MANJULA:9

What is a Nutrient?

A nutrient is a chemical substance that comes from the food you eat. The energy you need for the metabolic processes in your body and for maintaining a constant internal environment comes from these nutrients. So if you think about all the basic reactions going on in your body to keep you breathing, your heart beating, your brain working and allowing you to move about, they all derive their energy from nutrients.

What are Essential Nutrients?

Essential nutrients refers to classes of nutrients found in food. Essential nutrients are simply those that are vital for the normal growth, maintenance and development of the body.

There might be a slight confusion about essential nutrients that must be addressed. The term ‘essential’ when applied to amino acids and certain fatty acids, applies to those that need to be taken in the diet as they are not synthesized by the body. Essential amino acids include Methionine, Valine, Leucine, Isoleucine, Phenylalanine, Tryptophan, Threonine and Lysine. Essential fatty acids are Linolenic acid, Linoleic acid and Arachidonic acid, to name a few.

The 6 Essential Nutrients you can’t live without

Again the term ‘essential’ implies that these six essential nutrients are necessary in order to maintain and develop a healthy body.

These are the 6 Essential Nutrients your body needs daily:

1. Proteins – they make up most of the cell structure including the cell membrane. Genetic information in the cell is stored as Protein in the form of DNA. All the enzymes, that catalyze metabolic reactions in the human body, are protein in nature.

2. Fats – are used in making steroids and hormones. Cholesterol also makes up the cell membrane and provides a degree of rigidity to it. Fats also serve as solvents for hormones and fat-soluble vitamins.

3. Carbohydrates – form the major part of stored food in the body for later use of energy. Glucose which is a monosaccharide is the body’s primary source of energy. When in excess, it is stored in the liver as Glycogen. Carbohydrates are also important for fat oxidation and can also be converted into protein.

4. Vitamins – are mostly co-enzymes which are required for the normal functioning of enzymes. Vitamin C and E are antioxidants, while Vitamin K is required for blood clotting. They cannot be synthesized in the body, so must be taken in the diet.

5. Minerals – are needed in small amounts to make co-factors. These are inorganic ions needed by the enzymes for activation. Other minerals are systemic electrolytes and essential in co-regulation of ATP.

6. Water – serves as a carrier, distributing nutrients to cells and removing wastes through urine. It is also a compulsory agent in the regulation of body temperature and ionic balance of the blood. Water is completely essential for the body’s metabolism and is also required for lubricant and shock absorber.

Of the six essential nutrients you just read about, 3 of them are called Macronutrients, while the other 2 are Micronutrients.

Macronutrients

Macronutrients include carbohydrates, fats, and proteins. They are called macronutrients as they are required in large amounts to fuel the body. Energy is measured in calories and they are essential for the body to grow, repair and develop new tissues, conduct nerve impulses and regulate life process.

• Carbohydrates – are required for energy. Glucose, which is a monosaccharide, is the most essential source of energy in the body. The brain works entirely on glucose alone. When an immediate source of energy is required, glucose is converted into glycogen which is stored in the liver. When energy is needed it is converted into glucose again and used to release energy. Carbohydrates provide 17 kilojoules of energy per gram.

• Fats – have the highest caloric content. This means they provide the largest amount of energy when burnt. When measured by a calorimeter, fats provide about 37 kilojoules per gram, making them twice as energy-rich than protein and carbohydrates. Extra fat is stored in adipose tissue and is burnt when the body has run out of carbohydrates. Fat is also needed to take up fat-soluble vitamins.

• Proteins–  are the third and last source of energy. They are the last to be used of all macronutrients. In cases of extreme starvation, the muscles in the body, that are made up of proteins, are used to provide energy. This is called muscle wasting. Proteins also provide 17 kilojoules per gram.

Is Water a Macronutrient?

You probably wonder if water should be included in this category. Water might not always be considered a macronutrient, but it sure is an essetial nutrient needed for all body functions in large amounts. For example the USDA lists water as part of Macronutrients (see here). Then again you have UNICEF not including water as not part of macronutrients.

Water is found in the body’s cells and transports nutrients to cells and removes toxins from our body. Water regulates the body temperature by our sweat. We get about 50% of the water we need from our food. Remember that water contains no calories.

Micronutrients

These nutrients include minerals and vitamins. Unlike macronutrients, these are required in very minute amounts. Together, they are extremely important for the normal functioning of the body. Their main function is to enable the many chemical reactions to occur in the body. Nevertheless micronutrients do not function for the provision of energy.

• Vitamins – are essential for normal metabolism, growth and development, and regulation of cell function. They work together with enzymes and other substances that are necessary for a healthy life. Vitamins are either fat-soluble or water-soluble. Fat soluble Vitamins can be stored in the fatty tissues in the body when in excess, and so are not excreted easily. This means that you do not need to eat them as often as Water soluble vitamins. The latter are excreted in urine when in excess and so need to be taken daily. Water soluble vitamins include Vitamin B and C. Green leafy vegetables are rich in Vitamin B, whereas Vitamin C is found abundantly in citrus fruits. Fat soluble vitamins are Vitamin A, D, E and K. Green leafy vegetables, milk and dairy products and plant oils provide these vitamins.

• Minerals – are found in ionized form in the body. They are further classified into macrominerals andmicrominerals (or trace minerals). Macrominerals present in the body include Calcium, Potassium, Iron, Sodium and Magnesium to name a few. Iron is a constituent of Hemoglobin which is present in blood. Hence macrominerals constitute a larger percent of the body and are needed in more amounts, as compared to micro minerals. Microminerals include Copper, Zinc, Cobalt, Chromium and Fluoride. They are mostly co-factors, and are necessary for the function of enzymes in the body, but are needed only in minor quantities. Approximately 4% of the body’s mass consists of minerals