I captured this photo in my kitchen yesterday for a daily photo challenge I am participating in this month. I choose watermelon as an illustration of the word, “refreshing” – the topic of the day. I decided to look up the health benefits and discovered a common error published about watermelon. It is widely reported that it contains vitamin A , however there is no true vitamin A in plant foods, including watermelon. It occurs only in animal foods. Plant foods contain the precursors to vitamin A, which are called carotenes. The presence of carotenes does not insure a conversion to vitamin A. I will address this misconception at greater length in a moment.
First, a bit of background and history about watermelon from The World’s Healthiest Food article:
As a member of the Cucurbitaceae family, the watermelon is related to the cantaloupe, squash and pumpkin, other plants that also grow on vines on the ground. Watermelons can be round, oblong or spherical in shape and feature thick green rinds that are often spotted or striped. They range in size from a few pounds to upward of ninety pounds.
While we often associate a deep red-pink color with watermelons, in fact there are varieties that feature orange, yellow, or white flesh. While most watermelons have seeds that are black, brown, white, green or yellow, a few varities are actually seedless.
The scientific name for watermelon is Citrullis lanatus.
Originating in Africa, watermelons were first cultivated in Egypt where testaments to their legacy were recorded in hieroglyphics painted on building walls. The fruit was held is such regard that it was placed in the tombs of many Egyptian kings. It is not surprising that watermelon played such an important role in this country, and subsequently in countries in the Mediterranean region, since water was often in short supply in these areas, and people could depend upon watermelon for its thirst-quenching properties.
Watermelons were brought to China around the 10th century and then to the Western Hemisphere shortly after the discovery of the New World. In Russia, where much of the commercial supply of watermelons is grown, there is a popular wine made from this fruit. In addition to Russia, the leading commercial growers of watermelon include China, Turkey, Iran and the United States.
The health benefits I discovered, in summation:
- Watermelon is said to be high in lycopene, reducing the risk of some cancers and heart disease.
- It is said to be particularly hydrating.
- It is said to relax the body’s blood vessels just like Viagra does.
- It contains magnesium, potassium, and vitamin C but, not vitamin A.
Watermelons contain oxidants that prevent free radicals’ production in the body. Lycopene is one of the major antioxidants in watermelon. Lycopene is responsible for the red colour in watermelon, and it can be found in most fruits, but the watermelon contains the largest amount. Lycopene contributes to the watermelon benefits because it is helpful in reducing the risk of prostate cancer and heart disease. Read more about Lycopene in watermelon.
Watermelon juice contains 90% water, making it a particularly convenient option for anyone who would want to rehydrate their body.
WebMD reports, “Watermelon may be a natural Viagra, says a researcher. That’s because the popular summer fruit is richer than experts believed in an amino acid called citrulline, which relaxes and dilates blood vessels much like Viagra and other drugs meant to treat erectile dysfunction .”We have known that watermelon has citrulline,” says Bhimu Patil, PhD, director of the Fruit and Vegetable Improvement Center at Texas A&M University, College Station. Until recently, he tells WebMD, scientists thought most of the citrulline was in the watermelon rind. “Watermelon has more citrulline in the edible part than previously believed,” he says. How could watermelon be a natural Viagra? The amino acid citrulline is converted into the amino acid arginine, Patil says. “This is a precursor for nitric oxide, and the nitric oxide will help in blood vessel dilation.”
I read something along these lines in several articles, “The watermelon is also rich in Vitamin A that is essential in preventing infections and night blindness.” Unfortunately, the public has been given a lot of misinformation about vitamin A. If you look on the back of a can of tomatoes, it will say the tomatoes contain a certain amount of vitamin A. There are many books on nutrition that tell you to get lots of vitamin A by eating carrots and green vegetables as well.
However, when we look up vitamin A in the biochemistry textbooks, or in the Merck Manual, we learn that there is no vitamin A in plant foods, including watermelon. It occurs only in animal foods. Plant foods contain the precursors to vitamin A, which are called carotenes.
Carotenes are converted into the true vitamin A in the intestines of animals, including humans. The carotene with the highest conversion factor, that is, the carotene that is most easily converted, is beta-carotene. Various enzymes and vitamins are needed to split beta-carotene into molecules of true vitamin A. It takes at least 6 molecules of carotene to produce one molecule of vitamin A. So while it is true that humans can convert some of the carotenes in their food into vitamin A, many conditions interfere with this conversion. And babies and children do not make this conversion at all. You can give the baby carrot juice until he turns orange – and he will turn orange – but he will not make this conversion.
So enjoy the hydrating, refreshing experience of watermelon when in season, however, don’t look toward watermelon as a viable source of vitamin A. For Vitamin A, have liver, eggs, milk, cheese and butter from animals on pasture. Also recommended is Fermented Cod Liver Oil.
Watermelon – overview
Watermelon – benefits
6 Responses to Watermelon – beneficial but, not a source of Vitamin A
Thanks for posting such great information, Sandrine. I don’t think enough people know about the retinol to Vitamin A conversion issue. Diabetics do not make the conversion well either. It’s so important to keep educating people. Egg yolks and liver are much better first foods for babies than carrots and squash.
Bravo, Caroleah! I planned to reach out to you this week — so good to see you here! I agree with you – egg yolks and liver are much better first foods for babies … however, carrots and squash could be added for variety. A side dish … so to speak!
Yum! I love watermelon. I recently learned that in Chinese medicine it is considered a cooling food, so it is good for hot flashes, for example!
If children can’t make the conversion, at what age does the body start to do this?
From our educational materials: “This is why babies and growing children right up to age 18 need more vitamin A in their diet as a function of body weight than adults do. The books on infant feeding back in the 1930s and 1940s recommended 2 teaspoons of cod liver oil per day for infants over 3 months old.”
Oh wow, 18 years. Ok. Thank you Sandrine 🙂