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Do Vitamin C Supplements Really Work?

By Ronni Gordon
Beth Israel Deaconess Medical Center correspondent

Vitamin C supplementsWith cold and flu season upon us, it may be tempting to reach for one of the products that offer a blast of Vitamin C, but it's better for your overall health to reach for a piece of fruit instead.

"We get a tickle in our throat and then we wonder, 'What can I do to make this better?'" said Elisabeth Moore, a registered dietitian at Beth Israel Deaconess Medical Center.

People may view supplements such as Airborne and Emergen-C as a quick and easy fix; each contains 1,000 mg of Vitamin C along with other vitamins and minerals.

But, Moore said, "I don't recommend Vitamin C in high doses. I'd rather see people get it through the food they're eating or through multivitamins."

For years, Vitamin C has been seen as a remedy for the common cold, but research shows that for most people, Vitamin C supplements or Vitamin-C rich foods do not reduce the risk of getting a cold.

Dr. George Blackburn, Chief of the Nutrition/Metabolism Laboratory at BIDMC, agrees.

"Treating a cold with Vitamin C supplements is misdirected effort; whereas rest, fluids and a healthy diet will provide all the Vitamin C needed and provide the most effective and rapid recovery," he says.

However, people who take Vitamin C supplements regularly might have slightly shorter colds or somewhat milder symptoms when they do have a cold. Using Vitamin C supplements after cold symptoms start does not appear to be helpful.

The minimum daily requirement of Vitamin C for adults is 75 mg for women and 90 mg for men, with an extra 35 milligrams needed by smokers. According to Moore, "a significant amount more than that won't have a huge added benefit."

Vitamin C, also known as ascorbic acid, is a water-soluble nutrient that acts as an antioxidant, helping to protect cells from damage caused by free radicals (compounds that are formed when our bodies break down food or when we are exposed to tobacco smoke or radiation and air pollution). Vitamin C is also needed for the growth and repair of tissues in all parts of the body, and it helps the immune system work to protect the body from disease.

The body does not store Vitamin C, so it is important to eat foods containing it. Citrus fruits, such as oranges and grapefruit, along with their juices, have high amounts of Vitamin C; other fruits that have high amounts of Vitamin C include:

  • Cantaloupe
  • Kiwi fruit
  • Mango
  • Papaya
  • Pineapple
  • Strawberries, raspberries, blueberries, cranberries
  • Watermelon

Vegetables that have the highest amounts of vitamin C include:

  • Broccoli, Brussels sprouts, cauliflower
  • Green and red peppers
  • Spinach and other leafy greens
  • Sweet and white potatoes
  • Tomatoes and tomato juice
  • Winter squash

Moore says that most fruits and vegetables have some Vitamin C in them, so it's easy to get enough in our diets. Five servings a day of fruits and vegetables - or about 2 1/2 cups - averages out to between 200 to 250 mg of Vitamin C.

"Even if you eat half that, it would still be adequate," she says.

Because the body cannot store the vitamin, serious side effects of taking too much are rare, but taking more than 2,000 mg a day can cause diarrhea, nausea and stomach cramps. In addition, many vitamins or minerals in excessive amounts put a strain on the kidneys, because they must work to excrete it. Vitamin C deficiency, which can lead to scurvy, is rare in the United States (it can be prevented with as little as 10 mg of Vitamin C a day).

Airborne, originally advertised as a way to prevent and treat colds, toned down its claims after settling a false-advertising lawsuit in 2008.

The class-action lawsuit originated after a 2006 TV report questioned a clinical trial used by Airborne as proof that its product works. Shortly afterwards, the lawsuit was filed by California firms representing a customer who said the formula did not work. Later, the Center for Science in the Public Interest, which conducts periodic reviews of dietary supplements, joined the suit. Airborne is now marketed as an immune booster.

Whatever its claims, there are better alternatives if you feel a cold coming on or if you already have one.

"I would focus on rest, fluids, and maintaining a healthy diet," Moore said.

Above content provided by Beth Israel Deaconess Medical Center. For advice about your medical care, consult your doctor.

Posted December 2011

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