Vitamin C: Benefits, uses, side effects, dosage, precautions

In the sea of information available, both online and offline, it can be overwhelming to discern what is accurate and what isn’t about this vital nutrient. This guide is designed to provide a comprehensive and reliable source of information about vitamin C. It includes insights into its benefits, practical uses, potential side effects, recommended dosage, and necessary precautions when consuming vitamin C.

We’ll look into the science behind vitamin C, exploring its discovery history and primary sources. We’ll investigate its health benefits and common uses, and clarify the myths and misconceptions surrounding it. Additionally, we’ll provide a clear guideline about the recommended daily dosage and the potential side effects of excess or deficiency.

What is vitamin C?

Vitamin C, scientifically known as ascorbic acid, is a crucial nutrient for normal functioning [1]. It’s a water-soluble vitamin, which means it dissolves in water and is not stored in the body. Instead, the excess amounts of the vitamin are excreted through urine, necessitating a continuous intake through our diet or supplements.

Renowned for its potent antioxidant properties, vitamin C protects our cells against damage from harmful molecules called free radicals. Furthermore, it aids in various bodily functions, including producing collagen (a protein essential for skin, ligaments, and blood vessels), enhancing iron absorption, and maintaining our immune defense system.

In short, vitamin C is more than just an essential vitamin; it’s a multi-functional nutrient that contributes to our overall health and well-being.

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What is the history of vitamin C?

The history of vitamin C is intriguing, dating back to the era of long sea voyages when sailors fell victim to a disease known as scurvy. The disease, characterized by symptoms like fatigue, swollen gums, joint pain, and anemia, was later discovered to be caused by a vitamin C deficiency.

Vitamin C was discovered in the 20th century [2]. In 1928, Hungarian biochemist Albert Szent-Györgyi isolated a substance from adrenal glands that he initially named ‘hexuronic acid’. 

However, it wasn’t until 1932 that the substance was conclusively identified as vitamin C, marking a significant turning point in nutritional science. Szent-Györgyi was awarded the Nobel Prize in Physiology or Medicine in 1937 for his work in biological oxidation processes, including his discovery of vitamin C.

The discovery of vitamin C shed light on its pivotal role in preventing scurvy, boosting immunity, and promoting overall health. Since then, it has become a subject of intense research, expanding our understanding of its potential benefits and uses. 

Its significance in human health and nutrition cannot be overstated, and vitamin C continues to be a vital nutrient in our dietary needs and health management strategies.

Vitamin C sources

Natural sources: Rich food providers of vitamin C

Vitamin C is widely available in a variety of fruits and vegetables. Here are some of the top natural sources:

  • Citrus fruits: These are often the first that come to mind when thinking of Vitamin C. Oranges, lemons, limes, and grapefruits are all high in vitamin C.
  • Berries: Strawberries, raspberries, blueberries, and cranberries are not only delicious but also excellent sources.
  • Kiwi and papaya: These tropical fruits provide a hefty dose of vitamin C.
  • Leafy greens: Dark green leafy vegetables like kale, spinach, and collard greens are packed with vitamin C.
  • Other vegetables: Broccoli, Brussels sprouts, and cauliflower are also rich in vitamin C.

Remember, vitamin C is sensitive to heat and can be destroyed during cooking or processing, so try to consume these foods fresh or minimally cooked where possible.

Vitamin C supplements: When diet isn’t enough

Although a balanced diet rich in fruits and vegetables is the best way to get vitamin C, there may be times when you need to take supplements. 

People who smoke, have limited food choices, are pregnant or nursing, or have certain medical conditions may need more vitamin C than others.

There are different types of Vitamin C supplements that you can choose from like tablets, capsules, chewables and powders [3]. They are generally well-tolerated and can conveniently ensure you get enough of this essential nutrient. 

Health benefits of vitamin C

1. Boosts immunity 

One of the most prominent roles of vitamin C is its contribution to immune defense. It enhances various immune cell functions and promotes their ability to protect against infection. It also aids the skin’s defensive barriers against pathogens, providing a frontline defense against multiple illnesses.

2. Protects cells

As a powerful antioxidant, vitamin C effectively counteracts damaging free radicals in the body. Limiting the damage caused by free radicals plays a protective role in conditions like heart disease, arthritis, and cancer. Its antioxidant properties also contribute to slowing the aging process.

3. Improves skin health

Collagen, a protein that gives structure and elasticity to the skin, hair, nails, and connective tissues, is produced by the body with the help of Vitamin C. By promoting collagen synthesis, it can help maintain skin health and slow the appearance of wrinkles. This makes it a popular ingredient in many skincare products.

