, 95% CI: -0.682 to -0.356). On the right of the inflection point (cotinine ≥130 ng/mL), the serum cotinine level increased with increased α-Klotho level ( β =0.085, 95% CI: 0.000 to 0.170). CONCLUSIONS Based on our study results, serum cotinine level was associated with the serum α-Klotho level.

Relationship between oxidative balance score and serum Klotho concentrations in adults aged 40-79 years

“…Furthermore, another study based on a small sample of sedentary and healthy men (n = 22) found, interestingly, that moderate-intensity training, as opposed to sprint-intensity training, increased serum Klotho concentrations 31 . Yao et al analyzed the NHANES database data from 2007 to 2016 and found a signi cant threshold effect between serum cotinine and serum α-Klotho levels 32 .…”

Association between smoking, smoking cessation and serum α-klotho levels among American adults: National Health and Nutrition Examination Survey

“…In subgroup analyses, the p -value for the interaction between smoking and race on serum α-klotho levels was less than 0.001. Racial disparities may be linked to variations in tobacco brand preferences, smoking intensity, pharmacokinetics influenced by cytochrome P450 (CYP2A6) enzyme activity, and smoking habits [ 27 ]. The exact mechanism is unclear and needs to be further explored in subsequent studies.…”

“…Based on previous studies, the following covariates were included in this study: age, sex, race/ethnicity, body mass index (BMI) [ 24 , 25 ], alcohol status [ 26 , 27 ], hypertension [ 28 , 29 ], diabetes [ 12 , 30 ], stroke [ 31 , 32 ], liver disease [ 33 , 34 ], CVD (coronary heart disease, angina, or congestive heart failure) [ 5 , 13 ], CKD [ 35 , 36 ], chronic obstructive pulmonary disease (COPD) [ 37 , 38 ], and cancer [ 14 , 39 ]. The race/ethnicity categories consisted of non-Hispanic White, non-Hispanic Black, Mexican American, and other races.…”

The Longevity Protein Klotho: A Promising Tool to Monitor Lifestyle Improvements

“…Serum cotinine is a specific marker of smoking and reflects exposure to nicotine. The levels of klotho decrease as smoke exposure increases, then it reaches a tipping point where klotho levels start to increase [102]. Further research on the effect of cigarette use on klotho levels is needed.…”