What is vitamin C?
Vitamin C, also known as ascorbic acid, is an organic acid. This is both colourless and odourless and water-soluble. There are four different forms of ascorbic acid, but only L-(+) ascorbic acid is biologically active. The term vitamin C is often used not only for L-(+) ascorbic acid, but also for all derivatives of this acid that have a similar effect. Substances that the body can convert to L-(+) ascorbic acid also belong to vitamin C. This includes, for example, dehydroascorbic acid (DHA).
Vitamin C and its discovery
The cause of research into the versatile vitamin was the sailors disease scurvy. In the 16th and 17th centuries, many sailors suffered from a vitamin deficiency. They were susceptible to infections, complained about muscle wasting and weakness or had a high fever. Since the disease was only observed among sailors, it had little relevance to the rest of the population. With the expansion of merchant shipping in the 17th century, however, the number of cases increased drastically.
As a result, scurvy came into the focus of medical research. In the mid-18th century, the British naval doctor James Lind examined the disease. Although he did not know the cause of the complaints, he accidentally administered lemon juice to some of the patients. These patients quickly showed a significant improvement in symptoms and were healthy a short time later.
In 1907, the Norwegian doctors Holst and Fröhlich were able to demonstrate in guinea pigs that scurvy is a vitamin deficiency disease. In doing so, they laid the foundation stone for the actual discovery of vitamin C in 1928 by the American biochemist Charles Glen King and the Hungarian physician Albert Szent-Györgyi.
In 1934, vitamin C was artificially synthesised for the first time by Walter Norman Haworth and Tadeus Reichstein. After that, industrial production also started, whereby the demand for the artificial vitamin C was initially low.
Vitamin C therapy experienced an upswing in the 1960s, primarily thanks to Linus Pauling. The American chemist and two-time Nobel laureate propagated the prophylactic effects of vitamin C against infections and cancer and took up to 18 grams of the vitamin every day until his death at the age of 93.
Vitamin C effect
Vitamin C is an extremely versatile vitamin that the organism needs for various metabolic processes. The vital substance is primarily known for its effects on the immune system, but it is also involved in the development of connective tissue, for example.
The antioxidant vitamin C.
Vitamin C plays a crucial role in the human body as an antioxidant. An antioxidant can slow down or even completely prevent the oxidation of other substances. In the human organism, antioxidants are particularly important for the inactivation of reactive oxygen species (ROS), so-called free radicals or oxygen radicals.
Free radicals are highly reactive and aggressive metabolic intermediates. The oxygen compounds contained always endeavour to form a connection with other electrons. These electrons are snatched from other atoms or molecules, so that new radicals are created. As a result of this unfortunate chain reaction, oxidative stress occurs in the body.
Free radicals and oxidative stress not only damage proteins, fatty acids, carbohydrates, collagen, elastin as well as cell walls and cell organelles, they also react with the DNA. As a result, point mutations, enzyme disorders and cell function disorders occur.
Among other things, free radicals increase the risk of:
- Heart attack
- Diabetes mellitus type 2 (diabetes)
- Autoimmune diseases such as rheumatism or Crohn's disease
As an antioxidant, vitamin C is therefore essential for maintaining health. Due to its high antioxidative potential, vitamin C is added to many foods such as meat or sausages.
Vitamin C as a cofactor
Vitamin C is involved as a cofactor in various metabolic reactions. For example, the body needs vitamin C for the synthesis of collagen. Collagen is a protein that is found in connective tissue, bones and cartilage. For example, hydroxylation - a chemical reaction to introduce so-called hydroxy groups - of the amino acid proline by hydroxyproline without vitamin C as a cofactor is not possible.
Vitamin C is also involved in the production of steroid hormones such as cortisol or testosterone and in the synthesis of bile acids and amino acids. The vitamin also promotes the absorption of zinc and iron.
Vitamin C deficiency
A vitamin C deficiency always arises when the body's own vitamin reserves are exhausted and the food intake is insufficient to meet the need. A vitamin C blood level between 11 and 28 µmol/l indicates an undersupply, whereas blood values below 11 µmol/l indicates a clear clinical deficiency with corresponding deficiency symptoms. However, the vitamin C deficiency develops rather slowly and therefore often remains undetected at first.
How does a vitamin C deficiency arise?
Unlike many other living things, humans are not able to produce vitamin C. The body is therefore dependent on a vitamin-rich diet or supplementation. A vitamin C deficiency can mainly result from an unbalanced diet with little fruit and vegetables.
But even people who eat fresh fruit and vegetables every day can suffer from an undersupply. Impairment of the gastrointestinal tract, for example in the case of inflammatory bowel diseases such as Crohn's disease or ulcerative colitis, can lead to a reduced intake. Likewise, there are people who have a poor intake of vitamin C for genetic reasons.
