18 February 2015 Vitamin C: Enough is Enough

Vitamin C is one of the important nutrients found in fruits and veggies. It is an essential nutrient that the human body does not produce nor store, so we have to ingest Vitamin C regularly. It is a nutrient involved in a large number of body processes related to growth and repair. Vitamin C works with protein to make skin, tendons and blood vessels. It helps heal wounds and repair cartilage, bones and teeth. Adequate vitamin C results in less bruising, faster healing and healthier gums and teeth. Vitamin C is also an important antioxidant that plays a role in immune function.

Controversy exists about vitamin C’s role with the common cold. Some research shows that vitamin C levels in the body decrease at the start of a cold and that increasing vitamin C intake might be beneficial. Other evidence shows that the body holds on to vitamin C due to increased demand and that increased vitamin C intake is not helpful for combating a cold. Evidence supporting that high-dose vitamin C supplements prevent colds is lacking. Vitamin C does have weak antihistamine effects, so it might make cold symptoms milder and might shorten a cold’s duration.

Some researchers think that mild vitamin C deficiency may be more common than you think. Vitamin C deficiency can result in fatigue, anemia, bleeding gums, decreased ability to fight infection, increased bruising, nosebleeds, swollen and painful joints, and dry, splitting hair. Sustained vitamin C deficiency, after 3-5 months, can cause scurvy with symptoms of bleeding gums and loose teeth.

So, how much vitamin C is enough? The RDA primarily depends on age and gender. For example:

  • Adult men, 19 and older: 90 mg/day
  • Adult women, 19 and older: 75 mg/day
  • Adult pregnant women: 85 mg/day
  • Adult breastfeeding women: 120 mg/day
  • Adult smokers need an additional 35 mg/day because of the oxidative effect of smoke.

The tolerable upper limit (TUL) for vitamin C is 2,000 mg /day. Mega-dosing on vitamin C above the TUL may cause diarrhea, nausea, vomiting, heartburn, abdominal bloating and cramping, headache, insomnia and kidney stones. Also, prolonged use of large amounts of vitamin C may result in increased metabolism of the nutrient so that when it is decreased, one could develop rebound scurvy. As is the case with most nutrients, it is best to get enough vitamin C, but not in excessive amounts.

Most nutrition experts agree that a diet high in fruits and vegetables is the best approach to getting adequate vitamin C. Practical tips to get vitamin C include:

  • All fruits and vegetables contain some vitamin C, so include at least 5 servings per day.
  • Highest sources include guava (165 mg/1 medium), red bell pepper (95 mg/1/2 cup), papaya (95 mg per ½ medium), orange juice from frozen concentrate (75 mg per 6 oz), orange (60 mg per medium), broccoli (60 mg per ½ cup), green bell pepper (45 mg per ½ cup), kohlrabi (45 mg per ½ cup), grapefruit (40 mg per ½ medium)
  • Vitamin C is highest in uncooked or raw fruits and veggies. Cooking vitamin C-rich foods can reduce the vitamin C content. Microwaving and steaming can reduce losses.
  • Vitamin C content decreases after harvest. Eat fresh produce within a week. Frozen produce is an excellent choice because produce is flash-frozen shortly after harvest.
  • Orange juice from frozen concentrate is 25% higher in vitamin C than ready-to- drink orange juice. Drink the OJ within one week. Purchase ready-to-drink OJ 3-4 weeks before expiration date and drink within one week of opening.
  • A standard multivitamin often contains extra vitamin C.

References:
1. http://naturaldatabase.therapeuticresearch.com
2. http://www.nlm.nih.gov/medlineplus/ency/article/002404.htm
3. R Larson. American Dietetic Assn. Complete Food & Nutrition Guide, 4th ed. 2012.

Brenda Braslow, MS, RD, CDE

Brenda is a registered dietitian and certified diabetes educator in Denver,

Colorado who specializes in diabetes prevention and health enhancement.

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Disclaimer: The information provided here does not constitute medical advice. If you are seeking medical advice, please visit your healthcare provider or medical professional.

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Nutrients/Other Vitamins & Minerals

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