Ahhhh, vitamin C. Bright, colorful, sour, and tangy – just some of the words that may come to mind when considering this essential micronutrient and its familiar sources. Also known as ascorbic acid – literally the “no-scurvy” acid - we may think we are well-acquainted enough with vitamin C (citrus fruit, anyone?), but how much do we really know about it? What exactly is vitamin C and what does it do for us? What about vitamin C foods, the benefits of getting vitamin C, and what happens when we don’t get enough and develop a nutritional gap or deficiency? The answers to these questions may have us asking life to send some more lemons our way after all.
What do we need Vitamin C for?
Vitamin C is an essential nutrient that is required every day regardless of season. The term “essential” isn’t tossed around lightly, in fact, it’s a scientific term for nutrients that your body isn’t capable of producing on its own (at least not in sufficient amounts), and so they must be consumed in food or supplement form.
Vitamin C Benefits and Functions
The role of vitamin C in the body is varied and indispensable – it is well-known as an antioxidant, but it is also important in the production of collagen, L-carnitine, neurotransmitters, and even helps your body absorb iron.2
Vitamin C is really a behind the scenes powerhouse. It’s easy to take it for granted as a common, run of the mill nutrient, but getting the right amount of vitamin C per day contributes to our overall health and supports one of the most important functions in the body: our immune system.†
Vitamin C to Support Immunity
The functions of vitamin C, especially its antioxidant activity and role in collagen biosynthesis, are the key to its ability to support our immune system.†
Innate and Adaptive Immunity
The immune system is divided in to two categories, innate and adaptive, that work in harmony. Innate immunity is the first line of defense – it consists of the physical barriers (like skin and mucous membranes – this is important!) that keep pathogens from getting in, and also the immune cells,1 including white blood cells, that arrive at the scene at the first hint of a foreign body invader.
Adaptive immunity, like the name suggests, is more specific and adapts to and mounts responses to pathogens via another type of white blood cells - B and T cells - then “remembers” the response so it’s more efficient the next time.1
Vitamin C’s role in innate and adaptive immunity is several-fold
Micronutrients are critical in every stage of the immune response1 and vitamin C gets particular recognition for immune support, flexing its micro-muscles in both the innate and adaptive immunity ring. Without vitamin C, we wouldn’t be able to make the collagen that supports epithelial barriers that keep pathogens out. In addition, vitamin C contributes to the robustness of white blood cell activity at every stage of immune response.1†
Why is Vitamin C’s antioxidant activity important in immune function?
When your body deploys immune cells to confront incoming pathogens, they release reactive oxygen species (ROS) to fend off the invaders.1 Yes, ROS are as menacing as they sound. Vitamin C’s antioxidant activity helps protect healthy cells from becoming damaged in the ROS crossfire. Vitamin C also has been shown to help clean up the mess the immune cell soldiers leave behind.
Your immune system never takes a vacation
It works hard so you can go about your life unbothered, so toss one (or two) of those cute travel-size tangerines in your gym bag and be on the road to giving your immune system what it needs to keep operating.
What does Vitamin C do for the body aside from supporting immunity?
Luckily for us, the vitamin C functions that support the immune system don’t just happen in isolation; they also contribute to the healthy functioning of the skin and body.
Vitamin C for skin
If you’re a skincare buff, vitamin C may already be part of your daily, topical skincare routine. But how does vitamin C support skin health from the inside out? The key is its relationship to collagen and its antioxidant prowess.2
Our bodies depend on Vitamin C to form and maintain collagen2
Collagen is often lauded for giving skin its elasticity, or that youthful “bounce.” But did you know it’s also the body’s most abundant protein? It keeps our teeth in our gums, forms the groundwork for our bones, supports our skin, and makes up the majority of the composition of our tendons – in short, collagen is the basis for all those wonderful connective tissues2 that quite literally keep us together.
Collagen also helps to maintain the structure of blood vessels.2 Stronger blood vessels equal less bruising, and less wondering where that latest purple splotch on your leg came from.
It’s worth saying again: vitamin C is necessary for the body to produce collagen. Get enough vitamin C to support healthy and structurally sound skin and body.
Neutralize free radicals with Vitamin C
We have all heard of antioxidants, and we know we need a lot of them. Vitamin C is the multi-purpose water-soluble antioxidant that travels around the body and neutralizes those pesky free radicals that result from normal body processes, and helps prevent them from damaging our skin and other cells.2
Exposure to daily skin stressors like smoking, air pollution and UV rays can also produce free radicals and impact our vitamin C needs,3 so all the more reason to concentrate on a diet rich in fruits and vegetables to keep the vitamin C circulating in abundance for your skin’s health.
What more can Vitamin C’s antioxidant activity do?
“I work well with others.” That’s what vitamin C personified might say if asked to name one of its strengths in a job interview. And it’s true; vitamin C not only works well independently, it contributes to the improved functioning of other body processes through its antioxidant activity.
One example of vitamin C’s helping efforts is the antioxidant work it does in the intestines, where it converts non-heme iron (from plant food) to a more absorbable iron. Without adequate vitamin C, iron alone may not prevent low iron stores (read: major fatigue) from occurring.3
Vitamin C isn’t the only antioxidant in the building. Circulating vitamin C (a water-soluble antioxidant) helps regenerate and recycle vitamin E (a fat-soluble antioxidant), and allows vitamin E to continue going about its own antioxidant work.2,4 See, a true team player.
