Watermelon is a rich natural source of lycopene, a ‘carotenoid' of great interest to medical researchers because of its antioxidant capacity and potential health benefits. Carotenoids are the red, orange and yellow pigments found in plants.
Lycopenes exert protective effects against certain types of cancers and cardiovascular disease. Lycopene is an efficient antioxidant capable of devouring more than 10 times more oxygenated free radicals than vitamin E.
Watermelon is also the richest edible natural source of the amino acid L-citrulline. This is important because, once in the body, L-citrulline is converted into L-arginine, the amino acid that goes on to form a gas called nitric oxide, which helps to regulates blood pressure by influencing how our blood vessels dilate and contract.
The problem with L-arginine is that if you want to take it as a dietary supplement, it can have some pretty unpleasant side-effects, including nausea, stomach discomfort and diarrhoea.
Why not get this benefit by eating a piece of watermelon.
A study by researchers from Florida State University in Tallahassee, Florida, has found that six grams of L-citrulline from watermelon extract administered daily for six weeks improved arterial function and lowered blood pressure in four men and five postmenopausal women, who were aged between 51 and 57 and had “prehypertension”, but were otherwise healthy.
Prehypertension occurs when blood pressure readings are raised from what are considered ideal levels but haven’t yet reached the point where the blood pressure gets to the point where it significantly increases someone’s risk of having a heart attack or stroke. It’s defined as a systolic pressure of 120-139 mmHg (millimetres of mercury) and a diastolic pressure of 80-89 mm Hg.
Note that systolic pressure is the higher blood pressure reading that occurs when the heart is contracting and the lower diastolic pressure occurs when the heart is relaxing between beats.
Naturally, a key goal for doctors is to try to prevent people who have prehypertension from going on to develop high blood pressure and the risks that it brings. The study, which was the first to demonstrate beneficial effects of L-citrulline/L-arginine from watermelon supplementation on arterial function in humans, suggests that watermelon could act as a “functional food”, helping to reduce the risk of cardiovascular disease and possibly allowing some people to reduce their dependence on drugs for controlling blood pressure.
The authors of the study said that people with high blood pressure and stiff arteries, especially older people and those with chronic diseases like Type 2 diabetes, would benefit from L-citrulline in either a synthetic or natural (watermelon) form. They recommend an optimal dose of four to six grams a day
But that doesn’t mean that people with blood pressure should stop taking their medications and start buying watermelons. Firstly, any change in medication for blood pressure should only be done in consultation with your doctor or specialist. Secondly, this is a very small study, so the effectiveness of L-citrulline needs to be further tested on a much larger group of people.
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