A randomised controlled trial (RCT) involving 10,789 Chinese participants found in the highest stroke risk group (high homocysteine, low platelet levels), 1.8% of individuals taking folic acid had a stroke vs. the 5.6% not taking folic acid.
In the lowest risk group (low homocysteine, high platelet levels), 3.0% of subjects taking folic acid had a stroke, compared with 3.3% of subjects not taking it.
“Our analysis has shown that baseline low platelet count and elevated homocysteine can jointly increase the risk of first stroke,” said the study’s senior author and director of the Heart Center of Peking University First Hospital in China, Dr Yong Huo.
“If the findings are further confirmed by prospective trials, we can raise the prospect that we can identify patients at high risk of developing first stroke by measuring both platelet and homocysteine, and we can remarkably lower stroke risk among this subgroup of patients with folic acid.”
Whilst the results are worthy of future research, the study may not have quite the relevance here in Europe as it does in China.
In the UK for example, it is not standard medical practice to evaluate someone's stroke risk on the basis of homocysteine and platelet levels in the blood.
In addition, the UK is one of a handful of European countries, which fortify certain foods with folic acid aiding in the supplementation needs of the general population.
Not all strokes are caused by high blood pressure and people of different populations may differ in genetics or lifestyle factors that may contribute to stroke risk.
The participants, part of the China Stroke Primary Prevention Trial (CSPPT), were aged 45 to 75 years old who had hypertension or were on anti-hypertensive medication.
The research team randomly assigned the subjects into one group: 5,408 patients, who received a combined daily oral dose of 10 milligrams (mg) of the antihypertensive enalapril and 0.8 mg folic acid.
The second group consisted of 5,381 patients, who were given a daily dose of enalapril only.
Altogether 210 first strokes occurred in the enalapril-only group, and 161 first strokes in the enalapril-folic acid group over a median follow up of 4.2 years.
The team calculated that the first stroke risk reduction from 5.6% to 1.8% among patients with low platelet count and high homocysteine levels represented a 73% risk reduction.
However, the folic acid had no effect among those with high platelet count and low homocysteine levels.
Cost-effective stroke prevention strategies
“If confirmed, these results have enormous public health implications given the high incident rate of stroke in many developing countries, in addition to China,” Huo said.
“Based on our findings, we can detect hypertensive adults at particular high risk of stroke and incorporate a folic acid supplement tailored to individual genetic, nutritional and clinical characteristics.
We are on the right path to figuring out cost-effective primary prevention strategies for stroke.”
In an accompanying editorial, Dr J. David Spence, director of the Stroke Prevention and Atherosclerosis Research Centre at Robarts Research Institute said that, “Patients with lower platelet counts and higher homocysteine levels are more likely to have been at higher risk because they had vitamin B12 deficiency”.
“Among folate-replete subjects, the main nutritional determinant of high homocysteine levels is B12 deficiency.”
Multi-vitamin a ‘wise move’
Also commenting on the study’s findings, Dr Gill Jenkins a GP and advisor to the Health & Food Supplements Information Service (HSIS) noted that, “Several large controlled trials and meta-analyses have shown that folic acid supplementation can reduce the risk of stroke.
“Given the evidence demonstrating the capability of folic acid supplementation in reducing homocysteine levels and risk of stroke, the results of the current study are not surprising.
“People who have high blood pressure or are concerned about their cardiovascular health or risk of stroke should consult their doctor and should not change any medication they are taking without their doctor’s advice.
“However, the findings of this study suggest that taking a B vitamin or multi-vitamin and multi-mineral supplement containing folic acid would be a wise move for all adults in the UK.”
Source: Journal of the American College of Cardiology
Published online ahead of print: DOI: 10.1016/j.jacc.2018.02.072
“Platelet Count Affects Efficacy of Folic Acid in Preventing First Stroke”
Authors: Xiangyi Kong, Xiao Huang, Min Zhao