Vitamins are essential for a properly functioning metabolism. The body is unable to produce most vitamins by itself, so it needs to absorb them through food. We need 13 vitamins in particular. An overview of the key information is below.
The body needs vitamins to survive. They may not supply any energy, but they play an essential role in the human metabolism. All foods contain a certain amount of vitamins. However, as a general rule, the fresher and less processed your food, the better. Some vitamins are sensitive to heat, light or oxygen, which can lower the vitamin content of food. This means it’s important to prepare fruit and vegetables carefully. Unlike minerals, vitamins can be produced synthetically. Synthetic vitamins have the same chemical structure as natural vitamins and therefore have the same effect. If vitamins are synthetically added to foods, these are known as fortified foodstuffs.
In human nutrition, 13 vitamins play an important role. The body can produce vitamins D and B3 itself, but all other vitamins need to be absorbed through food. Vitamins are either water-soluble or fat-soluble. The technical term for the latter is “lipophilic vitamins”. They are most easily absorbed in combination with fat, such as olive oil. The body stores these vitamins up in fat tissue and the liver. As a result, it is less apparent if we occasionally consume less of these vitamins, or even develop a deficiency. Water-soluble vitamins are known as “hydrophilic vitamins”. They are distributed in parts of the body containing water, such as the blood and intercellular space. The body is unable to store water-soluble vitamins, with the exception of vitamin B12.
Vitamin B1 is required for key reactions in energy and carbohydrate metabolism, and fulfils specific functions within the nervous system. Deficiencies can be caused by the excessive consumption of alcohol, among other things. Possible symptoms include muscle atrophy, myocardial insufficiency and confusion. The recommended daily intake of vitamin B1 is 1 mg for women and 1.2 mg for men. This is equivalent to 80 g of sunflower seeds or 180 g of wholegrain pasta.
Vitamin B2 is involved in a number of reactions within carbohydrate, fat and protein metabolism, and in energy extraction. Symptoms of a deficiency include cracks at the corners of the mouth, rashes around the nose and inflammation of the oral mucosa. Women need 1.1 mg a day, while men need 1.4 mg. This is equivalent to 0.9 l of milk or six hard-boiled eggs.
Nowadays, vitamin B3 is better known as niacin. As the body is able to produce niacin itself, it is not classified as a vitamin in the traditional sense. Niacin is an essential component in energy production. It is needed for the body’s energy, carbohydrate and fat metabolism. Deficiencies are very rare. The recommended daily intake is 12 mg for women and 15 mg for men. This is equivalent to 100 g of roasted peanuts or 135 g of raw chicken breast.
Vitamin B6 plays an important role in amino acid metabolism. It is also involved in nervous system functions and our immune response. Possible signs of a deficiency include dermatitis, a cracked mouth or lips and neurological disturbances. Women’s recommended intake is 1.4 mg per day; men’s is slightly higher at 1.6 mg. This is equivalent to 270 g of raw pork loin or 265 g of raw salmon.
Vitamin B12 is almost exclusively found in animal-based foods. It enables cell division and blood formation, and is a necessary component in healthy nerve cells. Vitamin B12 deficiency can lead to anaemia and nerve damage. The recommended daily intake for adults is 4 µg. This is equivalent to 140 g of beef or 240 g of full-fat Emmental cheese.
The most well-known vitamin is probably vitamin C, also known as ascorbic acid. It is only found in plant-based foods. It protects the cells from free radicals – aggressive molecules missing an electron that take electrons from other molecules in order to stabilise. This leads to oxidative stress, which can contribute to conditions such as arthritis and cardiovascular disease. Vitamin C also strengthens the immune system and promotes iron absorption. It is essential for building connective tissue and bone. Minor deficiencies can result in slow tissue repair, increased vulnerability to infections and a decline in performance. Severe deficiencies can lead to bleeding in the skin, mucous membranes, muscles and internal organs. Women’s recommended intake is 95 mg per day, while men require 15 mg more. 110 mg of vitamin C is equivalent to 65 g of raw red peppers or 140 g of kiwi fruit.
The body needs folic acid when dividing, diversifying and regenerating cells. Signs of a deficiency include anaemia and changes in the blood count. A deficiency during pregnancy increases the risk of birth defects and premature births. Pregnant women should therefore consume 550 mg of folic acid a day. The standard recommended daily intake for adults is just 300 mg. This is equivalent to 200 g of steamed spinach or 90 g of dried chickpeas.
Good to know: pregnant women in their first trimester and those trying to conceive should take 400 mg of synthetic folic acid a day, in addition to a folate-rich diet.
Pantothenic acid is present in many foods. Deficiencies are therefore very rare. This vitamin contributes to our cells’ energy metabolism process and helps build up and break down carbohydrates, proteins and fats. The recommended daily intake of 6 mg is equivalent to 300 mg of raw salmon or 275 g of raw mushrooms.
Biotin can be found in both animal- and plant-based foods, and is often bound to proteins. This vitamin is essential for enzymes that play a central role in metabolising nutrients. Deficiencies are very rare. Possible symptoms include changes to the skin, general weakness and depression. The recommended daily intake for adults is 40 mg. This is equivalent to three eggs or 200 g of oats.
As with most vitamins, the body is unable to produce minerals by itself. Find out more about the role of different micro and trace elements.
Vitamin A is also known as retinol. It is only found in animal-based foods. It protects the skin and mucous membranes, and plays a key role in reproduction, growth, development, the immune system and eyesight. Deficiencies lead to poor eyesight and increased vulnerability to infections. The recommended daily intake is 700 mg for women and 850 mg for men. This is equivalent to 1.8 l of whole milk or 228 g of raw tuna.
Vitamin D is the only vitamin that the body can produce on its own – with the help of the sun. However, the body still gets 10–20% of its vitamin D from food. Vitamin D promotes the absorption of calcium and phosphorous in the intestines. It therefore regulates the absorption of minerals and calcium levels in the blood. It also supports the development of muscles, bones and teeth, and strengthens the immune system. The most important forms are vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). A deficiency can cause symptoms such as fatigue, sleep disturbances and muscle weakness. The recommended daily intake for adults is 15 µg. This is equivalent to 180 g of raw salmon.
Vitamin E is an antioxidant. It neutralises free radicals and protects fats in the blood and cell membranes. Deficiencies can lead to problems with muscle metabolism and the nervous system. Women’s recommended intake is 12 mg per day, while men need 2 mg more. 14 mg is equivalent to 30 g of rapeseed oil or 80 g of mayonnaise.
Vitamin K contributes to blood clotting and growing and maintaining bone. Deficiencies are rare and are generally only caused by certain diseases or medications. The recommended daily intake is 60 µg for women and 70 µg for men. This is equivalent to 65 g of lettuce or 25 g of steamed broccoli.
Our Health Consultation advisors can give you tips on how to achieve a balanced and nutritious diet.
Anyone who eats a balanced diet will normally get enough vitamins from their food and won’t need to take nutritional supplements. But specific groups may need additional nutrients, such as older people, pregnant women, those wishing to conceive, or people with chronic illnesses like Crohn’s disease. They may need to take nutritional supplements. However, this should always be done in consultation with a medical professional.
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