Vitamin C requirements may be increased in certain situations. Anyone who smokes, does a lot of sports or is in a stressful phase of life needs more vitamin C. Risk groups for an undersupply of vitamin C are above all:
- Pregnant and lactating women
- Older people
- High-performance athletes
- People who are increasingly suffering from psychological stress
- People with an unhealthy lifestyle
- Chronically ill people
- Mentally ill people
- Homeless people
Vitamin C deficiency - The consequences
A lack of ascorbic acid can have serious consequences. The most well-known disease that is due to a vitamin C deficiency is scurvy. Scurvy is very rare today. Study results suggest that a vitamin C deficiency can increase the risk of degenerative eye diseases and diseases of the intervertebral discs. The following symptoms can also indicate a vitamin C deficiency:
- Rough and dry skin
- Tendency to bruises
- Pain in the limbs and joints
- Bleeding gums
- Poor wound healing
- Weight loss
- Neurological disorders
- Tooth loss
Vitamin C in foods
Citrus fruits are known as the main classic suppliers of the vitamin. Cabbage vegetables such as broccoli, Brussels sprouts or kale are also rich in vitamin C. The US Department of Agriculture (USDA) has created a comprehensive table with thousands of foods and their vitamin C content.
Vitamin C occurrence in food (mg per 100 g)
Fruits and fruit juices:
- Acerola, raw: 1677
- Acerola juice: 1600
- Litchis: 183
- Kiwi: 161
- Orange juice: 144
- Orange: 136
- Lemon: 129
- Strawberries: 59
- Goji berries, dried: 49
Vegetables and vegetable juices:
- Parsley: 133
- Kale 93
- Broccoli: 93
- Brussels sprouts: 85
- Peppers: 80
- Tomato juice: 70
- Cress: 69
- Kohlrabi: 62
- Asparagus: 31
Meat, fish and shellfish:
- Chicken, offal: 16
- Mussels: 8
- Crabs: 7
- Chicken, meat: 1.6
- Tuna: 1
Egg, milk and milk products:
- Cow's milk: 16
- Cottage cheese: 4
- Goat milk: 1
- Egg: 0
Nuts and seeds:
- Hazelnuts: 6
- Pumpkin seeds: 2
- Sunflower seeds: 1
Vitamin C in fruits and vegetables
This table shows that fruits and vegetables are the main suppliers of vitamin C. However, it should be noted that the vitamin content can vary depending on the variety and cultivation. The important thing is: Vitamin C is extremely sensitive and decomposes primarily through light and heat. Spinach, which is stored at a temperature of 20 degrees for two days, loses 80 percent of its vitamin content.
Prevent vitamin loss
Since vitamin C is water-soluble, larger amounts are lost when washing fruits and vegetables. The washing loss is particularly high if the food is cut into pieces before washing. Cutting, grating and pureeing also accelerates the enzymatic degradation.
In order to avoid vitamin loss during cooking, the cooking time should be kept as short as possible. Vegetables should therefore always be added to boiling water. If you want to freeze your vegetables, you should blanch them briefly beforehand. This stops the enzymatic breakdown of vitamins and the vegetables remain rich in vitamins.
Vitamin C in acerola berries
The acerola cherry has the highest vitamin C content of all plants. The fruit is not only rich in vitamin C, but also contains significant amounts of pro-vitamin A, vitamin B1 and vitamin B2.
The stone fruit originally comes from South America. Today it is mainly grown in Mexico, Florida, Guatemala, Panama and Brazil. Even if the name suggests it, the acerola is not related to the local cherry.
Just like the cherry, however, the acerola cherry is up to three centimeters large, is round and has a red colour. The fruit is ripe within 25 days and can be harvested from the tree up to four times a year. It tastes quite sour and is not transportable due to its thin skin. That is why there are hardly any fresh acerola berries to buy in Europe.
The vitamin supplier is available in the form of a juice or powder. In particular, the powder can be used as a nutritional supplement and, in addition to vitamin C, also provides secondary plant substances and minerals such as potassium or iron.
Vitamin C in baobab
Baobab is the African baobab fruit and is known as a superfood from Africa. Baobab has been used as a natural remedy in Africa for centuries.
The baobab trees native to the Savannah can reach a height of up to 25 m and can live for several thousand years. The tree carries fruit for the first time at the age of 20. The baobab fruit is egg-shaped and has a hard shell covered with hair. Inside there are seeds that contain the white pulp.
Baobab as a dietary supplement
In Europe, baobab is mainly available in powder form. The powder not only contains an average of six times more vitamin C than oranges, it is also rich in potassium and calcium. The content of polyphenols is also worth mentioning. These aromatic compounds not only affect colour and taste, but can also have a positive effect on health.
Vitamin C overdose
Vitamin C has a low toxicity and little side effects even at higher doses. In order to avoid possible side effects, a daily dose of 2000 mg should not be exceeded.
Vitamin C side effects
The possible side effects of vitamin C supplementation at higher doses include:
- Inflammation of the esophagus
- Stomach cramps
- Skin symptoms
- Sleep disorders
There are often kidney stones in the list of possible side effects with long-term intake of vitamin C. Ascorbic acid is partly converted to oxalic acid in the body. This, in turn, is part of calcium oxalate stones, which can form in the urinary tract.
While some studies have found that vitamin C does not increase the risk of kidney stones, other research suggests that there is a connection. Overall, however, the absolute risk of kidney stone disease due to vitamin C supplementation can be classified as low.
