This nutrition glossary includes definitions of both common nutritional terms and terms specific to the Nutrition Data Web site. The convenient alphabetic links allow you to quickly navigate between different sections of this glossary.
Anthocyanidins: See Flavonoids.
Antioxidant: Antioxidants are chemical substances that help protect against cell damage from free radicals. Well-known antioxidants include vitamin A, vitamin C, vitamin E, carotenoids, and flavonoids.
Ascorbic Acid: See Vitamin C.
Bioflavonoids: See Flavonoids.
Body Mass Index (BMI): Body Mass Index is a standardized ratio of weight to height, and is often used as a general indicator of health. Your BMI can be calculated by dividing your weight (in kilograms) by the square of your height (in meters). A BMI between 18.5 and 24.9 is considered normal for most adults. Higher BMIs may indicate that an individual is overweight or obese.
Caloric Ratio Pyramid™: The Caloric Ratio Pyramid is a color-coded triaxial graph on which a food’s percentages of carbohydrates, fats, and protein are plotted. The Caloric Ratio Pyramid was created by Nutrition Data to provide a quick visual indicator of a food’s macronutrient content. For a more detailed explanation, please see Nutrition Data’s Caloric Ratio Pyramid page.
Calorie: Calorie is a unit of measurement for energy. One calorie is formally defined as the amount of energy required to raise one cubic centimeter of water by one degree centigrade. For the purpose of measuring the amount of energy in food, nutritionists most commonly use kilocalories (equal to 1,000 calories), and label the measurement either as “kcal” or as “Calories” with a capital “C.” One kcal is also equivalent to approximately 4.184 kilojoules.
Campesterol: See Sterol.
Carotenoids: Carotenoids are natural fat-soluble pigments found in certain plants. Carotenoids provide the bright red, orange, or yellow coloration of many vegetables, serve as antioxidants, and can be a source for vitamin A activity.
Cholecalciferol: See Vitamin D.
Cholesterol: Cholesterol is a soft, waxy substance present in all parts of the body including the nervous system, skin, muscles, liver, intestines, and heart. It is both made by the body and obtained from animal products in the diet. Cholesterol is manufactured in the liver for normal body functions including the production of hormones, bile acid, and vitamin D. It is transported in the blood to be used by all parts of the body.
In the blood stream, cholesterol combines with fatty acids to form high-density (HDL) and low-density (LDL) lipoproteins. LDLs are considered the “bad cholesterol,” since they can stick together to form plaque deposits on the walls of your blood vessels, leading to atherosclerosis.
One-fourth of the adult population in the U.S. has high blood cholesterol levels. More than half of the adult population has blood cholesterol levels that exceed the desirable range, as specified by the medical community. Elevated cholesterol often begins in childhood. Some children may be at higher risk than others due to a family history of high cholesterol.
Cobalamine: See Vitamin B12.
Copper: Copper is a trace element that is essential for most animals, including humans. It is needed to absorb and utilize iron. The influence of copper upon health is due to the fact that it is part of enzymes, which are proteins that help biochemical reactions occur in all cells. Copper is involved in the absorption, storage, and metabolism of iron. The symptoms of a copper deficiency are similar to iron-deficiency anemia. Copper may be absorbed by both the stomach and small-intestinal mucosa, with most absorbed by the small intestine. Copper is found in the blood bound to proteins.
Because your individual needs may differ from the established Daily Values, Nutrition Data allows you to maintain your own individual set of target values for nutrient intake. These “Individualized Daily Values” (IDV) can be set on Nutrition Data’s My Preferences page.
Dietary Fiber: Dietary fiber comes from the thick cell walls of plants. It is an indigestible complex carbohydrate. Fiber is divided into two general categories: water-soluble and water-insoluble.
Soluble fiber has been shown to lower cholesterol. However, in many studies, the degree of cholesterol reduction was quite modest. For unknown reasons, diets higher in insoluble fiber (mostly unrelated to cholesterol levels) have been shown to correlate better with protection against heart disease in human trials. Soluble fibers can also lower blood-sugar levels, and some doctors believe that increasing fiber decreases the body’s need for insulin—a good sign for diabetics.
Insoluble fiber acts as a stool softener, which speeds digestion through the intestinal tract. For this reason, insoluble fiber is an effective treatment for constipation. The reduction in “transit time” has also been thought to partially explain the link between a high-fiber diet and a reduced risk of colon cancer.
Dietary Reference Intakes (IDV): See Daily Values.
