Vitamin C : What it is?

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what is vitamin c

Are you thinking to add vitamin C tablets to your medicine cabinet?

Though many vitamin supplements are certainly beneficial to your health, it is important to know which one is right for you and what benefits it can do.

Today we’ll explore what literature and research say about the benefits of vitamin C, the difference between synthetic and naturally acquiring vitamin C, and help you correctly reap the benefits.

In my years of clinical practice, it has been a worthwhile tool for many health conditions as long as you use it in the correct way and with the correct dose.

What is vitamin C?  

Vitamin C which is known as ascorbic acid is a water-soluble vitamin. It can’t be synthesized in the body, so sources of vitamin C come from dietary intake and supplements. 

The discovery of vitamin C

Vitamin C was first discovered by Dr. Albert Szent-Györgyi from Hungary. The antioxidant property of vitamin C led him to his discovery. He uncovered that browning in plants is caused by oxidative damage at the cellular level. (Browning is an enzymatic oxidation reaction that takes place in some foods, mostly fruit, and vegetables, causing the food to turn brown.) The browning was finally found to be delayed by the citrus juice which contains a large amount of vitamin C.

There is great interest in the clinical roles of vitamin C because of evidence that oxidative damage is a root cause of many diseases.

What are the benefits of vitamin C?

Promote wound healing 

It is because vitamin C not only protects from external environmental stress but also provides mechanical support by stimulating new collagen synthesis and providing tensile strength to the newly built collagen. This not only helps improve wound healing but also gives adequate strength to the healing wounds.

A well-designed trial in 2020 studied the role of vitamin C in the healing of foot ulcers by comparing the placebo group and the vitamin C group. Healing at 8 weeks was significantly better in the vitamin C group. Healing without amputation occurred in all patients in the vitamin C group.

Delay signs of aging

  • Reduce oxidative stress

 Oxidative stress due to the overproduction of free radicals is the most significant cause of aging. As an antioxidant, vitamin C combats oxidative stress and prevents premature aging.

  • Promote collagen synthesis 

Loss of collagen with age also accounts for the appearance of wrinkles, and fine lines. Vitamin C not only acts as a cofactor for lysyl, and prolyl hydroxylase which stabilizes collagen molecules but also promotes new collagen synthesis.

The trial on the role of topically applied vitamin C in skin aging focused on skin changes, monitored by high-frequency ultrasound. It concluded that topical vitamin C is efficient as skin rejuvenation therapy.

Fade skin hyperpigmentation 

The ability of vitamin C to inhibit melanin (a substance in the skin that produces pigmentation)  brings up topical vitamin C products to treat skin hyperpigmentation like melasma and age spots. 

Immune booster

Vitamin C contributes to the immune response by promoting the cellular functions of your adaptive immune system. As an antioxidant, it can also combat free radicals in the body, thereby reducing inflammation and boosting immunity.

  • Can vitamin C treat cold symptoms?

In the 1970s, Linus Pauling, winner of two Nobel prizes, suggested that vitamin C could successfully treat or prevent the common cold. This made most people believe that vitamin C is a cold medicine.

But according to the evidence to date, vitamin C does not prevent colds. Also if people took vitamin C after they got a cold, it didn’t improve their symptoms.

Help iron absorption

As a doctor, I often encourage my patients with iron deficiency anemia to take vitamin C because vitamin C is a powerful enhancer of iron absorption and can reverse the inhibitory effects of substances such as tea and phytates which decrease iron absorption.

Potential role in cancer 

There have been mounted discoveries on the role of vitamin C in cancer treatment. 

Empowering cancer immunotherapy

Some studies advocate that high doses of vitamin C can modulate anti-cancer immune response and help to overcome resistance to cancer immunotherapy.

Dose-dependent effect of vitamin C on cancer 

Interestingly, though being an antioxidant, vitamin C exhibits a dual mode of action by giving pro-oxidant activity at higher doses.

This has the potential to kill cancer cells by cytotoxic effects without adversely affecting normal cells.

Vitamin C kills cancer cells with the mutation

Vitamin C also appears to be involved in epigenetic regulation ( genetic mechanism of cancer growth ). Cancer cells are known to have aberrant DNA methylation patterns required for survival and cancer progression. DNA demethylation is regulated by the TET enzymes, which are frequently mutated (decreased or absent) in malignancies.

Vitamin C-mediated restoration of TET enzymes enables the re-expression of tumor suppressor genes ( normal genes that slow down cell division or tell cells to die at the right time ) in cancer cells.

Is vitamin C a multitargeting agent in cancer therapy?

Although a high dose of vitamin C has potential benefits for cancer, further investigations are needed to evaluate the results.

Cardiovascular health

Unfortunately, there is no evidence that vitamin C can promote cardiovascular health contrary to what people believe.

