At a glance
A water-soluble vitamin that humans cannot produce themselves and that is needed as an antioxidant, as an enzyme cofactor and for collagen formation.
In Vykea: calcium ascorbate (470 mg per sachet)
Calcium ascorbate is a buffered, low-acid form and therefore gentler on the stomach than pure ascorbic acid.

Vitamin C is a water-soluble vitamin and one of the best-known micronutrients of all. Chemically, it is L-ascorbic acid and its salts, the ascorbates. Unlike most animals, humans cannot produce vitamin C themselves, because they lack an enzyme in the relevant metabolic pathway. It must therefore be obtained regularly from food. Vitamin C acts as an antioxidant, is a cofactor for numerous enzymes, is involved in collagen formation and the immune system, and improves the absorption of iron from plant foods. In Omnia All-In-One we use calcium ascorbate, a buffered, low-acid form of vitamin C, at 470 mg per sachet. This entry explains the forms, food sources, functions, requirements, laboratory testing, possible signs of deficiency and interactions of vitamin C.

The natural, biologically active form is L-ascorbic acid. It is a weak acid and tastes sour. There are also the salts of ascorbic acid, the ascorbates, such as sodium ascorbate, calcium ascorbate, potassium ascorbate and magnesium ascorbate. In these salts, the acidic hydrogen ion is replaced by a mineral, which is why the compounds are largely acid-free and gentler on the stomach. These are also referred to as buffered vitamin C. In addition, there is a fat-soluble form, ascorbyl palmitate, and the trademarked Ester-C, a calcium ascorbate with small amounts of the metabolite threonate.

Once in the body, vitamin C in its active form is always called ascorbate, regardless of the salt. The individual forms therefore differ less in their effect than in their acid load and tolerability. Calcium ascorbate is a buffered, low-acid form: the vitamin is present as a calcium salt and irritates sensitive stomach linings less than pure ascorbic acid. Each gram of calcium ascorbate also contains a small amount of calcium. Omnia uses calcium ascorbate.

Good sources of vitamin C are above all fresh fruit and vegetables. Particularly high levels are found in acerola cherries and camu camu fruit, which contain many times as much as oranges. Sea buckthorn, rose hips, peppers, broccoli, Brussels sprouts, kale and other types of cabbage, as well as citrus fruits, kiwi, blackcurrants and strawberries, are also rich in vitamin C. Potatoes also make a noticeable contribution because of the quantities often eaten.

Vitamin C is very sensitive to heat, light, oxygen and contact with metals. Storage, soaking, prolonged cooking and keeping food warm cause considerable losses; with gentle preparation, the loss averages around 30%, and with unfavourable handling it is considerably higher. Gentle cooking methods such as brief steaming, fresh preparation and avoiding keeping food warm for long periods preserve the content best.

Vitamin C is involved in a wide range of metabolic processes:

The next section shows which of these functions are authorised as health claims.

The following health claims are authorised for vitamin C in the EU:

These claims apply to vitamin C in general and therefore also to the form used in Omnia, calcium ascorbate.

The following values are taken from the D-A-CH reference values of the German Nutrition Society (DGE). The DGE revised the reference value for adults in 2015.

The nutrient reference value for labelling (NRV) is 80 mg per day. The European Food Safety Authority (EFSA) was unable to derive a tolerable upper intake level for vitamin C on the basis of the available data. In its earlier assessment, EFSA concluded that an additional intake of up to 1,000 mg per day (on top of the normal diet) is generally not associated with gastrointestinal complaints in adults. Very high single doses can cause soft stools or diarrhoea in sensitive individuals.

In some life stages and situations, vitamin C requirements are higher or vitamin C status is poorer. Smokers have measurably higher requirements, as tobacco smoke increases oxidative stress and uses up more vitamin C; the DGE gives higher reference values for them. Requirements are also increased during pregnancy and breastfeeding, with regular alcohol consumption, with chronic diseases, with acute infections and fever, with physical stress, after operations and injuries, and with intensive endurance and competitive sport.

Vitamin C status can also suffer when absorption from the gut is impaired, for example with chronic inflammatory bowel disease. A very one-sided diet with little fresh fruit and vegetables is another reason for low intake. In Germany, most people reach the reference value through their diet, but part of the population falls below it.

Vitamin C does not perform its tasks in the body in isolation but interlocks with other nutrients at several points. The nutritional science literature describes three well-documented relationships in particular.

Firstly, vitamin C improves the absorption of iron from plant sources. Plant foods mainly contain what is known as non-haem iron, which is present in the trivalent form (Fe³⁺) and is less soluble and less readily absorbed in the gut. Vitamin C acts in two ways here: it reduces trivalent iron to the more soluble divalent form (Fe²⁺) and at the same time forms a soluble complex that keeps the iron available over a wide pH range. A recent review describes how this mechanism facilitates the uptake of non-haem iron by the intestinal cells (enterocytes) and can therefore be of practical importance for a mixed or plant-focused diet. You will find the details of this relationship below in the section on iron absorption.