While the essential amino acids requirements vary among different individuals, the Food and Agricultural Organization of the United Nations (FAO) has proposed a standard that specifies the minimum amount of each essential amino acid that should be supplied per gram of protein consumed. This standard is the reference by which protein quality is determined. By comparing the limiting (i.e., lowest level) amino acid in a food with this standard, the amino acid score is determined. A score of 100 or above indicates a complete or high-quality protein; a score below 100 indicates a lower-quality protein.
Some researchers break flavonoids down into subclasses that include isoflavones, anthocyanidins, flavans, flavonols, flavones, and flavanones. However, these subclassifications are not universally recognized.
Folate: See Vitamin B9.
Folic Acid: See Vitamin B9.
Fullness Factor™ (FF): The Fullness Factor is a dietary index, created by Nutrition Data, to predict the satiating effect of a food from the food’s nutrient content. For a detailed explanation of the Fullness Factor, please see Nutrition Data’s Fullness Factor page.
Insoluble Fiber: See Dietary Fiber.
International Unit (IU): IU is a measurement unit that is primarily used on nutrition labeling for vitamin A. One IU is equivalent to 0.3 mcg of retinol, 0.6 mcg of beta-carotene, or 1.2 mcg other provitamin-A carotenoids.
Iron: Iron is one of the human body’s essential minerals. It forms part of hemoglobin, the component of the blood that carries oxygen throughout the body. People with iron-poor blood tire easily because their bodies are starved for oxygen. Iron is also part of myoglobin, which helps muscles store oxygen. With insufficient iron, adenosine triphosphate (ATP; the fuel the body runs on) cannot be properly synthesized. As a result, some iron-deficient people can become fatigued even when they are not anemic.
Isoflavones: See Flavonoids.
Isoleucine: See Essential Amino Acids.
Isomer: An isomer is a variation in the arrangement of atoms in two or more otherwise similar chemical compounds.
Lipid: A general classification to denote water-insoluble compounds, such as fatty acids and sterols.
Lysine: See Essential Amino Acids.
Under certain circumstances magnesium has been found to improve vision in people with glaucoma. Similarly, magnesium has demonstrated an ability to lower blood pressure.
Maltitol: See Sugar Alcohol.
Manganese: Manganese is an essential trace mineral that is required in small amounts to manufacture enzymes necessary for the metabolism of proteins and fat. It also supports the immune system and blood-sugar balance and is involved in the production of cellular energy, reproduction, and bone growth.
Manganese works with vitamin K to support normal blood clotting. Working with the B-complex vitamins, manganese helps promote a positive outlook when faced with stress, frustration, and anxiety.
Mannitol: See Sugar Alcohol.
Menadione: See Vitamin K.
Methionine: See Essential Amino Acids.
Microgram (mcg): A microgram is a unit of measure equal to one one-millionth of a gram (g).
Micronutrient: See Macronutrient.
Milligram (mg): A milligram is a unit of measure equal to one one-thousandth of a gram (g).
Monosaccharides: Monosaccharides are simple carbohydrates that consist of a single sugar molecule. Examples include glucose, fructose, and galactose.
Monounsaturated Fat: See Unsaturated Fat.
Nutrient Balance Indicator™: The Nutrient Balance Indicator is a radial graph that was created by Nutrition Data to provide visual feedback about the density and balance of essential nutrients in a food. For a more detailed explanation, please see Nutrition Data’s Nutrient Balance Indicator page.
Nutrient Density: Nutrient density is the measurement of the amount of a nutrient per fixed portion of food. By its own convention, Nutrition Data calculates nutrient densities based on a 200-Calorie serving size. If you know the nutrient density of a food, you can better compare its nutritional value to that of other foods, regardless of serving size.
Nutritional Target Map™: The Nutritional Target Map is a color-coded graph that was created by Nutrition Data to provide a quick visual indicator of a food’s ND Rating and Fullness Factor. The Nutritional Target Map is used for food consumption analysis done in conjunction with Nutrition Data’s Better Choices Diet. For a more detailed explanation, please see Nutrition Data’s Nutritional Target Map page.
Phosphate: See Phosphorus.
Phosphorus: Phosphorus is an essential mineral that is usually found in nature combined with oxygen as phosphate. Most phosphate in the human body is in bone, but phosphate-containing molecules (phospholipids) are also important components of cell membranes and lipoprotein particles, such as good (HDL) and bad (LDL) cholesterol. Small amounts of phosphate are engaged in biochemical reactions throughout the body.
The role of phosphate-containing molecules in aerobic exercise reactions has suggested that phosphate loading might enhance athletic performance, though controlled research has produced inconsistent results.
