Anthocyanins, a class of flavonoid compounds found in berries, red/purple fruits, and vegetables, have been investigated for their potential cardiovascular benefits, including effects on blood clot formation. Several in vitro and animal studies suggest that anthocyanins possess antiplatelet and antithrombotic properties, which may theoretically reduce the risk of blood clots. For example, research has shown that anthocyanin extracts from berries can inhibit platelet aggregation and decrease expression of pro-thrombotic factors in laboratory settings (PMID: 28930260).

However, clinical evidence in humans is limited and largely preliminary. Some small human studies have indicated improvements in markers of platelet function and reduced oxidative stress after anthocyanin supplementation, but these trials are few, often of modest quality, and do not directly measure the incidence of blood clot-related events (such as deep vein thrombosis or stroke). There is no consensus in medical guidelines recommending anthocyanins for blood clot prevention, and more rigorous, large-scale clinical trials are needed to confirm their efficacy and safety for this specific purpose.

In summary, while there is some scientific rationale and early evidence for anthocyanins' antithrombotic effects, the current level of evidence supporting their use specifically for blood clot prevention in humans is low to moderate.