Secondly, vitamin C works together with vitamin E in the antioxidant network. Vitamin E is fat-soluble and mainly protects the fatty components of cell membranes from oxidative stress. In doing so, it is itself converted into an oxidised form (the tocopheroxyl radical) and temporarily loses its effectiveness. Water-soluble vitamin C can convert this oxidised form back into active vitamin E at the membrane surface, keeping it available for further tasks. The two vitamins therefore complement each other: vitamin E is active in the fat-soluble environment and vitamin C in the water-soluble environment. You can find more about this partner vitamin in the Vitamin E entry.

Thirdly, vitamin C is needed for the formation of collagen. It serves as a cofactor for the enzymes that modify certain building blocks in immature collagen, thereby enabling cross-linking into the stable, triple-stranded structure. Collagen is the most important structural protein of skin, blood vessels, bones, cartilage, gums and teeth. Without sufficient vitamin C, mature, resilient collagen cannot be formed to the usual extent.

These relationships are general principles of nutritional science and not a promise of effect for any individual product.

Vitamin C improves the absorption of iron from plant foods. The trivalent iron contained in plant foods is less readily absorbed in the gut than divalent iron. Vitamin C reduces trivalent iron to the more soluble divalent form and forms soluble complexes with it that facilitate absorption. If vitamin C is consumed together with an iron-rich plant-based meal, the amount of iron absorbed can be increased significantly. This relationship is well documented and underlies the authorised claim that vitamin C increases iron absorption. This can be of practical importance for people who follow a plant-focused diet.

Note: Whether iron deficiency is present in an individual case and how it is treated should be left to a doctor.

Vitamin C status is determined by a doctor from a blood sample. The usual method is to measure ascorbic acid in serum or plasma (reference range approximately 4 to 15 mg/l, depending on the laboratory and method). The value mainly reflects intake over the last few days. The content in the white blood cells (leucocytes) can be more informative about tissue supply; it better reflects longer-term status but is more complex to determine.

Correct sample collection is important, because vitamin C breaks down quickly in the blood sample: the sample should be processed promptly, ideally within a short time, and kept cool and protected from light. Blood is usually taken after fasting.

Note: Interpreting the values and any supplementation should be left to a doctor.

A mild shortfall often causes no clear symptoms. Possible non-specific signs are tiredness, exhaustion, reduced performance, irritability and increased susceptibility to infections. Because vitamin C is necessary for collagen formation, more pronounced signs of deficiency mainly affect the connective tissue: bleeding gums, gum inflammation, delayed wound healing and increased fragility of small blood vessels with pinpoint bleeding into the skin.

Severe and prolonged vitamin C deficiency leads to the condition known as scurvy, which is rare in industrialised countries today. It is characterised by pronounced changes in the gums, bleeding, joint complaints and severe weakness, among other things. Such signs are not conclusive and can have many causes.

Note: Investigation and diagnosis should be left to a doctor.

The following information summarises the areas of use described in the specialist literature.

Note: This information does not replace medical advice; targeted or higher-dose use should be left to a doctor.

Vitamin C is better utilised when spread over the day than in a single very high dose, as the percentage absorbed in the gut decreases as the single dose increases and excess vitamin C is excreted via the kidneys. Very high doses can cause gastrointestinal complaints such as soft stools in sensitive individuals.

Note: Caution is needed with high doses if you are prone to certain types of kidney stones, have impaired kidney function or have the rare iron storage disease haemochromatosis; in these cases, additional intake should be checked with a doctor.

Vitamin C interacts with other nutrients and some medicines.

The most important positive interaction concerns iron: vitamin C increases the absorption of iron from plant foods (see above). Vitamin C works together with vitamin E in the antioxidant network and regenerates its active form. A permanently very high vitamin C intake, on the other hand, can impair the absorption of copper, and high doses can reduce the absorption of sodium selenite.

Some medicines can increase vitamin C requirements or lower vitamin C status, including corticosteroids and oestrogens, for example in oral contraceptives. Acetylsalicylic acid and other non-steroidal painkillers can affect the absorption and excretion of vitamin C. Conversely, vitamin C can alter the absorption of some active ingredients.

Note: If you take medicines regularly, you should check with a doctor before taking additional, higher-dose vitamin C.

Calcium ascorbate is one of the buffered, low-acid forms of vitamin C. Here, the vitamin is present as the calcium salt of ascorbic acid, with the acidic hydrogen ion replaced by calcium. As a result, the compound is largely acid-free and is regarded as gentler on the stomach than pure ascorbic acid, which can be an advantage particularly for sensitive individuals and at higher amounts. In the body, calcium ascorbate, like other forms of vitamin C, is converted into active ascorbate. Each gram of calcium ascorbate also contains a small amount of calcium. In Omnia, vitamin C is present as calcium ascorbate.

Vitamin C is contained in Omnia All-In-One:

The amount stated refers to the vitamin C content, not to the weight of the calcium ascorbate. The % of NRV is based on the labelling value of 80 mg. One daily dose corresponds to one sachet.

Food supplements are not a substitute for a balanced, varied diet and a healthy lifestyle.

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