Vitamin C is needed for the manufacturing of collagen and elastin, two important connective tissues that help keep veins strong and toned. Vitamin E is also helpful (avocado, nuts, and olive oil) Stay hydrated and consume flavonoid-rich foods. The beneficial effects of flavonoids are believed to result from their ability to strengthen the walls of blood vessels and to prevent free radical stress inside the vessels. Rutin is one of the flavonoids that have been researched as potentially helpful. Buckwheat, apples, and figs contain rutin.