Buckwheat is a pseudocereal seed, not a true grain. People grind it into flour, cook the groats, or take it as an extract. Another common preparation is tea made from the roasted hulls.
The seed supplies a flavonoid called rutin. Rutin supports strong blood vessel walls and encourages healthy circulation.
This supplement is generally safe. It can slow blood clotting though. Anyone taking anticoagulant medications should be careful.