The NICE Organization in the UK also doesn’t recommend using vitamin C to reduce cardiovascular risk.

Vitamin C deficiency

Vitamin C deficiency can cause a clinical syndrome called scurvy.

It is relatively uncommon in developed countries like Europe, in contrast to countries like India where over a third of the population has this deficiency.

However, deficiency in developed countries accounts for not having enough fruits, and vegetables in the diet. 

Signs of vitamin C deficiency 

  • Due to weakened connective tissues,

              Easy skin bruising,

              Hemorrhage around hair follicles ( Perifollicular hemorrhage),

              Corkscrew-shaped body hairs,

              Dry and thick skin ( hyperkeratosis ),

              Swollen and bleeding gums, tooth loss,

              Painful swollen joints, and weak bones

  • Poor immunity 
  • Slow wound healing
  • Iron deficiency anemia
  • Fatigue and malaise

Are synthetic vitamins equally effective as food-derived vitamins?

The answer is no, even if they have the same bioavailability (proportion of active form of drug, or substance that can reach the blood).

Synthetic vitamins

Synthetic vitamin C which is known as ascorbic acid is just a synthetic fraction of natural vitamin complex.

Natural vitamin complex

Natural vitamin complex is better than synthetic one in the way that as the concomitant dietary consumption of nutrients, vitamins, and phytochemicals confer all the health benefits you’ve known about vitamin C. For instance, when you take vitamin C-rich fruits such as kiwis which also contain significant amounts of other antioxidants like vitamin E, vitamin C enhances the bioavailability of vitamin E. This in turn upsurges the antioxidant effects of vitamin C.

The Lee Principle of Nutrition by the Father of nutrition, Dr. Royal Lee, states that in nature, a vitamin is never a single chemical. Rather it is a group of interdependent compounds that form a “nutrient complex” so intricate that only a living cell can create it. And just as no single component of a watch keeps time, no one compound in a vitamin complex accounts for the vitamin’s nutritive effect on the body.

The nutrition Source

Citrus fruits such as orange, kiwi, lemon, guava, and grapefruit, other vitamin C-rich fruits such as papaya, cantaloupe, strawberries, and vegetables like broccoli, cauliflower, spinach, Brussel sprouts, and capsicums are all good natural sources of vitamin C.

For example, one cup of orange juice provides  97 mg of vitamin C.

                      Half a cup of red pepper contains 95 mg of vitamin C.

Reminder to preserve all the vitamin C content in food

High-heat cooking temperatures or prolonged cook times can break down vitamin C. As it is water-soluble, the vitamin can also seep into the cooking liquid and be lost if the liquids are not eaten.

How much vitamin C can you take per day?

Recommended Dietary Allowances (RDAs) for vitamin C 

Males: 90 mg/day

Females: 75 mg/day

Pregnant: 85 mg/day; not to exceed 2000 mg/day 

Nursing: 120 mg/day; not to exceed 2000 mg/day

Smokers require 35 mg/day more vitamin C than nonsmokers.

It is reminded not to take vitamin C with large amounts of sugar as sugar can sabotage vitamin C absorption.

Is a high dose of Vitamin C beneficial?

There are no benefits to taking very large doses. This is because vitamin C absorption in the body is dose-dependent. Once the vitamin C level reaches its saturation point, further absorption decreases, and any excess amount will be excreted in the urine. The National Institute of Health (NIH) stated that when you take an amount > 1000 mg/day, absorption of vitamin C decreases to less than 50%.

Side effects of megadose

Side effects can occur with doses >2000 mg/day, and include diarrhea, kidney stone formation in those with renal disease, and increased iron absorption and overload in those with hemochromatosis (a hereditary condition with iron excess).

Truths and myths about vitamin C

Myths – Vitamin C can cure a common cold or Covid-19.

             Vitamin C might be a cure for cancer.

             Vitamin C is good for cardiovascular disease.

             The more vitamin C, the better.

Truths – Vitamin C boosts immune function.

              It promotes wound healing.

              It helps iron absorption.

              It has antioxidant action.

              It is beneficial for skin health.

              Larger doses of vitamin C do nothing good.


The common question that I encountered during my clinical practice was whether supplements should be taken or not.

My personal opinion is that requirement for supplements differs from the individual.

For example, when you can’t get enough vitamin C from food because of dietary restrictions or absorption problems, or when you have extra needs such as being a smoker or constantly exposed to UV radiation or have a clinical indication that requires a vitamin C prescription, supplements do benefit.

Otherwise, you can’t just substitute balanced nutrition by popping supplement pills.


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Dr Tun Min is s GP working in NHS UK and writing articles about supplements and vitamins based on personal clinical experience and clinical research.

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