News & tips on health, fitness and nutrition

Sunday, November 8, 2009

Citrus Fruit Benefits

Citrus fruits have a lot more to offer than just vitamin C.

Oranges are the best citrus source of vitamin C, right?

Yes. One medium orange has about 70 milligrams (mg) of vitamin C, nearly enough to meet your basic daily needs. But ounce for ounce, lemons actually contain the most (77 mg in 3.5 ounces), followed by oranges (53 mg), pink grapefruit (37 mg), white grapefruit (33 mg), limes (29 mg), and tangerines (27 mg). The exact amount depends on where the fruit was grown, how it was handled, and even where on the tree it was located.

What else is in citrus?

Citrus fruits are a good source of folate and potassium, with small amounts of magnesium, calcium, and other nutrients. They are often rich in fiber — notably pectin, a soluble fiber that helps lower cholesterol. One medium orange has 3 grams of fiber. They also contain dozens of phytochemicals, including carotenoids and limonoids. Citrus flavonoids such as hesperetin (in oranges), naringin (in grapefruit), and tangeritin (in tangerines) have been shown in lab studies to have cholesterol-lowering, antioxidant, anti-inflammatory, and anti-cancer properties. Red/pink grapefruit is one of the best sources of the carotenoid lycopene.

Is citrus juice better than the whole fruit?

A cup of citrus juice has more vitamin C than a piece of whole fruit because it is concentrated (it takes nearly a pound of oranges to make a cup of juice). But it is also higher in sugar and calories—and lacks the fiber of the whole fruit. A glass of orange or grape-fruit juice is a good way to start the day (especially if it's fortified with calcium), but it is better to eat whole fruit, which has less effect on blood sugar and is more filling. Fresh OJ is slightly higher in C and other nutrients than juice made from concentrate.

Is the peel good for you, too?

Yes. Many of the substances in the pulp are also in the peel, though you're not likely to eat much of it. The peel consists of two parts: the inner spongy white albedo, which is the primary source of pectin, and the outer flavedo (or “zest”), where carotenoid pigments and fragrant volatile oils are found. Some nutrients in the pulp, such as vitamin C and folate, are also found in the peel.

Why are some oranges tinged with green?

Oranges grow in warm climates but need cool nights to turn orange. If nights are warm, oranges can remain slightly green. Another factor is “re-greening,” when fully developed oranges absorb some of the chlorophyll produced by the tree and turn partly green again. These oranges are extra-ripe and often sweeter. To make oranges uniformly orange, producers often expose them to ethylene (a harmless gas that some fruits naturally release) or treat them with vegetable dye. Whatever the color, oranges are always picked when mature and do not ripen further off the tree.

Do citrus fruits help reduce kidney stones?

There's some evidence that orange juice and lemonade may reduce the risk of certain kinds of stones (calcium stones) by boosting citrate levels in the urine. However, grapefruit juice may, according to preliminary studies, increase the risk. Follow your doctor's advice.

What is the grapefruit/drug effect?

Grapefruit and its juice can boost blood levels of certain medications to potentially dangerous levels. Substances in the fruit—possibly naringin, a flavonoid that provides the tart taste—inhibit an enzyme in the small intestine that helps break down the drugs. The interaction happens fast and can last 24 hours or longer. But it's highly unpredictable, varying from person to person and even from grapefruit to grapefruit. If you take medication and consume citrus, check with your doctor or pharmacist. The drugs include many cholesterol-lowering statins, as well as certain calcium channel blockers (for high blood pressure), tranquilizers, anti-histamines, and HIV drugs. Seville oranges (sour like grapefruit) may have a similar effect, as may pomelos and tangelos.

Can grapefruit help you lose weight?

It's a myth that grapefruit contains a special enzyme that digests and burns fat and promotes weight loss. While there are no such fat-burning substances, grapefruit is low in calories (40 in half a medium fruit) and filling, which is why it may help some people lose weight.

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