Vitamin C interactions
Possible interactions include:
- Aluminum: Vitamin C can increase the absorption of aluminum from medicines containing aluminum, such as phosphate binders. This can be particularly problematic for people with kidney disease.
- Chemotherapy drugs: Antioxidants such as vitamin C can reduce the effectiveness of drugs used in chemotherapy.
- Estrogen: If vitamin C is taken with hormonal contraceptives or during hormone replacement therapy, the level of estrogen can increase.
- Protease inhibitors: Protease inhibitors are used in HIV therapy for example. Vitamin C can reduce the effectiveness of these drugs.
- Statins: Vitamin C supplementation can reduce the effect of statins.
- Warfarin: High doses of vitamin C reduce the blood-thinning effects of warfarin.
Vitamin C - Daily requirement and dosage
To prevent deficiency symptoms, the German Nutrition Society (DGE) recommends an intake of 20 to 155 mg of vitamin C per day, depending on age and gender.
Infants, children and adolescents:
- Infants: 0 to 12 months: 20 mg
- 1 to 4 years: 20 mg
- 4 to 7 years: 30 mg
- 7 to 10 years: 45 mg
- 10 to 13 years: 65 mg
- 13 to 15 years: 65 mg
- 15 to 19 years: 90 to 105 mg
- 19 to 65 years and older: 95 to 110 mg
Pregnant women from the fourth month of pregnancy have an increased need and should therefore take at least 105 mg of vitamin C daily. The daily requirement for breastfeeding women is even 125 mg. The DGE also recommends that smokers take 135 to 155 mg of vitamin C per day.
Interpretation of the guidelines
The recommended daily requirement is sufficient for an otherwise perfectly healthy person to prevent acute vitamin deficiency with corresponding deficiency symptoms. External factors such as UV radiation, pollution, poor eating habits but also infections or chronic diseases can increase the need for vitamin C.
It should also be noted that only part of the vitamin ingested is ultimately available to the body. This is because the availability of ascorbic acid also depends on absorption in the intestine, transport to the tissues, and reabsorption in the kidneys.
Vitamin C - The right dosage
There are different opinions regarding the correct dosage. Frei et al. came to the conclusion that the optimal dosage for the prevention of deficiency states is 200 mg of vitamin C per day.
The Linus Pauling Institute at Oregon State University, on the other hand, recommends 400 mg of vitamin C per day for adults, which is well above the recommended daily dose of the German Nutrition Society. The researchers base their results on various studies that investigated the relationship between taking supplements and vitamin levels in the blood plasma. In the healthy test subjects, the best effect was found when taking 400 mg of vitamin C per day.
However, the scientists at the Linus Pauling Institute point out that this dosage is only used to maintain health and not to treat diseases. People suffering from an illness may have a significantly increased need and must adjust their dosage accordingly.
Vitamin C dosage in pregnant women and nursing mothers
Vitamin C is very important for the development of the unborn child during pregnancy. A vitamin C deficiency in the mother-to-be can affect the child's brain development. In a study by the University of Copenhagen, developmental disorders in the area of the hippocampus were found in a vitamin C deficiency. This part of the brain is primarily responsible for memory and learning.
Likewise, in a study by Schjoldager et al. a lack of vitamin C leads to a decreased placenta function and a smaller placenta size. A vitamin C deficiency can also lead to a lower birth weight this way.
For ethical reasons, the study results are based only on experiments with guinea pigs. However, since these, like humans, cannot produce vitamin C themselves, they are well suited as a study model.
In order to prevent undesirable developments in the unborn child, pregnant women should therefore take care of an adequate intake of vitamin C and adhere to the recommendations of the German Nutrition Society.
Vitamin C while breastfeeding
When breastfeeding, the need for vitamin C is increased by up to 50 percent. Around 50 mg of vitamin C are required per 750 ml of breast milk. Children need vitamin C for healthy development. A 2005 study shows that a vitamin C-rich diet during breastfeeding reduces the risk of atopic diseases in children. Atopic clinical pictures include neurodermatitis, allergic rhino-conjunctivitis and allergic bronchial asthma.
Studies show that breastfed children have better vitamin C levels than children who are fed with powdered milk. Even if the mother has little vitamin C in the blood, the children are adequately cared for. In order to prevent a mother's deficiency, it may make sense to take food supplements while breastfeeding. The dosage should be based on the daily requirement for breastfeeding mothers recommended by the DGE.
Vitamin C - Need and dosage for athletes
Those who exercise regularly should eat according to the DGE's recommendations to supply their body with all nutrients and vital substances. However, recommendation adjustments may be necessary, especially for competitive athletes. So athletes have a higher need for carbohydrates, proteins and micronutrients.
The function of the mitochondria in the muscle cells is important for success in endurance and strength training, because the energy source adenosine triphosphate (ATP) is obtained in these cell power plants. ATP is an important prerequisite for muscle movement. The antioxidant vitamin C can protect the mitochondria of the body cells from the free radicals that accumulate during sports.
