Nutrition is essential materials to live, there are six major classes of materials 1.Fat 2.Carbohyadrates (& fiber) 3.Protetin 4.Vitamins 5.Minerals 6. Water.

These nutrient classes can be generally grouped into the categories of macronutrients (needed in relatively large amounts), and micronutrients (needed in smaller quantities). The macronutrients are carbohydrates, fats, fiber, proteins and water. The other nutrient classes are micronutrients. The macronutrients (excluding fiber and water) provide energy, which is measured in kilocalories, often called "Calories" and written with a capital C to distinguish them from small calories. Carbohydrates and proteins provide four Calories of energy per gram, while fats provide nine Calories per gram. Vitamins, minerals, fiber, and water do not provide energy, but are necessary for other vital functions. Other micronutrients not categorized above include antioxidants and phytochemicals. Most foods contain a mix of some or all of the nutrient classes. Some nutrients are required on a regular basis, while others are needed less frequently. Poor health can be caused by an imbalance of nutrients, whether an excess or a deficiency.
1.Fat 2.Carbohydrate 3.Protein 4.Vitamins 5.Minerals 6.Water. 7.Phytochemicals 8.Antixidants

1. FAT-

Fat provides 9 calories from one gram. Fats are composed of fatty acids (long carbon/hydrogen chains) bonded to a glycerol. Fat is classified as saturated or unsaturated. Saturated fats have all of their carbon atoms bonded to hydrogen atoms, whereas unsaturated fats have some of their carbon atoms double-bonded in place of a hydrogen atom. Unsaturated fats are generally healthier than saturated fat. Saturated fat is typically solid at room temperature (such as butter), while unsaturated fat is a liquid (such as olive oil). Unsaturated fats may be further classified as monounsaturated (one double-bond) or polyunsaturated (many double-bonds). Certain fatty acids are essentials to maintain health because it cannot be synthesized in body, it must be consumed in diet. Omega 3 and Omega 6 are essentials fatty acids. Omega-3 fatty acids are another important group of essential fatty acids. Together, omega-3 and omega-6 fatty acids play a crucial role in brain function as well as normal growth and development. EFAs belong to the class of fatty acids called polyunsaturated fatty acids (PUFAs). They are generally necessary for stimulating skin and hair growth, maintaining bone health, regulating metabolism, and maintaining reproductive capability. Deficiencies in EFAs can lead to reduced growth, a scaly rash called dermatitis, infertility, and lack of ability to fight infection and heal wounds.It is important to maintain an appropriate balance of omega-3 and omega-6 (another essential fatty acid) in the diet, as these two substances work together to promote health. Omega-3 fatty acids help reduce inflammation, and most omega-6 fatty acids tend to promote inflammation. An inappropriate balance of these essential fatty acids contributes to the development of disease while a proper balance helps maintain and even improve health. A healthy diet should consist of roughly 2 - 4 times more omega-6 fatty acids than omega-3 fatty acids.Good sources of essential fatty acids include: fish, flax seeds, hemp seeds, soy beans, pumpkin seeds, sunflower seeds, and walnuts.

2. Carbohydrates

Carbohydrate provides 4 calories from one gram.Carbohydrates are the most abundant class of organic compounds found in living organisms. Chemically, carbohydrates are organic molecules in which carbon, hydrogen, and oxygen. Carbohydrates may be classified as monosaccharides, disaccharides, or polysaccharides by the number of monomer (sugar/saccharide) units they contain. Monosaccharides contain 1 sugar/saccharide unit, disaccharides contain 2, and polysaccharides contain 3 or more. Polysaccharides are often referred to as complex carbohydrates because they are long chains of sugar units, whereas monosaccharides and disaccharides are simple carbohydrates. The difference is important to nutritionists because complex carbohydrates take longer to metabolize since their sugar units are processed one-by-one off the ends of the chains. Simple carbohydrates are metabolized quickly and thus raise blood sugar levels more quickly resulting in rapid increases in blood insulin levels compared to complex carbohydrates.
Fiber-Fiber does not provide any calorie. Dietary fiber consists mainly of cellulose, a large carbohydrate polymer, which is indigestible because humans do not have enzymes to digest it. Whole grains, fruits (especially plums, prunes, and figs), and vegetables are rich in dietary fiber. Recommended intake of daily fiber is 25-30 grams per day to prevent constipation,colon cancer and to reduce blood cholesterol.

