What does vitamin C do for you?

Vitamin C helps you build collagen, arm immune cells, absorb plant iron, protect cells and make key hormones and brain chemicals — and since your body can't make it, it all has to come from food or supplements.

The list is longer than most people realise. The Linus Pauling Institute lists 18 enzymes and two enzyme families that rely on vitamin C, and says as little as 10 mg a day prevents scurvy. That's far less than your cells use.

So what does vitamin C do for you, and where does the evidence stop? This guide covers both.

Table of Contents

1. Why Your Body Depends on Vitamin C
2. Building the Tissue That Holds You Together
3. Keeping Your Immune Cells Supplied
4. Protecting Cells and Unlocking Plant Iron
5. What Does Vitamin C Do for You Beyond Immunity and Skin?
6. What Vitamin C Probably Won't Do for You
7. Getting Vitamin C Where Your Body Needs It
8. Bio Absorb Nutraceuticals Liposomal Vitamin C — Liquid or Capsules
9. Frequently Asked Questions
10. Conclusion
11. Research References

1. Why Your Body Depends on Vitamin C

Most animals make their own vitamin C, but humans can't. That's why the NIH classes it as an essential nutrient and puts your body's entire store at about 300 mg near scurvy and roughly 2 g when full. The same fact sheet lists white blood cells, eyes, adrenal and pituitary glands, and the brain as the places vitamin C is most concentrated, with far lower levels in your blood.

Running low is more common than scurvy's rarity suggests. In US survey data from 2017–2018, 6.8% of adults were deficient in vitamin C, including 14.6% of smokers compared with 4.4% of non-smokers. Our guide to the early signs of vitamin C deficiency explains how a shortfall tends to show up well before scurvy does.

2. Building the Tissue That Holds You Together

Collagen is the protein that gives skin, blood vessels, tendons and bone much of their strength, and your body can't finish making it without vitamin C. The Linus Pauling Institute's enzyme table lists 9 collagen-processing enzymes that depend on it, and a shortfall in that work is the likely reason poor wound healing is a classic sign of deficiency.

Skin shows how much this matters. A review of vitamin C in skin health reports 2 to 5 times more vitamin C in the outer layer of skin than in the layer beneath it. Across the skin, vitamin C supports collagen production and helps defend against UV damage. Levels also run lower in aged or sun-damaged skin, though researchers can't yet say whether that's a cause or an effect. It's also unclear whether vitamin C applied to the skin works as well as getting enough from your diet. Our guide to vitamin C and collagen for skin, joints and tissue repair goes deeper on the evidence.

3. Keeping Your Immune Cells Supplied

Your immune cells are among the most vitamin C–hungry cells in your body. A review of immune function found that white blood cells hold 50 to 100 times more vitamin C than your blood and fill up at intakes of about 100 mg a day. Neutrophils, the immune system's rapid responders, draw on that store as they hunt down and destroy microbes.

That demand shaped the official target. The RDA of 90 mg a day for men and 75 mg for women is based on vitamin C's roles in white blood cells. This puts it well above the amount needed just to prevent scurvy. What extra vitamin C does for immunity once you already have enough is more contested, and our guide to what the research actually shows about vitamin C and immune function works through that evidence.

4. Protecting Cells and Unlocking Plant Iron

Vitamin C is also your body's main water-soluble antioxidant. According to the Linus Pauling Institute, it's the primary non-enzyme antioxidant in plasma and tissues, and smokers are advised to get 35 mg more a day because smoke adds oxidative stress. It also recycles used vitamin E, which protects the fatty parts of your cells, back into its working form.

Its other job here is practical. The NIH notes that vitamin C improves absorption of non-heme iron, the form found in plant foods, and that half a cup of raw red pepper supplies about 95 mg. Pairing beans, lentils or fortified cereal with a vitamin C–rich food puts that to work. Our guide to how the vitamin C and iron pairing works covers when the effect matters most.

5. What Does Vitamin C Do for You Beyond Immunity and Skin?

Much of vitamin C's work happens out of sight. It acts as a cofactor, a helper molecule that certain enzymes need in order to work, and the Linus Pauling Institute's enzyme table includes several jobs that get far less attention than immunity:

• Fuel from fat. Vitamin C helps make carnitine, which your body needs to burn fat for energy.
• Brain chemistry. It helps the enzyme that turns dopamine into norepinephrine (noradrenaline), a chemical messenger in your brain and nervous system.
• Hormone finishing. Another vitamin C–dependent enzyme completes a final processing step for peptide hormones.
• Gene control. Two enzyme families, TET and Jumonji, use vitamin C to strip chemical tags from DNA and histones, which helps set which genes are active. Researchers still describe this role as emerging.

The carnitine link has been tested in people, though on a small scale. Young adults with low vitamin C burned 25% less fat per kilogram on a 60-minute treadmill walk, and in a follow-up of 8 people, 500 mg a day quadrupled fat burning versus placebo. The authors call their results preliminary, but they fit the long-standing view that the fatigue of early deficiency comes partly from a carnitine shortfall.