For example, Nakhostin-Roohi et al. significantly reduced muscle damage in her 2008 study with the administration of 1000 mg of vitamin C before a 30-minute sports session. Lipid peroxidation by radicals and highly reactive oxygen species, which can lead to cell damage, was also less pronounced than in the placebo group.
A high dose of vitamin C supplementation of 3 g vitamin C per day also showed positive effects on the condition of the muscles in another study. After excessive training, a lower creatine kinase value in the blood was found in the subjects of the vitamin C group. This indicates that fewer muscle cells have been damaged. The subjects also complained less about sore muscles and the glutathione ratio as a marker for oxidative stress was more positive than in the comparison group.
However, not all studies can confirm these positive effects. For example, vitamin C supplementation in a study by Theodorou et al. from 2011 had no effect on muscle performance. Endurance performance cannot always be improved by taking dietary supplements with vitamin C.
Smokers need vitamin C
Incomplete burning of tobacco creates around 4,000 chemical compounds, many of which are considered carcinogenic. In addition, with every puff of the cigarette, numerous free radicals are released, which damage the DNA and other structures in the body. Smoking not only leads to narrowing and hardening of the blood vessels, but often also to a vitamin C deficiency. This in turn increases the risk of consequential damages.
Smokers have a significantly lower vitamin C level than non-smokers. There is a clear deficit, especially in people who smoke more than 20 cigarettes a day. There are probably two reasons for this: On the one hand, smokers consume significantly more vitamin C because they have increased oxidative stress. On the other hand, smokers generally eat less healthy than non-smokers. But even with a daily consumption of nutritious fruits and vegetables, the vitamin C level in smokers is often too low due to the high consumption.
Vitamin C and COPD
Difficulty breathing, coughing and bronchitis are the typical signs of a chronic obstructive pulmonary disease (COPD). COPD primarily affects smokers. A Korean research team conducted a study involving more than 3,000 participants. 512 of these participants were COPD patients.
In this study, low vitamin C intake proved to be a risk factor for a chronic obstructive pulmonary disease. Already with the intake of 85 to 140 mg of vitamin C per day, the risk of becoming ill with heavy smokers could be reduced by around 76 percent as compared to subjects with a daily intake of less than 48 mg.
Improved lung function in smokers
Vitamin C also appears to have a positive effect on lung function in smokers. As a result of the chronic inflammation caused by cigarette smoke in the airways, many smokers suffer from breathing difficulties. In the pulmonary function test, smokers who consume more than 70 mg of vitamin C daily perform significantly better.
Long-term smokers can develop emphysema over the years. As a result of irreversible destruction of the lung tissue, there is an abnormally increased air content in the lungs. In addition to shortness of breath and a blue coloration of the skin, the typical symptoms of the disease also include a narrow breathing width.
In animal experiments, vitamin C has been shown to be effective in preventing emphysema. The vitamin not only counteracts oxidative stress, it also stimulates collagen synthesis in the lung tissue. In the rodents there was also an increase in the so-called vascular endothelial growth factor, which stimulates the growth of the vascular endothelium. As a result, the lung tissue damaged by the smoke was able to regenerate better.
Vitamin C supplementation in smokers could thus be used for drug prevention of pulmonary emphysema. To test the effectiveness in humans, however, further studies are necessary. In any case, smokers should take into account the increased need for vitamin C and consume at least 130 mg of vitamin C daily.
Smoking during pregnancy and vitamin C
It should be known by now that smoking during pregnancy has negative consequences for the health of the unborn child. Doctors estimate that every fifth pregnant woman still smokes cigarettes. The list of possible damages to the child is long:
- increased risk of a miscarriage or stillbirth
- reduced birth weight
- premature detachment of the placenta
- neurological damage
- less brain matter
- malformations on fingers, hands or legs
- increased risk of cancer
Women who do not want to stop smoking cigarettes during pregnancy can at least partially reduce the negative effects of cigarette smoke on their child by taking vitamin C. If the mother takes 500 mg of vitamin C daily during pregnancy, the child's lung function improves. The primary goal should of course always be abstinence from tobacco.
Need and dosage for cancer patients
The cancer cases are increasing worldwide. In 2012, 14 million people fell ill with the malignant disease. The World Health Organisation (WHO) expects more than 20 million people to be diagnosed with cancer every year in 2030.
The most common types of cancer in men include prostate, colon and lung cancer. In contrast, women develop breast and colon cancer. According to a British study, 40 percent of all cancer cases could be prevented by a change of lifestyle. In addition to smoking, nutrition and the supply of nutrients and vital substances have a decisive influence on cancer development.
Vitamin C in cancer therapy
In the early 1970s, Linus Pauling propagated that vitamin C, as an antioxidant, plays a crucial role in cancer therapy. Pauling and his colleagues gave end-stage tumor patients an infusion of 10 g of vitamin C daily over a period of 10 days. The treatment was then continued with an oral dose. There was a significant increase in the average survival time of patients.
In a Monti et al. study in 2012, patients with metastatic pancreatic cancer also received intravenous vitamin C administration. However, the dose here was 50, 75 or 100 g per infusion and was in combination with chemotherapy. Despite the short treatment duration of eight weeks, the primary tumor decreased in some patients.
