Figure 1: Vitamin C is probably the best-known vitamin. From immune defence to cellular protection, it is involved in many important processes in the body.
Vitamin C rightly holds a special position among essential nutrients: the water-soluble vitamin is, among other things, extremely important for the immune system and for cellular protection. In addition, ascorbic acid protects cells from oxidation and is involved in collagen formation. In this blog article you will learn which other roles vitamin C plays in the human body, which foods are particularly rich in vitamin C, and how much vitamin C should be taken per day. You will also find information on correct intake and on choosing a suitable vitamin C supplement.
Are vitamin C and ascorbic acid the same thing?
In everyday language the terms “vitamin C” and “ascorbic acid” are often used synonymously. Strictly speaking, however, this is not correct, since vitamin C is, from a chemical point of view, L-ascorbic acid, a specific form of ascorbic acid. Other forms of ascorbic acid, such as dehydroascorbic acid, also occur in the human body.
People also often distinguish between “natural” and “synthetic” ascorbic acid. Chemically, natural vitamin C and synthetically produced ascorbic acid are indistinguishable. Their physiological effect is also the same. The only difference is that ascorbic acid obtained from plants comes with additional plant constituents (bioflavonoids), which, however, only marginally affect the vitamin’s bioavailability.
The chemical structure of vitamin C was first elucidated in 1933 by Walter Norman Haworth, who received the Nobel Prize for his work. The health effects of vitamin C had, however, already been noticed earlier: in 1752 a ship’s surgeon accidentally discovered that eating fresh fruit had a positive effect on the treatment of the then-common seafaring disease scurvy. Sailors often suffered from tooth decay, joint inflammations and muscle wasting, because fresh, vitamin C‑rich foods were generally not available at sea.
The many roles of vitamin C in the body
Figure 2: Vitamin C is not only important for the immune system, but also plays a central role for the health of bones and blood vessels as well as for hormone production.
Vitamin C is considered an all‑rounder and a “vitamin for all occasions”. Indeed, ascorbic acid is of enormous importance for humans. The vitamin is absorbed through the small intestine and distributed through the body with the help of so‑called transport proteins. Below you will find a selection of bodily areas and processes in which vitamin C plays a central role.
Immune system
Vitamin C is widely known for making an important contribution to the normal function of the immune system and for supporting the body’s defences. Especially in the cold season, strengthening the immune system and effective protection against pathogens is essential. Vitamin C also acts as an antioxidant and neutralises free radicals before they can damage cells and tissues.
Iron metabolism
Vitamin C has the ability to convert iron and calcium in the intestine into more bioavailable forms. This makes it easier for them to enter the bloodstream and fulfil their functions in the body. Calcium is particularly important for bone health, while the mineral iron contributes to blood formation and numerous metabolic processes. By supporting iron absorption, vitamin C can help reduce tiredness and fatigue.
Collagen formation
Vitamin C also plays a crucial role in the formation and strengthening of connective tissue. Ascorbic acid contributes to the formation of collagen fibres, which in turn ensure the elasticity of skin, tendons and ligaments. Collagen is also an important component of vessel walls. Vitamin C thus makes a significant contribution to the elasticity and health of blood vessels. Due to its blood‑thinning properties, it can also help prevent diseases associated with arteriosclerosis (e.g. high blood pressure, heart attacks, strokes).
Hormones
Without an adequate supply of vitamin C the body is not able to produce certain hormones. The vitamin is involved in a process in the hypothalamus that is a prerequisite for the formation and effectiveness of some hormones. These include, in addition to the stress‑related hormones noradrenaline and adrenaline, the thyroid hormones thyroxine and triiodothyronine. Neurotransmitters such as serotonin can also hardly be synthesised by the body without the involvement of vitamin C.
How much vitamin C should be taken per day?
The question of how much vitamin C should be consumed daily is the subject of some controversy. The American chemist and Nobel laureate Linus Pauling, for example, was convinced that the recommended amounts were far from sufficient, and he himself took 18 g of ascorbic acid daily. Pauling justified his view by pointing out that the amounts of vitamin C produced by animals that can synthesise vitamin C themselves are many times higher than those that humans typically obtain from their diet. Interestingly, the human body was in fact once able to produce ascorbic acid itself; this ability was lost in the course of evolution.
The German Nutrition Society (Deutsche Gesellschaft für Ernährung, DGE) recommends an intake of 95 mg (women) and 110 mg (men) of vitamin C per day for healthy adults. Other reference values depend on age and sex. For infants and children under 4 years of age the DGE recommends 20 mg of vitamin C per day. For 13‑ to 15‑year‑olds the recommended intake increases to 85 mg daily. Males aged 15 to under 19 are recommended 105 mg per day, females 90 mg per day.
Reference values can also vary due to certain life situations or illnesses. Smokers have lower vitamin C concentrations in their blood than non‑smokers due to higher metabolic losses. As a result, their daily vitamin C requirement also increases to 135 mg for female smokers and 155 mg for male smokers. The need for vitamin C is also increased during pregnancy and breastfeeding. Reference values here rise to 105 mg (pregnant women) and 125 mg (breastfeeding women) per day.
