The liver of mammals, fowl, and fish is commonly eaten as food by humans (see offal). Pork, lamb, veal, beef, chicken, goose, and cod livers are widely available from butchers and supermarkets while stingray and burbot livers are common in some European countries.
| Nutritional value per 100 g (3.5 oz) | |
|---|---|
| Energy | 561 kJ (134 kcal) |
2.5 g | |
3.7 g | |
21 g | |
| Vitamins | Quantity %DV† |
| Vitamin A equiv. | 722% 6500 μg |
| Riboflavin (B2) | 231% 3 mg |
| Niacin (B3) | 94% 15 mg |
| Vitamin B6 | 41% 0.7 mg |
| Folate (B9) | 53% 212 μg |
| Vitamin B12 | 1083% 26 μg |
| Vitamin C | 26% 23 mg |
| Minerals | Quantity %DV† |
| Iron | 128% 23 mg |
| Sodium | 4% 87 mg |
This nutritional data is from 1992 and refers to raw pork liver only. Liver nutrients vary among species. | |
| †Percentages estimated using US recommendations for adults, [1] except for potassium, which is estimated based on expert recommendation from the National Academies. [2] | |
Animal livers are rich in iron, copper, the B vitamins and preformed vitamin A. Daily consumption of liver can be harmful; for instance, vitamin A toxicity has been proven to cause medical issues to babies born of pregnant mothers who consumed too much vitamin A. [3] For the same reason, consuming the livers of some species like polar bears, dogs, or moose is unsafe. A single serving of beef liver exceeds the tolerable upper intake level of vitamin A. [4] 100 g cod liver contains 5 mg of vitamin A and 100 μg of vitamin D. [5] Liver contains large amounts of vitamin B12, and this was one of the factors that led to the discovery of the vitamin. [6]
From Middle English liver, from Old English lifer, from Proto-Germanic *librō, from Proto-Indo-European *leyp- "to smear, smudge, stick", from Proto-Indo-European *ley- "to be slimy, be sticky, glide". Cognate with Saterland Frisian Lieuwer "liver", West Frisian lever "liver", Dutch lever "liver", German Leber "liver", Danish , Norwegian and Swedish language lever "liver" the last three from Old Norse lifr "liver".
In the Romance languages, the anatomical word for "liver" (French foie, Italian fegato, Spanish hígado, etc.) derives not from the Latin anatomical term, jecur, but from the culinary term ficatum, literally "stuffed with figs", referring to the livers of geese that had been fattened on figs (foie gras). [7]
Liver can be baked, boiled, broiled, fried, stir-fried, or eaten raw (asbeh nayeh or sawda naye in Lebanese cuisine, liver sashimi). In many preparations, pieces of liver are combined with pieces of meat or kidneys, like in the various forms of Middle Eastern mixed grill (e.g. meurav Yerushalmi ). Spreads or pâtés made from liver have various names, including liver pâté, pâté de foie gras, chopped liver, liverwurst, liver spread, and Braunschweiger. Other liver sausages include mazzafegato or salsiccia matta. A traditional South African delicacy, namely skilpadjies, is made of minced lamb's liver wrapped in netvet (caul fat), and grilled over an open fire.
Some fish livers are valued as food, especially the stingray liver. It is used to prepare delicacies, such as poached skate liver on toast in England, [8] as well as the beignets de foie de raie and foie de raie en croute in French cuisine. [9] Cod liver (usually tinned in its oil and served seasoned) is a popular spread for bread or toast in several European countries. In Russia, it is served with potatoes. Cod liver oil is commonly used as a dietary supplement. Liver of burbot is eaten in Finland: it is common for fish vendors and supermarket fish aisles to sell these fish with liver and roe sacks still attached. These parts are often eaten boiled or added to burbot soup. Burbot and its liver are a traditional winter food. [10]
The livers of polar bears, walruses, bearded seals, and huskies can contain very high levels of preformed vitamin A, [11] and their consumption has led to vitamin A poisoning (hypervitaminosis A) according to several anecdotal reports. The Inuit will not eat the liver of polar bears or bearded seals. It has been estimated that consumption of 500 grams of polar bear liver would result in a toxic dose for a human. [11] Russian sailor Alexander Konrad, who accompanied explorer Valerian Albanov in a tragic ordeal over the Arctic ice in 1912, wrote about the awful effects of consuming polar bear liver. [12] Also, in 1913, Antarctic explorers on the Far Eastern Party Douglas Mawson and Xavier Mertz were believed to have been poisoned, the latter fatally, from eating husky liver, though this claim has been recently contested. [13]
Mercury content in some species can also be an issue. In 2012, the Government of Nunavut, Canada warned pregnant women to lower their intake of ringed seal liver due to elevated levels of mercury. [14]
The neurotoxin in the liver of the pufferfish (which is consumed in Japanese cuisine as fugu, tightly regulated by Japanese law) contains the highest concentration of the tetrodotoxin, which characterizes the species. Consequently, the liver has been illegal to serve since 1984.