Drisko et al. and Padayatty et al. achieved similar results in their studies with the intravenous administration of vitamin C. However, it should be noted that these are studies with relatively few participants and without a control group.
Vitamin C in colorectal cancer
A special mode of action of vitamin C in colorectal cancer was covered by Yun et al. in their preclinical study from 2015. They found that vitamin C selectively targets cancer cells with so-called KRAS or BRAF mutations.
Approximately 40 percent of all intestinal tumors have a mutation in the KRAS gene and are insensitive to therapy with the monoclonal antibodies cetuximab and panitumumab. 10 percent of all patients with colorectal cancer have a mutation in the BRAF gene. These tumors are considered to be particularly aggressive.
Cells affected by this mutation increasingly form a specific glucose transporter on their surface. This allows vitamin C to get into the cell and destroy the cancer cells.
So far, the researchers have only been successful in animal experiments, but further clinical studies with cancer patients will follow in the future. If the therapy also proves to be effective here, it could be useful for patients with pancreatic cancer. KRAS mutations are also common here.
Improved life quality for cancer patients
High dose therapy with vitamin C is well tolerated by most cancer patients. In some studies, the subjects reported an improved quality of life. They are less likely to suffer from vomiting and nausea or chronic fatigue. Vitamin C supplementation also appears to reduce the toxicity and thus the side effects of chemotherapy.
Oral supplements against cancer
Success in the treatment of cancer could only be achieved by the intravenous administration of high doses of vitamin C. With oral supplementation, the researchers were unable to achieve sufficiently high vitamin levels in the blood. The oral intake of vitamin C therefore plays a role in the prevention of cancer.
Cancer prevention with vitamin C
Scientific studies repeatedly indicate that vitamin C could play a role in the prevention of cancer. A 1991 meta study showed a significant preventive effect of vitamin C on the development of cancer of the larynx, esophagus, oral cavity and pancreas. Relationships between vitamin C and breast, stomach, cervical and colon cancer have also been found.
Likewise, taking vitamin C appears to reduce the risk of lung cancer. Another meta-analysis from 2014 comes to the following conclusion: If the daily intake of vitamin C increases by 100 mg, the risk of lung cancer is reduced by around seven percent.
The available studies allow the conclusion that the intake of vitamin C and the infusion therapy with high-dose vitamin C improve the quality of life of tumor patients and reduce the side effects of chemotherapy or radiation therapy. Although the anti-tumor effects have been proven in many studies, further research is required to establish them firmly in standard cancer therapy.
For cancer prevention, the regular intake of vitamin C through food and, if necessary, via food supplements is recommended.
Occurrence in the body
The human organism is not able to produce vitamin C, but it can store the substance. Organs and tissues such as the spleen, brain or adrenal glands serve as storage. Vitamin C is also found in the blood plasma and in some of the white blood cells (leucocytes). The storage capacity for vitamin C averages between 1000 and 5000 mg.
Vitamin C supplements
Dietary supplements with vitamin C are available in different preparations. First of all, a distinction can be made between synthetic and natural vitamin C. For example, natural vitamin C is obtained from the acerola cherry, while synthetic vitamin C is produced in the laboratory from the starting substance D-glucose.
Natural vs. synthetic vitamin C
Animal studies have shown clear differences in the bioavailability of artificial and natural vitamin C. Vitamin C from fruits is better absorbed and used by most animals. However, these results could not be replicated in human studies. The synthetic vitamin C can be used by humans as well as the natural form.
However, vitamin C of natural origin has one major advantage: it is usually not in isolation, but in combination with secondary plant substances. In contrast to artificially produced ascorbic acid, vitamin C from fruits normally also provides secondary plant substances that can increase the vitamin effect and also ensure that the vitamin is not broken down too quickly.
Vitamin C capsules
Vitamin C is available in capsules and in powder form. The vitamin C capsules make it easier to take them on a regular basis because they are tasteless and can be swallowed quickly. They are also stomach-friendly and well tolerated. As the capsule gradually dissolves in the stomach, the vitamin C level rises more slowly and continuously.
Vitamin C powder
Natural vitamin C is also available as a powder. The vitamin C powder is ideal for people who do not like to swallow capsules or tablets. The taste depends on the original substance. This is how the acerola powder, which is rich in vitamin C, tastes fruity and fresh with a pleasantly acidic note. Vitamin C powder can simply be stirred into water or yoghurt or mixed into a smoothie or similar. The dosage can be individually adjusted as required.
Vitamin C and health
Vitamin C and stress
The human organism reacts to stress or excessive strain with stress. The stress can be very different in nature. Inner triggers include, for example, performance or time pressure, physical exertion, fear or problems in the partnership. External stress factors, on the other hand, are primarily noise, heat or cold.
When stressed, the body releases more stress hormones such as cortisol. Cortisol increases the blood sugar level so that the body has a sufficient amount of glucose available. But it also affects blood pressure and numerous other metabolic processes.
Chronic stress risks
Stress is a normal process. However, if the stress persists, the body can no longer recover from it. Chronic stress has a negative impact on the hormone metabolism and thereby promotes the development of depression and obesity. Chronic stress also increases the risk of cardiovascular diseases and Alzheimer's disease.
