This re-analysis of the VITATOPS study which found that the homocysteine lowering B vitamins didn’t appear to reduce risk of another stroke, looked at the difference between 6609 patient who were on aspirin, compared to 1463 that were not. Those not on aspirin had a significant reduction in stroke risk, as was predicted from earlier studies showing that homocysteine levels predict stroke risk. Those taking aspirin with the B vitamins had no reduction in risk. This is the second ‘negative’ study which, on re-analysis, supports the theory that aspirin knock out the benefits of B vitamins.
An editorial in the Lancet by stroke expert Dr Gustavo Saposnik says“the available evidence, suggests that the discordant results from observational studies and previous randomised trials could be explained by antiplatelet drugs attenuating or cancelling a small benefit of homocysteine-lowering therapy with B vitamins in cardiovascular prevention. The findings from the study also suggest that, in patients with raised homocysteine, vitamin-B supplementation might potentially have a role in primary stroke prevention (for non-antiplatelet users). However, vitamin-B supplementation does not seem to have a significant benefit in secondary prevention of stroke and cardiovascular disease when antiplatelet therapy is taken routinely.”
This finding is particularly important for those who do not have heart disease, but are taking aspirin as a preventive – especially in homocysteine is raised. Despite the current recommend to GPs not to prescribe aspirin to those without heart disease because a) it doesn’t work and b) can cause internal bleeding, many still make this erroneous recommendation. For example, following a series of studies showing that aspirin is ineffective for primary prevention, and recommendations to stop prescribing it in 2009 and 2010, prescriptions only decreased from 32 to 31 million between 2009 and 2011.
This emerging likleyhood that aspirin is cancelling out the benefit of homocysteine lowering B vitamins adds further reason to stop taking aspirin for the prevention of heart disease if you don’t have it. If you do have heart disease, and need to be on antiplatelet medication such as aspirin my advice is to monitor your homocysteine carefully. If it is significantly high then the B vitamins may still help. For example, studies that have successfully and substantially lowered homocysteine levels above 15mmol/l have shown benefit. Exactly how aspirin interferes with the function of B vitamins is not yet clear.