In our study, we first revealed the relationship between CKD in 1414 health check-up populations aged 18–88 years from Guangdong, China with lifestyle behaviors by the use of a 1:1 paired case-control study. The major finding of this study was that lifestyle behaviors including skipping breakfast ≥ three times per week, consuming baked food frequently, sleep efficiency ≤ 75% were risk factors for the development of CKD, while proper consumption of oil, aquatic product, soybean, and nuts contributed to prevent CKD. Furthermore, after adjusting the traditional risk factor, those lifestyle behaviors were still found to be associated with the incidence of CKD. The results underscored the importance of lifestyle behaviors in the management of CKD. Supporting evidence revealed that lifestyle behaviors had complicated associations with the risks of hypertension, CVD (stroke and heart failure), metabolic syndrome, cancer, T2DM, and CKD with T2DM. As we all know, diabetes, hypertension and obesity are important traditional risk factors for CKD. To develop targeted prevention strategies, it is important to investigate the nontraditional risk factors of CKD, such as lifestyle-related factors, which are likely modifiers of CKD risk. In a cross-sectional study enrolling 25,493 middle-aged participants, those with unhealthy lifestyles were more likely to have proteinuria. Ryoma Michishita et al found that changing from a healthy to an unhealthy lifestyle could significantly increase the incidence of CKD. Conversely, keeping healthy lifestyle behaviors, such as habitual moderate exercise and no bedtime snacking, was important to reduce the risk of CKD.
In our investigation, baked foods were first observed to be associated with CKD. In cases, the proportion of consuming baked food frequently was 1.683 times higher than that in controls. The specific mechanisms underlying the baked foods on the prevalence of CKD were unclear. One possibility was that high 18:2 trans fatty acids which were abundant in baked products were associated with increased risk of nonfatal myocardial infarction. Typically, CVD including nonfatal myocardial infarction was strongly associated with the development of CKD. Furthermore, the intermediate products of the Maillard reaction and caramelization, such as dicarbonyl compounds, which possibility increased the total body AGEs load which might lead to diabetes, obesity and renal failure[34, 35]. We also hypothesized that the acrylamide (ACR), commonly detected in the baked foods, was a risk factor for CKD. After exposure, ACR renal tubular cells undergo vacuolar degenerative changes, inflammatory cell infiltration, and periglomerular edema. The nephrotoxicity of ACR increased serum urea, creatinine, uric acid, and renal proinflammatory cytokine levels, while also inducing lipid peroxidation and DNA damage. Hence, we concluded that the increasing consumption of baked foods might impair renal function and promote the development of CKD.
To our investigation, the moderate consumption of the aquatic product was protective factors for preventing CKD. Admittedly, it is controversial whether aquatic product intake takes a positive effect on health or not. Fernanda Santin et al defined an "unhealthy" pattern including fish intake based on exploratory factor analysis in a cross-section study and concluded that "unhealthy" patterns lead to diminished renal function and developed CKD. While in a cohort study enrolling 4133 healthy individuals aged 18–30 years, Inwhee Park et al found that the intake of LCω-3PUFA, which mainly provided by fish, was inversely associated with the development of CKD.
Additionally, kipping breakfast was a risk factor for CKD, which was in line with previous studies. Then, individuals with moderate consumption of soybean and nuts were at a lower risk of CKD. Similar conclusion was found in a prospective cohort study including 15,792 white and black adults from four U.S. communities. Individuals with CKD were more likely to have a lower sleep efficiency. In a meta-analysis, Xiu HongYang et al confirmed that short sleep duration or sleep efficiency ≤ 75% were associated with increased mortality in CKD patients. In contrast, among African Americans, sleep quality could be improved by improving sleep hygiene behaviors. As for cooking oil, different kinds of cooking oil had different influences on diseases including renal function. In an animal model stereological study, the authors revealed that 20% sesame oil might lead to renal deformities. However, saturated FAts in animal oil caused insulin resistance which contributes to the development of CKD. Interestingly, in our work, the moderate consumption of cooking oil (25–30 ml/d) had a positive effect on the CKD prevention regardless of the type of cooking oil.
Several potential limitations should also be considered. First, collecting of lifestyle information based on self-reported questionnaires and retrospective data analysis were possibilities of information bias and recall bias. To reduce bias, trained researchers would relieve participants during progresses finishing the questionnaire. Graphic explanations next to the titles and reference photos with a standardized portion size for food consumption provided for individuals. Second, the data were incomplete for some individuals, which may result in misclassification of diagnosis. As the missing rate was lower than 12% and the original data set was large enough, using the predictive mean matching method to impute the data. Third, it had the potential for residual confounders from unmeasured demographics data such as educational attainment, marriage status and monthly household income.
The large sample size provided an opportunity to adjust for a large range of confounding. On one hand, some participants might have health checkups more than once because of the analysis including data from 2015 to 2018; on the other hand, they would change their lifestyle behaviors for keeping health after health examination. Only included the first biochemical test result, as well as CKD diagnosis. Especially, adult dietary habits remained stable. In this way, we could avoid the possibility of reverse cause and reduce the consistency between the cases and controls.