Knowledge blog

What are the functions of water-soluble vitamins?

Vitamins part 2

In Part 1 we have already dealt with the fat-soluble vitamins A, D E and K2. In part 2, you will learn about the functions of B vitamins and, of course, the well-known vitamin C.

Themen dieses Blogartikels:


What are the functions of water-soluble vitamins? - Vitamins part 2

After we have already dealt with the fat-soluble vitamins A, D E and K2 in Part 1, we are still missing the water-soluble vitamins, which are in no way inferior to the fat-soluble vitamins. What are the functions of B vitamins and of course the well-known vitamin C?
You can find out here in part 2 on vitamins.

Knowledge for your ears!

No time to read? Here you can listen to Claire's article.

Table of Contents

• What are water-soluble vitamins?
• Vitamin C (ascorbic acid)
• Vitamin B1 (thiamine)
• Vitamin B2 (riboflavin)
• Vitamin B3 (niacin)
• Vitamin B5 (pantothenic acid)
• Vitamin B6 (pyridoxine)
• Vitamin B7 (biotin)
• Vitamin B9 (folic acid)
• Vitamin B12 (cobalamin)
• Bibliography

What are water-soluble vitamins?

Water-soluble vitamins are those vitamins which, unlike fat-soluble vitamins, do not have to be taken with fat and are not stored in fatty tissue. Unlike fat-soluble vitamins, they are hardly stored in the body and must therefore be continuously supplied through food.

The group of water-soluble vitamins includes vitamin C and the B vitamins. With the water-soluble vitamins, there is hardly any danger of overdosing, since they are simply excreted in the urine if the intake is too high.

Vitamin C (ascorbic acid)

The all-rounder among the vitamins - this is how vitamin C is often referred to. Ascorbic acid was discovered during seafaring. Sailors suffered during long voyages, lost teeth, got muscle and bone atrophy, were exhausted and eventually died. The reason for the disease, which was later called scurvy, was a pronounced vitamin C deficiency, which was mainly accompanied by the loss of connective and supporting tissue. Today we know: Vitamin C does more than just maintain collagen function.

What are the functions of vitamin C in the body?
Vitamin C is important for:
• Formation of connective tissue and collagen formation
• Blood vessels, skin, gums and teeth
• Wound healing
• Protection from free radicals and regeneration of vitamin E
• Strengthening of the immune system (also after physical stress)
• Cell protection from premature aging processes
• Cell metabolism
• Iron absorption
• Formation of messenger substances, hormones and sperms
• Energy balance
• A healthy psyche

Wie äußert sich ein Vitamin C Mangel?

Ein Vitamin C Mangel kann führen zu:

• Zahnfleischbluten und Zahnausfall
• Gelenk- und Knochenschmerzen und Gelenkentzündungen
• Müdigkeit, Erschöpfung und Schwindel
• Depression
• Durchfall
• Herzschwäche
• Infektanfälligkeit

Vitamin C kommt in Sanddorn, Zitrusfrüchten, Hagebutten, schwarzen Johannisbeeren, Paprika, Grün- und Rosenkohl, Erdbeeren und Kartoffeln vor. Der Tagesbedarf liegt bei 90-110 mg, das entspricht ca. 60 g schwarzen Johannisbeeren, 80 g Paprika oder auch 200 g Zitrusfrüchten. Damit enthält Paprika deutlich mehr Vitamin C als die dafür bekannten Zitrusfrüchte.

Vitamin B1 (thiamine)

Energy metabolism in particular is dependent on vitamin B1. Recently, thiamine has been investigated in its role in cell regulation. Indeed, a molecule that regulates the cell cycle is influenced by thiamine. Thus, thiamine may be relevant to cell cycle control ( Cell metabolism, i.e., metabolism, remains at the forefront of thiamine's functions.

What does thiamine do in the body and what happens with a B1 deficiency?
Vitamin B1, also called thiamine, is important for:
• The energy metabolism
• The cell metabolism
• Stimulus transmission in the nervous system
• Glucose metabolism and metabolism of amino acids
• Energy production from food

A vitamin B1 deficiency can lead to:
• Fatigue, irritability and loss of appetite
• Memory problems, headaches and lack of concentration
• Depressed mood or depression
• Decreasing physical performance

Vitamin B1 is found in whole grain products, pork, nuts, seeds and legumes. The daily requirement is at least 1 mg.