Phylloquinone: See Vitamin K.
Phytonadione: See Vitamin K.
Phytosterol: Phytosterol is any plant-derived sterol. (See Sterol.)
Polysaccharides: Polysaccharides are complex carbohydrates, made up of multiple sugar molecules. Examples of polysaccharides include cellulose, starch, and dextrin.
Polyunsaturated Fat: See Unsaturated Fat.
Potassium: Potassium is an essential mineral that helps regulate heart function, blood pressure, and nerve and muscle activity. Potassium is also required for carbohydrate and protein metabolism and helps maintain the proper pH within the body. Those with higher potassium intakes tend to have lower blood pressure and people with low blood levels of potassium who are undergoing heart surgery are at an increased risk of developing heart arrhythmias and an increased need for cardiopulmonary resuscitation. Excessive sodium intake can increase your body’s requirements for potassium.
Protein: Protein is one of the basic components of food and makes all life possible. Amino acids are the building blocks of proteins. All of the antibodies and enzymes, and many of the hormones in the body, are proteins. They provide for the transport of nutrients, oxygen, and waste throughout the body. They provide the structure and contracting capability of muscles. They also provide collagen to connective tissues of the body and to the tissues of the skin, hair, and nails.
Protein Quality: See Essential Amino Acids.
Retinol: See Vitamin A.
Retinol Activity Equivalent (RAE): The Retinol Activity Equivalent is a relatively new unit for expressing vitamin A activity. One mcg of RAE is equivalent to 1 mcg of all-trans-retinol, 12 mcg of all-trans-beta-carotene, or 24 mcg of other provitamin A carotenoids. These RAE conversion factors are based on recent studies that show that the conversion of provitamin A carotenoids to retinol is only half as great as previously thought.
Riboflavin: See Vitamin B2.
Saturated Fat: A saturated fat is a fat or fatty acid in which there are no double bonds between the carbon atoms of the fatty acid chain. Saturated fats are usually solid at room temperature. Diets high in saturated fat have been shown to correlate with an increased incidence of atherosclerosis and coronary heart disease. Dehydrogenation converts saturated fats to unsaturated fats, while hydrogenation accomplishes the reverse.
Common saturated fats include butter, lard, palm oil, coconut oil, cottonseed oil, and palm kernel oil. Saturated fat is found in dairy products, especially cream and cheese, and in meat, as well as in many prepared foods. Some studies suggest that replacing saturated fats in the diet with unsaturated fats will increase one’s ratio of HDL to LDL serum cholesterol.
Alternatives to saturated fats include monosaturated fats such as olive oil and polyunsaturated fats such as canola oil and corn oil.
Selenium: Selenium is an essential trace mineral. Selenium activates an antioxidant enzyme called glutathione peroxidase, which may help protect the body from cancer. Yeast-derived forms of selenium have induced “apoptosis” (programmed cell death) in cancer cells in test tubes and in animals. One study found that men consuming the most dietary selenium developed 65% fewer cases of advanced prostate cancer than did men with low levels of selenium intake.
Selenium is also essential for healthy immune functioning. Even in a nondeficient population of elderly people, selenium supplementation has been found to stimulate the activity of white blood cells. Selenium is also needed to activate thyroid hormones.
In a placebo-controlled study, selenium supplementation indicated a reduction in disease activity in people with autoimmune thyroiditis (thyroid inflammation). In a double-blind trial, selenium supplementation of infertile men improved the motility of sperm cells and increased the chance of conception.
Sodium: Sodium is a mineral, an essential nutrient. It helps to maintain blood volume, regulate the balance of water in the cells, and keep nerves functioning. The kidneys control sodium balance by increasing or decreasing sodium in the urine. One teaspoon of salt contains about 2,300 milligrams of sodium, more than four times the amount the body requires per day.
Most Americans consume far more sodium than their bodies need. Many foods contain sodium naturally, and it is commonly added to foods during preparation or processing or as a flavoring agent. Sodium is also found in drinking water, prescription drugs, and over-the-counter medications.
In the United States, about one in four adults have elevated blood pressure. Sodium intake is only one of the factors known to affect high blood pressure, and not everyone is equally susceptible. The sensitivity to sodium seems to be very individualized. Usually, the older one is, the more sensitive one is to salt.
Soluble Fiber: See Dietary Fiber.
Sorbitol: See Sugar Alcohol.
Sterol: A sterol is any of a class of solid cyclic alcohols, found in both plants (e.g., campesterol, stigmasterol, beta-sitosterol) and animals (e.g., cholesterol).
