Folic Acid Supplementation Reduces Risk of First Stroke in China Study
Key Takeaway: Since over three-quarters of stroke instances are first events, it’s important to monitor known risk factors, such as diabetes. A recent study in China found that folic acid supplementation decreased the risk of first stroke, except in those with the lowest blood glucose concentration. Considering the prevalence of diabetes worldwide, increased intake of folate through custom nutrient premixes could have a substantial impact on the risk of first stroke.
Stroke is ranked second worldwide as a cause of death. Primary prevention of stroke is important, particularly since 77% of strokes are first events.[i] Diabetes, estimated to affect 415 million people worldwide,[ii] is an important risk factor for stroke. Some countries, such as the United States, in an attempt to lower the incidence of neural tube defects in the offspring of folate-deficient mothers, have adopted mandatory fortification of grain with folic acid, which has markedly increased total dietary folate intake in the population and decreased the prevalence of folate deficiency.[iii] Many other countries, however, such as China, do not have mandatory folic acid fortification and significant numbers of people worldwide have low folate intakes. Previously, a study in China[iv] (China Stroke Primary Prevention Trial- CSPPT) found that folic acid supplementation overall decreased the risk of first stroke by 21%. These investigators have now used the data collected from this longitudinal study to address the question of whether folic acid supplementation would reduce the risk of first stroke in hypertensive subjects and to what extent this relationship was modified by Type 2 diabetes.[v]
In an analysis of 20,327 participants from the CSPPT, who were hypertensive, but without history of stroke or myocardial infarction, the investigators found that the risk of first stroke doubled in those with the highest blood glucose concentration (glucose concentration ≥ 7 mmol/L) or diabetes compared to participants with normal fasting blood glucose concentration ≤ 5 mmol/L. It was also noted in this study that folic acid supplementation (800 μg/day) in participants with hyperglycemia or full-blown diabetes reduced the increase in risk of first stroke from 91% to 35%. Overall, the investigators found that regardless of the level of fasting blood glucose, folic acid supplementation decreased the risk of first stroke, except in those with the lowest blood glucose concentration (FBG ≤ 5 mmol/L). Given the rising prevalence of diabetes worldwide, especially in those large parts of the world that do not have mandatory folic acid fortification, increased intake of folate could have a substantial impact on the risk of first stroke.
[iii] Jacques P. et al. 1999. The effect of folic acid fortification on plasma folate and total homocysteine concentrations. New England Journal of Medicine 340: 1449-1454.
[iv] Huo Y. et al. 2015. Efficacy of folic acid therapy in primary prevention of stroke among adults with hypertension in China. The CSPPT randomized trial. Journal of the American Association 313: 1325-1335.
[v] Xu RB et al. Longitudinal association between fasting blood glucose concentrations and first stroke in hypertensive adults in China: effect of folic acid intervention. American Journal of Clinical Nutrition (2017) doi: 10.3945/ajcn.116.145656 [Epub ahead of print].