Although vitamins do not provide energy, they are an essential part of a healthy diet.

Our bodies need them, albeit in small quantities, to be able to function normally. Since our bodies cannot produce them themselves in sufficient quantities, we must ensure that we take in enough vitamins through our diet.

There are two groups of vitamins, namely fat-soluble and water-soluble vitamins.

Fat-soluble vitamins are soluble in fat and oil.

Water-soluble vitamins (C and B) are soluble in water and are easily lost when washing and cooking food.


Vitamins are absorbed at the level of the small intestine. For fat-soluble vitamins, this occurs by analogy with the absorption of fats. So we need fat in our diet and bile salts in the small intestine.


Our bodies convert vitamins into active components that we call regulators because they regulate metabolism. In this process, each vitamin has its own task.

Bone metabolism

  • Calcium metabolism: vitamin D
  • Attachment of carbon dioxide to osteocalcin: vitamin K
  • Synthesis of proteins involved in bone formation: vitamin D

Mineral metabolism

  • Iron metabolism with vitamins B2 and C
  • Calcium and phosphorus metabolism with vitamin D


  • Psychological functioning: biotin and vitamin B11
  • Nerve cell nerve conduction: vitamin B1
  • Neurotransmitter function: vitamin B6
  • Brain development: vitamins B6 and B12
  • Cognitive ability: vitamin B12
  • Nervous system: vitamin B2

Vitamin metabolism

  • Vitamin E enhances the absorption of vitamin A
  • Vitamin B6 is involved in the conversion of tryptophan into niacin

Physiological processes

  • Immunity: vitamins B6, C, A, E and D
  • Cell division: vitamins B12 and D
  • Blood clotting: vitamins K and E
  • Anti-inflammatory: vitamin D
  • Reproduction and fertility: vitamin A
  • Formation of rhodopsin and twilight vision: vitamin A
  • Gene expression: vitamins A, D and E
  • Growth and development: vitamins A and others
  • Cell differentiation: vitamins A and D

Coenzyme (digestion, synthesis and conversion of macronutrients)

  • Synthesis of fatty acids: Vitamin B5 and Biotin
  • Protein metabolism: vitamins B6, B2, B11, B12 and biotin
  • Gluconeogenesis: biotin
  • Carbohydrate metabolism: vitamins B3 and B1
  • Fat metabolism: vitamins B2 and B3
  • Energy metabolism: vitamins B1, B2, B3 and B5
  • Digestion: vitamins B3 and biotin

Metabolism of other substances

  • Synthesis of neurotransmitters: vitamin C
  • Cholesterol: vitamin B5
  • Homocysteine: vitamins B6, B11 and B12
  • Blood coagulation factors: vitamin K
  • Hormones: steroid hormones - vitamins A and C
  • DNA and RNA synthesis: vitamins B11 and B12

Blood formation

  • Vitamin C, B2, B6, B11 and B12


  • Vitamin B2, C, E and beta-carotene

Tissue structures

  • Collagen (connective tissue): vitamin C
  • Firmness and bone mineralisation: vitamin D
  • Healthy skin: most of the B-complex vitamins, B3, B6 and A
  • Cell membrane: vitamin E
  • Muscle mass: vitamin D
  • Control of bone and cartilage formation: Vitamin C
  • Integrity of epithelial cells (mucous membranes, cornea, skin and intestines): vitamins B2, A and biotin


A and beta-carotene

Egg yolk, oily fish, whole milk and whole milk products, cheese, butter, fat, meat, liver

Added to margarines, frying butter, etc.

Beta-carotene: yellow, red, orange and green vegetables and fruits


Whole grain cereals, potatoes, milk, dairy products, vegetables, fruit, meat, meat substitutes


See vitamin B1


Eggs, meat, fish, dairy products, vegetables, cereals


See other B-vitamins


Nuts, peanuts, vegetables, fruit, milk, milk products, whole grain cereals, potatoes, meat, meat substitutes


See other B-vitamins


Milk, dairy products, meat, meat substitutes, vegetables, fruit, whole grain cereals, potatoes, leafy vegetables


Only in foods of animal origin.

Inactive forms can be found in algae, seaweed


Vegetables, fruit, potatoes


Egg yolk, oily fish, whole milk, whole dairy products, cheese, butter, liver, fat, meat

Added to margarines, frying butter, etc.


Sunflower oil, wheat germ oil, nuts, seeds, whole grain cereals, vegetables, fruit

Added to margarines, oil, frying butter, etc.


Soybean oil, olive oil, green vegetables (cabbage, broccoli, spinach), whole grain cereals, animal foods (limited).

Q1 = vegetable origin

K2 = animal origin

Relationship to health

Causes of vitamin deficiencies

Vitamin deficiencies are mainly caused by insufficient dietary intake. For example, poor quality due to a one-sided diet, insufficient eating or loss due to the way foods are preserved and prepared.

Furthermore, a deficiency can also be caused by a (temporarily) increased requirement, reduced bioavailability (external factors such as smoking, medication, etc. / internal factors such as illness / increased losses) or a reduction in effectiveness (insufficient conversion into active form or insufficient formation).

Risk groups for vitamin deficiencies:

  • Vegans
  • Alcoholics
  • Chronic medication users
  • Young people
  • Smokers
  • Babies, premature babies
  • Elderly people
  • Dark-skinned people
  • Pregnant and breastfeeding women
  • Chronically ill people with poor nutritional status
  • People on extreme diets

If there is a vitamin deficiency, the breakdown and synthesis processes are incomplete.

Examples of symptoms of vitamin deficiency

  • Depression: vitamins B1 and B6
  • Night blindness: vitamin A
  • Cracks in the corners of the mouth: vitamin B2
  • Bone fractures: vitamin D
  • Digestive disorders: vitamin B1
  • Delayed wound healing: vitamin C
  • Anaemia: vitamins B6, B11 and B12
  • Nervous disorders: vitamin B1
  • Memory loss: vitamin B12

Vitamin excess

Headaches, general malaise, anorexia and gastrointestinal complaints may be common symptoms of vitamin excess.

Did you know that...

... alcohol reduces the bioavailability of vitamins B1 and B2?

... the bioavailability of vitamin K from green vegetables is limited?

- Translated from Dutch by Tamara Swalef -