Stigmasterol: See Sterol.
Sugar Alcohol: Sugar alcohols, sometimes called polyols, are a class of carbohydrates that are more slowly or incompletely absorbed by the human digestive system than sugars. Common sugar alcohols include sorbitol, mannitol, maltitol, and xylitol. Sugar alcohols contribute less Calories to the diet than most other types of carbohydrates, but may cause digestive discomfort.
Thiamin: See Vitamin B1.
Tocopherol: See Vitamin E.
Tryptophan: See Essential Amino Acids.
Both kinds of unsaturated fat can replace saturated fat in the diet. Substituting unsaturated fats for saturated fats helps to lower levels of total cholesterol and LDL cholesterol in the blood.
Vitamin B1 (Thiamin): Vitamin B1 is a water-soluble vitamin that the body requires to break down carbohydrates, fat, and protein. Every cell of the body requires vitamin B1 to form adenosine triphosphate (ATP). Vitamin B1 is also essential for the proper functioning of nerve cells.
Vitamin B2 (Riboflavin): Vitamin B2 is a water-soluble vitamin that helps the body process amino acids and fats, activate vitamin B6 and folic acid, and convert carbohydrates to adenosine triphosphate (ATP). Under some conditions, vitamin B2 can act as an antioxidant.
Vitamin B3 (Niacin): Vitamin B3 is required for cell respiration and helps release the energy in carbohydrates, fats, and proteins. It also supports proper circulation and healthy skin, functioning of the nervous system, and normal secretion of bile and stomach fluids. It is used in the synthesis of sex hormones, treating schizophrenia and other mental illnesses, and as a memory-enhancer.
Nicotinic acid (but not nicotinamide) supplementation improves the blood cholesterol profile, and has been used to flush the body of organic poisons, such as certain insecticides. People report more mental alertness when this vitamin is in sufficient supply.
A shortage of niacin may be indicated with symptoms such as canker sores, depression, diarrhea, dizziness, fatigue, halitosis, headaches, indigestion, insomnia, limb pains, loss of appetite, low blood-sugar, muscular weakness, skin eruptions, and inflammation.
Vitamin B5 (Pantothenic Acid): Vitamin B5 is a water-soluble vitamin involved in the Kreb’s energy production cycle and is needed for the production of acetylcholine, a neurotransmitter. Vitamin B5 also triggers the adrenal glands, is essential in transporting and releasing energy from fats, and enables the synthesis of cholesterol, vitamin D, and steroid hormones. Pantethine—a vitamin B5 byproduct—has been shown to lower cholesterol and triglycerides in the blood.
Vitamin B6: Vitamin B6 is a water-soluble vitamin and is part of the vitamin B complex. Vitamin B6 plays a role in the synthesis of antibodies by the immune system, which are needed to fight many diseases. It helps maintain normal nerve function and also acts in the formation of red blood cells. Vitamin B6 is also required for the chemical reactions needed to digest proteins. The higher the protein intake, the more the need for vitamin B6.
Large doses of vitamin B6 can cause neurological disorders and numbness. Deficiency of this vitamin can cause mouth and tongue sores, irritability, confusion, and depression. Vitamin B6 deficiency is uncommon in the United States.
Vitamin B9 (Folate): Vitamin B9, also known as folic acid, is a B vitamin necessary for cell replication and growth. Folic acid helps form building blocks of DNA, which holds the body’s genetic information, and building blocks of RNA, needed for protein synthesis. Folic acid is most important, then, for rapidly growing tissues, such as those of a fetus, and rapidly regenerating cells, like red blood cells and immune cells. Folic acid deficiency results in an anemia that responds quickly to folic acid supplements.
The need for folic acid increases considerably during pregnancy. Deficiencies of folic acid during pregnancy are associated with low birth weight and an increased incidence of neural tube defects in infants. Most doctors, many other health-care professionals, and the March of Dimes recommend that all women of childbearing age supplement with 400 mcg per day of folic acid. Such supplementation may protect against the formation of neural tube defects during the time between conception and when pregnancy is discovered.
Vitamin B12 (Cobalamine): Vitamin B12 is a water-soluble vitamin needed for normal nerve cell activity, DNA replication, and production of the mood-affecting substance SAMe (S-adenosyl-L-methionine). Vitamin B12 acts with folic acid and vitamin B6 to control homocysteine levels. An excess of homocysteine has been linked to an increased risk of coronary disease, stroke, and other diseases such as osteoporosis and Alzheimer’s.
