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How Vitamin C Boosts the Immune System

Written by Dr. Group, DC Founder
A bowl of grapes.

When you feel the sniffles coming on, what’s your go-to remedy? Do you reach for a refreshing glass of orange juice? Do you listen to your grandma’s advice to eat lots of vitamin C-rich fruits and veggies to help you feel better?

As it turns out, the age-old wisdom to load up on this potent vitamin to get and stay healthy is more than an old wives’ tale. Vitamin C is a proven antioxidant that has many essential functions in the body, including supporting the immune system.[1] But how does vitamin C boost your immune system to keep you healthy? Read on to find out more about what vitamin C can do to help you feel your best.

What Is Vitamin C?

Vitamin C — also known as ascorbic acid — is a water-soluble nutrient that is best known for its powerful antioxidant properties. Antioxidants support the immune system by protecting cells throughout the body from the effects of harmful free radicals. Vitamin C’s antioxidant powers strengthen the immune system and protect the body from pathogens and free radical damage.[2]

This potent nutrient inhibits histamine levels in the blood.[3] Lowering histamine reduces allergy symptoms and reduces the duration of minor illnesses (it acts like a natural "antihistamine"). When you're stuffy and dealing with the sniffles, vitamin C can get you back to feeling like yourself faster.

But vitamin C does much more. It plays a role in making collagen, which keeps tendons, ligaments, and blood vessels strong — and plays a role in wound-healing.[4]

This super-vitamin also helps the body absorb iron, increasing the bioavailability of this essential mineral.

The body doesn’t produce vitamin C on its own, so you must get it from your diet or through nutritional supplements. Colorful fruits and vegetable high in vitamin C include:[2]

  • Berries
  • Tomatoes
  • Citrus fruits
  • Leafy greens
  • Broccoli
  • Brussels sprouts
  • Bell peppers

How Does Vitamin C Boost Your Immune System?

Vitamin C has long been touted as a natural immune booster, which means it keeps it functioning properly. While the Recommended Dietary Allowance (RDA) for vitamin C is 75 mg per day for women and 90 mg per day for men,[4] many people like to take hyper-doses or mega-doses to supercharge their immunity.

Linus Pauling, the Nobel Prize-winning chemist who discovered that DNA was a double helix, was a big proponent of using hyper-doses of vitamin C for colds as well as more serious illnesses.[5]

Let’s explore how it works.

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Acts as a Strong Antioxidant

We’ve all heard the adage "an apple a day keeps the doctor away," but it may work better with a juicy vitamin C-rich orange. If you get the summer or winter sniffles, there is evidence that vitamin C supplementation may shorten the duration of symptoms by a day or more if you take it regularly (so-called "prophylactic use").[6]

These amazing health benefits from vitamin C are thanks to the vitamin’s antioxidant properties. Vitamin C is known to regenerate other important antioxidants in the body, like vitamins A and E.[7] Vitamins C and E work together for added antioxidant defense to help keep you healthy.

Some people like to take vitamin C at the first signs of a cold or flu or other illness (i.e., sore throat, lethargy, headache, and chills), hoping it will reduce the duration and severity of symptoms. There's some evidence that this works, but more evidence suggests that daily supplementation works better.[6, 8]

Protects Your Cells

Vitamin C increases the production of white blood cells in the body, key players in your immune system that protect against bacteria and viruses.[9] When one of these invaders enters the body, it attaches itself to a healthy cell in order to multiply. Evidence suggests that vitamin C has can defend against organisms that harm healthy cells.[10]

Vitamin C protects cells throughout the entire body because it plays a role in the production of collagen — a major building block of skin, bones, muscles, tendons, blood vessels, body tissues, and teeth.[11] Collagen forms and repairs connective tissues inside your digestive system to keep your gut healthy and strong. A healthy gut leads to a healthy immune system![12]

Getting plenty of vitamin C can also keep your skin healthy, which is your body’s first line of defense.[13]

Helps You Breathe Easier

Feeling stuffed up and having trouble breathing is super uncomfortable and frustrating. Fortunately, supplementing with vitamin C can ease the incidence and severity of some respiratory symptoms.[4]

There’s evidence that the more vitamin C you consume, the better your lung function will be, both when you’re healthy and sick.[14, 15] Vitamin C supplementation has been shown to halve respiratory symptoms after short-term heavy physical stress, too.[16]

When your airways are not hydrated, it can lead to respiratory discomfort and you may experience a cough. Taking more vitamin C may keep your respiratory tract hydrated. That the respiratory tract can do its work, protecting you from potential pathogens and clearing them out.[17]

Works Synergistically With Zinc

Like vitamin C, zinc plays a central role in supporting the immune system. When taken together, the two micronutrients work in concert with one another. These two essential nutrients can ease respiratory symptoms, including those caused by viruses.[18]

In our modern world, pollution in the environment around us can cause oxidative stress in the body. Oxidative stress happens every day. While some oxidation occurs every day during bodily processes, when your antioxidants can’t keep up, it causes cellular degeneration, and ultimately aging. This is why health concerns become more frequent with age.

Making sure you have enough vitamin C and zinc in your system can reduce the risk of oxidative stress.[19] This, in turn, will help keep you healthy, especially if you’ve been in close contact with others who are feeling unwell. Choose an organic, plant-based zinc supplement like Global Healing’s liquid Zinc that is gentle on your stomach.

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Best Vitamin C Supplement

Vitamin C is an essential nutrient that you must regularly consume for you to maintain a healthy body. Even with a nutritious diet, you may find it challenging to get enough vitamin C from foods. A supplement may help.

