Leptin is associated with the size of the apolipoprotein(a) particle in African tribal populations living on fish or vegetarian diet

Objective: Apolipoprotein(a) [or apo(a)] isoform size, which is strongly genetically determined, showed significant association with the cardiovascular risk. Subjects on a fish diet have lower lipoprotein(a) levels, larger apo(a) isoform sizes and lower leptin levels than their vegetarian diet counterparts. We hypothesized that leptin may contribute to a potential association between the type of diet and the size of apo(a) isoforms. Methods: Anthropometric data, dietary nutrients, lipoprotein profile, plasma leptin levels, and apo(a) isoforms were evaluated in two related homogenous African tribal populations of Tanzania, one on a primarily freshwater fish diet (n=278), and the other on a vegetarian diet (n=326). Results: We observed a strong negative association between leptin levels and size of each of the apo(a) isoforms in both fish and vegetable diet groups, and in both genders. However, leptin was not associated with levels of lipoprotein(a). In multivariate analysis, a strong and independent association between leptin and size of apo(a) isoforms was observed. The size of apo(a) isoforms was strongly associated with high and low leptin states. Subjects with low leptins had 30% larger sizes of apo(a) isoforms than their high leptin counterparts. Conclusions: High leptin subjects have smaller, potentially more atherogenic, apo(a) isoform sizes than low leptin ones. We suggest that omega-3 rich diet can influence the levels of apo(a) and/or Lp(a) even though they are mainly genetically determined. These findings may have implications for understanding the interaction between leptin and cardiovascular risk.