Which foods are high in vitamin C?
Figure 3: Fruits and vegetables such as sea buckthorn, acerola, rosehip, bell peppers and broccoli are particularly rich in vitamin C.
Because the human body can neither produce nor store vitamin C, a daily intake from food is essential. Many people are taught from childhood that fruit and vegetables contain a lot of vitamin C and are therefore very healthy. Fruit varieties with a high vitamin C content include:
- sea buckthorn berries
- blackcurrants
- citrus fruits (e.g. oranges, lemons)
- acerola cherries
- rose hips
- strawberries
- papaya
But many vegetables as well as herbs, nuts, legumes and cereals can also serve as sources of vitamin C. Did you know, for example, that 100 g of parsley contains as much as 160 mg of vitamin C? While larger amounts of vitamin‑rich fruit can be enjoyed fairly easily — for example in a tasty smoothie — vegetables and herbs are often consumed only in small quantities. If you want to pay attention to or increase your vitamin C intake, feel free to reach for the following foods more often:
- parsley
- wild garlic
- red bell peppers
- broccoli
- cabbage
- spinach
- potatoes
- tomatoes
- walnuts
- sugar snap peas
- soybean sprouts
Preparation tips: avoid vitamin C loss
Because vitamin C is an extremely sensitive micronutrient, not only the choice of foods but also storage and processing are crucial for vitamin content. In general, the vitamin C content of fruit and vegetables decreases the longer they are stored. Blanching vegetables such as broccoli and then freezing them can counteract a drastic reduction in vitamin C content.
When preparing foods, bear in mind that ascorbic acid does not tolerate heat well. If you prepare a “hot lemon” for a cold or to strengthen your immune system, you should therefore be aware that the hot water reduces the vitamin C content of the lemon.
It is advisable to eat fruit and vegetables raw and unpeeled where possible, since particularly high levels of vitamin C are usually found in or just under the skin. Vegetables are best eaten as raw salad or, alternatively, gently steamed or cooked. If you do cook vegetables in water, you should by no means throw away the cooking water afterwards. Because vitamin C is water‑soluble, a large part of it passes into the water during cooking.
How common is vitamin C deficiency?
The German Nutrition Society (DGE) notes that the recommended vitamin C intake in Germany is roughly reached or even exceeded across all age groups. [1] According to data from the National Consumption Study II, the mean intake of vitamin C among 15‑ to 80‑year‑olds was just under 100 mg per day. [2]
Although vitamin C deficiency is not common in this country, there are factors that can favour a deficiency state. For example, oxidative stress triggered by smoking as well as alcohol or drug abuse can increase the requirement for vitamin C. Gastrointestinal diseases that impair the absorption of vitamin C in the intestine, as well as the taking of antibiotics or the contraceptive pill, are further possible causes of deficiency symptoms.
A severe vitamin C deficiency that persists for months is known as scurvy or the “seafaring disease”. Today, however, a latent vitamin C deficiency is much more common. Because it typically manifests with non‑specific symptoms such as tiredness, muscle pain, decreased performance and an increased susceptibility to infections, a latent deficiency is rarely recognised and diagnosed. If you suspect a vitamin C deficiency, you can have a blood sample taken by your doctor. Determination of the vitamin C concentration in blood plasma can establish whether you are in fact taking in too little vitamin C.
To prevent a deficiency from developing in the first place, attention should be paid to a regular and adequate intake of vitamin C. Anyone who follows the well‑known rule of eating at least five portions of fruit and vegetables a day can normally cover their requirement entirely through diet and prevent a vitamin C deficiency.
Notes on buying a suitable vitamin C supplement
Figure 4: Vitamin C supplements are available as capsules, tablets, lozenges or powders.
Vitamin C supplements can usefully complement dietary intake of ascorbic acid. They are also recommended for people who have an increased need for vitamin C due to illness or lifestyle factors.
However, the range of vitamin C supplements available today is so large that choosing can be challenging. Forms range from capsules and tablets to powders such as Natural Vitamin C Acerola Plus from Unimedica, which can simply be stirred into drinks, shakes or yoghurt. Children often prefer lozenges such as the Vitamin C lozenges from Unimedica with delicious lemon flavour.
Purity and dosage are also decisive factors that determine the quality of a vitamin C supplement. Make sure to choose a product that is GMO‑free and free from maize. This criterion is met by both the high‑dose Vitamin C capsules from Unimedica and the Vitamin C tablets from Unimedica. Both products also offer 99% purity and are manufactured under strictly controlled conditions in Germany.
The different forms of vitamin C
In addition to the dosage form and purity, attention should be paid to the form in which the vitamin C is present when choosing a supplement.
