According to the WHO, Nutrition is the intake of food, considered in relation to the body’s dietary needs. Good nutrition – an adequate, well balanced diet combined with regular physical activity – is a cornerstone of good health. Poor nutrition can lead to reduced immunity, increased susceptibility to disease, impaired physical and mental development, and reduced productivity.
In hospitals, nutrition may refer to the food requirements of patients, including nutritional solutions delivered via an IV (intravenous) or IG (intragastric) tube.
Nutritional science studies how the body breaks food down (catabolism) and repairs and creates cells and tissue (anabolism) - catabolism and anabolism metabolism. Nutritional science also examines how the body responds to food.
Brigham Young University states that "nutritional Science investigates the metabolic and physiological responses of the body to food and diet, including the role of nutrients in the cause, treatment, and prevention of disease."
Nutrition is present in all processes of life. Right from the very moment the sperm fertilizes an egg, through fetal development in the uterus, to the birth, human growth, maturity, old age, and eventual death. Even after death the human body serves as nutrition for other organisms. Anything that involves life and chemical or biochemical movement has nutrition at its core.
Anything that lives is dependent on energy, which results from the combustion of food.
Types of Nutrients
As of 2014, nutrients are thought to be of two types: macro-nutrients which are needed in relatively large amounts, and micronutrients which are needed in smaller quantities. The macronutrients include Carbohydrates, fibers and Micronuritents such as Antioxidants and phytochemicals which are said to influence and protect our body system. Most foods contain a mix of some or all of the nutrient types, together with other substances, such as toxins of various sorts. Some nutrients can be stored internally (e.g., the fat-soluble vitamins), while others are required more or less continuously. Poor health can be caused by a lack of required nutrients or, in extreme cases, too much of a required nutrient. For example, both salt and water (both absolutely required) will cause illness or even death in excessive amounts.
This macronutrients which includes Carbohydrate(provides energy), the Protein(amino acids that provide structural material), Dietary Fiber (reduces constipation and gastrointestinal problems), Lipids(cell membranes and some other molecules are built). The Energy been provided is measured either in kilocalories (kcal) or Joules. 1 kcal = 4185.8 joules.
Carbohydrates are polyhydroxyl alcohols having potentially active aldehydes and ketones. They are made up of Carbon, Hydrogen and Oxygen atoms bonded together. They include Monosaccharide; disaccharides can be referred to Simple Carbohydrate. Oligosaccharides and Polysaccharides which can be referred to as complex carbohydrate. They constitute a large part of Rice, Yam, Noodles and bread. Some simple carbohydrates follow metabolic that result in the catabolism to glucose, while Nutritionally, polysaccharides are more favored for humans because they are more complex molecular sugar chains and take longer to break down - the more complex a sugar molecule is the longer it takes to break down and absorb into the bloodstream, and the less it spikes blood sugar levels. Spikes in blood sugar levels are linked to heart and vascular diseases.
Proteins are complex biological substances necessary to build protoplasm. They are largely peptides and consist of units called amino acids. All proteins contains carbon hydrogen, oxygen, and nitrogen. Some contain Sulphur, phosphorus, iron iodine and other elements. They are usually from plants or animal origin. Every function in the living cell depends on proteins. Excess amino acids are discarded, typically in the urine. For all animals, some amino acids are essential (an animal cannot produce them internally) and some are non-essential (the animal can produce them from other nitrogen-containing compounds). Excess amino acids from protein can be converted into glucose and used for fuel through a process called Gluconeogenesis.
Dietary fiber is the part of a plant that is resistant to the body’s digestive enzymes. Only a relatively small amount of fiber is digested or metabolized in the stomach or intestines. Most of it ends up in the stool. Although most fiber is not digested, it delievers several important health benefits, it retains water resulting in softer and bulkier stool that prevents constipation and hemorrhoids. A high fiber diet also reduces the risk of colon cancer, perhaps by speeding the rate which stool passes through the intestine and by keeping the digestive system clean, in addiction fiber finds substances that would normally result in the production of cholesterol, and eliminates these substances from the body, it helps lower Blood cholesterol levels, reducing the risk of heart disease. It may help lower blood glucose levels because it can slow the absorption of sugar. Additionally, fiber, perhaps especially that from whole grains, is thought to possibly help lessen insulin spikes, and therefore reduce the risk of type 2 diabetes.
Molecules consist of carbon, hydrogen, and oxygen atoms. Fats are triglycerides - three molecules of fatty acid combined with a molecule of the alcohol glycerol. Fatty acids are simple compounds (monomers) while triglycerides are complex molecules (polymers). Humans have a requirement for certain essential fatty acids such as Linoleic acid(omega 6 fatty acids) and alpha-linolenic acid (omega 3 fatty acids) in the diet because they cannot be synthesized from simple fatty acid in the diet. Omega 6 can be found in vegetable oils while omega 3 is found in the green leaves of plants and in selected seeds, nuts and legumes and also found in fish oils.
