Nutrition spotlight

Vitamin C Overview: Sources, Benefits, & Do You Need to Supplement?

Jacqueline Kaminski
Jacqueline Kaminski
| Stay Updated with NASM!

We are always told to drink orange juice when we are sick, but why? To increase our levels of Vitamin C of course! But what role does vitamin C play in our health?

Vitamin C is one of the major water-soluble vitamins, which means it is not stored in the body so daily sources are needed. Unlike most animals, humans are unable to synthesize vitamin C — making it an essential nutrient. See the NASM Guide to Micronutrients for more information on a wide range of micronutrients. 

What Does Vitamin C Do?

Vitamin C is a very potent antioxidant and plays an essential role in maintaining a strong immune system. Its structure can very easily donate electrons to stabilize other molecules in the body from damaging oxidants such as pollutants and chemicals, as well as help regenerate glutathione and vitamin E. Vitamin C is also found in high concentrations in our leukocytes, white blood cells that fight against infection. Intakes of at least 100mg/day can fully saturate these cells (aka build a strong immune system)!

Vitamin C also seems to be extremely beneficial in fighting against respiratory infections. Studies have shown that patients with acute respiratory infections (i.e., pneumonia, tuberculosis) administered vitamin C recovered faster than individuals without vitamin administration. Meta-analyses have shown that intakes of 200mg or more daily are effective in decreasing the duration and severity of the common cold. Makes sense as to why we stalk up on orange juice when we feel unwell, doesn’t it?

Added Benefits of Vitamin C

Aside from immunity, vitamin C is essential to produce collagen. Collagen is a major protein that makes up our skin, tendons, connective tissues, bones, and cartilage. But its function in the development of our tissues isn’t just structural! Vitamin C plays important role in wound healing since our skin contains very high concentrations of vitamin C.

This essential nutrient is also involved in various metabolic pathways responsible for the transportation of fatty acids, synthesis of catecholamine hormones (norepinephrine, vasopressin), and improved absorption of non-heme iron (a form of iron commonly found in plants).

As you can see, vitamin C plays many essential roles in our body. So how can we ensure we are consuming plenty in our diet? Well as you may have guessed… oranges or orange juice is very rich in vitamin C, as are all citrus fruits.

Vitamin C Sources

The highest concentrations of vitamin C can be found in:

  • Red peppers
  • Oranges
  • Grapefruit
  • Kiwi
  • Broccoli
  • Strawberries
  • Brussels sprouts
  • Potatoes
  • Tomatoes
  • Green peppers

Using Vitamin C to Stay Healthy

To prevent diseases like scurvy, very low levels of vitamin C are required. One orange a day would prevent the onset of the disease. However, the goal with most individuals is to not solely prevent disease but ensure a healthy body as well! For most individuals, consumption of 100-200mg/day is adequate to prevent sickness and ensure a strong immune system.

Highly active individuals who have a chronic disease, are elderly, smoke, or are pregnant/lactating often have increased requirements. For example, smokers are encouraged to consume an additional 35mg/day to fight oxidative damage caused by cigarettes and tobacco. It’s recommended athletes consume close to 200mg/day to promote recovery and training adaptations.

What ARe Signs that you are running low on vitamin C?

- Swollen/bleeding gums

- Fatigue

- Hair loss

- Poor wound healing

- Iron deficiency anemia (due to decreased absorption) - see these foods that are high in iron!

Believe it or not, vitamin C is the fourth leading micronutrient deficiency in the United States. Why? Well due to its poor storage capacity, daily intakes are needed, and many individuals do not consume enough fruits and vegetables to meet recommended intakes. Additionally, sedentary lifestyles that contribute to the onset of metabolic diseases, such as Type 2 diabetes, significantly increase the risk for common infections. In these cases, increased intakes are required.

Should YOu Supplement Vitamin C?

What about supplements? Can they satisfy your daily vitamin C needs? Absolutely! Vitamin C can be injected intravenously or taken as an oral supplement. Vitamin C is most seen in the form of ascorbic acid. While other forms may exist, no study to date has determined one form to be superior to another.

Is it better to consume vitamin C via food or supplements? Natural vs synthetic ascorbic acid is chemically identical. However, there is some debate as to whether natural sources may be more beneficial due to other components such as additional vitamins, minerals, fiber, and phytochemicals. Research has shown mixed results in both animal and human models regarding synthetic or food-derived vitamin C absorption. Overall, most animal studies showed no difference in the bioavailability of synthetic or food-derived vitamin C.

However, absorption of vitamin C decreases to less than 50% when doses of 1000mg or more are ingested. Intakes exceeding 3000mg/day can lead to gastrointestinal issues such as diarrhea or can lead to more serious conditions such as kidney stones and iron overload. This dosage is only for synthetic forms of vitamin C since toxicity is extremely rare with food intake.


Vitamin C is a vital nutrient and should be incorporated into our diets daily. Its role in our health is vast, ranging from protecting against pathogens, fighting inflammation, maintaining immunity, contributing to the strength of structural tissues in our body, and healing our skin.

Since this vitamin is water-soluble, daily intakes are needed to maintain a healthy body. While 100mg per day may sound like a tall order, it is easy to satisfy that requirement. One orange contains about 70mg of vitamin C! Consuming two per day or taking a daily multivitamin will very easily ensure you are meeting your daily needs. So, make sure you are eating your fruits and vegetables! Our bodies thrive off vitamin C!


The Author

Jacqueline Kaminski

Jacqueline Kaminski

Jackie Kaminski is a registered dietitian/ nutritionist with a Master's degree in Exercise Physiology & Sports Nutrition from Florida State University. Her first introduction to working with professional athletes was back in 2017 when she worked at the UFC performance institute in Las Vegas, Nevada. Since then, Jackie has worked with various professional fighters and other clientele and now operates under her company she started back in March, The Fight Nutritionist LLC. The Fight Nutritionist is dedicated to providing the most effective nutrition plans to ensure her athletes are performance at their absolute best. All of her plans are individualized to the athlete and are backed by the latest research to ensure complete safety and efficacy. Jackie is also a member of the international society of sports nutrition, where she often participates in different research projects and data collection with other ISSN members from Nova University. When Jackie isn’t working, you can find her at Combat Club where she trains kickboxing and Muy Thai. As a sports dietitian, Jackie’s aim is to provide her athletes with the necessary fuel to excel in training and provide the proper education to ensure her athletes are engaging in the safest health practices (as they relate to combat sports). You can find her on LinkedIn here.


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