Stroke: Distinguishing Ischemia from Hemorrhage Keeps Prevention from Becoming a Risk

Stroke: Evidence-Based Prevention and the Boundaries of Medication Use

The conclusion in one sentence

Stroke prevention must distinguish ischemia from hemorrhage and primary prevention in people who have never had an event from secondary prevention in those with established disease. The same medication or supplement cannot be applied to everyone. PMID: 39755190

Stroke is not simply “a blocked blood vessel”

The first issue to clarify when discussing stroke is its pathological type. Ischemic stroke is closely associated with thrombosis, atherosclerosis, and interrupted blood flow, whereas hemorrhagic stroke involves blood-vessel rupture and intracranial bleeding. An intervention that reduces ischemic events is not necessarily beneficial for hemorrhagic risk. Grouping every stroke under broad claims such as “invigorating the blood,” “dissolving clots,” or “improving circulation” therefore erases the most important boundary in treatment.

Professor Lin has long emphasized that distinct vascular pathologies should not be collapsed into a single concept of “vascular blockage”; atherosclerotic stenosis and venous thrombosis arise through different mechanisms. The same reminder applies to stroke: establish the disease type before discussing treatment and prevention, and do not self-diagnose on the basis of vague symptoms or marketing claims. PMID: 34686265

LDL, statins, and ischemic stroke

Lowering LDL reduces major vascular events. Meta-analyses of large randomized trials do not support sweeping claims that “higher LDL is healthier” or that “lowering LDL does not improve cardiovascular outcomes.” A higher LDL level is a risk factor, but a risk factor does not mean that every individual will inevitably develop disease. Clinical decisions must still account for medical history, overall risk, and treatment goals. PMID: 21067804

Professor Lin’s view is that statins lower cholesterol and reduce heart attacks and strokes, with benefits generally outweighing harms in people at high cardiovascular risk. This core position is consistent with the current body of meta-analytic evidence. The literature supports statins for preventing total and ischemic stroke, and patients should not stop treatment on their own because of lists of adverse effects circulating online. PMID: 39755190

The literature on statins and hemorrhagic stroke has been updated, and current findings still point in different directions. Some reviews identify a concern that remains to be resolved, while a Mendelian randomization study suggests a protective direction for intracerebral hemorrhage. The core benefit for ischemic stroke therefore remains intact, but the details concerning hemorrhagic stroke cannot be settled in a single sentence. Nor should the evolution of the evidence be portrayed as Professor Lin personally revising his position. PMID: 40629568

Aspirin requires a distinction between primary and secondary prevention

Professor Lin’s original article cited a news report available at the time stating that daily aspirin could reduce the risk of coronary heart disease in people who had never experienced a heart attack or stroke. The literature has since been updated. Subsequent randomized trials show that when healthy or moderately at-risk populations take aspirin for primary prevention, modest cardiovascular benefits may be offset by bleeding harms; people therefore should not begin long-term use on their own. This is a reassessment of earlier news data as science advances, not a rewriting of Professor Lin’s original article or historical position. PMID: 30221597

A trial in healthy older adults likewise found no significant reduction in ischemic stroke with low-dose aspirin but did observe an increase in intracranial bleeding. For people who have never had a cardiovascular event, “taking it must be better than not taking it” is not a safe principle. A clinician should decide whether aspirin is appropriate after assessing the individual’s bleeding and cardiovascular risks. PMID: 37494038

Secondary prevention is different. For people who have already had a heart attack or stroke and have been prescribed aspirin by a clinician, evidence generally supports a reduction in recurrent events. Professor Lin distinguished primary from secondary prevention and noted that people at high risk may still need aspirin; that direction is consistent with the literature. Patients should not mistakenly apply new evidence about primary prevention to themselves and stop a prescribed medication without guidance. PMID: 41281152

Supplements cannot replace stroke treatment

Nattokinase is often claimed to dissolve clots, lower blood pressure, prevent cardiovascular and cerebrovascular disease, or even be more suitable than aspirin. The literature collected by ECU, however, provides neither a head-to-head clinical prevention comparison with aspirin nor sufficient cardiovascular-event or stroke endpoints to establish a preventive effect. Professor Lin’s insistence that unspecified assertions of “research proves” should not be used to endorse these claims is consistent with evidence-based principles. PMID: 39076715

“Natural means free of adverse effects and safe to take with other medications” is not a reliable assurance either. A case of cerebellar hemorrhage has been reported after nattokinase was combined with aspirin. A case report cannot quantify the risk for everyone, but it is enough to refute the claim that the combination is “absolutely safe and suitable for all.” People taking antiplatelet or anticoagulant medication have even stronger reason not to add such products on their own. PMID: 18310985

Ginkgo biloba extract also failed to reduce cardiovascular events or mortality in a randomized trial directly evaluating cardiovascular prevention, so it cannot be treated as a method for preventing heart disease or stroke. Meta-analytic evidence on vitamin D supplements likewise does not support their use to reduce stroke or major cardiovascular events. PMID: 20123670

If studies of hirudin-related interventions for acute ischemic stroke have been completed only in mice and cell models, their findings cannot be rewritten as proven efficacy in humans. A clear evidence gap remains between a mechanism, an animal experiment, and a genuine improvement in patient outcomes. Professor Lin’s objection to presenting preclinical research as a treatment for human stroke is consistent with the literature. PMID: 35724604

Food and beverages: association is not a prescription

Cohort research on coffee and tea has observed an association between moderate consumption and lower risks of stroke and dementia. Professor Lin also explicitly described this as an association, not causation. Such findings can rebut the alarmist claim that replacing some water with tea or coffee amounts to “slow suicide,” but they cannot justify prescribing the same intake to everyone or replace the management of blood pressure, blood lipids, smoking, and existing disease. PMID: 34784347

Similarly, research on dietary menaquinone found no significant association with stroke risk. This does not mean that a specific component of natto has been proven to prevent stroke. Foods, extracts, and medications are not interchangeable categories of evidence. Interpretation must focus on what a study actually measured: a risk factor, a surrogate marker, or a clinical outcome such as stroke. PMID: 24326161

Principles for real-world decisions

When assessing information about stroke, first ask whether the study population resembles you, whether it addresses primary or secondary prevention, whether its endpoint is a laboratory value or an actual stroke event, and whether its evidence comes from randomized human trials or from cell and animal models. Anyone with a history of stroke, heart disease, or intracranial hemorrhage, or anyone currently using antithrombotic medication, should check with a healthcare professional before starting, stopping, or adding any product. The soundest approach is not to seek one product that purports to solve every vascular problem, but to let disease type, individual risk, and the level of evidence jointly determine care. PMID: 30667501