The formula works on blood flow from three angles. None of them is unusual. What Boostaro does is put them in one daily capsule.
1. More raw material for nitric oxide
Your body converts L-Citrulline into L-arginine, which blood vessel walls use to make nitric oxide. Nitric oxide tells the smooth muscle in blood vessels to relax, so they widen and blood moves more easily. Citrulline is used instead of arginine because more of it survives digestion.
2. Protecting the nitric oxide you make
Nitric oxide breaks down fast, especially when there's a lot of oxidative stress in the body. Pine Bark Extract and Vitamin C are antioxidants, and pine bark in particular has been studied for blood vessel function, sometimes in combination with arginine.
3. Supporting the vessels themselves
Vitamin C and L-Lysine are used to build collagen, a structural part of blood vessel walls. Magnesium helps muscle and nerve function, including the muscle in vessel walls. Vitamin K2 helps manage where calcium goes in the body. Nattokinase is an enzyme that affects blood clotting, which is why it's in a circulation formula and also why it needs care with medication.
What this adds up to is support, not a switch you flip. Blood flow depends on your heart, blood pressure, weight, sleep, smoking, alcohol and medication. A supplement can help around the edges. It can't overrule those.