Essential Nutrients: Vitamins and Minerals

Essential nutrients are vital! They cannot be produced by the body itself and must therefore be obtained from food. Which vitamins and minerals are involved? What do they do in the body and which foods contain them?

Vitamins

In science, a vitamin is understood to be a complex chemical compound that the body needs for vital functions. Vitamins are essential nutrients that must be supplied with food, as humans cannot produce them at all or not in the required amounts. Vitamins are taken in with food in the form of “ready-made” vitamins or as so-called provitamins. Provitamins are precursors of vitamins that the body converts into the actual vitamins. Vitamins control or promote certain metabolic processes. The body needs only very small amounts. Vitamin deficiency is very rare in Western societies – requirements can be met by a balanced diet. Supplementation with vitamin preparations is only useful in some cases.

Vitamins can be divided into two main groups: fat-soluble and water-soluble vitamins. This distinction shows how the vitamins are best absorbed. The organism can absorb fat-soluble vitamins more easily if a small amount of fat is eaten at the same time, for example in the form of vegetable oil.

Essential fat-soluble vitamins

The fat-soluble vitamins include vitamins A, D, E and K. They are stored in the body and therefore tend to accumulate if too much of them is taken in.

• Vitamin A (retinol) is particularly important for the eyes, skin and mucous membranes. It is a starting material for the synthesis of the visual pigment rhodopsin. If there is a lack of vitamin A, night blindness is therefore one of the first symptoms. Other symptoms include hair loss, increased sensitivity of the skin, keratinisation of the cornea and disorders of bone growth. Excessive doses can be dangerous, especially during pregnancy, as they can lead to miscarriages and malformations. Vitamin A is found in animal foods such as liver, butter, cheese and egg yolk. The precursor provitamin A – better known as beta-carotene – is found mainly in vegetables, e.g. carrots, red peppers, spinach, tomatoes and broccoli.

  

  Liver Fish Egg yolk Dairy products

  • Contributes to the maintenance of normal vision
  • Contributes to the normal function of the immune system
  • Has a role in the process of cell specialisation
  • Contributes to the maintenance of normal skin

  The recommended daily intake of vitamin A for adults is 800 µg.[*]

• Vitamin D (calciferol) is the only vitamin that humans can produce themselves. It is also called the “sunshine vitamin” – the body only produces it when the skin receives enough sunlight (UV rays). It acts directly on serotonin production, so that sunlight indirectly lifts the mood. The starting material is cholesterol. The alternative name “calciferol” indicates that it influences calcium and phosphate metabolism. A deficiency in childhood leads to rickets (bone deformities, especially in the legs and wrists), and in old age to osteomalacia – an increased susceptibility to fractures. Excessive doses of vitamin D lead to thirst, nausea and vomiting. Vitamin D is contained in few foods, but particularly in oily fish (salmon) and dairy products.

• Vitamin E (tocopherol) comprises a larger group of substances that differ in structure and biological function. Vitamin E protects the body’s cells from harmful influences, for example from aggressive oxygen compounds (free radicals). Deficiency symptoms are rare with a balanced diet, as vitamin E can be stored in fatty tissue. Deficiency occurs only in people who eat a completely fat-free diet over a long period or who suffer from an intestinal disease that disrupts absorption via the gut. These diseases include coeliac disease, short bowel syndrome after surgery, Crohn’s disease and diseases of the bile ducts. Signs of deficiency are disorders of muscle and nerve function. The body absorbs vitamin E through dietary fat. Vegetable oils and nuts are particularly rich in vitamin E.

• Vitamin K consists of vitamin K1 (phylloquinone) and vitamin K2 (menaquinone). They are involved in the formation of various blood clotting factors and in bone formation. A deficiency is hardly possible in healthy people. Vitamin K is found mainly in green leafy vegetables such as lettuce, spinach and cabbage. But it is also contained in pulses, potatoes, wholegrain and dairy products.

