lycopene

It’s finally summer. Warmer temperatures and local Farmer’s markets motivate us to eat lots of fresh fruits and greens. A healthy summer diet maintains our health and can be even supportive in the management of various diseases. For example, some patients with treated blood pressure are able to taper off blood pressure medications by eating not only healthier but also smarter, losing weight and exercising more.

American Heart Association guidelines recommend eating 9 servings of fresh fruit and vegetables per day. Although reasonable, it is often difficult to implement these recommendations into one’s busy life. In addition to consuming more fruits and greens, is it possible to eat smarter and implement more so-called functional foods to positively affect blood pressure and ultimately cardiovascular health?

One of my friends brought my attention to the beneficial effects of watermelon. Since then I am hooked. For me, watermelon in the form of juice works best – either in the office or during work outs to help with next day muscle soreness.

Watermelons are sweet and popular fruits of summer, originating from sub-Saharan Africa, usually consumed fresh in slices, diced in fruit salads, or as juice. They contain more than 90% of water and are low in fat. Against popular belief watermelons are neither high caloric nor do they have high sugar levels. They contain approximately 6-7 g total sugars which is half of total sugars found in apples, bananas, mangos, sweet cherries, kiwis, pineapples etc., and comparable to blackberries, blueberries, grapefruits, and oranges, just to name a few.

Studies have shown that watermelon can lower blood pressure and improve arterial compliance. Watermelons seem to work like an anti-aging remedy on arteries. But how does watermelon reduce blood pressure and make arteries “younger”?

Watermelon contains three functional important bioactive components: lycopene, arginine and citrulline. These are potent antioxidants and converted into nitric oxide, the principal vasodilatory molecule produced by endothelial cells, the inner layer of your arteries. For decades, doctors have prescribed nitroglycerin which gets converted to nitric oxide in patients with chronic angina to dilate heart arteries and relieve chest pain.  

A variety of factors can reduce the production of nitric oxide and ultimately lead to increased arterial stiffness and higher blood pressure levels such as aging, unhealthy diets, and poor exercise habits. Many people reach for arginine supplements, but the body does not absorb it well. Citrulline on the other hand is easy absorbed and converted into arginine and ultimately nitric oxide.

Watermelon provides these artery-bioactive compounds and studies indicate beneficial influence on cardiovascular health. For example, one study showed that higher lycopene levels improve arterial compliance. Watermelon bioactive compounds also seem to be anti-inflammatory and to positively impact cholesterol levels including lowering of the so-called “bad” LDL cholesterol without impacting the “good” HDL cholesterol.

In addition, watermelon is also a good food source of glutamine and Vitamin C, both of which display antioxidant properties and have been shown to enhance arterial dilation. Studies that have examined the effects of watermelon on vascular function support the notion that this functional food may improve blood pressure and arterial stiffness. 

As recommended by the American Heart Association guidelines for the detection, prevention, management and treatment of high blood pressure, a healthy lifestyle is an integral part of health maintenance and high blood pressure should be treated with lifestyle changes and in some patients with medication.

So, as long as the watermelon season lasts, let’s be health smart and add it to our diet: fresh in slices, diced in fruit salads, or as juice and take advantage of this natural remedy.

References:

1. Vlachopoulos C, Xaplanteris P, Aboyans V, Brodmann M, Cífková R, Cosentino F, et al. The role of vascular biomarkers for primary and secondary prevention. A position paper from the European Society of Cardiology Working Group on peripheral circulation: Endorsed by the Association for Research into Arterial Structure and Physiology (ARTERY) Society. Atherosclerosis. 2015; 241(2): 507–532.
2. Seals DR, Kaplon RE, Gioscia-Ryan RA, LaRocca TJ. You’re only as old as your arteries: translational strategies for preserving vascular endothelial function with aging. Physiology (Bethesda). 2014; 29(4):250–264.
3. Ellis AC, Dudenbostel T, Locher JL, Crowe-White K. Modulating Oxidative Stress and Inflammation in Elders: The MOXIE Study. J Nutr Gerontol Geriatr. 2016 Oct-Dec;35(4):219-242.
4. Figueroa A, Sanchez-Gonzalez MA, Perkins-Veazie PM, Arjmandi BH. Effects of watermelon supplementation on aortic blood pressure and wave reflection in individuals with prehypertension: a pilot study. Am J Hypertens. 2011; 24(1):40–44.
5. Figueroa A, Sanchez-Gonzalez M, Wong A, Arjmandi B. Arterial stiffness and blood pressure are reduced after watermelon supplementation in obese with prehypertension and hypertension. The FASEB Journal. 2012; 26:385.
6. Figueroa A, Wong A, Hooshmand S, Sanchez-Gonzalez MA. Effects of watermelon supplementation on arterial stiffness and wave reflection amplitude in postmenopausal women. Menopause. 2013; 20(5):573–577.

Tanja Dudenbostel is an Internist, Hypertension Specialist within Cardiology at the University of Alabama at Birmingham where I divide my time as an Assistant Professor between clinical research and seeing patients in cardiology.