Vitamin C: Nutrient commonly found in oranges
A nutrient is a component in foods that an organism uses to survive and grow. Macronutrients provide the bulk energy an organism's metabolic system needs to function while micronutrients are used to build and repair tissues, regulate body processes, and to provide the necessary cofactors for metabolism to be carried out. Both types of nutrients can be acquired from the environment.
Methods of nutrient intake are different for plants and animals. Plants take in nutrients directly from the soil through their roots and from the atmosphere through their leaves. Animals (including humans) and protists (single celled organisms) have specialized digestive systems that work to break down macronutrients for energy and utilize micronutrients for both metabolism and anabolism (constructive synthesis) in the body.
Organic nutrients consist of carbohydrates, fats, proteins (or their building blocks, amino acids), and vitamins. Inorganic chemical compounds such as dietary minerals, water (H2O), and oxygen may also be considered nutrients. A nutrient is considered essential if it must be obtained from an external source either because the organism cannot synthesize it or because insufficient quantities are produced. Nutrients needed in very small amounts are called micronutrients while those needed in large quantities are called macronutrients. The effects of nutrients are dose-dependent; shortages are called deficiencies.
Carbohydrates: Commonly found in pasta
Fats: Especially the essential fatty acids
Vitamins: Commonly found in fruit vegetable
While all nutrients are vital for the normal functioning, survival and growth of the human body, their chemical structures and functions are different and thus grouped into five different categories stated below:
Carbohydrates: Carbohydrates are compounds made up of types of sugars. Carbohydrates are classified by their number of sugar units: monosaccharides (such as glucose and fructose), disaccharides (such as sucrose and lactose), oligosaccharides, and polysaccharides (such as starch, glycogen, and cellulose).
Proteins: Proteins are organic compounds that consist of amino acids joined by peptide bonds. The body cannot manufacture some of the amino acids (termed essential amino acids); the diet must supply them. Proteins, in nutrition, are broken down through digestion by proteases back into free amino acids.
Proteins: Commonly found in eggs
Fats: Fats consist of a glycerin molecule with three fatty acids attached. Fatty acids are unbranched hydrocarbon chains, connected by single bonds alone (saturated fatty acids) or by both double and single bonds (unsaturated fatty acids). The body does not manufacture certain fatty acids (termed essential fatty acids) and the diet must supply them.
Vitamins: Vitamins are organic compounds essential to the body. Vitamins are classified as either water-soluble or fat-soluble. In humans there are 13 vitamins: 4 fat-soluble (A, D, E, and K) and 9 water-soluble (8 B vitamins and vitamin C).
Dietary minerals: The five major minerals in the human body are calcium, phosphorus, potassium, sodium, and magnesium. All of the remaining elements in a human body are called "trace elements". The trace elements that have a specific biochemical function in the human body are iron, cobalt, copper, zinc, manganese, molybdenum, iodine, and selenium.
Water: From a biological standpoint, water has many distinct properties that are critical for the proliferation of life. It carries out this role by allowing organic compounds to react in ways that ultimately allow replication. All known forms of life depend on 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.
Substances that provide energy
Substances that support metabolism
Substances that provide energy.
Carbohydrates: Carbohydrates perform numerous roles in living organisms. Polysaccharides serve for the storage of energy (e.g. starch and glycogen) and as structural components (e.g. cellulose in plants and chitin in arthropods). The 5-carbon monosaccharide ribose is an important component of coenzymes (e.g. ATP, FAD and NAD) and the backbone of the genetic molecule known as RNA. The related deoxyribose is a component of DNA. Saccharides and their derivatives include many other important biomolecules that play key roles in the immune system, fertilization, preventing pathogenesis, blood clotting, and development.
Proteins: Proteins are the chief actors within the cell, said to be carrying out the duties specified by the information encoded in genes. With the exception of certain types of RNA, most other biological molecules are relatively inert elements upon which proteins act. The best-known role of proteins in the cell is as enzymes, which catalyze chemical reactions. Many proteins are also involved in the process of cell signaling and signal transduction. Antibodies are protein components of an adaptive immune system whose main function is to bind antigens, or foreign substances in the body, and target them for destruction. Structural proteins confer stiffness and rigidity to otherwise-fluid biological components.
Fats: Fats are also sources of essential fatty acids, an important dietary requirement. They provide energy as noted above. Vitamins A, D, E, and K are fat-soluble, meaning they can only be digested, absorbed, and transported in conjunction with fats. Fats play a vital role in maintaining healthy skin and hair, insulating body organs against shock, maintaining body temperature, and promoting healthy cell function. Fat also serves as a useful buffer against a host of diseases. When a particular substance, whether chemical or biotic, reaches unsafe levels in the bloodstream, the body can effectively dilute—or at least maintain equilibrium of—the offending substances by storing it in new fat tissue. This helps to protect vital organs, until such time as the offending substances can be metabolized or removed from the body by such means as excretion, urination, accidental or intentional bloodletting, sebum excretion, and hair growth.
Substances that support metabolism.
Vitamins: Vitamins have diverse biochemical functions. Some, such as vitamin D, have hormone-like functions as regulators of mineral metabolism, or regulators of cell and tissue growth and differentiation (such as some forms of vitamin A). Others function as antioxidants (e.g., vitamin E and sometimes vitamin C). The largest number of vitamins, the B complex vitamins, function as enzyme cofactors (coenzymes) or the precursors for them; coenzymes help enzymes in their work as catalysts in metabolism.
Dietary minerals: Dietary minerals have numerous functions in the human body. They involve in the formation of bones, red blood cells, skin, hair, nails and have prominent roles in the enzyme system.