Essential water-soluble vitamins

The water-soluble vitamins include the vitamins of the B complex and vitamin C. They are hardly stored in the body. As a rule, they are excreted again via the kidneys. A continuous supply through food is therefore necessary.

• Vitamin B1 (thiamine) is contained in almost all animal and plant foods. It is involved in numerous catabolic metabolic processes. The deficiency disease is called “beriberi”, but as a rule no longer occurs in Western countries. At most, deficiency symptoms can occur in alcoholics, as alcohol disrupts the absorption of vitamin B1 from the gut. Foods with a high content of vitamin B1 are sunflower seeds, pork, oat flakes, soya products and wild rice.

• Vitamin B2 (riboflavin) is also involved in numerous metabolic processes. It is also needed for the formation of the red blood pigment haemoglobin. A pure vitamin B2 deficiency is rare. Vitamin B2 is contained in meat, fish, wholegrain products and numerous (green) vegetables.

• Vitamin B3 (niacin), also called nicotinic acid, is involved in protein, fat and carbohydrate metabolism. It has an antioxidant effect and takes part in many enzymatic processes. Nicotinic acid is important for the regeneration of skin, muscles, nerves and DNA. A niacin deficiency shows on the skin, through increased scaling and inflammatory skin diseases, but also in the gastrointestinal tract. Inflammation of the oral mucosa can also occur. Meat and meat products are the best source of niacin. But salmon and herring are also recommended. Plant sources of B3 include buckwheat, peanuts, mushrooms and dried apricots.

• Vitamin B5 (pantothenic acid) is involved in the building up and breaking down of carbohydrates and fats and in the synthesis of cholesterol. An inadequate supply is very rare, but can occur, for example, in connection with intestinal diseases, alcohol abuse or chronic inflammation. Liver, herring and beef, but also fish, egg yolk and milk are a good source of vitamin B5. Broccoli, oat flakes, avocado and pulses supply vitamin B5 on the plant side.

• Vitamin B6 (pyridoxine, pyridoxal and pyridoxamine) occurs in numerous foods and is involved in protein metabolism and blood formation. Deficiency symptoms include cramps as a result of nerve damage, muscle wasting, angular cheilitis, anaemia and a generally higher susceptibility to infection. Wheat bran, bananas, sunflower seeds, avocados, goose meat, walnuts and tuna are good sources of vitamin B6.

• Vitamin B7 (biotin) is needed for healthy skin, hair and nails. Biotin is also involved in fat and protein metabolism. Biotin deficiency shows as hair loss, scaly red skin rashes, depression and a general state of exhaustion. A deficiency arises from a one-sided diet and alcoholism. Biotin is found mainly in oat flakes, peanuts, tomatoes, boiled eggs and beef liver.

• Vitamin B9 (folic acid) is involved in growth processes, cell division and blood formation in the body. Pregnant women and women wishing to conceive should take in somewhat more of it. There is also an increased requirement in malabsorption, as is the case in people affected by the autoimmune disease coeliac disease, but also in people with alcohol dependence. Tingling of the tongue, a burning tongue, pallor, diarrhoea and weight loss are symptoms of folic acid deficiency. Good food sources for meeting folic acid requirements are spinach, wholegrain products, walnuts, almonds, orange juice and pulses.

• Vitamin B12 (cobalamin) occurs mainly in animal foods. Vitamin B12 is important for growth, cell division and blood formation. Anaemia is therefore a symptom of deficiency, which as a rule occurs rarely. Eggs, beef, minced meat, cheese, milk, fish and oysters are important sources of vitamin B12.

• Vitamin C (ascorbic acid) is known for its numerous functions: it is found in collagen, the building block of skin, bones, teeth and connective tissue. Its deficiency disease, well known from seafaring, is scurvy, which is rare today. Older people and smokers have an increased requirement. Vitamin C is found mainly in fruit (citrus fruits, strawberries, plums) and vegetables (cauliflower, broccoli, peppers).

