Tuesday, 8 July 2014

Watermelon - Sweet, Juicy and Unexpectedly Healthy

A big slice of sweet and juicy watermelon is one of the joys of summer. Unlike many other fruits, watermelon doesn't have a reputation for being especially healthy. It's true that it does have a high water content, which makes it such a refreshing summer treat, but it also contains some important and very helpful nutrients.

Watermelon slices; public domain photo
by jhusemannde
Watermelon is low in fat and calories. It's a good source of vitamins C and A and a significant source of potassium. It also contains many other vitamins and minerals, but in low concentrations. However, it's a great source of phytonutrients (or phytochemicals). Phytonutrients are nutrients from plants that aren't essential for our survival but are believed to have important benefits for our health.

Watermelon is rich in an amino acid called citrulline, one of its phytonutrients. Our body converts citrulline into another amino acid called arginine. Arginine helps cells to divide and wounds to heal. It's also converted to nitric oxide in the body. This chemical opens up blood vessels and improves blood flow. Citrulline has been found to lower blood pressure in prehypertensive people. These people have raised blood pressure approaching the level required for a classification of hypertension. Researchers have found that it's actually the arginine produced from the citrulline in watermelon that is lowering the blood pressure.

Lycopene is a red pigment and antioxidant in watermelon that is also found in tomatoes, papaya, guava and pink grapefruit. Antioxidants are thought to prevent cell damage. The deeper the red colour of a watermelon, the more lycopene it contains. Since lycopene is fat soluble, its absorption through the intestinal wall is enhanced by the ingestion of a small quantity of a healthy oil at the same time as the lycopene.

More watermelon slices; public domain photo by
Petr Kratochvil
Lycopene may reduce the risk of a heart attack in susceptible people. A recent study by researchers at Cambridge University showed interesting results. The researchers found that taking a daily tablet containing a high lycopene content for two months widened blood vessels in people with heart problems by 53%. The tablet had no effect on people whose blood vessels were functioning normally. It's important to realize that the lower concentration of lycopene in foods may not have the same effect as the concentrated lycopene in tablets.

Lycopene may also have health benefits with respect to cancer, but the evidence is mixed. Tomatoes were one thought to reduce the risk of prostate cancer and perhaps other cancers as well, but recent research has shown inconsistent results. The benefits of tomatoes were at first ascribed to their lycopene content, but that's in doubt, too. Like other fruits and vegetables, tomatoes contain many different chemicals. A chemical other than lycopene or even a mixture of chemicals may be responsible for the benefits of tomatoes in those experiments that show positive results.

The best plan for someone who wants to use foods to stay healthy is to eat a wide variety of nutritious foods, including watermelon, in order to obtain as many beneficial nutrients as possible. One of my favourite nutrition quotes is "Every time you eat is an opportunity to nourish your body". This is so true!