Vitamin C nutrient shortfalls in diet
Now that we’ve scratched the surface of the functions and benefits of vitamin C, let’s discuss shortfalls and the best sources of Vitamin C to replenish with.
Extreme and prolonged vitamin C deficiency▲ leads to the (oft solely associated with sailors and prolonged sea voyages) disease called scurvy. Not planning to be ship-bound for that long without a fresh fruit in sight? Clinical vitamin C deficiency may be rare in modern-day society, but sadly almost half of all Americans still don’t meet the minimum requirements of vitamin C intake, let alone the recommended amounts to maintain a healthy status.1
National Health and Nutrition Examination Survey (NHANES) data from 2005-2016 for the US population show that a large percentage of us – almost half the population (46%) – aren’t getting the Estimated Average Requirement (EAR), the minimum requirement of vitamin C, from their diet alone.1 That’s a lot of antioxidants being left on the table.
So, while we may not be one eye patch, wooden peg leg, and scurvy diagnosis away from a pirate’s life, these vitamin C shortfalls in the population are below the amount for optimal health, which can impact our wellbeing.
Symptoms of Vitamin C deficiency
Many of the symptoms of vitamin C deficiency are actually “connected” to the breakdown of collagen without vitamin C there to help maintain it.2
Then how much Vitamin C do I need?
The recommended dietary allowance (RDA) for vitamin C varies based on life stage (infant, child, pregnant, breastfeeding, etc.), age, and biological sex. The minimum recommended amount for males ages 19 and up is 90 mg/day and females ages 19 and up should get a least 75 mg of vitamin C per day.2
That being said, antioxidant experts recommend at least 200 mg/day of vitamin C to optimize health benefits and better ensure constant adequate plasma concentrations of the micronutrient.2 200 mg/day sound like a lot? You can actually get there with five servings of fruits and vegetables per day. While it’s always best to meet your nutrient needs through your diet, sometimes that’s easier said than done. Supplements are a solid and convenient way to fill gaps when your diet is not sufficient to reach recommended daily amounts of vitamin C.
Special considerations for Vitamin C need
Finally, keep in mind if you’re exposed to certain environmental factors - say, pollution or smoking – then you actually have a higher Vitamin C need than most and might reach a deficient state faster. The RDA for smokers, for example, is 35 mg/day higher than for those that don’t light up.2 Toxins and pollutants create more free radicals, and Vitamin C helps combat those negative effects3.
How much Vitamin C is too much?
Water-soluble vitamins like vitamin C don’t have storage closets in our bodies like their fat-soluble vitamin counterparts. In the event vitamin C is over-consumed, the body will quickly excrete the excess, making it generally safe to consume without concern over reaching toxic levels.2
The tolerable upper intake level (UL) for vitamin C is set at 2 g (2,000 mg) daily. At consumption levels higher than that, some among us may experience diarrhea or other temporary gastrointestinal discomfort.2
It’s important to note that these same water-soluble properties make vitamin C all that more important to replenish on a regular basis.
Foods with Vitamin C
We’ve hinted at some good dietary sources - namely fresh fruits and vegetables - of vitamin C already. Fresh is key, because the vitamin C content of food actually diminishes over prolonged storage time. Also keep in mind that, since it’s water-soluble, vitamin C is susceptible to being destroyed, dissolved,4 or drained away during kitchen and cooking prep.
The good news is that many of the best food sources of vitamin C are usually consumed raw4 and are naturally ready to grab-and-go.
Which foods have Vitamin C?
Broccoli, lemons, strawberries, red bell pepper, kiwi, and brussels sprouts – these foods all pack a mean vitamin C punch. Notice a (colorful) pattern? Meeting vitamin C needs without fruits and vegetables from diet alone is nearly impossible. Meats, beans, breads, and milk products simply aren’t great sources of vitamin C.
How much Vitamin C is in an orange?
65 mg per medium-size orange,2 if we’re wondering. We might automatically associate vitamin C with oranges, but there are enough vitamin C packed food sources out there to satisfy any palate and keep things fresh. Here are some sources to start from:4
Sweet red and green peppers
The Benefits of Taking Vitamin C Year-Round
Vitamin C might arguably be the most modest and unassuming of the essential micronutrients, but we’ve seen how it works wonders behind the scenes to prop up giants like our immune systems and, quite literally, the entire connective system of our bodies. No matter the season, it’s important to get enough to “anti-oxidize” the effects of daily living and your environment – remember, your individual needs are as unique as you and your lifestyle. Armed with the knowledge of the benefits of vitamin C and where to get more of it, you can take those lemons from the decorative bowl to the cutting board and put them to work for your health from the inside out. And when diet alone isn’t enough, a personalized vitamin pack can fill in those gaps and keep you thriving.
▲ Vitamin C deficiency: US population - 4%; women 10%; Smokers - 20% 
† These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.
Pfeiffer CM, et al: The CDC's Second National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population Is a Valuable Tool for Researchers and Policy Makers, The Journal of Nutrition, Volume 143, Issue 6, June 2013, Pages 938S–947S
Carroll is a nutrition scientist and communicator with over 25 years of experience as a clinician, researcher, and educator at major universities, medical centers, and nutrition industry settings. She is a passionate advocate of nutritional health and established the nutrition education and science platforms at Pharmavite. Carroll is an expert in personalized nutrition and has published several scientific papers on vitamin and mineral inadequacies and the impact on health and wellbeing. Prior to joining Pharmavite, Carroll taught nutrition at UCLA Medical School and Santa Monica College and was a chief clinical dietitian and researcher.