For a good 15 years now, health insurance companies have seen an alarming increase in stress-related sick leave. Out of 15 days of absence per head and year, 2.5 days of absence are due to psychological stress-related complaints such as anxiety and stress disorders as well as depression. Looking at these numbers, it becomes clear why it is important to tackle stress and its consequences at an early stage.
Vitamin C against stress
In laboratory animals, researchers were able to reduce the release of cortisol during stress in experiments with high-dose vitamin C. At the same time, they achieved stress-related physical reactions and reduced stress-related mortality through an ascorbic administration.
Brody et al. investigated in their 2002 study whether these results can also be transferred to humans. 120 healthy adults took part in the double-blind, placebo-controlled study. The Trier Social Stress Test was used to generate psychological stress. Half of the subjects consumed 3000 mg of vitamin C daily for two weeks prior to this test. The other half received a placebo preparation.
As compared to the placebo group, the participants in the vitamin C group experienced less stress. Although their cortisol level rose just as quickly, it also dropped faster.
The researchers also found a positive influence on blood pressure: Both the systolic and diastolic blood pressure values rose less in the ascorbic group under stress. In addition to this, the blood pressure dropped back to the baseline value after around 10 minutes, whereas the placebo subjects still had elevated blood pressure values even after 40 minutes.
The exact mechanism of action of vitamin C on stress and its effects is not yet known. The wide range of stress-reducing active properties are nevertheless remarkable. In particular, patients who have a tendency to cardiovascular diseases and are simultaneously exposed to chronic stress could benefit from vitamin C supplementation.
Vitamin C and scurvy
Scurvy is a condition caused by severe vitamin C deficiency. Therefore, the disease belongs to the so-called hypo- or avitaminosis. In infants, scurvy is also called Möller-Barlow syndrome.
The history of scurvy
Scurvy was already known in Egypt in the second millennium BC. A vitamin deficiency disease is also mentioned in the writings of the well-known doctor Hippocrates and the Roman author Pliny. However, the cause of the disease was still unknown at this time.
From the 15th to the 18th century, scurvy was the main cause of death among sailors. The one-sided diet at sea without fresh food led to a pronounced vitamin deficiency for many sailors. In 1754, the ship's doctor James Lind accidentally discovered that citrus fruits help against this dreaded disease. Scurvy lost at least part of its scare.
Numerous cases of illness only appeared again in soldiers during the two world wars as well as in the German concentration camps and in the Soviet labor camps.
Scurvy - Typical symptoms
The deficiency disease develops gradually, so that symptoms often only appear after several months. Typical complaints include:
- Bleeding gums
- Growths on the gums
- Tooth loss
- Poor wound healing
- Skin inflammation and bleeding
- Muscular dystrophy
In the worst case, scurvy can lead to death from heart failure.
Scurvy in modern times
Although scurvy does not play as important a role as it did before, the disease has not been eradicated. However, it occurs today in developing countries especially among malnourished people.
But people in industrialised countries can also suffer from a pronounced vitamin C deficiency. Alcoholics, people with chronic bowel diseases or eating disorders are particularly at risk. Since scurvy is not widespread, there is a risk that the disease will be overlooked despite the characteristic symptoms. In 2011, an eight-year-old boy died of scurvy in Wales.
Patients with scurvy symptoms or people with non-specific symptoms who can be assigned to a risk group should therefore be tested for scurvy. A simple determination of the vitamin C level in the blood is sufficient for this.
Vitamin C as an antioxidant
Antioxidants protect the body from free radicals. These highly reactive oxygen compounds have an unstable chemical structure because they lack an electron. In order to become complete again, they look for a suitable electron that they steal from an intact molecule. This electron theft is also known as oxidation.
The molecule that has lost its electron to the radical molecule is now also missing an electron. It itself becomes a free radical that is looking for a suitable particle. In this way, a chain reaction begins, which ultimately leads to oxidative stress.
Free radicals, oxidative stress and the consequences
A high level of oxidative stress can cause various types of damage to the body. The free radicals impair the function of the cells or even lead to cell death. They damage the DNA and inactivate enzymes.
The damage can manifest itself as follows:
- Gray skin without elasticity
- Reduced eyesight
- High blood pressure
- Joint problems
Protection through antioxidants
Antioxidants like vitamin C can protect the body from the harmful free radicals in two different ways. Vitamin C voluntarily releases an electron to free radicals and thus protects the body's own cells from the oxidation process. If an electron is torn from a vitamin C molecule, it does not become a free radical, but a stable radical. This way, the dangerous reaction chain is broken.
The antioxidant potential of vitamin C
Various studies confirm the antioxidant properties of vitamin C. However, the use of supplements with vitamin C to protect against cardiovascular diseases or other consequences of radical exposure is controversial. A 2007 meta-analysis reported increased mortality in connection with the regular intake of supplements with antioxidants such as vitamins C, A and E.
However, it should be noted that most of these studies examine the effects of isolated and artificial vitamin C. There are indications that vitamin C from natural sources such as acerola or baobab does not show these harmful effects.