Mood follows a similar pattern. In a trial in hospital patients, many of them low in vitamin C, 500 mg twice a day for about 8 days restored normal blood levels and was linked to a 71% drop in mood disturbance. Vitamin D served as the comparison. That's a striking result, but it comes from people who were depleted and unwell, so it doesn't show that extra vitamin C lifts mood in people who already get enough.

6. What Vitamin C Probably Won't Do for You

Because vitamin C does so much, it's tempting to assume that more means better health. Large trials suggest otherwise, at least for people who already eat reasonably well:

• In 14,641 US male physicians, 500 mg a day for a mean of 8 years had no effect on major cardiovascular events (a hazard ratio of 0.99, where 1.0 means no difference).
• In the same trial, vitamin C had no effect on total cancer across 1,943 cases (a hazard ratio of 1.01).
• The Linus Pauling Institute reports that a 2012 meta-analysis of 29 randomised trials found no effect of oral vitamin C, taken alone or with other antioxidants, on deaths from any cause.

That doesn't rule out a role for vitamin C in heart health, and it points to a ceiling rather than a failure. The NIH notes that cells appear saturated at intakes of 100 mg a day or more, so supplements would be expected to change little in people already near that point. The physicians in the heart and cancer trial were well-nourished and their vitamin C levels weren't measured, which leaves open whether people who start low would respond differently. The energy and mood findings above came largely from that group. If you're unsure where you stand, a blood test and a talk with your doctor are a better next step than a bigger dose.

7. Getting Vitamin C Where Your Body Needs It

Every job in this guide depends on vitamin C reaching your cells, and for most people a varied diet with plenty of fruit and vegetables covers the basics. Absorption has limits, though: the NIH reports that 70–90% is absorbed at intakes of 30–180 mg a day, but less than 50% above 1 g a day. Absorbed vitamin C your body doesn't use leaves in urine, which is the focus of our guide to why most of a large vitamin C dose is wasted.

Delivery format is one variable you can control. Liposomal vitamin C wraps the vitamin in tiny fat-based bubbles. A 2025 scoping review found that 9 of 10 trials showed better absorption, with 1.3 to 7.2 times higher blood exposure than standard vitamin C. The review is candid about its limits, noting that no trial measured excretion and very few looked at any effect on the body. The absorption advantage is well supported, but better health outcomes haven't been shown, and our complete guide to liposomal vitamin C explains how the delivery system works.

Bio Absorb Nutraceuticals Liposomal Vitamin C — Liquid or Capsules

If you decide to supplement, check the form, the allergen profile and whether an independent lab has tested it. Bio Absorb Nutraceuticals makes its Liposomal Vitamin C in two formats: the Liposomal Vitamin C Liquid 1000mg (Corn-Free) and the Liposomal Vitamin C Capsules 1000mg (Corn-Free). The liquid has a natural orange flavour and mixes into water or juice, while the capsules need no refrigeration and have no taste. Both use liposomal delivery, although, as the research above shows, its established advantage is absorption rather than outcomes. They also share the same formulation and allergen profile: verified corn-free, non-GMO, gluten-free, nut-free, dairy-free and vegan. If you're sensitive to corn, that verified corn-free status is worth looking for on any vitamin C label.

They're made in a GMP-certified facility in Canada, non-irradiated and third-party tested every batch, and both carry a 100% money-back guarantee with no need to return empty bottles. The choice mostly comes down to routine: the liquid suits people who like to split their intake across the day, while the capsules are easier to take on the road. Product details change over time, so rather than quote them here, see current pricing and serving details for the liquid or the full product specification for the capsules.

Frequently Asked Questions

What does vitamin C do for your skin?

It helps your body make collagen, the protein that keeps skin firm, and it helps protect skin from UV damage. A review of vitamin C's roles in skin health found that skin holds high levels of vitamin C, especially in its outer layer, and that levels tend to be lower in aged or sun-damaged skin. Whether creams and serums work better than getting enough from your diet hasn't been settled.

Does vitamin C give you energy?

Not the way caffeine does. Vitamin C helps make carnitine, which your body needs to burn fat for fuel, and in one small study people with low vitamin C burned 25% less fat per kilogram during a 60-minute walk. Once your levels are adequate, extra vitamin C is unlikely to give you a noticeable lift.

Can vitamin C improve your mood?

It may if your levels are low. In a trial in hospital patients, vitamin C was linked to a 71% drop in mood disturbance and a 51% drop in psychological distress, but those patients were unwell and often depleted. If low mood persists, that's a reason to see your doctor rather than to take more vitamin C.

How quickly can you run low on vitamin C?

