Vitamin C

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.

* 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.

*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 person^1,5.

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.