What is vitamin C?

Vitamin C, or L-ascorbic acid, is an essential water-soluble nutrient that is naturally found in some plant foods. It is essential because, unlike most plants and animals, humans can’t produce it. It’s also a water-soluble vitamin, which means the body cannot store it, so we need to get a constant supply through our diets. 

Vitamin C benefits

Vitamin C is widely recognised as a powerful antioxidant and for its role in supporting the immune system. It is also involved in many other processes and pathways in the body and affects a number of organ systems. Some of its main roles include: 

Vitamin C as an antioxidant

One of vitamin C’s many immune-supporting roles is as an antioxidant (1). This means it's able to mop up free radicals, which cause oxidative stress and inflammation in the body.

Oxidative stress is when there is an imbalance of antioxidants and free radicals in the body. High levels of oxidative stress can be found in multiple organs, including the heart, pancreas, kidneys, brain and lungs, and if not kept in check, can cause damage to these tissues and others. 

Free radicals are chemicals in the body that have been oxidised, i.e. have lost an electron. Electrons like to be in pairs, so this causes them to become unstable and highly reactive, oxidising everything they come into contact with. They scavenge the body to find other electrons to steal so they can become a pair and stabilise. 

Free radicals are produced naturally in our cells and pose a constant threat to our bodies. They are generated by processes like the metabolism of oxygen and food, exercise and exposure to environmental toxins and pollutants like cigarette smoke, chemicals, air pollution, radiation, etc. 

Antioxidants, such as vitamin C, donate some of their electrons to free radicals without turning into free radicals themselves This neutralises free radicals, acting as a natural ‘off’ switch, and reducing oxidative stress, which is the imbalance between antioxidants and free radicals in the body. In other words, they come in to help ‘clean up the mess’ that has been left behind from our natural bodily processes of metabolism, energy production and detoxification.

Vitamin C’s antioxidant power also protects all of your cell structures, including proteins, lipids, DNA, RNA, mitochondria and cell membranes, from oxidising damage and gives your whole body a natural line of defence. If these free radicals build up in high amounts, it can damage cells, cause ageing and inflammation and lead to chronic disease. 

Some studies suggest that a higher intake of vitamin C-rich fruits and vegetables may be associated with a lower risk of many chronic conditions (2).

Vitamin C and the immune system

Vitamin C also plays an important role in immunity. It's needed for the production and modulation of immune cells that help protect your body from invading pathogens, and supports a number of other cellular functions of both the innate and adaptive immune systems (3). These systems help to prevent you from developing chronic diseases and respond quickly to acute illnesses and infections. 

Consuming extra vitamin C may be beneficial for those who do a lot of intense physical exercise, as this causes the immune system to raise inflammation, supporting the repair and building of muscles.

Vitamin C and collagen formation

Vitamin C is required for the formation of collagen in the body (4). Collagen is the glue that holds our bodies together and contributes to the maintenance of healthy blood vessels, skin, bones, cartilage, gums and teeth of which collagen is a vital structural component.  

Vitamin C and energy production 

Vitamin C is involved in the synthesis of L-carnitine (5), which supports energy metabolism and helps to reduce fatigue and tiredness. It's also a vital nutrient for our adrenal glands, which are responsible for regulating the body’s stress response. In cases of chronic stress, our adrenal hormones can become imbalanced, leading to fatigue. Vitamin C can also help to reduce the overall burden and energy demands of stress on the body through its role in reducing oxidative stress. 

Vitamin C and cognition

Vitamin C supports the normal functioning of the nervous system. It plays a role in the production of norepinephrine, our ‘get up and go’ or ‘fight or flight’ neurotransmitter, and dopamine and serotonin, important neurotransmitters that support our moods and motivation (6). It also protects our brain cells from the harmful effects of oxidative stress via its antioxidant activities. 

Vitamin C and iron absorption

Vitamin C helps to increase the absorption of plant sources of iron (non-heme iron) (7).

Vitamin C and heart health

Vitamin C may help to protect heart health and prevent heart disease. A 2008 meta-analysis of 13 randomised controlled trials showed that supplementing with 500 milligrams of vitamin C daily significantly reduced levels of LDL cholesterol and triglycerides (8).

It has also been shown that a higher intake of vitamin C was associated with a lower risk of death from stroke or coronary heart disease in elderly people (9).

