Vitamin C is an essential vitamin to all of us. We may often hear Vitamin C interchanged with ascorbic acid. It is also a water soluble vitamin which means that it doesn’t have to be taken with food and that if too much is consumed it usually can be easily passed out of the body via urine1.

Many of us consume Vitamin C on a fairly regular basis eating citrus fruits and vegetables. The importance of vitamin C is that it helps to prevent many ailments including scurvy1. Most are familiar with the stories of scurvy, pirates and those sailing on ships who died or suffered from bleeding gums, and other ailments that wouldn’t heal1. It took awhile for people to figure out that eating vitamin C helped to prevent scurvy therefore they began packing out citrus fruits like limes to bring with them on long ship voyages so that people would survive. The reason this is necessary is that humans cannot actually synthesize vitamin C they must eat food that has it in it while other animals can synthesize it themselves1.

Why does scurvy occur? Vitamin C is required for the biosynthesis of collagen which helps make up connective tissue, L-carnitine, and certain neurotransmitters; vitamin C is also involved in protein metabolism and without these the body can’t heal so wounds and sores stay bad or get worse1. Vitamin C is also an important physiological antioxidant and has been shown to regenerate other antioxidants within the body, including alpha-tocopherol (vitamin E)2,3.

Vitamin C has been shown in research that it helps with decreasing the effects of free radicals which lead to oxidative stress to the body1. It does this by helping increase antioxidant activity in the body which may help decrease oxidative stress which can lead to the development of certain cancers, cardiovascular diseases, and more than1.

The RDA (recommended dietary allowance): is the recommended average daily intake of vitamin C that most need to consume daily1.

AI (adequate intake): is an assumed intake level needed when not enough data is available1.

Tolerable Upper Intake Level (UL): Maximum daily intake unlikely to cause adverse health effects1.

The graph below is from the National Institute of Health Offices of Dietary Supplements1.

Table 1: Recommended Dietary Allowances (RDAs) for Vitamin C5
AgeMaleFemalePregnancyLactation
0 to 6 months 40 mg* 40 mg*    
7 to 12 months 50 mg* 50 mg*    
1 to 3 years 15 mg 15 mg    
4 to 8 years 25 mg 25 mg    
9 to 13 years 45 mg 45 mg    
14 to 18 years 75 mg 65 mg 80 mg 115 mg
19+ years 90 mg 75 mg 85 mg 120 mg
Smokers Individuals who smoke require 35 mg/day more vitamin C than nonsmokers.

* Adequate Intake (AI)

The graph below is from the National Institute of Health Offices of Dietary Supplements1.

Although orange and grapefruit juice is listed here the fruits are also shown and healthy fiber is found in fruits but is missed in the juice4.

DV stands for daily value and this is shown as to what percentage of vitamin C this provides per day with 100% being the highest1. There are levels listed that are higher than 100% showing that more is being consumed than the daily value, but recall as mentioned earlier as vitamin C is a water soluble the excess can usually be easily removed from the system1.

Table 2: Selected Food Sources of Vitamin C6
FoodMilligrams (mg) per servingPercent (%) DV*
Red pepper, sweet, raw, ½ cup 95 158
Orange juice, ¾ cup 93 155
Orange, 1 medium 70 117
Grapefruit juice, ¾ cup 70 117
Kiwifruit, 1 medium 64 107
Green pepper, sweet, raw, ½ cup 60 100
Broccoli, cooked, ½ cup 51 85
Strawberries, fresh, sliced, ½ cup 49 82
Brussels sprouts, cooked, ½ cup 48 80
Grapefruit, ½ medium 39 65
Broccoli, raw, ½ cup 39 65
Tomato juice, ¾ cup 33 55
Cantaloupe, ½ cup 29 48
Cabbage, cooked, ½ cup 28 47
Cauliflower, raw, ½ cup 26 43
Potato, baked, 1 medium 17 28
Tomato, raw, 1 medium 17 28
Spinach, cooked, ½ cup 9 15
Green peas, frozen, cooked, ½ cup 8 13

*DV = Daily Value. The U.S. Food and Drug Administration (FDA) developed DVs to help consumers compare the nutrient contents of products within the context of a total diet. The DV for vitamin C used for the values in Table 2 is 60 mg for adults and children age 4 years and older7. This DV, however, is changing to 90 mg as the updated Nutrition and Supplement Facts labels are implemented8. The updated labels and DVs must appear on food products and dietary supplements beginning in January 2020, but they can be used now9. FDA requires current food labels to list vitamin C content, but this requirement will be dropped with the updated labels. Foods providing 20% or more of the DV are considered to be high sources of a nutrient, but foods providing lower percentages of the DV also contribute to a healthful diet.

Interestingly there is another box listed in the dietary supplement graph mentioning smokers. In fact it has been found that smokers need 35mg more vitamin C as well as those exposed to secondhand smoke than the average person1,5.

Another at risk group for low levels of vitamin C are babies who are fed evaporated or boiled milk as cow’s milk, unlike humans has very little vitamin C in it and as we know developing babies need all the essential vitamins and minerals to survive1.

References:

  1. https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/#en4 Opens in new window
  2. Jacob RA, Sotoudeh G. Vitamin C function and status in chronic disease. Nutr Clin Care 2002;5:66-74. [PubMed abstract Opens in new window]
  3. Frei B, England L, Ames BN. Ascorbate is an outstanding antioxidant in human blood plasma. Proc Natl Acad Sci U S A 1989;86:6377-81. [PubMed abstract Opens in new window]
  4. https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/expert-answers/juicing/faq-20058020 Opens in new window
  5. Institute of Medicine. Food and Nutrition Board. Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids Opens in new window. Washington, DC: National Academy Press, 2000.
  6. U.S. Department of Agriculture, Agricultural Research Service. 2011. USDA National Nutrient Database for Standard Reference, Release 24. Nutrient Data Laboratory Home Page, http://www.ars.usda.gov/ba/bhnrc/ndl Opens in new window
  7. U.S. Food and Drug Administration. Guidance for Industry: A Food Labeling Guide Opens in new window (14. Appendix F: Calculate the Percent Daily Value for the Appropriate Nutrients). 2013.
  8. U.S. Food and Drug Administration. Food Labeling: Revision of the Nutrition and Supplement Facts Labels. Opens in new window 2016.
  9. U.S. Food and Drug Administration. Food Labeling: Revision of the Nutrition and Supplement Facts Labels and Serving Sizes of Foods That Can Reasonably Be Consumed at One Eating Occasion; Dual-Column Labeling; Updating, Modifying, and Establishing Certain Reference Amounts Customarily Consumed; Serving Size for Breath Mints; and Technical Amendments; Proposed Extension of Compliance Dates. Opens in new window 2017.