Vitamin B12 deficiency causes fatigue. A small trial reported that even some people who are not deficient in B12 showed a marked increase in energy after vitamin B12 injections. However, the relationship between B12 injections and the energy level of people who are not vitamin B12-deficient has been rarely studied. Oral B12 supplements are unlikely to achieve the same results as injectable B12, because the body has a relatively poor absorption rate for this vitamin.
Vitamin C (Ascorbic Acid): Vitamin C is an essential water-soluble vitamin that has a wide range of functions in the human body.
One of vitamin C’s important functions is acting as an antioxidant, protecting LDL cholesterol from oxidative damage. When LDL is damaged, the cholesterol appears to lead to heart disease, but vitamin C acts as an important antioxidant protector of LDL. Vitamin C may also protect against heart disease by reducing the stiffness of arteries and the tendency of platelets to coagulate in the vein.
The antioxidant properties also protect smokers from the harmful effects of free radicals. Small doses of vitamin C taken by nonsmokers before being exposed to smoke have been shown to reduce the free radical damage and LDL cholesterol oxidation associated with exposure to cigarette smoke.
Vitamin C has a range of additional functions. It is needed to make collagen, a substance that strengthens many parts of the body, such as muscles and blood vessels, and plays important roles in healing and as an antihistamine. Vitamin C also aids in the formation of liver bile, which helps to detoxify alcohol and other substances. Evidence indicates that vitamin C levels in the eye decrease with age and that vitamin C supplements prevent this decrease, lowering the risk of developing cataracts.
Vitamin C has been reported to reduce activity of the enzyme aldose reductase, which theoretically helps protect people with diabetes. It may also protect the body against accumulation or retention of the toxic mineral lead. People with recurrent boils (furunculosis) may have defects in white-blood-cell function that are correctable with vitamin C supplementation.
Vitamin D (Cholecalciferol): Vitamin D is a fat-soluble vitamin that helps maintain blood levels of calcium, by increasing absorption from food and reducing urinary calcium loss. Both functions help keep calcium in the body and therefore spare the calcium that is stored in bones. Vitamin D may also transfer calcium from the bone to the blood, which may actually weaken bones. Though the overall effect of vitamin D on the bones is complicated, some vitamin D is certainly necessary for healthy bones and teeth.
Vitamin D is also produced by the human body during exposure to the ultraviolet rays of the sun. However, seasonal changes, latitude, time of day, cloud cover, smog, and sunscreen can all affect UV exposure. Vitamin D deficiency is more common in northern latitudes, making vitamin D supplementation more important for residents of those areas.
Vitamin D plays a role in immunity and blood cell formation and also helps cells differentiate—a process that may reduce the risk of cancer. From various other studies, researchers have hypothesized that vitamin D may protect people from multiple sclerosis, autoimmune arthritis, and juvenile diabetes. Vitamin D is also necessary to maintain adequate blood levels of insulin. Vitamin D receptors have been found in the pancreas, and some evidence suggests that supplements may increase insulin secretion for some people with adult-onset diabetes.
Vitamin E (Tocopherol): Vitamin E is an antioxidant that protects cell membranes and other fat-soluble parts of the body, such as LDL cholesterol (the “bad” cholesterol), from damage. Several studies have reported that supplements of natural vitamin E help reduce the risk of heart attacks.
Vitamin E also plays some role in the body’s ability to process glucose. Some trials suggest that vitamin E may help in the prevention and treatment of diabetes.
In the last decade, the functions of vitamin E have been further clarified. In addition to its antioxidant functions, vitamin E has now been shown to directly affect inflammation, blood cell regulation, connective tissue growth, and genetic control of cell division.
Vitamin K (Phylloquinone): Vitamin K is necessary for proper bone growth and blood coagulation. Vitamin K accomplishes this by helping the body transport calcium. Vitamin K is used to treat overdoses of the drug warfarin. Also, doctors prescribe vitamin K to prevent excessive bleeding in people taking warfarin but requiring surgery.
There is some evidence that vitamin K2 (menadione), not vitamin K1 (phylloquinone; phytonadione), may improve a group of blood disorders known as myelodysplastic syndromes (MDS). These syndromes carry a dramatically increased risk of developing acute myeloid leukemia. Comprehensive trials of K2 for MDS are needed to confirm these auspicious early results.
Zinc can reduce the body’s ability to utilize copper, another essential mineral. The ability to interfere with copper makes zinc an important therapy for people with Wilson’s disease, a genetic condition that causes copper overload. In healthy individuals, however, this effect is best offset by copper supplementation.