Anorexia: A result of nutrient deficiency
Carbohydrate: Following a diet consisting of very low amounts of daily carbohydrate for several days will usually result in higher levels of blood ketone bodies than an isocaloric diet with similar protein content. This relatively high level of ketone bodies is commonly known as ketosis and is very often confused with the potentially fatal condition often seen in type 1 diabetics known as diabetic ketoacidosis. Somebody suffering ketoacidosis will have much higher levels of blood ketone bodies along with high blood sugar, dehydration and electrolyte imbalance.
Proteins: A lack of protein in the diet leads to a feeling of low energy, moodiness, and the inability to handle stress well. It also causes weak and sore muscles, water retention, flakiness, dry skin and rashes, anxiety, nausea, depression, insomnia, and inability of wound healing. Also without protein to stabilize the blood sugar, the tendency to experience exhausting highs and lows in mood and energy increases. It also leads to illness like marasmus, kwashiorkor, cachexia, and protein c and protein s deficiency.
Fats: Essential fatty acids, or EFAs, are fatty acids that humans and other animals must ingest because the body requires them for good health but cannot synthesize them. Essential fatty acid deficiency results in a dermatitis similar to that seen in zinc or biotin deficiency. Those fatty acids that are not essential, that is the body can make them, deficiency is rare.
Vitamins: Vitamin deficiencies may result in disease conditions, including goiter, scurvy, osteoporosis, impaired immune system, disorders of cell metabolism, certain forms of cancer, symptoms of premature aging, and poor psychological health, among many others.
Dietary minerals: Deficiencies in dietary minerals can result in many disorders including anemia and goiter. Examples of mineral deficiency include, zinc deficiency, iron deficiency, and magnesium deficiency of which each has a host of health problems.
Carbohydrate: Excess carbohydrate intake has been shown to raise plasma triglycerides. In the human body, high levels of triglycerides in the bloodstream have been linked to atherosclerosis and, by extension, the risk of heart disease and stroke. High carbohydrate intake also lead to obesity and when consumed in the form of simple sugars, type 2 diabetes.
Protein: Extreme protein intake (in excess of 200 g per day), coupled with inadequate intake of other calorie sources (fat or carbohydrates), can cause a form of metabolic disturbance and death commonly known as rabbit starvation. Even when consuming other calorie sources, consuming more than 285 g of protein per day (for an 80 kg person) may be unsafe.
Fats: Numerous studies have also found that consumption of trans-fats increases risk of cardiovascular disease. Studies have also found that replacing saturated fats with cis unsaturated fats in the diet reduces risk of cardiovascular disease.
Vitamins: In large doses, some vitamins have documented side-effects that tend to be more severe with a larger dosage. The likelihood of consuming too much of any vitamin from food is remote, but overdosing (vitamin poisoning) from vitamin supplementation does occur. At high enough dosages, some vitamins cause side-effects such as nausea, diarrhea, and vomiting.
Minerals: High intake levels of minerals can cause nausea, vomiting, pain, cramps and diarrhea. It can also act as an anti-nutrient to other nutrients.
Anti-nutrients reduce nutrient absorption
Anti-nutrients are natural or synthetic compounds that reduce the body's ability to absorb essential nutrients. They are not a major concern for most people, but may become a problem during periods of malnutrition, or among people who base their diets almost solely on grains and legumes.
Nutrition studies focus on those anti-nutrients commonly found in food sources and beverages. The most widely studied anti-nutrients include:
•Phytate (phytic acid): Mainly found in seeds, grains and legumes. Phytate reduces the absorption of minerals from a meal. These include iron, zinc, magnesium and calcium.
•Tannins: A class of antioxidant polyphenols that may impair the digestion of various nutrients.
•Lectins: Found in all food plants, especially in seeds, legumes and grains. Some lectins may be harmful in high amounts, and interfere with the absorption of nutrients.
•Protease inhibitors: Widely distributed among plants, especially in seeds, grains and legumes. They interfere with protein digestion by inhibiting digestive enzymes.
•Oxalic acid and oxalates are present in many plants, particularly in members of the spinach family. Oxalates bind to calcium and prevent its absorption in the human body.
Excessive intake of required nutrients can also result in them having an anti-nutrient action. Excessive intake of fiber can reduce the transit time through the intestines to such a degree that other nutrients cannot be absorbed. Because calcium, iron, zinc and magnesium share the same transporter within the intestine, excessive consumption of one of these minerals can lead to saturation of the transport system and reduced absorption of the other minerals.
Lipase inhibitors interfere with enzymes, such as human pancreatic lipase, that catalyze the hydrolysis of some lipids, including fats. For example, the anti-obesity drug orlistat causes a percentage of fat to pass through the digestive tract undigested.
Amylase inhibitors prevent the action of enzymes that break the glycosidic bonds of starches and other complex carbohydrates, preventing the release of simple sugars and absorption by the body. Amylase inhibitors, like lipase inhibitors, have been used as a diet aid and obesity treatment. Amylase inhibitors are present in many types of beans; commercially available amylase inhibitors are extracted from white kidney beans.
Glucosinolates prevent the uptake of iodine, affecting the function of the thyroid and thus are considered goitrogens. They are found in broccoli, Brussel sprouts, cabbage and cauliflower.
Another particularly widespread form of anti-nutrients are the flavonoids, which are a group of polyphenolic compounds that include tannins. These compounds chelate metals such as iron and zinc and reduce the absorption of these nutrients, but they also inhibit digestive enzymes and may also precipitate proteins.
It should be noted however, that anti-nutrients aren't always "bad." Under some circumstances, anti-nutrients like phytate and tannins may have some beneficial health effects as well.