The putative benefits of this kind of diet for cardiovascular health are primarily correlative in nature; while they reflect a very real disparity in the geographic incidence of heart disease, identifying the causal determinant of this disparity has proven difficult.
这种饮食对心血管健康的(假定的)好处在本质上主要是相关的，而它们反映了地理发病率的现实差距？证明了这种差异的因果关系是非常难的。。
不管怎么翻译 都不通顺。。求大神帮忙看看 应该怎么理解这句话。