Constriction of the blood vessels is the body’s way to raise the blood pressure. By narrowing the passage in the blood vessels, blood flows more slowly to the organs and the extremities. Certain foods may contribute to this process. In the case of people with hypertension, these foods may be limited to help control blood pressure. People suffering from migraine headaches may choose to include these foods to help control capillary action and relieve their headaches.
Caffeine is a well-known vasoconstrictor and helps to reduce the incidence and intensity of migraine headaches. It is known that in a migraine, blood vessels dilate or enlarge, becoming engorged with blood that remains in the vessels and stretches them, causing pain. Caffeine is able to reduce the size of the blood vessels, forcing the blood out of them and reducing the pain. Foods containing caffeine are coffee, tea, sodas and energy drinks.
George L. Bakris, M.D. discusses sodium’s role in helping to control blood pressure in the body and its effects on the kidneys in the Merck Manual. Too much sodium contributes to raising the blood pressure and constricting the blood vessels, especially in the kidneys, which control the blood pressure and electrolyte balance in the body. Sodium should be reduced to no more than 2½ grams per day, Bakris advises.
Licorice root is a wonderful herb used for making tea, candy, alcoholic drinks and other flavorful spices and is helpful when used for digestive upsets and numerous other conditions requiring soothing of the body’s mucous membranes. The actice compound of licorice, glycyrrhizic acid, causes sodium retention and potassium loss in the kidney. This, in turn, raises blood pressure. Too much licorice can lead to the development of hypertension. The Scientific Committee on Food places the upper limit of glycyrrhizic acid intake at 100 milligrams a day. That's equal to about 60-70 grams of licorice.