Vasodilation is the relaxing of the arteries, a beneficial effect that can help to lower blood pressure. Many anti-hypertensive drugs achieve their effects through this mechanism. Vasodilator substances are also found naturally in foods. One example is citrulline, which is found in watermelons and cantaloupes. Substances such as potassium can also aid the management of blood pressure, albeit through other mechanisms. This and other substances beneficial to blood pressure occur naturally in various vegetables and fruits.
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Watermelons are rich in vitamin C, beta-carotene and lycopene – antioxidants that can help protect against damage by free radicals. Watermelons are also a source of the amino acid citrulline. In the body, citrulline is converted to arginine, which in turn is converted to nitric oxide. The last is a vasodilator. Citrulline is also present in cantaloupes.
Citrulline and Blood Pressure
Vasodilators such as citruline can be beneficial for blood pressure management. The January 2011 issue of the “American Journal of Hypertension” evaluated the effects of watermelon-extract supplementation on blood pressure in subjects with borderline hypertension. After six weeks of supplementation, there was a significant drop in blood pressure compared to subjects who were given placebo. The limitation of this study was that the sample size was small; in fact there were only nine subjects. Although this was the only study that specifically investigated the effect of watermelon extract on blood pressure, a large body of evidence corroborates the link between citrulline-rich foods and a reduction in blood pressure, as reviewed in the January 2010 issue of “Current Opinion in Clinical Nutrition and Metabolic Care.”
Citrulline is not the only type of vasodilator found in food. The 2010 issue of “Bratislavske Lekarske Listy” reports that garlic generates small amounts of hydrogen sulfide in the body, and this causes vasodilation and a reduction in blood pressure. The same study reports that garlic can also normalize blood lipids, protect cholesterol from free radical damage, and prevent blood clots. It is fitting that garlic has traditionally been regarded as a heart-healthy herb.
Nitrate, antioxidants and antiinflammatories
Nitrate is another vasodilator, and it is concentrated in spinach and beets. Digestion in the stomach produces nitric oxide from nitrate, and this signals the blood vessels to relax. Beets are also a source of unique phytonutrients called betalains; these have antioxidant and antiinflammatory properties. Spinach is also a source of antioxidant and antiinflammatory nutrients, especially epoxyxanthophylls.
Celery is the best food source of 3-n-butylphthalide. The October 1999 issue of “Zhongguo Yao Li Xue Bao” reports that 3-n-butylphthalide has an effect on the body’s production of substances that control arterial function, include nitric oxide, a vasodilator. The June 2010 “Journal of Neuroscience” also reports that this substance has further potential as therapeutic agent for the treatment or prevention of Alzheimer’s disease.