4. Reduces heart disease risk

Several studies have suggested vitamin C could help lower blood pressure in those with and without high blood pressure. It accomplishes this by relaxing the blood vessels that carry blood from the heart. Including vitamin C in your diet can reduce the chances of developing heart disease as it lowers the level of harmful cholesterol (LDL) and increases the level of beneficial cholesterol (HDL).

5. Improves eye health

The health benefits of vitamin C extend to eye health as well. It is concentrated in the eyes and can act as an antioxidant to protect against damage. Regular intake has been linked to a decreased risk of developing cataracts and age-related macular degeneration.

improves eye health

What is vitamin C used for?

1. Preventing and treating colds

Many people use Vitamin C to prevent and treat the common cold. While research has been inconsistent, some studies suggest that it can slightly reduce the duration and severity of cold symptoms. However, for the general population, it does not appear to prevent the onset of a cold.

2. Integrative therapy

High doses have been studied as a potential treatment in cancer patients. According to research, administering it intravenously can help slow the growth and spread of specific cancer cells. However, more research is needed to understand its effectiveness fully.

3. Dealing with stress

Getting enough Vitamin C is essential in minimizing stress’s physical and mental impacts [4]. It helps to quickly clear the stress hormone cortisol from the body, helping you bounce back from stressful situations more rapidly.

4. Skincare product ingredient

Many skincare products like serums, creams, and lotions contain Vitamin C due to its antioxidant properties, which helps to combat free radical and sun damage. Also, it promotes collagen production, resulting in smoother, firmer skin and reduced appearance of aging signs.

How to take vitamin C

The Recommended Daily Allowance (RDA) varies depending on age, sex, and life stage. For men, the RDA is 90 mg/day, and for adult women, it’s 75 mg/day.  

For pregnant and breastfeeding women, the RDA is higher. Smokers also require 35 mg/day more vitamin C than non-smokers due to increased oxidative stress.

Vitamin C supplements are available in various forms, including tablets, capsules, chewables, and powders. The form only significantly affects the supplement’s effectiveness if you take it consistently and in the recommended doses.

When choosing a supplement, look for products that have undergone third-party testing for quality assurance. If you’re on any medication or have an existing health condition, consult your healthcare provider before starting a supplement regimen, as vitamin C can interact with certain medications.

While supplements can help you meet your vitamin C needs, they shouldn’t replace a balanced diet rich in fruits and vegetables. Whole foods provide vitamin C and offer a host of other vitamins, minerals, fiber, and antioxidants.

Remember that more isn’t always better if you consider a vitamin C supplement. Very high doses (over 2,000 mg/day) can lead to side effects like digestive discomfort. 

Maintaining adequate vitamin C intake—whether through diet or supplements—is key to optimal health [5]. Remember to aim for a balanced diet first, then consider supplements as a backup, not a replacement.

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What are the adverse side effects of vitamin C?

Vitamin C is water-soluble, and any excess in the body is usually excreted through urine. However, consuming too much, especially in supplement form, can sometimes lead to side effects. 

These are typically associated with doses over 2,000 milligrams per day, though individual tolerance may vary. Here are some possible side effects of excessive intake:

Digestive distress

High doses of vitamin C can cause stomach upset, including symptoms like abdominal bloating, diarrhea, and nausea. These symptoms tend to resolve once you stop taking excessive amounts.

Kidney stones

Consuming large amounts of vitamin C can increase the amount of oxalate in your urine, increasing the risk of developing kidney stones, especially in individuals predisposed to this condition.

Iron overload

Vitamin C can enhance the absorption of iron from the diet. While this can be beneficial for individuals with iron deficiency, it can lead to an excess of iron in the body for others, damaging body tissues over time.

Dental problems

Chewable vitamin C tablets are acidic and, if used frequently, can erode tooth enamel over time.


Some people report difficulty sleeping when taking high doses of vitamin C, particularly if taken close to bedtime.

What happens if you have vitamin C deficiency?

A deficiency in vitamin C can lead to a range of health problems [6], the most severe of which is a disease known as scurvy. Here are the risks associated with vitamin C deficiency:


This is a rare but serious condition that occurs when you’ve had severe vitamin C deficiency for an extended period. Symptoms include swollen gums, anemia, and easy bruising and bleeding. If left untreated, scurvy can have serious complications, including severe jaundice, organ failure, and even death.

Poor immune function

Vitamin C plays a crucial role in the immune system. A deficiency can impair immunity, making you more susceptible to infections and illnesses.

Delayed wound healing

Vitamin C is necessary to produce collagen, a protein that helps heal wounds. A deficiency can therefore result in slower healing of wounds and injuries.

Iron deficiency anemia

Vitamin C helps improve iron absorption from the diet. Without enough vitamin C, your body may not absorb enough iron, leading to iron deficiency anemia.