Vitamin C deficiency & depletion 

Many foods contain vitamin C, but due to the effects of modern day living, we're finding ourselves not getting nearly the amount we need to meet our individual needs. The environmental toxins and air pollution we're exposed to in the home and outdoors, life’s increased demands that leaves us in a constant state of stress, and chronic diseases are some factors that increase our need for vitamin C. The food we eat is also not of the same quality that it used to be, meaning that our nutrient requirements are always increasing, and this includes its requirements for vitamin C.

Factors that leave us much more prone to having low vitamin C levels include: 

• Poor diet: Alcohol, refined sugar, caffeine and processed foods. These can cause high urinary excretion of vitamin C or high production of free radicals, which increases our need for antioxidants

• Toxins: Environmental pollutants, cosmetics, domestic products and smoking cause high levels of oxidative stress in the body and an increased need for antioxidants

• Chronic illness (i.e. diabetes, autoimmune conditions): Produces high levels of free radicals and oxidative stress as well as lowers the body’s immune defences

• Stress: Vitamin C is needed to produce stress hormones, so the higher levels of stress we have, the higher our need for vitamin C 

• Acute illness: Lowers the body’s defences and increases demands

• Medications: Aspirin and other non-steroidal anti-inflammatory drugs

• Nutrient decline in foods due to soil depletion, intensive farming and long food storage

• Iron deficiency

Vitamin C deficiency signs & symptoms

Signs and symptoms of vitamin C deficiency develop after a few weeks to months of vitamin C depletion. Severe vitamin C deficiency, although very rare these days, can lead to the development of a condition known as scurvy, which is related to defects in connective tissues and collagen.

Early signs & symptoms of vitamin C deficiency

In early stages of vitamin C deficiency, usually seen within a few weeks to one month of inadequate intake, non specific symptoms include physical and mental fatigue, weakness, lethargy, irritability, weight loss, recurrent infections, poor wound healing, and mild muscle and joint aches and pains. 

Later signs & symptoms: Scurvy

Symptoms of scurvy, related to defects in connective tissues, develop after 8 to 12 weeks of irregular or inadequate intake. Signs and symptoms can include chronic inflammation and weak blood vessels (due to decreased collagen production). Weak blood vessels can lead to easy bruising, excessive bleeding, swollen and bleeding gums, loose teeth, coiled hair, and broken facial capillaries (spider veins). Other signs and symptoms include anaemia, muscle and joint pain, bone pain, mood changes, and depression.

Vitamin C sources 

As a water-soluble vitamin, vitamin C does not stay in the body very long. In most cases, it's excreted within 24 hours. This means that it is absolutely necessary to get our vitamin C from external dietary sources or supplementation on a daily basis. 

Vitamin C-rich foods

Vitamin C is present to some degree in most fruits and vegetables, however, some types of fresh produce have more vitamin C than others. Contrary to popular belief, many fruits and vegetables contain more vitamin C than oranges and other citrus fruits.

Foods that contain the most vitamin C include: papaya, bell peppers, guava, Brussels sprouts, broccoli, oranges, strawberries, kiwi, pineapple and cantaloupe melon. 

These foods are best eaten raw and soon after preparation as cooking and exposure to oxygen can reduce the vitamin C content by about 25%.

Vitamin C supplements

Although it is possible to get enough vitamin C from foods, our modern lifestyles can make it difficult to consume the amount of fresh fruit and vegetables we need to prevent deficiency. If you are very physically active, under high amounts of stress or even just exposed to outside air pollution on a daily basis, your body’s needs for vitamin C increase so you would need to consume a large amount of fruits and vegetables to keep your blood levels within a steady range.

One of the easiest ways to ensure you are getting enough vitamin C to support all your body’s systems that require it is through vitamin c supplements. 

References 

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3614697/ 
2. https://pubmed.ncbi.nlm.nih.gov/12569111/ 
3. https://pubmed.ncbi.nlm.nih.gov/29099763/
4. https://pubmed.ncbi.nlm.nih.gov/33037252/
5. https://pubmed.ncbi.nlm.nih.gov/23747864/ 
6. https://pubmed.ncbi.nlm.nih.gov/24169506/
7. https://pubmed.ncbi.nlm.nih.gov/6940487/
8. https://pubmed.ncbi.nlm.nih.gov/19674720/
9. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2549941/