Collection of vitamin C-rich foods for supporting a healthy immune system

Does Vitamin C Help Support the Immune System?

Your immune system is an intricate network of organs, specialized cells and proteins that comprise your natural defenses and work together to keep you in top-notch health. In other words, it's pretty important! That's why immune support supplements are among the more popular nutritional formulas on the market—and of those, vitamin C is usually at or near the top of the list.

But there are some myths and misconceptions about vitamin C (also known as ascorbic acid). Most notably, consumers often choose high doses of vitamin C, thinking that's the best way to prepare themselves for health challenges. Getting a high dose, however, may not mean more benefits—if there are high plasma concentrations of vitamin C in your bloodstream, which can happen with higher doses, your body will flush out what it doesn't use.

So how does vitamin C help support the immune system, and the rest of your body—and should you take an immune support supplement? Let's get started.

What is vitamin C?

Fruits like pomegranates, oranges and strawberries a loaded with vitamin C

Vitamin C is an essential vitamin, which means your body can't produce it, so you must get it from your diet. It's naturally found in citrus fruits and vegetables like broccoli, Brussels sprouts, potatoes and peppers. It's also available in dietary supplements.

Ascorbic acid is a cofactor or a "helper molecule" in many biological processes. Your body uses it to make collagen, carnitine and even some neurotransmitters:

  • Collagen

    is a crucial component of connective tissue and plays a vital role in the structure of bones, joints and skin. It's also necessary for your skin's structure and resilience.
  • L-carnitine

    is needed to transport long-chain fatty acids for cellular energy production.
  • Neurotransmitters

    are chemical messengers that relay information between your brain and body about the world around you.

How does vitamin C protect the body?

In addition to these vital functions, vitamin C's importance to our health also lies in its antioxidant properties. As a powerful free radical scavenger, it helps protect the body against oxidative stress. Our body forms free radical compounds when it breaks down food for energy production, and it also encounters them in the environment. Exposure to UV light, pollution and cigarette smoke cause cellular stress, and ascorbic acid is terrific at quenching these undesirable compounds.

How is vitamin C good for healthy immune function?

Woman enjoying orange juice, a good source of vitamin C

As an antioxidant, vitamin C can help neutralize free radicals that can occur when your immune response gets triggered, explained Life Extension's Clinical Corporate Trainer, Dr. Kathryn Wilson, PhD. "Research also shows vitamin C can impact how your body deals with respiratory challenges," she said.

Vitamin C can also enhance phagocytosis, a cellular process where cells engulf large substances. As a function of the immune system, cells engulf foreign bacteria and microbes, promoting a healthy immune response. It's also been shown to support the specialization and production of T-cells and B-cells, vital components of your immune system's arsenal.

Complementing your lifestyle choices with supplements that help your body get the most from your vitamin C can be a great way to maintain a healthy immune system.

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Three impressive benefits of vitamin C

While vitamin C is most well-known as an immune support all-star and antioxidant, that's not all it does…not by a long shot. Here are three other impressive benefits:

  1. Protects memory and thinking

    —A large body of research shows that maintaining healthy vitamin C levels can have a protective effect against age-related cognitive decline and the changes that can affect areas of the brain associated with memory, learning and thinking.
  2. Maintains heart health

    —A 2018 analysis by researchers at John Hopkins University showed that increasing vitamin C intake may help maintain already-healthy blood pressure levels and promote cardiovascular health.
  3. Promotes healthy iron levels

    —Vitamin C has been shown to promote non-heme bioavailability—which means it helps your body absorb the iron in foods.

Vitamin C Myths—Busted!

With all the enthusiasm there is for vitamin C, there's also a lot of misinformation. Here are the three most popular myths.

  • "More vitamin C is better."

    —It's not uncommon to reach for some vitamin C supplements when we're experiencing immune challenges. Unfortunately, a higher intake of ascorbic acid when our defenses are already down won't make us fight challenges faster.
  • "Oranges are the best source of vitamin C."

    —Oranges and orange juice may be rich in vitamin C, but they're by no means the best or only source. You'll find vitamin C in broccoli, Brussels sprouts, red bell pepper, and other fruits like strawberries, papaya, kiwi and pineapple.
  • "You can't have too much vitamin C."

    —Your body gets rid of excess, but large doses are associated with digestive and other discomforts.

What foods are a good source of vitamin C?

Ascorbic acid is packed with health-promoting benefits, and making sure your body has enough of this nutrient starts with eating foods rich in vitamin C.

Here's a quick list of foods containing vitamin C and other immune-system-friendly nutrients.

  • Kale

    —This green cruciferous vegetable is packed with vitamin C. Just one cup of raw kale provides about 80% of your daily value. Add them to smoothies or sauteed it with other veggies.
  • Thyme

    —Not only does this spice enhance your cooking flavors, but it's also packed with vitamin C! Sprinkle it over your salads, or add it to soups, stews and other savory dishes.
  • Guavas

    —This tropical fruit native to Mexico and South America is loaded with vitamin C. Add it to smoothies, fruit salads, or enjoy on its own—the fruit, not the pastry!
  • Lemons

    —Not just for lemonade. Their rich vitamin C content provides about 90% of the daily value. Add lemon to salads, savory dishes, dessert, or some slices to your water.
  • Mushrooms

    —Not only do they contain vitamin C, but their zinc, selenium and vitamin D content make these friendly fungi a powerful, immune-supporting food. Sauté them or bake them as the perfect addition to a side dish.

What is the best form of vitamin C to take for my immune system?

Woman taking a vitamin C supplement with water

Vitamin C supplements come in different shapes and doses. You can find them as capsules, drops, effervescent tablets, and even chewables and gummies. It turns out that looking for the best vitamin C supplement for the immune system is all about the delivery system. In other words, how effective is the formula at making vitamin C accessible to the body and keeping it from being flushed out?

Life Extension's newest vitamin C supplement, Vitamin C 24-Hour Liposomal Hydrogel™ Formula, is a great example of why liposomal formulas can be more effective at ensuring the body has enough time to make use of ascorbic acid's health benefits. "It uses a novel delivery system that makes vitamin C available to the body for up to 24 hours and offers up to seven times greater absorption than standard vitamin C," noted Dr. Wilson.

The body does absorb most of the vitamin C in conventional formulas, but you need to take it throughout the day if it's not in liposomal form, rather than being "one and done." Why? As Dr. Wilson explained, conventional vitamin C formulations won't help maintain enough plasma concentrations to allow the body to use it before it's been flushed out.

Whichever brand or formula you choose, the secret to choosing high-quality supplements is to look for formulations that are clinically studied for optimal results. "When you purchase a supplement, you have to make sure you choose a reliable and transparent company," Dr. Wilson added.

Best vitamin C dosage for the immune system?

According to Dr. Wilson, getting 500 to 2000 mg of daily vitamin C is sufficient for basic support. However, when you're facing an immune system challenge, your needs for vitamin C may increase, and you may need to provide your body with higher doses of vitamin C to support immune health and function.

Should I take vitamin C with other supplements?

Vitamin C has an impeccable reputation for supporting immune health, but it's not the only nutrient that can help support a robust immune system.

Adding nutrients that work in tandem with vitamin C like elderberry, N-acetyl-L-Cysteine (NAC for short), and also vitamin D are excellent ways to ensure your immune system stays healthy.

About the Author: Jessica Monge has a bachelor's degree in biological sciences & neuroscience and a master's degree in comparative studies and related languages from Florida Atlantic University. She worked as a tutor, freelance writer and editor before joining Life Extension, where she is currently a Digital Content Writer.