Nutrient is so famous but why?

 IMPORTANCE OF NUTRIENT

A nutrient is a substance present in food that excerts a biological function in oour body and whose deficiency is incompatible with life

. There are six categories of nutrients: carbohydrates ,lipids, proteins, vitamins, the essential minerals and water. These are the molecules we cannot live without.

 For example alcohol is not a nutrient because although it provides energy, its deficiency does not result in any disease and we can perfectly live without .On the other hand, there are some substances present in food that have protective effects on our health, but there’s no proof that a lack of them inevitably causes disease or death, and for this reason they cannot be called nutrients. These beneficial non-nutritional substances are often referred to as ‘phytochemicals’, ‘nutraceuticals’, ‘extra nutritional substances’, or ‘bioactives’. In this course, we will mostly refer to them as ‘food bioactives’, to indicate that they are molecules present in food, and they exert a biological activity in our body that is likely to be beneficial, but they are not nutrients because we can also survive without them. Some examples of food bio actives are dietary fiber, plant sterols, polyphenols such as anthocyanins or carotenoids such as lycopene or lutein, and many more.

 Another concept that we need to understand right away is that of nutritional essentiality. We already said that all nutrients are essential ,in the sense that without them we cannot survive. However, in nutrition, when we refer to a nutrient as an ‘essential nutrient’ we actually mean something else. A nutrient is defined essential if our body is not able to build it from other nutrients and therefore it has to come as such from food. For example, saturated fats are not essential nutrients because our body can build them starting from unsaturated fats, or from carbohydrates. This does not mean that we don’t need saturated fats. They are vital nutrients, but they are not ‘essential’ because if they don’t come from food, we can make them ourselves starting from other nutrients. On the other hand, two polyunsaturated fats, namely linoleicacid and alpha-linolenic acid, are just as vital, but either we eat them with food, orwe are in trouble because there’s no way we can make them ourselves starting from otherstuff. For these reason, they are called ‘essential fatty acids.

 Our body is like a machine, it spends energy for its activity. And just like a car needs gas, our body needs food to get its energy .The unit of measure for the energy that comes from food is the kilocalorie, kcal. This pasta will provide me with 350 calories, give or take. But to wash the dishes and clean up after  wards I will need to do some work, which will cost me calories, probably around twenty .I also need to spend calories every day to walk, talk, perform all of my activities ,and even to just breathe and pump my heart, and even to digest and utilize the food I have just eaten. We all need to spend energy to survive and perform our activities, and our only way to get this energy back is from food. Food is our only way to get the energy we need to stay alive and to fuel all of our activities.This is what we call the energetic function of nutrients.

 We ‘burn’ the energetic nutrients in our cells to extract the energy we need for our activities and internal functioning. But there’s a lot more to it. Food is not only our fuel, it also is the stuff we are made of. Which is why a child who is growing ,a woman who is pregnant or an athlete who wants to build new muscle, will all need toeat a little bit more food to sustain growth and development. But our body is a remarkably complex machine that requires a lot of maintenance and repair every day. Our tissues break downand need to be repaired. Old cells die and need to be replaced with new ones. And soon. So even if we are not growing, all of us still need foodstuff every day to maintain and repair our tissues.

 This is what we call the structural function of nutrients. But there’s more. Besides building, maintaining and fueling our body, we also need substances from food to make it run smoothly. Take our muscles, for example. We need foodstuff to build our muscle, and we need foodstuff to provide energy to fuel it, but this is still not enough to make it work. For example, we also need just a tiny little bit of calcium to activate muscle contraction. It’s like the key of our car, we may have the car and we may have gas in it, but without the key ,it still won’t start. We need a lot of substances from food to control ,regulate, modulate, activate, coordinate the work of all the structures in our body. This is what we call the regulatory function of food and nutrients. So to recap, nutrients can have an energetic  function, which is to provide energy to fuel our body’s activities, a structural function ,to provide material we need to build and maintain the structures of our body, and a regulatory function, to make all of this structures work properly.