Vitamin B2 (riboflavin)

Riboflavin or also vitamin B2 is involved in some reactions by being important for the function of enzymes. It is used for the formation of so-called flavin coenzymes, which are often used in metabolism and are also changed, respectively consumed. But vitamin B2 can do even more.

Functions of vitamin B2 and deficiency symptoms
Vitamin B2 is important for:
• The energy metabolism
• Skin and mucous membranes
• Growth and development
• The nervous system
• The maintenance of red blood cells and normal iron metabolism
• Vision
• The protection against oxidative stress

A vitamin B2 deficiency can lead to:
• Cracked skin and torn corners of the mouth
• Skin inflammation and changes, increased desquamation of the skin
• Light sensitivity
• Anemia

Vitamin B2 is found in dairy products, eggs, soy, fish, whole grains, nuts, mushrooms, legumes, broccoli, kale and spinach. The daily requirement is 1.2 to 1.5 mg and can be found in a large portion of whole-grain pasta with spinach, mushrooms or broccoli, sprinkled with nuts or cheese.

Vitamin B3 (niacin)

Like vitamin B2, niacin is involved in the formation of coenzymes, which are mainly needed in the context of metabolism. Niacin is also called skin vitamin in the context of skin health. Numerous studies have investigated the positive effect of vitamin B3 on the skin in relation to wrinkles, acne, blemishes and redness ( What effect does niacin have?

Vitamin B3 is involved in reactions of:
• Energy metabolism
• Nervous system
• Psyche
• Skin and mucous membranes

What does a niacin deficiency look like?
A vitamin B3 deficiency can lead to:
• Inflamed and altered mucous membranes and skin lesions
• Physical weakness
• Mental impairment

Vitamin B3 is found, for example, in nuts, sea fish, whole grain products, lean meat, dairy products, eggs, legumes, dates and mushrooms. The daily requirement is 11 to 13 mg. Nowadays, niacin is found as nicotinamide in many skin creams and beverages.

Vitamin B5 (pantothenic acid)

Pantothenic acid is particularly important for energy production in mitochondria. Vitamin B5 is a component of coenzyme A. This is used to produce energy and is therefore a coenzyme. Our brain also needs energy all the time. An efficient conversion of nutrients into the energy carrier ATP takes place, among other things, via the citrate cycle, in which coenzyme A plays an important role.

Why do we need vitamin B5?
Vitamin B5 is important for:
• Energy metabolism
• Hormone production (steroid hormones, vitamin D)
• Formation of some neurotransmitters
• The mental performance

A vitamin B5 deficiency can lead to:
• Insomnia and fatigue
• Muscle pain
• Hormonal disorders
• Imbalance and concentration problems

Vitamin B5 is found in yeast, egg yolk, whole grain products, liver and offal, dairy products, fish, nuts and legumes. The daily requirement is 6 mg.

Vitamin B6 (pyridoxine)

Like other B vitamins, vitamin B6 serves, for example, as a cofactor in biochemical reactions in the body. Vitamin B6 is particularly involved in amino acid metabolism as pyridoxal phosphate. What are the functions of vitamin B6?

Vitamin B6, also called pyridoxine, is important for:
• Energy metabolism
• Protein and glucose storage metabolism
• Blood formation
• Hormone regulation
• Nervous system and psyche
• Immune system
• The cysteine formation
A vitamin B6 deficiency can lead to:
• Sleep and anxiety disorders
• Developmental disorders in children
• Anemia
• Muscle twitching and disturbed motor activity/movement sequences

Vitamin B6 is found in offal, fatty fish, whole grain products, nuts and seeds, bananas and potatoes. The daily requirement is 1.4-1.6 mg. The ideal form in dietary supplements is a phosphorylated form, i.e. as pyridoxal phosphate.

Vitamin B7 (biotin)

Biotin is now even found as an additive in some gummy bears. Like other vitamins, it plays a role in enzyme function - especially in energy metabolism. Biotin can do even more. It has been found that vitamin B7 also plays a role in gene regulation3. It is believed that over 2000 genes are regulated by biotin.