Faster than many people expect, because your body's store is small. The NIH notes that signs of deficiency can appear within about a month of intake below roughly 10 mg a day, starting with fatigue, a general sense of feeling unwell and inflamed gums. People who smoke, eat a limited range of foods or have certain chronic illnesses are at higher risk.

Is vitamin C from food as good as a supplement?

For absorption, they're effectively equivalent: the NIH notes that the ascorbic acid in supplements is absorbed as well as the ascorbic acid naturally present in foods. A varied diet with plenty of fruit and vegetables covers most people's needs and brings fibre and other nutrients, so it's the natural place to start. Supplements can fill the gap when your diet falls short or your needs are higher, for example if you smoke.

Can you take too much vitamin C?

Yes. The tolerable upper intake level for adults is 2,000 mg a day, and the most common complaints at high intakes are diarrhoea, nausea and stomach cramps. If you've had kidney stones, have kidney disease or haemochromatosis (an iron-overload condition), or take regular medication, talk to your doctor before taking high-dose vitamin C.

Conclusion

So what does vitamin C do for you? It builds collagen, supplies immune cells, protects cells, unlocks plant iron and keeps enzymes for energy, brain chemistry and gene control running, with the clearest benefits when levels are low. Liposomal forms gave 1.3 to 7.2 times higher blood exposure in 9 of 10 trials of different products; if you'd like that option, see current pricing and serving details for Bio Absorb Nutraceuticals' Liposomal Vitamin C Liquid or Liposomal Vitamin C Capsules.

Research References

1. Vitamin C and Immune Function. Nutrients, Vol. 9, Issue 11 (2017), article 1211. Review finding that white blood cells concentrate vitamin C to 50–100 times plasma levels and are saturated at intakes of about 100 mg a day.
2. The Roles of Vitamin C in Skin Health. Nutrients, Vol. 9, Issue 8 (2017), article 866. Review reporting 2–5-fold more vitamin C in the epidermis than the dermis, and lower levels in aged or photodamaged skin.
3. Marginal vitamin C status is associated with reduced fat oxidation during submaximal exercise in young adults. Nutrition & Metabolism, Vol. 3, article 35 (2006). Preliminary study in which low vitamin C status meant 25% less fat oxidation during a 60-minute walk, and repletion raised fat use fourfold versus placebo.
4. Effects of vitamin C and vitamin D administration on mood and distress in acutely hospitalized patients. The American Journal of Clinical Nutrition, Vol. 98 (2013), pp. 705–711. Randomised double-blind trial in which vitamin C normalised blood levels and was associated with a 71% reduction in mood disturbance.
5. Regulation of the Epigenome by Vitamin C. Annual Review of Nutrition, Vol. 35 (2015), pp. 545–564. Review of emerging evidence that vitamin C is a cofactor for TET and Jumonji enzymes that remove methyl marks from DNA and histones.
6. Vitamins E and C in the prevention of cardiovascular disease in men: the Physicians' Health Study II randomized controlled trial. JAMA, Vol. 300, Issue 18 (2008), pp. 2123–2133. In 14,641 male physicians, 500 mg of vitamin C daily for a mean of 8 years had no effect on major cardiovascular events.
7. Vitamins E and C in the prevention of prostate and total cancer in men: the Physicians' Health Study II randomized controlled trial. JAMA, Vol. 301, Issue 1 (2009), pp. 52–62. Across a mean of 8 years and 1,943 cancers, 500 mg of vitamin C daily had no effect on total or prostate cancer.
8. Do Liposomal Vitamin C Formulations Have Improved Bioavailability? A Scoping Review Identifying Future Research Directions. Basic & Clinical Pharmacology & Toxicology, Vol. 137, Issue 1 (2025), article e70067. Found higher bioavailability for liposomal vitamin C in 9 of 10 trials, with 1.3–7.2-fold higher AUC, while noting that just two trials assessed biological effects.
9. Vitamin C: Fact Sheet for Health Professionals. National Institutes of Health, Office of Dietary Supplements (2025). Source for body stores, absorption, RDAs, food sources, the 2,000 mg upper limit, saturation and iron absorption.
10. Vitamin C, Micronutrient Information Center. Linus Pauling Institute, Oregon State University (2026). Source for the table of vitamin C–dependent enzymes, the antioxidant role, US deficiency rates and the meta-analysis of vitamin C and mortality.

About the Author

David Kimbell is a health writer, digital entrepreneur and former aerospace engineer, based in Ottawa, Canada. He loves translating complex science into clear, actionable guidance for consumers seeking evidence-based solutions.

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Important Disclaimers

Medical Disclaimer: This article provides educational information only and is not intended as medical advice. Always consult with a qualified healthcare provider before starting any new supplement, especially if you have existing health conditions, take medications, or are pregnant or nursing.

FDA/Health Canada Statement: These statements have not been evaluated by the Food and Drug Administration or Health Canada. This product is not intended to diagnose, treat, cure, or prevent any disease.