A comparison of L-carnitine and several cardiovascular-related biomarkers between healthy vegetarians and omnivores

Objective: A plant-based diet has been associated with a reduced risk of cardiovascular (CV) diseases. This study aimed to determine the levels and correlations of CV-related biomarkers and the beneficial role of dietary habits. Methods: A total of 63 healthy vegetarians (n = 32) and omnivores (n = 31) were recruited. The baseline characteristics were recorded and measured (including lipid profiles, blood glucose, etc.). Liquid chromatography–mass spectrometry method was developed for the simultaneous determination of seven circulating CV-related biomarkers. Results: L-carnitine (L-Car), L-methionine, and ascorbic acid (AA) were significantly higher in vegetarians than in omnivores. In the vegetarians, L-Car had a negative correlation with triacylglycerols (P = 0.042) and blood glucose (P = 0.048) and a positive correlation with high-density lipoprotein cholesterol (P = 0.049). L-Car was also positively correlated with L-lysine (P = 0.009), L-methionine (P = 0.006), and AA (P = 0.035). The vegetarians’ AA also had a negative correlation with L-homocysteine (P = 0.028). In the omnivores, L-Car was negatively correlated with total cholesterol (P = 0.008), low-density lipoprotein cholesterol (P = 0.004), and high-density lipoprotein cholesterol (P = 0.038). Omnivores’ body mass index was positively correlated with L-homocysteine (P = 0.033), and age was positively correlated with trimethylamine N-oxide (P < 0.001) and blood glucose (P = 0.007), but not in vegetarians. Conclusions: Our results suggest that vegetarians have an elevated level of L-Car, which might be associated with endogenous biosynthesis and diet composition. Circulating L-Car might play an important role in CV protection, especially in vegetarians.