Natural Food Grade Vitamin C
L-ascorbic acid, commonly known as vitamin C, plays several essential roles in the body. Unlike most animals, humans cannot synthesise it, and must obtain it from the diet. Since it is water soluble, it cannot be stored long term in the body, and regular consumption is necessary to maintain optimal levels.
Vitamin C acts as an essential cofactor for eight different enzymes, it is necessary for the synthesis of collagen, the neurotransmitter norepinephrine, peptide hormones. It is also an essential cofactor in the tyrosine breakdown pathway and in lipid metabolism. Vitamin C is a very potent antioxidant, protecting the body from oxidative stress, which is associated with many modern diseases and aging.
Vitamin C is necessary for wound healing, and for maintaining the the integrity of capillaries. It protects against heart disease, plays a role in regulating the immune system, and has been shown to decrease the risk of strokes. It is also necessary for a healthy skin.
Although severe vitamin C deficiency and scurvy are extremely rare in industrialised countries, research suggests that the levels required to obtain the full health benefits of ascorbic acid are much higher than those necessary to prevent overt deficiency symptoms, and significantly higher than the recommended daily intake of 75-90mg.
Vitamin C 3D model image by Ben Mills. The image is in the public domain.
Vitamin C is essential for the biosynthesis of collagen. Collagen is the main structural protein of connective tissue, which includes skin, tendons, bone, blood vessels and cartilage. It is mainly produced by specialised cells called fibroblasts.
Collagen is a triple helix molecule it is made from three long peptide chains wound around each other in a helical structure. During its synthesis, the lysine and proline amino acids must be hydrolysed by the enzymes prolyl-3 hydroxylase, prolyl-4 hydroxylase, and lysyl hydroxylase. Hydroxylation of the amino acids improves the cross-linking between the three peptides in each molecule. Vitamin C is an essential co-factor for the three hydroxylase enzymes, in its absence the triple helix formed is less stable, and does not have the biophysical properties of collagen.
This explains the symptoms of scurvy, the severe vitamin C deficiency disease. The defective collagen can’t form strong connective tissue. This is reflected by fragile capillaries, deteriorating and bleeding gums, which eventually lead to the loss of teeth, and discoloured skin.
Another symptom of vitamin C deficiency is that wounds do not heal. Vitamin C levels are rapidly depleted in tissue surrounding an injury, indicating that it is necessary for the process of healing. The increased need for vitamin C is probably due to increased collagen synthesis in the skin, required to repair the wound. Vitamin C has other roles in healing, such as limiting the damage from free radicals created by the inflammatory response to injury, and promoting keratinocyte differentiation. Keratinocytes are the main cell type in the outer layer of skin.
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Vitamin C and Fat Metabolism
Vitamin C is an essential cofactor for the enzymes trimethyllysine dioxygenase and Gamma-butyrobetaine dioxygenase, which are active in the synthesis of L-carnitine. Carnitine, which is synthesised from the amino acids lysine and methionine, is essential for the transport of fatty acids across mitochondrial membranes so they can be metabolised through beta oxidation to produce energy. Hence vitamin C is vital for fat metabolism. It has been hypothesised that a shortage of the vitamin might make losing weight more difficult by slowing down the rate at which fat is broken down for energy
Other Enzyme Cofactor Roles of Ascorbic Acid
Vitamin C is an essential cofactor for three other enzymes which take part in the synthesis of neurotransmitters and in protein metabolism.
It acts as a cofactor for dopamine beta hydroxylase, an enzyme which converts dopamine to norepinephrine. Norepinephrine, also known as noradrenaline, is a neurotransmitter, when released from neurones in the sympathetic nervous system, it increases the heart rate. In the brain it acts on the amygdala, where attention and responses to threats are co-ordinated. It is a stress hormone and co-ordinates the body’s fight-or-flight response. It is possible that the fatigue and lassitude associated with the vitamin C deficiency disease, scurvy, might be explained by an inability to produce sufficient norepinephrine
Peptidyl-glycine alpha-amidating monooxygenase is another enzyme that is dependent on ascorbic acid as an electron donor. It catalyzes the addition of amide groups to peptide hormones.
Ascorbic acid is also a cofactor of 4-Hydroxyphenylpyruvate dioxygenase, which is necessary for the breakdown of tyrosine, and the control of the levels of tyrosine in the blood. Tyrosine is an amino acid, and a precursor to neurotransmitters, especially dopamine and norepinephrine.