Minerals

Minerals are micronutrients that humans need, in addition to carbohydrates, proteins and fats (macronutrients) and vitamins, to regulate metabolic processes. Minerals are inorganic food components that occur in plant and animal foods. Since the organism needs them in different amounts, they are divided into macrominerals and trace elements. The body needs magnesium, calcium, sodium, chloride, potassium and phosphorus in larger amounts. By contrast, the trace elements iron, iodine, chromium, fluorine, zinc, selenium, copper, manganese and molybdenum make up a particularly small proportion of body mass.

Inadequate supply of minerals is very rare in healthy people with a varied diet. A balanced diet of natural foods including fruit, vegetables, wholegrain products, pulses, dairy products and meat ensures an adequate intake of minerals.

Essential macrominerals

• Magnesium takes part in the formation of more than 300 enzymes. Magnesium is crucial for muscle and nerve function and plays an important role in energy metabolism. Together with calcium, magnesium is involved in many metabolic processes. Calcium ensures muscle contraction, magnesium muscle relaxation, and so prevents muscle cramps. It also regulates blood pressure, supports the production of messenger substances and the transmission of nerve impulses, and stimulates the formation of new synapses in the brain. There is an increased requirement in, among others, pregnant women, breastfeeding mothers, migraine and headache patients, older people, children and adolescents, diabetics and athletes. Magnesium deficiency becomes noticeable through muscle cramps, especially in the calves, and eyelid twitching. One consequence of prolonged and severe magnesium deficiency is cardiac arrhythmia.

• Calcium: 99% of the calcium in the body is stored in the bones; the rest is in the cells and in the blood. Calcium is indispensable for the formation of bones and teeth, for muscle contractions, blood clotting and a normal heart rhythm. Calcium deficiency arises from chronic alcoholism and can occur with special diets. Malabsorption is promoted by vitamin D deficiency (and associated diseases such as rickets, osteoporosis, osteomalacia, chronic renal insufficiency), but can also occur with severe lactose intolerance. Tingling of the skin, a sensation of ants crawling, numbness and muscle cramps are symptoms of deficiency. There is an increased requirement for pregnant women and breastfeeding mothers, but also in hyperthyroidism and vitamin D deficiency. With a normal diet – i.e. without supplementing calcium tablets – and normal metabolism and without underlying diseases, it is not possible to trigger hypercalcaemia. Milk and dairy products (yoghurt, quark, kefir, buttermilk, cottage cheese) cover on average about 50% of the daily calcium requirement. Hard cheeses such as Parmesan, Gouda, Emmental, Tilsit etc. in particular have a very high calcium content. Plant calcium is found mainly in the leaves of plants such as broccoli, kohlrabi, Swiss chard and leeks.

• Sodium is a mineral that occurs in all cells and secretions of the body. The most important dietary source is table or cooking salt (NaCl), which is a compound of sodium and chloride. 1 gram of salt contains 0.6 grams of chloride and 0.4 grams of sodium. Sodium regulates the acid–base balance, the water balance, muscle contraction, blood pressure and neural functions. Half of the requirement is contained in foods; the other half is added during cooking or at the table. Anyone who wants or needs to consume less salt can rely on the simple rule “don’t add extra salt”. A low-salt diet is indicated in particular for people with heart disease, hypertension and heart failure, but also for patients with renal insufficiency or kidney failure. Highly processed and cured foods such as ham, salami, pretzel sticks and crisps, but also some cheeses (feta, Parmesan, Brie, processed cheese) have a very high sodium content.

• Chloride occurs in the human body, as in nature, only in combination with other elements. The best known is table salt, sodium chloride, which is also the body’s most important source of chloride. Together, sodium and chloride regulate the electrolyte, water and acid–base balance. Other compounds are magnesium chloride and thiamine chloride (vitamin B1).
  

• Potassium is important for energy metabolism, blood pressure regulation, heart and muscle function and for the conductivity and excitability of nerves. A diet with lots of plant products is rich in potassium. Sodium and potassium are interdependent – foods rich in sodium are usually low in potassium. Potassium-rich foods include fruit juices, cocoa (powder), low-fat dairy products, wholegrain products, tomato purée and fruit (especially bananas, apricots, figs and grapes).
  