About 70% of the non-fat mass of the human body is water. Nobody is completely sure how much water the human body needs - claims vary from between one to seven liters per day to avoid dehydration. We do know that water requirements are very closely linked to body size, age, environmental temperatures, physical activity, different states of health, and dietary habits.
Somebody who consumes a lot of salt will require more water than another person of the same height, age and weight, exposed to the same levels of outside temperatures, and similar levels of physical exertion who consumes less salt. Most blanket claims that 'the more water you drink the healthier your are' are not backed with scientific evidence. The variables that influence water requirements are so vast that accurate advice on water intake would only be valid after evaluating each person individually.
Dietary minerals are the other chemical elements our bodies need, apart from carbon, hydrogen, oxygen and nitrogen. The term "minerals" is misleading, and would be more relevant if called "ions" or "dietary ions" (it is a pity they are not called so). People whose intake of foods is varied and well thought out - those with a well balanced diet - will in most cases obtain all their minerals from what they eat.
Minerals are often artificially added to some foods to make up for potential dietary shortages and subsequent health problems. The best example of this is iodized salt - iodine is added to prevent iodine deficiency, which even today affects about two billion people and causes mental retardation and thyroid gland problems. Iodine deficiency remains a serious public health problem in over half the planet.
Sodium: a very common electrolyte; in general not found in dietary supplements, despite being needed in large quantities, because the ion is very common in food: typically as sodium chloride, or common salt. Excessive sodium consumption can leading to high blood pressure and osteoporosis. The American Heart Association (AHA) announced on November 5, 2012 that sodium consumption should be limited to 1,500 milligrams per day, and that includes everybody, even healthy people without high blood pressure, diabetes or cardiovascular diseases.
Potassium: it is a systemic (affects entire body) electrolyte, essential in co-regulating ATP.
Deficiency - Hypokalemia (can profoundly affect the nervous system and heart).
Excess - Hyperkalemia (can also profoundly affect the nervous system and heart).
Chloride - It is key for hydrochloric acid production in the stomach.
Deficiency - hypochleremia (low salt levels, which if severe can be very dangerous for health).
Excess - hyperchloremia (usually no symptoms, linked to excessive fluid loss).
Calcium- It is important for muscle, heart and digestive health. Builds bone, assists in the synthesis and function of blood cells.
Phosphorus- It is a component of bones and energy processing.
Magnesium- It processes ATP and required for good bones.
Zinc- It is required by several enzymes.
Iron- It is required for proteins and enzymes, especially hemoglobin.
Deficiency - anemia.
Excess - iron overload disorder; iron deposits can form in organs, particularly the heart.
Manganese - It is a cofactor in enzyme functions.
Deficiency - wobbliness, fainting, hearing loss, weak tendons and ligaments. Less commonly, can be cause of diabetes.
Excess - interferes with the absorption of dietary iron.
Copper - it is a component of many redox (reduction and oxidation) enzymes.
Deficiency - anemia or Pancytopenia (reduction in the number of red and white blood cells, as well as platelets) and a Neurodegeneration.
Excess - can interfere with body's formation of blood cellular components; in severe cases convulsions, palsy, and insensibility and eventually death.
Iodine- it is required for the biosynthesis of thyroxine (a form of thyroid hormone).
Deficiency - developmental delays, among other problems.
Excess - can affect functioning of thyroid gland.
Selenium- it is a cofactor essential to activity of antioxidant enzymes.
Deficiency - Keshan disease (myocardial necrosis leading to weakening of the heart), Kashing-Beck disease (atrophy degeneration and necrosis of cartilage tissue).
Excess - garlic-smelling breath, gastrointestinal disorders, hair loss, sloughing of nails, fatigue, irritability, and neurological damage.
Molybdenum - It has a vital role in uric acid formation and iron utilization, in carbohydrate metabolism, and sulfite detoxification.
Vitamins are recognized as organic essential nutrients, necessary in the diet for good health. (Vitamin D is the exception: it can be synthesized in the skin, in the presence of UVB radiation.) Certain vitamin-like compounds that are recommended in the diet, such as carnitine, are thought useful for survival and health, but these are not "essential" dietary nutrients because the human body has some capacity to produce them from other compounds. Vitamins are classified as water soluble (they can dissolve in water) or fat soluble (they can dissolve in fat). For humans there are 4 fat-soluble (A, D, E, and K) and 9 water-soluble (8 B vitamins and vitamin C) vitamins, a total of 13.
Water soluble vitamins need to be consumed more regularly because they are eliminated faster and are not readily stored. Urinary output is a good predictor of water soluble vitamin consumption. Several water-soluble vitamins are manufactured by bacteria.