Folic acid for the primary prevention of stroke: a systematic review and meta-analysis

 And why the fuck was this research done? Your mentors and senior researchers are totally incompetent in knowing about previous research?

• folic acid (11 posts to February 2012)

Folic acid for the primary prevention of stroke: a systematic review and meta-analysis

Jianjian Yang¹Jia Wang²Bo Li³Yaxi Zhang^4*

• ¹Department of Cardiology, Wenzhou Central Hospital, Wenzhou, Zhejiang, China
• ²Department of Public Health, Weihai Maternal and Child Health Hospital, The Affiliated Weihai Second Municipal Hospital of Qingdao University, Weihai, Shandong, China
• ³Zhangcun Town Health Center in Huancui District, Weihai, Shandong, China
• ⁴Department of Neurology, Wenzhou Central Hospital, Wenzhou, Zhejiang, China

Objectives: Results from studies were inconsistent with regard to the effect of folic acid on the primary prevention of stroke. The aim of this study was to analyze the association between folic acid and the primary prevention of stroke using the data from observational studies and randomized controlled trials (RCTs).

Methods: Eligible publications published until June 2024 were searched in the database of PubMed, Web of Science and Embase. This study included all observational studies and RCTs of folic acid with first stroke as the reporting endpoints. Relative risks (RRs) and 95% confidence intervals (CIs) were pooled in the random-effects model to assess the effect of folic acid on the primary prevention of stroke.

Results: Results from 12 observational publications with 16 research, including 312,320 participants, were combined to explore the association between dietary folic acid intake and the primary prevention of stroke. The results showed that high dietary folic acid intake was associated with a 17% reduction in stroke incidence (RR:0.83; 95% CI: 0.73–0.94), and the effect of dietary folic acid was greater in areas without grain fortification (RR:0.80; 95% CI: 0.67–0.95). The pooled results from 12 RCTs, totaling 75,042 participants, indicated that folic acid supplementation was not associated with the stroke primary prevention (RR:0.92; 95% CI: 0.80–1.05), but folic acid supplementation was effective in areas without grain fortification (RR:0.78; 95% CI: 0.68–0.89).

Conclusion: Our meta-analysis demonstrated that dietary folic acid is effective in stroke primary prevention, and folic acid supplementation is effective in stroke primary prevention only in areas without grain fortification.

Systematic review registration: https://www.crd.york.ac.uk/PROSPERO/#myprospero, identifier CRD42024516991.

1 Introduction

Stroke is the leading cause of death and disability globally (1). There has been a twofold increase in the number of new strokes over the last 30 years, with around 795,000 strokes reported per year. On average, one person dies from a stroke every 3 min and 30 s (2, 3). Even those who survive a stroke have high rates of disability, requiring long-term rehabilitation and chronic care (4, 5). Therefore, the primary prevention of stroke is very important.

Among the range of preventive tactics, homocysteine (Hcy)-lowering medications have garnered significant interest, since research has indicated that Hcy may have an impact on stroke (6–8). Folic acid is crucial regulator in the metabolism of Hcy, and a shortage in folate can cause an accumulation of Hcy (9, 10). The efficacy of folic acid for stroke prevention has been debated for almost 30 years (11). Resent studies were designed to explored the relationship of dietary folic acid or folic acid supplements with stroke risk, and they found that both dietary folic acid and folic acid supplementation reduced the risk of stroke, but the combined results included primary and secondary prevention of stroke (11, 12). There is growing acknowledgment that there are major differences in the efficacy of folic acid for primary vs secondary prevention of stroke (13). The efficacy of folic acid for stroke primary prevention remains uncertain.

Several observational studies (9, 14–24) and RCTs (25–36) have investigated the link between folic acid and stroke primary prevention, however the findings were inconsistent. Of these, seven research (9, 14, 15, 17, 20, 21, 23) discovered an inverse relationship between dietary folic acid and the incidence of stroke, and one RCT demonstrated the protective effects of folic acid supplementation for stroke primary prevention. Another nine studies (14, 16–20, 22) and eleven RCTs (25–35) showed that folic acid was not associated with stroke incidence. Thus, we conducted a systematic review and meta-analysis to combine and synthesize the findings from the existing research.

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