(And their “Sidekicks:” Lemons, White and Pink Grapefruit, Kumquats, Tangerines, Limes)
- Vitamin C
Most of us know that vitamin C is important to health. In fact, we’ve all heard so much about vitamin C in years past we’ve come to think of it as almost an “old-fashioned” vitamin; it doesn’t seem nearly as interesting as some of the nutrients that have captured media attention in recent years. This is a mistake, since a steady supply of vitamin C is crucial to our current and future health because it wages a constant battle against serious diseases like cancer as well as everyday afflictions like the common cold.
Vitamin C is the primary water-soluable antioxidant in your body. It’s the first line of defense both inside and outside cells, protecting against the ravages of free-radical damage. Humans cannot manufacture vitamin C in their bodies and thus need constant replenishment of this crucial vitamin from dietary sources. As just one orange supplies nearly a quarter of my daily Vitamin C recommendation—along with a host of other significant nutrients—you can see why this delicious fruit and its sidekicks deserve their status as SuperFoods.
It’s alarming how many of us are deficient in this readily available vitamin. While the RDA for vitamin C is 90 mg for adult males and 75 mg for women, up to one-third of Americans consume less than 60 mg of vitamin C daily. This inadequate intake of C could be having serious negative health implications. And the truth is that the RDA for Vitamin is, to my mind, too low. What’s a more beneficial amount of C? The optimal daily intake of vitamin C should be 350 mg or more a day from food.
While oranges are extremely rich sources of vitamin C, they also provide other nutrients that work hard to preserve your health, including over 170 different phytochemicals and more than 60 flavonoids. The phytonutrients in citrus include flavanones, such as hesperidin and naringenin, anthocyanins, hydroxycinnamic acids, and a variety of other polyphenols. One of the flavanones—hesperidin—seems to be the most important flavanone studied thus far, as animal studies have shown that it lowers high blood pressure and cholesterol. These nutrients working together have anti-inflammatory, antitumor, antiviral, antiallergenic, and blood clot-inhibiting properties, as well as the powerful antioxidant abilities they share with vitamin C. Here are just some of the serious conditions that the nutrients in oranges work to prevent:
- Cardiovascular disease
- Rheumatoid arthritis
- Macular degeneration
- Birth defects
- Cognitive decline
Once you appreciate the vital role of oranges and their sidekicks in keeping you healthy, you’ll make a point of regularly including them in your diet.
Citrus and Disease
Cancer begins in the body long before any sign or symptom indicates the disease is growing and spreading. One instigator of cancer is DNA that is damaged by free radicals. One of the functions of vitamin C is to protect the DNA from free-radical damage and prevent cancer before it even begins. The evidence seems to indicate that citrus can be particularly helpful in preventing the development of DNA damage and possibly cancer in areas of the body where cellular turnover is particularyly rapid, such as the digestive system. Thus citrus shows evidence of lowering the risk for esophageal and oropharyngeal/laryngeal (mouth, larynx, and pharynx) cancers as well as stomach cancers. Diets that are rich in citrus fruits can lessen the risk for these cancers by as much as 50 percent.
There’s also evidence that citrus can act to help reduce your risk of developing lung cancer. We know that consuming foods rich in beta-cryptoxanthin—the orange-red carotenoids that are found in high amounts in oranges (as well as in corn, pumpkin, papaya, tangerines, and red bell peppers)—may significantly lower lung cancer risk.
Red, or blood, oranges in particular have a class of polyphenols called anthocyanins, which give the fruit its red color. One study demonstrated that drinking blood-orange juice on a daily basis rapidly improved and normalized the functioning of the cells that line the blood vessels in nondiabetic subjects with risk factors for cardiovascular disease.
Blood oranges are also high in vitamin C and carotenoids, which are also likely contributors to their favorable effect on the cells that line the blood vessels, as measured by blood flow. The same study also showed that red orange juice had a significant anti-inflammatory effect (measured by a decrease in inflammatory markers in the blood). A reduction in oxidative stress markers has also been reported for consumption of regular of regular orange juice.
Aside from the vitamin C we all know about, oranges are rich in folate, which is particularly important for any woman who is pregnant or planning to become pregnant because of its proven ability to lower the level homocysteine, an amino acid that, at high levels, has been correlated with numerous adverse health conditions. The peel and the inner white pulp of the orange contain hesperidin, a phytonutrient that has been shown to lower blood pressure and cholesterol levels in laboratory animals. (Try grating orange rind—particularly from organic oranges—on salads or fish to get these important benefits.)
There is evidence that citrus is an important factor in preventing cardiovascular disease, primarily due to the folate in citrus fruits, which works to lower the levels of homocysteine—a significant risk factor for cardiovascular disease. The potassium in citrus works to lower blood pressure and this, too, lowers the risk of cardiovascular disease.
Citrus fruit can also help to mitigate cardiovascular disease because of its ability to prevent the oxidation of cholesterol. Free radicals oxidize cholesterol. Only after being oxidized does cholesterol stick to the artery walls, building up in plaques that may eventually grow large enough to impede or fully block blood flow, or rupture to cause a heart attack or stroke. Since vitamin C can neutralize free radicals, it can help prevent the oxidation of cholesterol.
The vitamin C and other phytonutrients in oranges also seem to be of benefit in preventing asthma, osteoarthritis, and rheumatoid arthritis—all inflammatory conditions. Free-radical damage to cellular structures and other molecules can result in painful inflammation as the body tries to clear out the damaged parts. Vitamin C, which plays a role in preventing the free-radical damage that triggers the inflammatory cascade, is associated with reduced severity of asthma, osteoarthritis, and rheumatoid arthritis.
Interesting research on animals also shows promise that citrus fruits could play a helpful role in lower the risk for the development of diabetes.
Perhaps vitamin C is most well known for helping to prevent the common cold. It turns out that the evidence supports this claim. One cup (8 ounces) of orange juice has been shown in studies to help maintain a healthy immune system, which can reduce susceptibility to illness. Studies also report that vitamin C may help shorten the duration or lessen the severity of a cold.
The C Solution
Are you getting enough vitamin C? A single navel orange, at only 64 calories, provides 23 percent of my daily dietary vitamin C recommendation of 350 mg or more. (That same navel orange provides 89 percent of the adult male RDA and 107 percent of the adult female RDA.)
Remember that the concentration of vitamin C in orange pulp is double that found in thepeel and ten times that found in the juice. This means you should make a point of buying orange juice with pulp. But even if you eat an orange a day and drink high-pulp orange juice, you still may be below optimal intake. In fact, only a limited number of fruits and vegetables are rich in vitamin C.
Here are the top common sources of vitamin C. Try to make them a regular part of your daily diet:
|1 large yellow bell pepper||341 mg|
|1 large red bell pepper||312 mg|
|1 large orange bell pepper||238 mg|
|1 large green bell pepper||132 mg|
|1 cup raw chopped broccoli||79 mg|
|1 common guava||165 mg|
|1 cup fresh strawberries||94 mg|
|1 cup cubed papaya||87 mg|
|1 navel orange||80 mg|
|1 medium kiwi||75 mg|
|1 cup cubed cantaloupe||68 mg|