Weak bones

Long-term vitamin C deficiency can lead to weak bones and teeth, as vitamin C is essential for bone formation and maintenance.

Mood changes and depression

There’s evidence suggesting that vitamin C deficiency could lead to poor mood and even depression, though more research is needed in this area.

mood changes and depression

Who should be cautious about vitamin C intake?

While most people can safely consume vitamin C through their diet and in supplement form, specific individuals should be careful [7]. These include:

  • People with a history of kidney disorders or kidney stones: Excessive vitamin C can increase the risk of kidney stones in these individuals.
  • Those undergoing regular medical tests: High doses of vitamin C can interfere with specific lab tests, like cholesterol and blood sugar tests.
  • Individuals with a genetic condition called G6PD deficiency: They should avoid high doses of vitamin C, as it can lead to hemolysis (a condition where red blood cells break down prematurely).

Most common myths about vitamin C–debunked

As with many other nutrients, several misconceptions and myths surround vitamin C [8]. We aim to debunk these myths to ensure you have the correct information and can make informed decisions about your health. 

1. More vitamin C will prevent colds

While vitamin C plays a role in immune function, it’s a myth that high doses can prevent the common cold. Most research shows that for the general population, taking vitamin C does not reduce the risk of getting a cold for the general population. However, it might slightly reduce the duration and severity of colds in some individuals.

2. Vitamin C causes kidney stones

The link between vitamin C and kidney stones is often misunderstood. While excessive vitamin C intake can increase the risk of kidney stones in individuals predisposed to the condition, regular intake does not cause kidney stones in healthy individuals.

3. All fruits are high in vitamin C

Not all fruits contain high levels of vitamin C. While citrus fruits are renowned for their vitamin C content, apples, bananas, and pears contain relatively small amounts.

4. Vitamin C serum works instantly on the skin

Vitamin C serums can significantly benefit skin health, including increased collagen production and protection against UV damage. However, these results usually take time and consistent use to become noticeable. It’s a myth that vitamin C serums can deliver instant results.

5. You can’t take too much vitamin C

Because vitamin C is water-soluble and excess is excreted in urine, some people believe you can’t take too much. However, taking vitamin C in excessive amounts (usually from supplements) can lead to side effects like digestive distress and increase the risk of kidney stones.

Closing thoughts

Vitamin C’s benefits span various health aspects, from boosting immune function to supporting skin health. It’s naturally present in many fruits and vegetables and also available as a dietary supplement for those who may struggle to meet their daily intake.

However, as with any nutrient, it’s essential to approach vitamin C with a balanced perspective. While it’s a vital part of our diet, consuming excessive amounts—usually supplements—can lead to side effects. On the other hand, a deficiency can lead to health problems such as scurvy and poor wound healing.

Vitamin C is a powerful nutrient but not a magic bullet. It’s one piece of the puzzle in a balanced, nutrient-rich diet. The best way to meet your vitamin C needs is by incorporating various Vitamin C-rich foods into your diet. 

Before starting any supplement regimen or making significant changes to your diet, it’s important to consult a healthcare provider. They can provide personalized advice based on your individual health needs and circumstances. This is always recommended to ensure your safety and well-being.


Is vitamin C good to take everyday?

Yes, Vitamin C is good to take every day because it’s an essential nutrient our bodies can’t produce on their own, playing a crucial role in immune function, skin health, and other bodily processes. However, it’s generally recommended to obtain it through a balanced diet rich in fruits and vegetables, and supplements should only be used when necessary and under the guidance of a healthcare provider.

Is vitamin C very important?

Yes, vitamin C is essential as it is a vital nutrient required for the growth, development, and repair of body tissues. Its functions include the formation of collagen, absorption of iron, the proper functioning of the immune system, wound healing, and the maintenance of cartilage, bones, and teeth.

Why avoid taking vitamin C at night?

Avoiding vitamin C supplementation at night is often suggested because it’s a natural diuretic, which can increase urine production, potentially leading to interrupted sleep due to increased bathroom visits. Additionally, some people might experience mild insomnia or sleep disturbances when taking high-dose Vitamin C, particularly close to bedtime.

What type of vitamin C is best?

The best type of Vitamin C largely depends on your health needs and dietary habits. However, ascorbic acid, the most common form of Vitamin C found in foods and supplements, is generally well-absorbed and beneficial for most individuals.

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The information included in this article is for informational purposes only. The purpose of this webpage is to promote broad consumer understanding and knowledge of various health topics. It is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified health care provider with any questions you may have regarding a medical condition or treatment and before undertaking a new health care regimen, and never disregard professional medical advice or delay in seeking it because of something you have read on this website.