• Phosphorus is a structural component of bone, is involved in signal transmission, oxygen transport and processes of energy production and storage, activates hormones and interacts with calcium metabolism. Phosphate deficiency is very rare. There is an increased requirement in people with alcohol dependence and in patients whose intestinal absorption is impaired (Crohn’s disease, ulcerative colitis, coeliac disease, chronic diarrhoea). A phosphorus deficiency is hardly possible because phosphorus is so widespread in food. The most important sources of phosphate are milk and dairy products, fish and cereals; vegetables, fruit and potatoes are also rich in phosphate.
  

Essential trace elements

Trace elements are present in the body in smaller amounts: they make up less than 0.01 per cent of body mass and the daily intake is less than 100 milligrams. Trace elements are iron, iodine, fluorine, zinc, selenium, copper, manganese, chromium and molybdenum

• Iron is a component of the blood pigment haemoglobin, which transports oxygen. Iron is involved in the production of metabolism-stimulating enzymes and in energy production during endurance exercise. Vegetarians and people with chronic inflammatory bowel diseases can have iron deficiency because of the malabsorption that occurs. It can occur after (major) blood loss. Angular cheilitis (cracked corners of the mouth) indicates a deficiency, as do tiredness, pallor, brittle nails, hair loss and shortness of breath. Requirements are increased in rapidly growing adolescents and pregnant women. Iron is found in meat, fish, liver, green vegetables, wholegrain cereals, nuts and soya products.

• Chromium regulates blood sugar levels. Chromium increases fat burning and carbohydrate utilisation (glucose metabolism). There are no specific deficiency symptoms. Pulses, chocolate, calf’s liver, mushrooms, wheat germ, honey, nuts and wholegrain cereals are good sources of chromium.

• Fluorine is involved in the formation of tooth enamel and plays a major role in building strong bones, ligaments and connective tissue. Fluorine deficiency can show as an increased tendency to tooth decay. Fluorine is contained in seafood, toothpaste, fluoridated table salt and especially in liquids such as black tea, coffee, mineral and medicinal waters.

• Zinc has an important function in wound healing. It is involved in strengthening the immune system and ensures healthy skin and hair. It is contained in meat, especially offal, but wholegrain cereals, vegetables and beans are also very good sources of zinc.

• Selenium protects cells and fats from oxidation together with vitamins C and E (it is a so-called antioxidant) and maintains the elasticity of body tissue. It is an indispensable component of numerous proteins. An adequate intake of selenium supports the immune defences and is important for a normally functioning thyroid. Selenium is also needed for sperm production. Sources of selenium are fish, meat, wholegrain cereals and soya beans.

• Iodine is a component of the thyroid hormone thyroxine, which is of central importance for maintaining normal metabolism in practically all organ systems. Iodine is also responsible for growth and energy production in cells and is involved in carbohydrate and fat metabolism. Pregnant women should ensure an adequate iodine intake; otherwise the child may suffer from impaired brain development and growth disorders, which are irreversible. Iodine deficiency can be observed in hypothyroidism. To ensure an adequate iodine intake, iodised salt should be used. Iodine is also present in sea fish and shellfish. To absorb iodine well, an adequate supply of selenium and iron must be ensured.

• Copper is needed, together with iron, to activate important enzymes. It is involved in pigmentation of skin and hair and in the production of red blood cells. Copper also helps to maintain the nervous system. Plant foods with a high copper content are nuts, seeds, pulses (above all buckwheat) and cereal products. Animal foods include fish, shellfish and organ meat.

• Manganese is a component and cofactor of enzymes. It is important for protein and energy metabolism. Plant foods supply manganese: nuts, brewer’s yeast, pulses, wholegrain products and also black tea.

• Molybdenum is a component of enzymes and is involved in electron transfer processes. Molybdenum deficiency is extremely rare and shows itself with symptoms such as confusion, disorientation and tachycardia, up to and including coma. A high molybdenum content is found in dairy products and in practically all plant foods.