Pig liver is a traditional food of immigrant Okinawans in Hawaii. It used to be eaten on New Year's Eve. [15]
Vitamins are organic molecules that are essential to an organism in small quantities for proper metabolic function. Essential nutrients cannot be synthesized in the organism in sufficient quantities for survival, and therefore must be obtained through the diet. For example, vitamin C can be synthesized by some species but not by others; it is not considered a vitamin in the first instance but is in the second. Most vitamins are not single molecules, but groups of related molecules called vitamers. For example, there are eight vitamers of vitamin E: four tocopherols and four tocotrienols.
Vitamin A is a fat-soluble vitamin and an essential nutrient for animals. The term "vitamin A" encompasses a group of chemically related organic compounds that includes retinol, retinal, retinoic acid, and several provitamin (precursor) carotenoids, most notably beta-carotene. Vitamin A has multiple functions: it is essential for embryo development and growth, for maintenance of the immune system, and for vision, where it combines with the protein opsin to form rhodopsin – the light-absorbing molecule necessary for both low-light and color vision.
Retinol, also called vitamin A1, is a fat-soluble vitamin in the vitamin A family that is found in food and used as a dietary supplement. Retinol or other forms of vitamin A are needed for vision, cellular development, maintenance of skin and mucous membranes, immune function and reproductive development. Dietary sources include fish, dairy products, and meat. As a supplement it is used to treat and prevent vitamin A deficiency, especially that which results in xerophthalmia. It is taken by mouth or by injection into a muscle. As an ingredient in skin-care products, it is used to reduce wrinkles and other effects of skin aging.
A nutrient is a substance used by an organism to survive, grow, and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi, and protists. Nutrients can be incorporated into cells for metabolic purposes or excreted by cells to create non-cellular structures, such as hair, scales, feathers, or exoskeletons. Some nutrients can be metabolically converted to smaller molecules in the process of releasing energy, such as for carbohydrates, lipids, proteins, and fermentation products, leading to end-products of water and carbon dioxide. All organisms require water. Essential nutrients for animals are the energy sources, some of the amino acids that are combined to create proteins, a subset of fatty acids, vitamins and certain minerals. Plants require more diverse minerals absorbed through roots, plus carbon dioxide and oxygen absorbed through leaves. Fungi live on dead or living organic matter and meet nutrient needs from their host.
Vitamin deficiency is the condition of a long-term lack of a vitamin. When caused by not enough vitamin intake it is classified as a primary deficiency, whereas when due to an underlying disorder such as malabsorption it is called a secondary deficiency. An underlying disorder can have 2 main causes:
A dietary supplement is a manufactured product intended to supplement a person's diet by taking a pill, capsule, tablet, powder, or liquid. A supplement can provide nutrients either extracted from food sources, or that are synthetic. The classes of nutrient compounds in supplements include vitamins, minerals, fiber, fatty acids, and amino acids. Dietary supplements can also contain substances that have not been confirmed as being essential to life, and so are not nutrients per se, but are marketed as having a beneficial biological effect, such as plant pigments or polyphenols. Animals can also be a source of supplement ingredients, such as collagen from chickens or fish for example. These are also sold individually and in combination, and may be combined with nutrient ingredients. The European Commission has also established harmonized rules to help insure that food supplements are safe and appropriately labeled.
Cod liver oil is a dietary supplement derived from liver of cod fish (Gadidae). As with most fish oils, it contains the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and also vitamin A and vitamin D. Historically, it was given to children because vitamin D had been shown to prevent rickets, a consequence of vitamin D deficiency.
