Alliin is a sulfur-containing compound found in garlic (Allium sativum), and it serves as the precursor to allicin, which forms when garlic is crushed or chopped. Several preclinical and limited clinical studies suggest that garlic and its constituents, including alliin, may have antithrombotic (antiplatelet and anticoagulant) effects that could potentially support the prevention or management of thrombosis. The mechanisms proposed include inhibition of platelet aggregation, suppression of fibrinogen binding, and modulation of blood lipid profiles.

Most of the available evidence comes from in vitro (test tube) and animal studies. These studies indicate that alliin and related compounds can inhibit platelet aggregation and reduce blood coagulation. Some small clinical trials with garlic preparations (not pure alliin) have also shown modest reductions in platelet aggregation in humans, potentially lowering the risk of thrombus formation. However, it is important to note that direct evidence for alliin alone in the treatment or prevention of thrombosis in humans is scarce, with most human data derived from whole garlic or its extracts rather than isolated alliin.

Overall, while there is a scientific rationale and some supportive data for the use of alliin-containing garlic products in thrombosis, the quality and quantity of evidence specific to alliin are limited, and more robust clinical trials are needed. Thus, the evidence rating is 2, reflecting preclinical support and limited early human evidence, but not enough to recommend it as a standalone treatment.