Vitamin C is a very effective anti-oxidant and plays an important role in preventing oxidative stress in the body. Normal body metabolism creates free radicals, molecules with a free electron. These are highly reactive and form reactive oxygen species, which are also very unstable. Reactive oxygen species can oxidise phospholipids, cause DNA damage which results in mutations, and react with proteins and cell membranes causing tissue damage. The body requires anti-oxidant chemicals to scavenge the free radicals it produces, and vitamin C is one of the main ones. When the level of anti-oxidants falls below what is required to neutralise the reactive oxygen species produced, oxidative stress results, and is responsible for many of the modern diseases such as cardiovascular disease, hypertension, cancer, chronic inflammatory diseases and diabetes. Oxidative stress also speeds up the aging process.
Vitamin C and the Immune System
As well as being necessary for wound healing, vitamin C plays an important role in maintaining a healthy immune system. It stimulates the production and function of white blood cells, such as neutrophils, lymphocytes and phagocytes. Ascorbic acid promotes neutrophil chemotaxis, the rate at which the cells converge in response to a chemical signal, the rate at which they ingest foreign particles (phagocytosis), and enhances their ability use lysozyme to kill pathogenic microbes.
The anti-oxidant properties of vitamin C appear to be important in protecting phagocytic leukocytes from oxidative damage by the reactive oxygen species which they release to kill pathogens, such as superoxide radicals.
The common belief that it protects against the common cold are probably untrue. However, taking supplements regularly might help the disease pass faster and lead to milder symptoms. Studies indicate that taking supplements when the cold starts is too late to have an effect.
Vitamin C and Heart Disease
Coronary heart disease is caused by atherosclerosis, the buildup of cholesterol and lipid plaques on the walls of coronary arteries. This hardening of arteries can eventually lead to a heart attack. Two separate meta analyses of studies looked at the relationship between vitamin C consumption and the risk of coronary heart disease. The studies found that consuming a large amount of vitamin C, up to 400 mg per day, for a number of years lowered the risk of developing heart disease.
It is probable that the anti-oxidant properties of vitamin C are responsible for its role in protecting against heart disease, since oxidation of low density lipoproteins (LDL) is the first step in plaque formation. Thirteen randomized controlled trials, in which people were given either vitamin C or a placebo, concluded that vitamin supplements significantly reduced serum levels of LDL (bad cholesterol), and triglycerides, but had no effect on serum high density lipoprotein (good cholesterol) levels.
Although there are discrepancies in the conclusions of the various studies, the overall results suggest that vitamin C needs to be taken in doses of 400mg a day, or more, to achieve its full potential of protecting against heart disease.
Protection from Strokes
Atherosclerosis can lead to strokes, also known as a cerebrovascular event. Strokes occur when blood flow, and therefore oxygen supply, to the brain is interrupted.This happens either due to a weakened blood vessels rupturing and bleeding into the surrounding tissue (haemorrhagic), or when a blood vessel is blocked (ischaemic). About 80% of strokes are ischaemic, and are the result of advanced atherosclerosis, the buildup of plaques on the walls of blood vessels to such an extent that they block the flow of blood.
A Japanese study involving 2000 people over 20 years found that high serum levels of vitamin C significantly reduces the risk of having a stroke. The incidence of cerebrovascular events was 29% lower in people with the highest vitamin C levels, when compared with people with the lowest levels. The conclusions that vitamin C helps protect against strokes were supported by a the EPIC-Norfolk study of over 20,000 people, which found that the highest serum levels of the vitamin lowered the risk by 42%.
Effect on Blood Pressure and Prevention of Hypertension
Several studies have found an inverse correlation between blood pressure and ascorbic acid serum levels. It seems that another way in which vitamin C is good for cardiovascular health is by lowering blood pressure and preventing hypertension. What is not clear is the mechanism through which it acts. One hypothesis is that its anti-oxidant actions are again responsible. It is thought that vitamin C levels affect the synthesis of prostaglandins, such as prostacyclin, a vasodilator. Vasodilators act on the endothelium of blood vessels causing its smooth muscle cells to relax, and the vessels to dilate which lowers blood pressure. They are synthesised from polyunsaturated fatty acids, such as the omega-9 oleic acid. Fatty acids, in turn are susceptible to oxidation, which slows down the production of prostaglandins.
A comparison of the normal physiological antioxidants has concluded that ascorbate, the salt of vitamin C, is the most effective water soluble antioxidant in the human body. It also increases the availability of other antioxidants, such as vitamin E (alpha-tocopherol), by protecting it from oxidation.
Effect on Bioavailability of Iron
Iron deficiency leading to anaemia is one of the more common dietary deficiencies in the modern world. Iron is obtained from red meat and offal, but also from plant sources such as dark, leafy vegetables, dried fruit, beans and nuts. However, non-heme iron from plant sources is not as easily absorbed by the body as iron from meat which is present as heme, the iron containing portion of haemoglobin. Vitamin C improves the absorption of non-heme iron by preventing the formation of insoluble iron compounds, which cannot be absorbed in the intestines, and by reducing ferric ions to ferrous ions which can be taken up by mucosal cells.