If something impairs your ability to absorb vitamin C from food — such as smoking or living with a chronic health condition — a deficiency is possible.[20] Daily dietary supplements can provide peace of mind that you’re getting enough for optimal health. As a water-soluble vitamin, you will excrete any excess in urine.

Vitamin C supplements come in many different forms, including:

  • Powder
  • Chewable tablets
  • Capsules
  • Multivitamins
  • Liquids

Plant based sources are best because ascorbic acid is only one part of the vitamin C complex. Plant-derived vitamin C ensures that you get the suite of cofactors and bioflavonoids that improve absorption and function within the body. In contrast, 95 percent of store-bought vitamin C is synthetic, made from ascorbic acid only, and usually derived from GMO corn. Look for a plant-based, certified organic vitamin C supplement.

Global Healing’s Organic Plant-Based Vitamin C contains plant essences and Energized Trace Minerals™ for improved absorption. Its highly absorbable ascorbic is derived from the following plant sources:

  • Amla (Gooseberry) fruit Extract (Emblica officianalis)
  • Acerola fruit extract (Malpighia emarginata)
  • Kakadu plum fruit extract (Terminalia ferdinandiana)
  • Camu camu fruit extract (Myrciaria dubia)
  • Rosehip whole plant extract (Rosa canina)

Points to Remember

Vitamin C is an essential nutrient. As an immune system booster, it’s one of the most potent antioxidants available. Because it’s water-soluble, it isn’t stored in the body. You must continually replace it by eating vitamin C-rich foods or with dietary supplements.

Vitamin C is popular thanks to its wide array of health benefits, particularly its ability to strengthen the immune system. It improves wound healing time, protects cells, and produces collagen throughout the body. It also works with other antioxidants such as vitamin E and zinc. To fully receive its benefits, it’s important to consume it daily.

Vitamin C is generally safe for everyone, and the body eliminates what it doesn’t use. Too much vitamin C is unlikely to be harmful, but if you end up with too much of the vitamin, you may experience mild side effects such as diarrhea, nausea, or headaches.[21]

References (21)
  1. Carr A, et al. Vitamin C and immune function. Nutrients. 2017 Nov;9(11):1211.
  2. Vitamin C. US National Library of Medicine. Updated 04 Mar 2020. Accessed 17 Mar 2020.
  3. Johnston CS, et al. Antihistamine effect of supplemental ascorbic acid and neutrophil chemotaxis. J Am Coll Nutr. 1992 Apr;11(2):172-176.
  4. Vitamin C Fact Sheet for Health Professionals. Office of Dietary Supplements, National Institutes of Health. Updated 27 Feb 2020. Accessed 18 Mar 2020.
  5. Pauling Recommendation. Linus Pauling Institute. Oregon State University. Updated 27 Jan 2004. Accessed 24 Mar 2020.
  6. Douglas RM, et al. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev 2007;(3):CD000980.
  7. Chen LH. Interaction of vitamin E and ascorbic acid (review). In Vivo. 1989 May-Jun;3(3):199-209.
  8. Hemila H. The effect of vitamin C on bronchoconstriction and respiratory symptoms caused by exercise: a review and statistical analysis. Allergy Asthma Clin Immunol. 2014;10(1):58.
  9. Huijkens MJ, et al. Technical advance: ascorbic acid induces development of double-positive T cells from human hematopoietic stem cells in the absence of stromal cells. J Leukoc Biol. 2014 Dec;96(6):1165-1175.
  10. Hemila H, Louihala P. Vitamin C may affect lung infections. J R Soc Med. 2007 Nov; 100(11):495-498.
  11. DePhillipo NN, et al. Efficacy of vitamin C supplementation on collagen synthesis and oxidative stress after musculoskeletal injuries: a systematic review. Orthop J Sports Med. 2018 Oct; 6(10):2325967118804544.
  12. Vighi G, et al. Allergy and the gastrointestinal system. Clin Exp Immunol. 2008 Sep; 153(Suppl 1):3-6.
  13. Pullar JM, et al. The roles of vitamin C in skin health. Nutrients. 2017 Aug;9(8):866.
  14. Park HJ, et al. Dietary vitamin C intake protects against COPD: the Korea national health and nutrition examination survey in 2012. Int J Chron Obstruct Pulmon Dis. 2016; 11:2721-2728.
  15. Hong JY, et al. Effects of dietary antioxidant vitamins on lung functions according to gender and smoking status in Korea: a population-based cross-sectional study. BMJ Open. 2018;8(4):e020656.
  16. Hemila H. The effect of vitamin C on bronchoconstriction and respiratory symptoms caused by exercise: a review and statistical analysis. Allergy Asthma Clin Immunol. 2014;10(1):58.
  17. Larsson N, et al. Identification of vitamin C transporters in the human airways: a cross-sectional in vivo study. BMJ Open. 2015;5(4):e006979.
  18. Maggini S, et al. A combination of high-dose vitamin C plus zinc for the common cold. J Int Med Res. 2012;40(1):28-42.
  19. Wintergerst ES, et al. Immune-enhancing role of vitamin C and zinc and effect on clinical conditions. Ann Nutr Metab. 2006;50(2):85-94.
  20. Vitamin Deficiency Anemia. Mayo Clinic. Updated 10 Dec 2019. Accessed 20 Mar 2020.
  21. Nutrition and Healthy Eating. Mayo Clinic. Updated 18 Mar 2020. Accessed 20 Mar 2020.

†Results may vary. Information and statements made are for education purposes and are not intended to replace the advice of your doctor. If you have a severe medical condition or health concern, see your physician.


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