The Body's Nutrients Fuel and Building Blocks

For the body to function optimally, it needs a range of nutrients, which are used either as fuel, building materials, or support for the body's chemical processes. These nutrients are divided into macronutrients and micronutrients. The macronutrients provide energy and build the body's structure, while the micronutrients – vitamins and minerals – ensure that the body's functions run smoothly.

Macronutrients

Proteins consist of chains of amino acids and are essential for the body's growth, repair, and maintenance. They are found in muscles, skin, hair, enzymes, and hormones. The body can produce some amino acids itself, but the essential amino acids must come from the diet.

Good sources of protein include:

• Meat, poultry, and fish
• Eggs and dairy products
• Legumes such as beans and lentils
• Nuts and seeds

An adult normally needs 0.8–1.2 grams of protein per kilogram of body weight daily, depending on activity level.

Carbohydrates are the body's preferred energy source, especially for the brain and muscles during activity. They are divided into three main types:

• Sugars – found in fruit, milk, and candy
• Starch – found in bread, pasta, rice, and potatoes
• Dietary fiber – found in whole grains, vegetables, and legumes and are important for digestion

During digestion, carbohydrates are broken down into glucose, which is absorbed into the blood and transported to the cells. Excess glucose is stored as glycogen in muscles and the liver or as fat.

It is recommended that about 45–60% of daily energy intake comes from carbohydrates – preferably from whole grains and vegetables.

Fat is a concentrated energy source and important for building cell membranes, absorption of fat-soluble vitamins (A, D, E, and K), and production of hormones. There are several types of fat:

• Unsaturated fats – found in fish, nuts, olive oil, and avocado. These are considered the healthiest fats.
• Saturated fats – found in butter, cheese, meat, and coconut oil. Should be limited in larger amounts.
• Trans fats – found in certain industrial products and should be avoided entirely.

Fat contains 9 kcal per gram – more than twice as much as carbohydrates and protein. It is recommended that 25–35% of daily energy intake comes from fat, with only a small proportion from saturated fat.

Water does not provide energy, but is essential for almost all bodily functions. It transports nutrients, regulates body temperature, lubricates joints, and helps eliminate waste products.

An adult should drink about 1.5–2 liters of water per day, depending on activity, temperature, and diet. Certain foods – such as fruits and vegetables – also contribute to fluid intake.

Micronutrients

Vitamins are organic substances the body needs in small amounts to function. They are divided into:

• Fat-soluble vitamins (A, D, E, K): Stored in the body and found in fatty foods.
• Water-soluble vitamins (B-group and C): Excreted in the urine and must be supplied regularly.

Examples of vitamin functions:

• Vitamin A: Vision and skin
• Vitamin C: Immune system and wound healing
• Vitamin D: Absorption of calcium and bone health
• Vitamin B12: Blood production and nervous system

Minerals are inorganic substances that are necessary for bones, fluid balance, and muscle function, among other things. They are divided into:

• Macrominerals: e.g. calcium, potassium, magnesium, and phosphorus
• Trace elements: e.g. iron, zinc, selenium, and iodine

Some important functions:

• Calcium: Bones and teeth
• Iron: Transport of oxygen in the blood
• Zinc: Immune system and wound healing
• Magnesium: Muscles and energy metabolism

Balance is important

A healthy and varied diet typically contains all the necessary nutrients. A lack of nutrients can lead to fatigue, weakened immune system, osteoporosis, or anemia, while overconsumption – especially of energy – can lead to overweight and lifestyle diseases.

Dietary guidelines such as the official Danish dietary advice recommend eating plant-rich, varied, and not too much. This includes plenty of vegetables and whole grains, fish several times a week, healthy fats, and limiting salt, sugar, and processed meat.

Conclusion

The body's nutrients each play a crucial role in our health and energy levels. By understanding how macro- and micronutrients work – and in which foods they are found – we can make more informed choices and support the body as best as possible in everyday life.