Vitamin C can therefore help prevent anaemia when taken together with foods rich in iron, especially in vegetarians and people who are trying to cut down on the consumption of red meat.
Vitamin C and Healthy Skin
Both the collagen synthesis, and the anti-oxidant functions of vitamin C play a role in maintaining healthy skin. Studies in cultured cells have shown that vitamin C protects the skin from the ultraviolet light in sunlight. Its antioxidant activity protects against DNA damage caused by free radicals produced by exposure to UV light. It also limits lipid peroxidation and the release of inflammation-causing cytokines. Human studies suggest that consumption of vitamin C alone is not enough, but that vitamin E is necessary for this photo-protective effect. It seems that the two antioxidant vitamins work synergistically to protect the skin.
Oxidative damage to proteins is associated with aging of the skin. Vitamin C slows this process down by protecting against free radicals, and by allowing collagen to be synthesised in levels required to repair damage to the skin. It also increases the division rate of fibroblasts, the main cell type that produces collagen.
Two studies have concluded that increased vitamin C intake protects decreases wrinkle formation in middle aged women, with higher consumption of the vitamin leading to a better appearance.
Vitamin C Supplement From Natural Extracts
Many of the vitamin C supplements on the market contain synthetic L-ascorbic acid. However, vitamin C from foods is better absorbed. The advantage of natural fruit and herb extracts, is that apart from ascorbic acid they also contain other vitamins, phytochemicals, such as flavonoids, polyphenols and isothiocyanates. So far there is a lack of scientific studies on plant-specific chemicals, many are known to have antioxidant properties, and it is suspected that they have important roles in human health.
Xbrain’s Natural Food Form Vitamin C contains only natural extracts from fruit that are known to be rich sources of ascorbic acid. Each capsule contains extracts from acerola cherry, blackcurrants, rose hip, elderberry, and parsley leaf extract.
Acerola cherries are not related to true cherries, although the fruit look similar. They grow on ornamental shrubs in the West Indies and South South America, another name for them is Barbados cherry. It is the second richest source of vitamin C by weight, a 100g serving has aver 2000% of the recommended daily amount of the vitamin! They also contain vitamin A, vitamins from the B complex, minerals such as magnesium and calcium, and various flavonoids.
Image is by Eric Gaba wikimedia commons user: Sting. Used under the CC-SA-3.0 licence.
In Europe, blackcurrants are one of the richest domestically grown sources of vitamin C. A 100g serving provides more than 300% of the recommended daily amount of ascorbic acid. A study by the Scottish Crop Research Institute found that blackcurrants are particularly rich in phytochemicals, as expected from their very dark purple colour; the antioxidant potential of the domestic fruit is much higher than that of various imported ‘superfoods’. They are very rich in anthocyanins, such as 3-glucosides and 3-rutinosides of cyanidin and delphinidin, which are powerful free radical scavengers. They also have a role in starch digestion, slowing down the rate of sugar release from complex carbohydrates, which prevents big fluctuations in insulin levels.
The image is in the public domain.
Rose hips are the fruit of rose bushes. They are well known for their vitamin C content, during World War II the people of British were encouraged to gather rose hips and turn them into syrup, to make up for the citrus fruits that were unable to reach the island. A 28g (one ounce) serving of rose hips has 200% of the recommended daily amount of ascorbic acid.
Rose hips also contain a high level of lycopene, an important anti-oxidant often associated with tomatoes. Lycopene is a bright red phytochemical, which prevents the oxidation of low density lipoprotein (LDL), an important step in the formation of plaques on the walls of arteries in atherosclerosis, and protects the skin from the UV light. It has been shown to be beneficial in the treatment of rheumatoid arthritis, presumably due to its antioxidant and anti-inflammatory properties.
Rose hips are also a source of vitamins A, B, and E, of essential fatty acids, and flavonoids.
Rose hip image by MPF, used under the CC-SA-3.0 licence:
Parsley Leaf Powder
Parsley leaves are a good source of vitamin C, as well as vitamin K, vitamin A and folic acid. It is also rich in favonoids, such as zeaxanthin and anti-oxidants such as luteolin.
The medicinal properties of elderberry extract has been known for hundreds of years. Apart from its high vitamin C content, it is rich in polyphenolic compounds such as anthocyanins and flavonoids, which have anti-oxidant properties.
Elderberry image by Edal Anton Lefterov, used under the CC-SA-3.0 licence.
Vitamin C health benefits.
Vitamin C and the immune system
Vitamin C and the common cold
The rationale behind increasing the recommended vitamin C dosage
Vitamin C and blood pressure
Vitamin C and skin aging