B complex, calcium and potassium from food sources may protect against stroke

In this recent observational study published in Nutrition Research and Practice, Yongsoon Park and associates, of the Department of Food and Nutrition at Hangyang University in Seoul Korea, sought to elucidate which constituents in foods may account for findings in previous studies associating vegetable and fruit consumption with a reduction in stroke risk.  With regard to specific nutrients, Park acknowledges other research suggesting that decreased stroke risk has been associated with some, but not all antioxidants.  He also cites two randomized trials demonstrating no associations with reduced stroke risk and supplementation with some synthetic vitamins and antioxidant isolates.  Park notes that folate and B-vitamins from food, however, have received attention in recent studies as possibly protecting against stroke. 

Park writes the purpose of this study was to “test the hypothesis that intake of fruits and vegetables, which are major sources of antioxidant and vitamin B complex vitamins, reduces the risk of stroke.”

Subjects were recruited among patients admitted to Hanyang University Seoul Hospital for treatment of first event of stroke (n = 69) over a 20 month period.  The 69 participants were age, sex, and body mass indexed to healthy controls, and were not taking dietary supplements during the study period.  A semi-quantitative food frequency questionnaire (FFQ) including 117 food items common to Korean meals was administered for baseline dietary assessment.  Despite the statistically significant findings noted below, Park acknowledges limitations of the study: the small size of the food items accounted for, the small the number of subjects, and possible, unaccounted for residual confounding factors (such as socioeconomic status).

To quote, Park, the main results were as follows: “Multivariable-adjusted regression analysis showed that intakes of total fat, plant fat, calcium, potassium, vitamin B1, vitamin B2, vitamin B6, niacin, and folate were negatively correlated with the risk of stroke after adjusting for age, sex, BMI, and family history of stroke (Table 2). However, intake of antioxidant vitamins, such as carotene, vitamin C, and vitamin E was not associated with the risk of stroke.”  Writing further, Park observed “no association between intake of grain, fruits, seafood, milk and meat, and the risk of stroke.” 

Citing related findings the author speculated that the protective effects of vegetables, plants and plant fats (rich sources of B complex, calcium and potassium) may especially be due to the combined interaction of four relevant B vitamins needed to metabolize and in turn reduce levels of homocysteine; which, when elevated may be a risk factor for arterial endothelial dysfunction.  Park notes that clinical trials are needed to determine causality as well as clarify the actual mechanisms at work accounting for the inverse association observed between stroke risk and high vegetable intake.