Although the body can manufacture many vital chemicals, a lot of the materials we need must be acquired by eating. The energy needed to fuel the body is gained entirely through the food we consume. Once nutrients are absorbed into the bloodstream, they are then transported to different parts of the body where they are put to innumerable tasks.
What the body needs
There are six types of nutrient that the body needs to get from diet in order for it to function properly: fats, proteins, carbohydrates, vitamins, minerals and water. The last three are small enough to be absorbed directly through the lining of the gut, but fats, proteins and carbohydrates need to be broken down chemically into smaller particles before being absorbed. These particles are sugars, amino acids and fatty acids respectively.
Fats are a rich source of energy and help in the absorption of fat-soluble vitamins. Healthier fat sources include diary, nuts, fish and vegetable-based oils.
Proteins are the major structural components of all cells. Healthy protein sources include beans, lean meats, diary and eggs.
Carbohydrates are the main energy source for the brain. Whole grains and fruits and vegetables that are high in fibre are healthy sources of carbohydrates.
Vitamins are needed to make things in the body. Vitamin C for example, is needed to build collagen, which is used in various tissues.
Minerals are vital for building bones, hair, skin and blood cells. They also enhance nerve function and help to turn food into energy.
Some 65 per cent of the body is made up of water. This is constantly being lost through breathing and sweating, and it is critical that it is being replenished.
Building an eye
Every tissue in our body is built and maintained by the nutrients we absorb from our food. This tissues of the human eye for example, are built from amino acids and fatty acids, and are fuelled by sugars. The membranes and spaces are filled with fluids, and vitamins and minerals are needed to convert light into an electrical impulse – the basis of vision itself.
All of the cells of the eye (and the rest of the body) are surrounded by membranes that are built using fatty acids and proteins.
The eyes are an extension of the brain, and just like the brain, they need the sugars we get from carbohydrates for energy.
The eye is filled with fluid, which maintains the pressure in the eye and provides nutrients and moisture to the inner eye tissues. This fluid is 98 per cent water.
Eyelashes are made up of the protein keratin, which is built from amino acids. Other tissues of the eye are made of the protein collagen.
Vitamin A is bound to proteins in the eye known as visual pigments. When light hits the cells, the vitamin A changes shape, sending an electrical impulse to the brain.
Red blood cells
The tissues of the eye are oxygenated by the red blood cells, which need the protein haemoglobin and the mineral iron in order to carry the oxygen.
“The food of sight – Like all organs of the body, the eye utilizes all six of the essential nutrients. These give it structure and enable it to send visual information to the brain”