Natural vitamin C
Fruits such as acerola and rosehip, which naturally contain a lot of vitamin C, are a popular component of vitamin C supplements. For example, the organic acerola extract capsules from Unimedica contain 160 mg of pure, natural vitamin C per daily dose. Because acerola cherries spoil shortly after harvest, the fruit is usually not available fresh in Europe but is sold as a powder or in capsule form.
Buffered vitamin C
When a vitamin is described as “buffered”, it is pH‑neutral because almost all of the acid it contains has been neutralised. For this purpose the acid is bound during production using a basic material (usually calcium). The calcium ascorbate formed in this process is alkaline and does not irritate the stomach as much as other forms of vitamin C. For this reason, supplements with buffered vitamin C, such as the Buffered Vitamin C capsules from Unimedica or the Buffered Vitamin C + Zinc capsules from Unimedica, are particularly suitable for people with a sensitive stomach.
Liposomal vitamin C
Liposomal vitamin C is a form that can be particularly well absorbed and utilised by the body. According to a study from 2020, the bioavailability of 1,000 mg liposomal vitamin C dissolved in a glass of water is about 1.8 times higher than that of the same amount of pure vitamin C. [3] In liposomal supplements the vitamin C is encased in a protective shell of phospholipids. These protect the vitamin from stomach acid and ensure that it can be absorbed in the intestine without loss of active ingredient.
In addition to capsules such as the LIPOSOMAL PureWay‑C™ VITAMIN C capsules from Unimedica, liposomal vitamin C is also available in liquid form. Products such as Liposomal Vitamin C from Unimedica or Liposomal Vitamin C + Zinc from Unimedica are vegan and highly bioavailable.
Ascorbyl palmitate
Ascorbyl palmitate is also popular as a dietary supplement. The compound of ascorbic acid and palmitic acid is often sold as “vitamin C ester”. It is the only fat‑soluble form of vitamin C, which supports improved incorporation of the vitamin into cell membranes. Products containing ascorbyl palmitate, such as Vitamin C ascorbyl palmitate from Unimedica, thus ensure optimal bioavailability of the vitamin C they contain.
How should vitamin C be taken?
There are no universally valid recommendations regarding the timing of vitamin C supplementation. It is therefore advisable to follow the manufacturer’s instructions. In general, vitamin C can be taken in the morning or evening, with a meal or independently of meals. With the exception of liposomal vitamin C, it makes sense to split the daily dose. Three to six single doses spread over the day are recommended so that the body can absorb the vitamin C as effectively as possible.
Possible side effects
It is unlikely that healthy people will experience side effects from taking vitamin C. Because vitamin C is water‑soluble, excess amounts that the body does not need are usually simply excreted in the urine. The few groups for whom increased vitamin C intake can have harmful side effects include people with kidney damage or a predisposition to urinary and kidney stones, as well as people with the so‑called iron storage disease (haemochromatosis). In these cases the daily vitamin C dose should be closely monitored and the use of vitamin C supplements should only be undertaken after medical consultation.
The risk of overdose is also low for healthy people. According to the European Food Safety Authority (EFSA), those who supplement up to 1 g of vitamin C in addition to dietary intake need not expect harmful effects. The German Federal Institute for Risk Assessment (BfR) recommends a maximum amount of 250 mg vitamin C per day from dietary supplements. [4]
Can taking vitamin C protect against colds?
It is occasionally claimed that taking vitamin C can prevent colds and positively influence recovery. It is true that vitamin C is central to the normal functioning of the immune system, and that an insufficient intake can be associated with increased susceptibility to infection. However, it has not been scientifically proven that taking high doses of vitamin C actually prevents or cures colds. [5] [6]
Sources:
[1] DGE (2015): Selected questions and answers on vitamin C. https://www.dge.de/fileadmin/dok/gesunde-ernaehrung/faq/DGE-FAQ-Vitamin_C-2015.pdf (accessed: 09.04.2024)
[2] Max Rubner Institute (2008b): National Consumption Study II. Final report, Part 2, Karlsruhe: Max Rubner Institute, Institute for Consumer Nutrition Behaviour.
[3] Gopi S, Balakrishnan P. Evaluation and clinical comparison studies on liposomal and non‑liposomal ascorbic acid (vitamin C) and their enhanced bioavailability. J Liposome Res. 2021 Dec.
[4] BfR (2021): Maximum amount proposals for vitamin C in foods including dietary supplements. https://www.bfr.bund.de/cm/343/hoechstmengenvorschlaege-fuer-vitamin-c-in-lebensmitteln-inklusive-nahrungsergaenzungsmitteln.pdf (accessed: 08.04.2024)
[5] Gómez E, Quidel S, Bravo‑Soto G, Ortigoza Á. Does vitamin C prevent the common cold? Medwave. 2018 Aug 6. https://pubmed.ncbi.nlm.nih.gov/30113569/
[6] DGE: Does vitamin C help against colds? https://www.dge.de/presse/meldungen/2011-2018/hilft-vitamin-c-gegen-erkaeltungen/ (accessed: 09.04.2024)
Photos: Unsplash: engin akyurt, Jenny Hill, Philipp Deus, Diana Polekhina
