Vitamin C has often been associated with helping to alleviate symptoms of the flu and colds, such as coughing, sore throat and runny nose, because of its antioxidant properties that strengthen the immune system. Eating oranges is a good way to increase your vitamin C intake. However, controversy exists as to whether vitamin C in oranges is helpful in reducing or curing the common cold except in certain cases.
Oranges originated in Southeast Asia, and today they thrive in many countries including Portugal, Spain, North Africa and the United States, which is the world’s largest producer. Three basic types of orange include sweet, loose-skinned and bitter. Sweet oranges are large with skin that is difficult to remove. Seedless varieties, such as the navel, Valencia and the blood orange are best eaten raw. Loose-skinned oranges are easy to peel and include the mandarin orange family. Bitter oranges, used in marmalade, are too sour to eat raw.
Vitamins and minerals are necessary for maintaining the body's immune system. A medium-sized orange is an excellent source of vitamin C with 70 mg, which is about half the recommended daily allowance, or RDA, for children, almost a full day's allowance for adolescents and 85 percent RDA for people aged 19 years and older. The Linus Pauling Institute states that the antioxidants in oranges decrease the chance of illness, such as colds and flu, by protecting against free radical damage from body metabolism, toxins and pollution. Oranges contain 62 calories each with 52 mg of calcium and 13 mg magnesium. Rich in the antioxidant vitamin A for healthy mucus membranes to control infection and phlegm, one medium orange supplies 295 IU. Oranges contain 39 mg of folate, which boosts the immune system and helps prevent respiratory problems that may cause coughing. An orange provides 237 mg of potassium plus iron, magnesium and phosphorus, according to the USDA National Nutrient Database.
Prevention and Treatment of Colds
Oranges, despite their beneficial vitamin C content, may have no effect on preventing the common cold or helping to reduce the duration and severity of symptoms. If cold weather or heavy exercise has placed a drain on your immune system, vitamin C may be of benefit. Researchers at the Australian National University used 29 trial comparisons involving 11,077 study participants to analyze the effects of high doses of vitamin C -- 200 mg or more daily – to reduce the occurrence, length and severity of the common cold. Results of all the trials, published in the "Cochrane Database of Systematic Reviews," found a consistent reduction in incidence and duration of colds in 8 percent of adults and 13.5 percent of children. In five trials involving participants exposed to extreme physical stress, including soldiers, skiers and marathon runners, vitamin C reduced the risk of contracting a cold by one-half. Seven trials showed no benefits in length or severity of colds. One trial reported some advantage from an 8-g dose at the onset of symptoms – equal to the amount of vitamin C in 11 oranges -- but no advantage to doses up to 4 g of vitamin C daily, which is more than four times the RDA. Conclusions of the study showed an advantage of vitamin C for persons who undergo strenuous physical exercise or in cold environments but, to reap these benefits, you would need to consume about 30 oranges a day.
It would be difficult to consume enough oranges to help cure your cold since it takes mega-doses of vitamin C to have even the slightest benefit. More than 2 g of vitamin C per day may affect your digestive tract and cause stomach pain, burping and diarrhea. It is also unlikely that your body can absorb more than 400 mg at a time and mega-doses of vitamin C could be excreted from your body before it is able to provide any relief against coughs and phlegm, reports the Nutritional Supplements Health Guide.