Correlation between salivary and serum oxidized LDL levels : a pilot study on overweight/obese subjects

Background: Saliva contains a variety of substances and could be functionally equivalent to serum in reflecting the physiological state of the body, including metabolic variations. Salivary samples are non-invasive, safe, and easier to handle than serum. Oxidized LDL cholesterol (oxLDL) is an additional cardiovascular risk factor playing an important role in atheromatous plaque formation; overweight/obese subjects present an increase in oxLDL concentrations. The aims of the study were to assess oxLDL salivary levels, if detectable, and to verify their possible correlation with serum in overweight/obese subjects. Methods: Thirty-five consecutive overweight/obese subjects and 10 normal weight controls were enrolled. Serum and salivary oxLDL levels were measured by a commercial enzyme-linked-immunosorbent assay (ELISA method). Results: oxLDL levels were detectable in salivary samples and correlated (P = 0.001) with serum levels. Overweight/obese subjects showed serum and salivary oxLDL levels higher than controls (P = 0.000 and P = 0.022, respectively). Conclusions: Our study showed the presence of oxLDL in salivary samples and highlighted a correlation between salivary oxLDL levels and their counterpart in serum. Moreover, salivary oxLDL levels were higher in overweight/obese subjects than in controls. Therefore, a salivary sample could be functionally equivalent to serum in monitoring cardiovascular risk in overweight/obese subjects.