Figure 2.

The time–dose effect between the first meal and the prevalence of gallstones. The RCS curve based on the fully adjusted model was plotted to further explore the non-linear trend and threshold effect between the FMT and the presence of gallstones. Sex, age, race, education level, marital status, PIR, BMI, physical activity level, alcohol use, smoking status, diabetes status, hypertension status, energy level, protein intake, carbohydrate intake, dietary fiber intake, total fat intake, total saturated fatty acid intake, and cholesterol intake were adjusted. The red solid line represents the estimated values, and the shaded area represents the 95% CI. The intersection of the vertical black dashed line and the red solid line represents the inflection point. FMT, first meal time; PIR, ratio of family income to poverty; RCS, restricted cubic spline.