Why is biotin important?
Vitamin B7, also called biotin, is important for:
• Skin, hair, nails and mucous membranes
• Protein and carbohydrate metabolism
• Energy metabolism
• Nerves and psyche

Vitamin B7 deficiency can lead to:
• Brittle nails, hair loss, skin disorders
• Loss of appetite and nausea
• Poor wound healing
• Muscle pain

Vitamin B7 is found, for example, in offal, egg yolk, oatmeal, peanuts, spinach, mushrooms, lentils and many other foods in very small doses. The daily requirement is 30 to 60 µg.

Vitamin B9 (folic acid)

The best known of the B vitamins is probably folic acid. Especially in the context of pregnancy, it is often put in the mouth. Folic acid is important here for the nerve development of the fetus, especially in the first trimester of pregnancy and for the formation of maternal tissue.

Functions of folic acid
Vitamin B9, also called folic acid, is important for:
• New formation of cells
• Nervous system and psyche
• Blood formation
• Homocysteine and methyl metabolism
• Neural tube formation (this is the creation of the later central nervous system) of the fetus
Vitamin B9 deficiency can lead to:
• Malformations in unborn children and increased risk of premature birth and congenital heart defects
• Delayed speech development of the child
• Mental impairment

Vitamin B9 is found in leafy and cabbage vegetables, whole grains, liver, whole cereals, eggs, legumes, tomatoes and potatoes. The daily requirement is 300 µg. In the case of food supplements, care should be taken to ensure that vitamin B9 is contained in the methylated form, i.e. as methylfolate. Otherwise, the body must expend additional energy and substances to activate the folic acid.

Vitamin B12 (cobalamin)

The nerve vitamin sums it up quite well. Vitamin B12 is primarily relevant in terms of the central nervous system and in terms of energy production, DNA repair and synthesis, and methylation.

Vitamin B12 also has antioxidant properties and can reduce homocysteine levels in the body. Elevated homocysteine correlates with various diseases such as Alzheimer's disease and venous thrombosis. In addition, it speaks to a problematic methyl metabolism. This can be addressed with the physician or therapist.

Vitamin B12 is often seen as a critical factor in a vegan or vegetarian diet. However, supplementation can be useful in general, since eating offal is no longer so popular and vitamin B12 is mainly found in it.

What do you need vitamin B12 for and what happens when you have a B12 deficiency?
Vitamin B12, also called cobalamin, is important for:
• Red blood cell formation
• A functioning nervous system and the psyche
• Cell division
• Energy metabolism
• Homocysteine and methyl metabolism

Vitamin B12 deficiency can lead to:
• Psychological upsets
• Dementia, concentration difficulties, reduced memory capacity
• Irritability, mood swings
• Fatigue and pallor
• Anemia
• Tingling or numbness in fingers or toes

Vitamin B12 is found in meat, fish, eggs, dairy products and offal. The daily requirement is 4 µg. Vitamin B12 is largely produced by bacteria, some of which we can also find in our intestines. The high content of vitamin B12 in animal foods is due to its production by bacteria.

Supplement B vitamins - but how?

In the case of dietary supplementation, vitamin B12, like folic acid, should be supplied in the methylated form (methylcobalamin). The methylation and thus activation of vitamin B12 costs additional energy and methyl groups, which are withdrawn elsewhere. The homocysteine metabolism may then also no longer be positively influenced, as methyl groups are transferred here.

Did you miss part 1?

This article is the second part of the blog article series on vitamins. In part 1 you will learn more about the four fat-soluble vitamins A, D, E and K2. Learn more about their functions and symptoms of deficiency.


1 Bunik, V., Aleshin, V., Zhou, X. et al. (2020). Regulation of Thiamine (Vitamin B1)-Dependent Metabolism in Mammals by p53. Biochemistry Moscow 85, 801–807.­S0006297920070081

2 Chen, A. C., Damian, D. L. (2014). Nicotinamide and the skin. The Australasian journal of dermatology, 55(3), 169–175.

3 Rodriguez-Melendez, R., & Zempleni, J. (2003). Regulation of gene expression by biotin (review). The Journal of nutritional biochemistry, 14(12), 680–690.­j.jnutbio.2003.07.001