Vitamin C and the immune system
Vitamin C is known as the best immune booster. The vital substance stimulates the formation of white blood cells (leucocytes) and also contributes to the production of interferons.
Interferons are proteins or glycoproteins that not only stimulate the immune system, but also have an antiviral and antibacterial effect. Vitamin C also increases the activity of the so-called natural killer cells, which can identify and kill abnormal cells such as cancer cells or virus-infected cells.
Prevent colds with vitamin C
Children and older people in particular benefit from the immune-boosting effect of the vital substance. For example, children who ingested one or two grams of vitamin C daily in a placebo-controlled double-blind study did not stay away from school as often because of illness. They suffered from colds and coughs significantly less frequently than the children from the comparison group.
A study from 1998 also showed that a daily dose of 200 mg vitamin C can stimulate the effectiveness of immune cells in older people. Another study from the same year confirmed that the immune system of older women was significantly strengthened by taking vitamin C and vitamin E.
The prophylactic intake of vitamin C can not only reduce the frequency of colds, but also the duration. On average, the duration of the illness is reduced by eight percent in adults and by 14 percent in children. The symptoms of the common cold are also lower after vitamin C prophylaxis.
Vitamin C and bleeding gums
Vitamin C plays a crucial role in the health of the gums and teeth. Bleeding gums is a typical symptom of the vitamin deficiency disease scurvy. But a less pronounced deficit can also cause gum problems.
A lack of vitamin C can damage the gums by reducing collagen production. On the other hand, vitamin C shows an antihistamine effect. If this does not occur, inflammation increases.
Bleeding gums due to gingivitis
A common cause of bleeding gums is inflammation of the gums (gingivitis). In most cases, this is caused by a bacterial infection. Those affected not only suffer from bleeding gums, but also from pain. If left untreated, inflammation of the gums can even lead to tooth loss.
Vitamin C against inflammation of the gums and periodontitis
Vitamin C has proven helpful in the treatment of gingivitis. Dental care products with vitamin C in particular can increase the antioxidant activity of saliva and thus reduce inflammation.
Vitamin C has proven to be particularly effective in combating the bacterium Porphyromonas gingivalis. The bacterium is considered a marker for a particularly severe and aggressive form of periodontitis. This leads not only to bleeding gums, but to the loss of teeth after a short time. Vitamin C can reduce the toxic effects of the bacteria on the gum cells and thus counteract periodontitis.
Vitamin C and wound healing
Vitamin C plays a key role in wound healing. So the vital substance is involved in all phases of healing. An undiscovered deficiency can therefore be the cause of wound healing disorders.
Vitamin C in the exudation phase
Wound healing proceeds in phases that follow one another in time and in some cases also overlap. In the exudation phase, also known as the inflammatory phase, the focus is on stimulating the healing process and killing invaded pathogens. Lymphocytes, neutrophil granulocytes, monocytes and macrophages are of particular importance for cleaning the wound.
The neutrophil granulocytes in particular dissolve dead tissue and also absorb bacteria. Then they disintegrate and attract more immune cells. The organism needs vitamin C for this important process.
The second phase of wound healing
In the second phase of wound healing, the proliferative or granulation phase, new tissue forms that fills the wound. The so-called fibroblasts accelerate tissue regeneration through an increased synthesis of collagen. Vitamin C plays an important role in the formation of collagen.
The vital substance acts as a cofactor for the conversion of proline to hydroxyproline and from lysine to hydroxylysine. While hydroxyproline serves to strengthen the collagen molecule, hydroxylysine ensures the cross-linking of the collagen molecules. If these conversion processes do not take place, only defective structural proteins are formed.
Vitamin C in the third phase of wound healing
In the third wound phase, the defect tissue from the second wound healing phase is converted to scar tissue. If there is a problem with collagen formation due to a vitamin C deficiency, faulty and unsightly scars can result.
Vitamin C and arteriosclerosis
Arteriosclerosis refers to fat and connective tissue deposits as well as calcium deposits in the arterial blood vessels. The chronic disease of the arteries leads to circulatory disorders and, in the worst case, to a heart attack or stroke.
In addition to high blood pressure, the risk factors for arteriosclerosis include diabetes mellitus, smoking and increased blood lipid levels. Genetic predisposition also seems to play a role in the formation of arterial calcification.
Reduce risk factors
Recent studies show that vitamin C can positively influence both hyperlipidemia and hypertension as risk factors for arteriosclerosis. In vivo studies show that increased vitamin C intake can lower elevated cholesterol and triglyceride levels.
Especially patients with baseline values in the medium and high range can benefit from the supplementation. In addition to a reduction in the harmful LDL cholesterol, there was also a moderate increase in the health-promoting HDL cholesterol.
It is estimated that 50 to 60 percent of people with hypertension have calcified arteries. Vitamin C can have a positive effect on blood pressure regulation and thus protect against arteriosclerosis. The hypotensive effect is presumably based on better availability of nitrogen monoxide (NO). NO causes vasodilation and relaxation of the blood vessels. This also lowers blood pressure. 