Offal, also called variety meats, pluck or organ meats, is the internal organs of a butchered animal. The word does not refer to a particular list of edible organs, and these lists of organs vary with culture and region, but usually exclude skeletal muscle. Offal may also refer to the by-products of milled grains, such as corn or wheat.
Hypervitaminosis A refers to the toxic effects of ingesting too much preformed vitamin A. Symptoms arise as a result of altered bone metabolism and altered metabolism of other fat-soluble vitamins. Hypervitaminosis A is believed to have occurred in early humans, and the problem has persisted throughout human history. Toxicity results from ingesting too much preformed vitamin A from foods, supplements, or prescription medications and can be prevented by ingesting no more than the recommended daily amount.
Chromium deficiency is described as the consequence of an insufficient dietary intake of the mineral chromium. Chromium was first proposed as an essential element for normal glucose metabolism in 1959, but its biological function has not been identified. Cases of deficiency were described in people who received all of their nutrition intravenously for long periods of time.
Nutrition and pregnancy refers to the nutrient intake, and dietary planning that is undertaken before, during and after pregnancy. Nutrition of the fetus begins at conception. For this reason, the nutrition of the mother is important from before conception as well as throughout pregnancy and breastfeeding. An ever-increasing number of studies have shown that the nutrition of the mother will have an effect on the child, up to and including the risk for cancer, cardiovascular disease, hypertension and diabetes throughout life.
Vitamins occur in a variety of related forms known as vitamers. A vitamer of a particular vitamin is one of several related compounds that performs the functions of said vitamin and prevents the symptoms of deficiency of said vitamin.
Historically Inuit cuisine, which is taken here to include Greenlandic cuisine, Yup'ik cuisine and Aleut cuisine, consisted of a diet of animal source foods that were fished, hunted, and gathered locally.
Greenlandic cuisine is traditionally based on meat from marine mammals, birds, and fish, and normally contains high levels of protein. Since colonization and the arrival of international trade, the cuisine has been increasingly influenced by Danish, British, American and Canadian cuisine. During the summer when the weather is milder, meals are often eaten outdoors.
Vegan nutrition refers to the nutritional and human health aspects of vegan diets. A well-planned vegan diet is suitable to meet all recommendations for nutrients in every stage of human life. Vegan diets tend to be higher in dietary fiber, magnesium, folic acid, vitamin C, vitamin E, and phytochemicals; and lower in calories, saturated fat, iron, cholesterol, long-chain omega-3 fatty acids, vitamin D, calcium, zinc, and vitamin B12.
Herring are forage fish in the wild, mostly belonging to the family Clupeidae. They are an important food for humans. Herring often move in large schools around fishing banks and near the coast. The most abundant and commercially important species belong to the genus Clupea, found particularly in shallow, temperate waters of the North Pacific and North Atlantic Oceans, including the Baltic Sea, as well as off the west coast of South America. Three species of Clupea are recognized; the main taxon, the Atlantic herring, accounts for over half the world's commercial capture of herrings.
Cod and other cod-like fish have been widely used as food through history. Other cod-like fish come from the same family (Gadidae) that cod belong to, such as haddock, pollock, and whiting.
Selenium is an essential micronutrient for animals, though it is toxic in large doses. In plants, it sometimes occurs in toxic amounts as forage, e.g. locoweed. Selenium is a component of the amino acids selenocysteine and selenomethionine. In humans, selenium is a trace element nutrient that functions as cofactor for glutathione peroxidases and certain forms of thioredoxin reductase. Selenium-containing proteins are produced from inorganic selenium via the intermediacy of selenophosphate (PSeO33−).
Seal meat is the flesh, including the blubber and organs, of seals used as food for humans or other animals. It is prepared in numerous ways, often being hung and dried before consumption. Historically, it has been eaten in many parts of the world, both as a part of a normal diet, and as sustenance.
Vitamin B3, colloquially referred to as niacin, is a vitamin family that includes three forms, or vitamers: niacin (nicotinic acid), nicotinamide (niacinamide), and nicotinamide riboside. All three forms of vitamin B3 are converted within the body to nicotinamide adenine dinucleotide (NAD). NAD is required for human life and people are unable to make it within their bodies without either vitamin B3 or tryptophan. Nicotinamide riboside was identified as a form of vitamin B3 in 2004.
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