Vitamins – What they do and where you can actually get them

They are simply labelled with letters such as A, C, D or K – and yet our health, performance and even our mood depend on them: vitamins. Without them, the finely tuned machinery of our body breaks down. Even the slightest deficiency can lead to tiredness, difficulty concentrating or infections, whilst an optimal supply protects cells, regulates energy processes and strengthens the immune system. But where do we actually get our vitamins from, how do they work – and why aren’t a few multivitamin tablets enough?

Vitamins are organic compounds which the body – with the exception of vitamin D and niacin – cannot produce itself. We must therefore obtain them from our diet. They do not act as direct sources of energy, but as key substances that enable biochemical processes: from energy metabolism and blood formation to DNA repair.

A distinction is made between two main groups:

Vitamin A is essential for vision, the skin and the mucous membranes. It regulates cell growth and differentiation. A deficiency leads to night blindness, skin problems and an increased susceptibility to infection.

Strictly speaking, vitamin D is a hormone that the body produces itself in the skin when exposed to UV-B radiation. It regulates calcium balance, strengthens bones and muscles, and also regulates immune processes. A deficiency – which is widespread in our part of the world – increases the risk of osteoporosis, infections and even depression.

Vitamin E acts as an antioxidant and protects cell membranes from free radicals. It also supports the immune system. A deficiency is rare, but can occur in cases of fat malabsorption and leads to muscle weakness and nerve damage.

Vitamin K is essential for blood clotting and the absorption of calcium into the bones. Without vitamin K, the risk of internal bleeding and osteoporosis increases.

Vitamin C is well known as an immune system booster, but its role goes far beyond that: it strengthens connective tissue, improves iron absorption and acts as a powerful antioxidant. A deficiency leads to bleeding gums, muscle weakness and an increased susceptibility to infection.

The eight B vitamins (B1, B2, B3, B5, B6, B7, B9/folate, B12) act as co-enzymes in energy metabolism, blood formation and DNA synthesis.

Vitamins rarely act alone. Vitamin C improves iron absorption; vitamins D and K work together in bone metabolism; and B vitamins mesh together like cogs in a wheel. These synergies show that a balanced diet is more effective than isolated high-dose supplements.

Both diets can ensure an optimal intake of vitamins – provided they are followed sensibly:

Vitamins are essential for athletes: they regulate energy metabolism, muscle function and recovery. Vitamin D improves muscle strength, B vitamins optimise energy production, and vitamin C speeds up recovery. A deficiency reduces performance, slows down healing processes and increases susceptibility to infections.

Vitamins are the silent conductors of your metabolism. The most important source remains a varied diet – fresh, colourful and natural. However, this is not always enough: as we get older, the body’s ability to absorb nutrients decreases; in competitive sport, the demand increases; and certain medical conditions can lead to deficiencies. In such cases, high-quality supplements are more than just a stopgap – they fill gaps that are difficult to address through diet alone. Quality is key: targeted, sensibly dosed and, ideally, based on personalised advice.

In the next instalment of our series, we’ll be looking at minerals & trace elements. Tiny substances with a huge impact – from oxygen transport and nerve transmission to hormone production. Because sometimes, just one milligram can make the difference between peak performance and exhaustion.