Although health disparities are well documented among minority populations, they have not been fully explained by socio-economic status. We have demonstrated that Puerto Rican elders in Massachusetts are significantly more likely to have physical disability, depression, cognitive impairment, diabetes and other chronic health conditions than do non-Hispanic white elders living in the same neighborhoods. This suggests that the disparity is not due only to physical or neighborhood location, and that other factors must be influencing these differences. In that study, we also showed that the Puerto Rican elders had diets that were limited in diversity and were relatively low in micronutrient content. In our ongoing cohort study within our Boston Puerto Rican Center for Population Health and Health Disparities, we are investigating the relationships between psychosocial stress, its effect on physiologic burden or "allostatic load" and, in turn, how this is associated with the functional outcomes previously identified as areas of health disparity: depression, cognitive impairment and functional limitation. We further propose that the association between life stress, physiologic response and chronic conditions is modified by nutritional status, with a focus on B vitamins and antioxidant vitamins.