3. Protein

One gram protein provides 4 calories. Protein is composed of amino acids that are the body's structural materials. The body requires amino acids to produce new body protein (protein retention) and to replace damaged proteins (maintenance) that are lost in the urine. Amino acid requirements are classified in terms of essential (body cannot produce them) and non-essential (body can produce them from other nitrogen containing compounds) amino acids. Consuming a diet that contains adequate amounts of essential (but also non-essential) amino acids is particularly important for growing. Essential amino acids are phenylalanine, valine, threonine, tryptophan, isoleucine, methionine, leucine, and lysine. Dietary sources of protein include meats, tofu and other soy-products, eggs, grains, legumes, and dairy products such as milk and cheese.

4. Vitamins

Vitamins are organic compounds. They are required in small amounts. Vitamins have diverse biochemical functions, including function as hormones (e.g. vitamin D), antioxidants (e.g. vitamin A), and mediators of cell signaling and regulators of cell and tissue growth and differentiation. Vitamins are classified on the basis of solubility medium 1) Water soluble - Vitamin C & eight Vitamin B are soluble in water so they are known as water soluble. 2) Fat soluble - Vitamin A, D, E, K are absorbed through the intestinal tract with the help of lipids (fats).RDA (recommended daily allowance) is used to determine the daily intake of vitamins and minerals, RDAs are dietary standards(dose) established by the food and nutrition board of national academy of sciences.

CLICK HERE TO DOWNLOAD THE RDA CHART OF VITAMINS

5. Minerals

Minerals are inorganic compounds. The term "mineral" is archaic, since the intent of the definition is to describe ions, not chemical compounds or actual minerals. Minerals has various functions in body that includes but not limited, to build teeth and bones, hormones and enzymes formations ,to maintain acid-base balance,transfering nervous system message. Some dietitians recommend that these heavier elements should be supplied by ingesting specific foods. Minerals are classified on the basis of their require quantity,1)Macro minerals - minerals which are needed in large dose ,more than 200 mg per day, for example- calcium,magnesium,phosphorus,potassium,sulphur,sodium,chloride. 2) Trace minerals - minerals which are needed in very small quantity, per day, for example - iron, zinc , selenium, manganese , molybdenum ,iodine, copper , chromium ,fluoride.

CLICK HERE TO DOWNLOAD THE RDA CHART OF MINERALS

6. Water

About 70% of the non-fat mass of the human body is made of water. Water is vital both as a solvent in which many of the body's solutes dissolve and as an essential part of many metabolic processes within the body. Water is also central to photosynthesis and respiration. Water is also central to acid-base neutrality and enzyme function. To function properly, the body requires between one and seven liters of water per day to avoid dehydration; the precise amount depends on the level of activity, temperature, humidity, and other factors. With physical exertion and heat exposure, water loss will increase and daily fluid needs may increase as well. Some experts assert that 8-10 glasses of water (approximately 2 liters) daily are the minimum to maintain proper hydration. United States National Research Council in general recommended (including food sources): 2.7 liters of water total for women and 3.7 liters for men. Specifically, pregnant and breastfeeding women need additional fluids to stay hydrated. According to the Institute of Medicine-who recommend that, on average, women consume 2.2 litres and men 3.0 litres-this is recommended to be 2.4 litres (approx. 9 cups) for pregnant women and 3 litres (approx. 12.5 cups) for breastfeeding women since an especially large amount of fluid is lost during nursing. For those who have healthy kidneys, it is rather difficult to drink too much water, but (especially in warm humid weather and while exercising) it is dangerous to drink too little. People can drink far more water than necessary while exercising. People who exercise should drink 8-16oz before (15 minutes) exercise, 8-10 oz during (after every 15 minutes) exercise and 16-32 oz after exercise.

7. Phytochemicals

Phytochemicals are plant- or fruit-derived chemical compounds. "Phytonutrients" refer to phytochemicals or compounds that come from edible plants. Phytochemicals in freshly harvested plant foods may be destroyed or removed by modern processing techniques, possibly including cooking. For this reason, industrially processed foods likely contain fewer phytochemicals and may thus be less beneficial than unprocessed foods.

8. Antioxidants

An antioxidant is a molecule capable of slowing or preventing the oxidation of other molecules. Oxidation is a chemical reaction that transfers electrons from a substance to an oxidizing agent. Oxidation reactions can produce free radicals, which start chain reactions that damage cells. Vitamin A ,C ,E, Carotenoids,Sulphur,selenium has antioxidant properties.