Letter by Tikhonoff et al Regarding Article, “Dietary Fiber Intake and Risk of First Stroke: A Systematic Review and Meta-analysis”

In a recent systematic review and meta-analysis published inStroke, Threapleton et al1 reported a significant inverse associationbetween risk of stroke and total dietary fiber intake in primaryprevention setting from the United States, Northern Europe,Australia, and Japan. These findings support recommendationsto increase dietary fiber intake. As a North–South gradient infruit and vegetable consumption exists, studies performed in theMediterranean diet area should also be taken into account. Indeed,the consumption of vegetables is higher in Southern, Central, andEastern Europe (≈250 g/d) than in Northern Europe (140 g/d).2Threapleton et al1 also claimed for future studies focusing on differencesin dietary fiber intake.Nutritional data recorded at a population level, recently publishedby our group in Clinical Nutrition, may be complementaryin such topic. In 1647 subjects representative of Italian generalpopulation, we have recently reported an inverse associationbetween the incidence of stroke and the dietary fiber intake in a12-year follow-up.3This association was present both for solubleand for insoluble fiber, and independent of age, sex, and classicatherogenetic risk factors. This is consistent with a recent metaanalysisby Chen et al4 on dietary fiber intake and risk of stroke,suggesting no significant difference between sexes.Our analysis also allowed us to identify 2 clear cut-off values,1 for soluble (>25 g/d) and 1 for insoluble dietary fiber (>47g/d), over which the risk of stroke was significantly lower. Thehighest incidence of stroke was detected in subjects intaking ≤25g/d soluble and ≤47 g/d insoluble fiber, whereas higher dailyintake of soluble or insoluble fiber, also separately, significantlyreduced both the incidence and the multivariate risk of strokein the follow-up. These cut-off values could, therefore, be consideredas the minimal recommendable daily intake of solubleand insoluble fiber, respectively, to prevent stroke at a populationlevel. Actually, they are higher than those commonly and arbitrarilyproposed as adequate by scientific societies. Unfortunately,the majority of people from small-income countries consumes <5portions of vegetables and fruit daily recommended by the WorldHealth Organization, with a trend toward decline also because ofincrease in the consumer price index