Vitamin C for healthy blood vessels
A vitamin C deficiency leads to bleeding due to a change in the structure of the vessels. The vital substance is needed both for the synthesis and for the connection of the collagen strands in the walls of the blood vessels. Fragile vessels sclerose faster. Furthermore, the release of nitrogen monoxide from the vessel walls is impaired if the vessel structure is fragile.
Vitamin C for skin and bones
The vitamin is required for the formation of collagen, cartilage and bone tissue. Spots and spotty bleeding in the skin as well as a decrease in the bone material (osteoporosis) are therefore possible signs of a vitamin C deficiency.
The importance of vitamin C for the skin
The skin consists of three layers: epidermis (epidermis), dermis (dermis) and subcutis (hypodermis). This unique structure enables the creation of a barrier to protect against external harmful influences. Vitamin C is found in high concentrations in the skin. The vitamin takes on various tasks there.
Protection against UV radiation
As an antioxidant, vitamin C can protect the skin from the harmful effects of UV radiation. Under the influence of UV radiation, free radicals are created that can damage the skin. Oxidative stress not only causes the skin to age prematurely, it also increases the risk of skin cancer such as basalioma or melanoma.
Vitamin C can reduce UV-related damage to DNA in the keratinocytes of the skin and inhibit the release of inflammatory cytokines. Preclinical studies also showed a protective effect of vitamin C on the development of skin cancer through increased UV radiation.
Vitamin C against wrinkles
The antioxidant properties of the vital substance also seem to have a positive effect on the appearance of the skin. The regular intake of vitamin C with food can reduce wrinkles. The use of creams with vitamin C can also reduce the formation of wrinkles. This effect is probably based on the stimulation of collagen synthesis in the skin.
Vitamin C for bone health
Vitamin C is an antioxidant and co-factor involved in numerous metabolic processes in different cell types in the body. The vital substance not only plays an important role in skin health, but also in bone health.
The bone tissue consists on the one hand of the bone cells (osteocytes) and on the other hand of a hard substance, the so-called bone matrix. In addition to mucopolysaccharides, collagen fibres are the main component of the matrix. The bone matrix makes the bone pressure elastic and also serves to relieve pressure.
Since vitamin C is involved in collagen synthesis as a co-factor, the vital substance has a direct influence on the bone quality. The vitamin also appears to stimulate the osteoblasts to build up the bone substance.
Vitamin C against osteoporosis
Osteoporosis is a disease of the bone apparatus that is accompanied by excessive loss of bone substance. That is why the disease is popularly known as bone loss. The bones lose strength and break faster. Study results suggest that vitamin C can be used to prevent osteoporosis.
For example, the Framingham Osteoporosis Study showed a significant correlation between the intake of vitamin C and bone density, especially in older men. The more vitamin C the subjects' diet contained, the less bone loss was recorded during the four-year observation period.
This positive effect could also be demonstrated in other studies for women after menopause. They belong to the main risk group of osteoporosis. Women who additionally suffer from a vitamin D deficiency especially benefit from an increased vitamin C intake.
Vitamin C for the heart and blood vessels
Cardiovascular diseases are still the number one cause of death in Germany. 270 out of 100,000 people die of a heart disease every year. These include, for example, coronary heart disease (CHD), heart failure and heart attack.
Vitamin C for a healthy heart
The main cause of death from the vitamin C deficiency disease scurvy is heart failure. This shows how important an adequate supply of vitamins is for heart health. Scurvy is extremely rare in industrialised countries, but minor deficiencies can affect heart activity.
Various studies show that especially people with a low level of vitamin C in the blood have a higher risk of cardiovascular diseases. They also die more often from these diseases than people with normal vitamin C levels. For these negative effects, there is no real vitamin C deficiency, and even low values that actually still fall within the norm can increase the risk of developing the disease.
Vitamin C protects the vessels
Arteriosclerosis is the main cause of cardiovascular diseases such as peripheral arterial disease or coronary artery disease (CHD). This makes arteriosclerosis a major risk factor for heart attacks and strokes.
Vitamin C can have a positive effect on the health of the blood vessels. Above all, the vital substance can improve the functions of the vascular endothelium. The endothelium is a thin layer of cells that lines the inside of the blood vessels. The endothelial cells produce, among other things, nitrogen monoxide (NO). NO causes the vessels to widen and affects blood pressure and blood clotting.
500 to 2000 mg of vitamin C per day over a period of at least two weeks can, according to the research results of Ashor et al. significantly improve endothelial function.
Vitamin C for weak connective tissue
Vitamin C is essential for a tight connective tissue. The connective tissue consists of both elastic and collagen fibers. Vitamin C is an important part of collagen synthesis and therefore also a prerequisite for a tight connective tissue.
Vitamin C against cellulite
Many women suffer from the dimpled skin surface in the area of the thighs and buttocks. Cellulite develops in the fatty tissue under the skin. A woman's subcutaneous fat tissue is divided by a network of connective tissue. If the connective tissue weakens, the unloved dents appear.
Vitamin C strengthens the connective tissue by stimulating collagen synthesis and can therefore be used to treat and prevent cellulite.