Study showed warm watermelons provide more lycopene
Researchers from the U.S. Department of Agriculture (USDA) studied the effect of storage temperature on the carotenoid levels of three different kinds of watermelon. The researchers stored the watermelons at five, 13 and 21 degree celsius for 14 days. Researchers found that watermelons stored at 21 celsius (room temperature) gained 11 to 40 percent in lycopene and 50 to 139 percent in beta-carotene compared to watermelons stored at five and 13 degrees. The results of this study were published online on the Journal of Agricultural and Food Chemistry web site in July 2006.
lycopene watermelonEditor's Note - Lycopene is easily affected by temperature and processing
Lycopene, a powerful antioxidant, is found in abundance in tomatoes and other red-colored fruits. Studies found that lycopene may help reduce the risk of heart disease and some forms of cancer. The most compelling evidence so far is the role of lycopene in prostate cancer prevention.
Heat and processing destroy some nutrients, but heat and processing increase lycopene content. For instance, one hundred grams of cooked tomato paste provide 42 milligrams of lycopene, whereas the same amount of raw tomato only provides three milligrams of lycopene. Hence, to maximize the health benefits of eating lycopene-containing fruit, it is better to leave your watermelon out at room temperature and cook your tomatoes!
Researchers in the US have found that the watermelon contains more lycopene, the phytochemical associated with reduced prostate cancer risk and lower rates of heart disease, than tomatoes.
According to a report published in the June issue of Agricultural Research magazine, raw watermelon contains as much or more lycopene than tomatoes, even when compared to tomato juice which has undergone heat treatment - said to improve bioavailability of the chemical.
Lycopene is a red pigment that occurs naturally in certain plant and algal tissues. It gives watermelon and tomatoes their colour, but is also thought to act as a powerful antioxidant. Lycopene scavenges reactive oxygen species, which are aggressive chemicals that react with cell components, causing oxidative damage and loss of proper cell function.
Scientists have previously found that a high dietary intake of lycopene reduces the incidence of certain types of cancer. Lycopene levels in fat tissue, an indicator of lycopene consumption, have also been linked with reduced risk of heart attack.
Most clinical research dealing with lycopene has used tomatoes as the food source but US Agricultural Research Service scientists at the South Central Agricultural Research Laboratory (SCARL) in Lane, Oklahoma, and at the Phytonutrients Laboratory in Beltsville, Maryland, decided to look at lycopene levels in varieties of watermelon and to assess its bioavailability. Funding was provided in part by the National Watermelon Promotion Board.
The ARS scientists analysed 13 watermelon cultivars to establish the relative effect of genetic background on lycopene content. The 13 cultivars included different varieties of the fruit.
The researchers used tristimulus colorimeter readings to measure visible colour in the cut melons and compared the findings to the amounts of lycopene extracted from the melons. Lycopene content varied widely among cultivars and types, but the seedless ones tended to have more.
Results showed that watermelon has as much, or more lycopene as raw tomatoes and that the amount depends on both variety and growing conditions.
The ARS also assessed bioavailability of lycopene in watermelons in a study begun last year on 23 healthy adults. The scientists used tomato juice as the known benchmark for judging the relative bioavailability of lycopene.
The investigators found that lycopene concentration was similar regardless of whether subjects consumed 20 milligrams of lycopene from tomato juice or from watermelon juice, which was not heat-processed.
The investigators had expected lycopene availability to be greater from tomato juice because it had received heat treatment, which is believed to improve lycopene bioavailability.
"To our knowledge, this is the first study to show that lycopene from watermelon is bioavailable," said ARS scientist Clevidence. "Next, we would like to find out if plasma lycopene levels are higher when people eat watermelon with a meal containing fat than when they eat it by itself."
Watermelon also contains the vitamins A, B6, C and thiamin. Studies have shown that a cup and a half of watermelon contains about 9 to 13 milligrams of lycopene. On average, watermelon has about 40 per cent more lycopene than raw tomatoes. Red, ripe flesh is the best indicator of the sweetest and most nutritious watermelon.
"We think there are a lot of potential uses for watermelon that are just beginning to be explored," said Perkins-Veazie, author of the study. "It can be a so-called functional food, one that can help prevent certain diseases."
Other good sources of lycopene include red and pink grapefruit and
Every year more than 500,000 people die from cancer in the United States alone.
Many researchers and cancer specialists believe that up to 60% of those deaths can be prevented if Americans adopt healthier lifestyles.
According to Rachael Stolzenberg-Solomon, a researcher at the National Cancer Institute,
“The easiest and least expensive way to reduce your risk for cancer is just by eating a healthy diet.”
Here is an overview of ten important cancer fighting foods to include in your diet on a regular basis:
1. Garlic – Garlic contains a number of compounds that can protect against cancer, especially that of the skin, colon, and lungs.
2. Dark Leafy Greens – Dark greens are rich sources of antioxidants called carotenoids. These scavenge dangerous free radicals from the body before they can promote cancer growth.
3. Grapes – Grapes (and red wine) contain the chemical resveratrol, which is a very potent antioxidant that can prevent cell damage before it begins.
4. Green Tea – The flavonoids in green tea have been shown to slow or prevent the development of several types of cancer including colon, liver, breast, and prostate.
5. Tomatoes – The compound lycopene, (which is most easily absorbed from cooked tomatoes) has been shown to prevent prostate cancer, as well as cancer of the breast, lung, and stomach.
6. Blueberries – Of all the berries, blueberries are the richest in cancer fighting compounds. They are beneficial in the prevention of all types of cancer.
7. Flaxseeds – Flax contains lignans, which can have an antioxidant effect and block or suppress cancerous changes. The omega-3 fatty acids can also help protect against colon cancer.
8. Mushrooms – Many mushrooms contain compounds that can help the body fight cancer and build the immune system as well.
9. Cruciferous Vegetables – Vegetables such as broccoli, cauliflower, cabbage, and Brussels sprouts contain strong antioxidants that may help decrease cancer risk.
10. Whole Grains – Whole grains contain a variety of anti-cancer compounds including antioxidants, fiber, and phytoestrogens. These can help decrease the risk of developing most types of cancer.
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