Dr Kashif Prince &

Prof Dr Muhammad Sarwar Khan

Bodies of animals and human beings are made up of very complex structures and a very complex system is running the life. Life requires nutrients to carry on its normal functions like water carbohydrates, proteins, lipids, vitamins and minerals. Minerals are categorised into two groups depending on requirements of the body i.e. macro-mineral and micro-mineral. Macro-minerals are the minerals, which are needed in large quantities like calcium, phosphorus, magnesium, sodium, potassium, chloride and sulfur. Micro-minerals are needed in very minute quantities for normal functioning of the body. These are also called trace minerals i.e. chromium, cobalt, copper, fluorine, iodine, iron, manganese, molybdenum, selenium and zinc. All minerals either micro or macro are important for normal functioning of the body. Each mineral has a vital role in the animal body. Excess of it may cause poisoning and deficiency disturbs the normal functioning.

There is a continuous battle of living beings with disease-causing pathogens like bacteria, viruses and parasites. The department of our body systems which deal with the resistance against disease is called immunity. For the continuity of normal functions human beings need proper blend of all type of nutrients, including vitamins and minerals. Some minerals affect the immune system directly and others indirectly. One of the most important minerals for normal functioning of the immune system is selenium and similarly important vitamin is vitamin E. Both vitamin E and selenium are needed for normal functioning of the immune system.

Selenium along with vitamin E is important antioxidant which means it protects animal tissues from the oxidative damage caused by reactive oxygen species (ROS), actively formed during the normal functioning of cells. Production of such ROS depends on activity of the cells; more active the cell, more ROS will be produced. There is a dire need to clear such compounds from the body because they damage tissues. Due to antioxidant properties of vitamin E and selenium, they are important part of cells, which are very busy in metabolic processes like immune cells, which are basically white blood cells. There are two types of immunity. One is specific, which means a specific reaction is started in the body against a specific pathogenic invader. This type of immunity is for only one specific pathogen and does not protect against others. On the other hand, there is a second type of immune system, which is a general defence system. This means it protects all types of invaders. This is quicker and nonspecific and deals with all pathogenic invaders coming to body. It is observed in many studies that selenium deficiency alone or along with vitamin E deficiency impairs both types of immune responses.

There are two types of cells in our body that protect our internal systems from pathogenic invaders. One type of cells is called B lymphocyte and other T lymphocyte. They both differ in mode of clearing our body against invaders. B cells produce antibodies against the invading pathogens and T cells destroy infective cells. Both functions work together to do the clearing process smoothly. If any one of the process stops, the body has to face a severe loss of immunity. This is proved in various researches that vitamin E and selenium improve both types of cell functions.

For protection against pathogens science has developed the method of vaccination. Vaccinations are a good way to protect our body from invading pathogens. Animals deficient in selenium and vitamin show impaired response of body against vaccination and it is observed that vitamin E and selenium supplementation improves immune response of the treated animals. This is an important strategy to use vitamin E and selenium along with vaccines to boost the immune response. A lot of studies are conducted on mice, chicken, pigs and lambs to check the effect of selenium on immunity for various pathogens. Results show that immunity improves in terms of antibody production as compared to non-treated groups. Results are very pronounced in animals deficient in one or both minerals as compared to animals with adequate level of selenium in diet.

The role of selenium in immunity and disease resistance is well documented. Selenium in higher concentration is good for prevention of infection in animals. It has both specific and non-specific resistance against each type of pathogen i.e. bacteria, virus or protozoa. It differs in strength of the resistance, which it causes against various pathogens but its resistant effect is cannot be doubted.

Feed is the main source of selenium because minerals cannot be produced in our body. For animals, main source of feed is forage and forage takes all such minerals from salts. If soil is deficient in selenium, forage will be selenium deficient. Animals, which take feed from such forage, will not take proper selenium. Ultimately, when human beings will eat meat or other products from such selenium-deficient animals, they will also be selenium deficient. So it is needed that we know the selenium status of our body, our animals and the soil we are living on.–Contributed