Unlike most other mammals, we as humans don’t have the ability to make our own vitamin C. It’s true – vitamin C is one of the essential nutrients that we have to obtain from our diets, and deficiency is seriously bad news! Vitamin C, also known as ascorbic acid, is also a water-soluble vitamin, meaning that we don’t store it internally and need to have it regularly. While it has a reputation as being important for immune function, that is hardly all that vitamin C is responsible for. Vitamin C is used by the body for a huge number of functions, the two major categories of which are as an antioxidant and as an enzyme cofactor.
As an antioxidant, vitamin C is essential in the protection of many molecules in the body (proteins, lipids, carbohydrates, and nucleic acids, to be general about it!), from the damage generated by free radicals and reactive oxygen species. Maybe you’ve heard of these compounds before: they’re basically ions with a wiley electron, which can bond to other molecules and cause damage. Our bodies are constantly managing free radicals and reactive oxygen species (when oxygen has an extra electron, so it can also bind things it’s not “supposed” to and cause damage or generate toxic chemicals like carbon monoxide). These free radicals are generated sometimes on purpose, like by the immune system to kill off microbes, but they can also be created in the body from exposure to harmful toxins and pollutants (like cigarette smoke). Ascorbic acid helps to manage these free radicals – this is one of the reasons we take vitamin C to support our immune systems. Interestingly, vitamin C is also important to recycle other antioxidants, like vitamin E! Vitamin C is also used as an enzyme cofactor to generate critical compounds for joint and bone health, such as collagen, carnitine, and catecholamines.
Deficiency in vitamin C is serious. Severe deficiency is known as the potentially fatal disease scurvy. Symptoms of scurvy include bleeding, poor wound healing, and easy bruising with hair and tooth loss plus joint pain and swelling (note that all of these functions rely on proper ability of the body to generate collagen!). Scurvy is super rare in developed countries, because only 10mg of vitamin C a day is necessary to prevent it (the RDA of vitamin C for adult males and females is 90mg and 75mg, respectively). Consuming the RDA or more of vitamin C is associated with huge health benefits, including prevention of cardiovascular disease, multiple cancers, Alzheimer’s disease, cataracts, and more!! Interestingly, high doses of vitamin C are also used to treat many of these conditions plus diabetes. These high doses can be taken in capsule form, and some doctors use IV vitamin C as well – I know I’ve personally seen huge benefits from IV vitamins and minerals!
There is some evidence that there can be too much of a good thing, though that has mostly been in case reports. For now, the science says that up to 10 grams a day (that’s 10,000mg!) can be consumed by adults without concerns about toxicity or health detriments. That being said, there is a recommendation to keep regular consumption below 2000mg to avoid gastrointestinal upset. There is also some evidence that supplementing with vitamin C much above the RDA of 90mg could increase someone’s risk for kidney stones; that is just one reason why getting our nutrients from whole food sources is the best bet for health.
Vitamin C is known for being a supernutrient – and it totally lives up to the name! So, what are the best Paleo-friendly sources? Citrus probably comes to mind, and that would totally be right. In 1 medium orange, there are 70mg of vitamin C. Other amazing sources of vitamin C in the Paleo diet include strawberries (85mg/cup), red bell peppers (95mg/cup!), and broccoli (102mg/cup!!). Other great sources include all other citrus fruits, leafy dark green vegetables, and other fruits such as papaya, cantaloupe, guava, and berries. Some organ meats (adrenal glands in particular) are also good sources of vitamin C.
Erdman JW, MacDonald I, Zeisel SH, International Life Sciences Institute. Present knowledge in nutrition. 10th ed. Ames, Iowa: International Life Sciences Institute; 2012.
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Sauberlich, HE. A history of scurvy and vitamin C. In Packer, L. and Fuchs, J, eds. Vitamin C in health and disease. New York: Marcel Decker Inc. 1997: pages 1-24.
Food and Nutrition Board, Institute of Medicine. Vitamin C. Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. Washington, D.C.: National Academy Press; 2000:95-185.