Cod liver oil is a dietary supplement derived from liver of cod fish (Gadidae). [1] 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[ where? ] because vitamin D had been shown to prevent rickets, a consequence of vitamin D deficiency. [2]
Cod liver oil has traditionally come in many grades. Cod liver oil for human consumption is pale and straw-colored, with a mild flavor. Scandinavian Vikings produced cod liver oil by laying birch tree branches over a kettle of water, and fresh livers were laid over the branches. The water was brought to a boil and as the steam rose, the oil from the liver dripped into the water and was skimmed off. There was also a method for producing fresh raw cod liver oil. [3]
In the Industrial Revolution, cod liver oil became popular for industrial purposes. Livers placed in barrels to rot, with the oil skimmed off over the season, was the main method for producing this oil. The resulting oil was brown and foul-tasting. In the 1800s cod liver oil became popular as a medicine and both pale and brown oils were used. Brown oils were common because they were cheaper to produce. Some doctors believed in only using the fresh pale oil, while others believed the brown oil was better. The rancid brown oils tended to cause intestinal upset. [3]
The Möller Process was invented by Peter Möller in 1850. The livers are ground with water into a slurry, then this is gently simmered until the oil rises to the top. The oil is skimmed off and purified. [4] Other methods used in modern times include the Cold Flotation Process, pressure extraction, and pressure cooking. These all require further purification steps to get a pure oil. [5]
Though similar in fatty acid composition to other fish oils, cod liver oil has higher concentrations of vitamins A and D. According to the United States Department of Agriculture, a tablespoon (13.6 grams or 14.8 mL) of cod liver oil contains 4,080 μg of retinol (vitamin A) and 34 μg (1360 IU) of vitamin D. [6] The Dietary Reference Intake of vitamin A is 900 μg per day for adult men and 700 μg per day for women, while that for vitamin D is 15 μg per day. The Tolerable upper intake levels (ULs) are 3000 μg/day and 100 μg/day, respectively. People consuming cod liver oil as a source of omega-3 fatty acids should pay attention to how much vitamin A and vitamin D this adds to their diet. [7] [8]
Cod liver oil is approximately 20% omega-3 fatty acids. For this reason, cod liver oil may be beneficial in secondary prophylaxis after a heart attack. [9] Diets supplemented with cod liver oil have been demonstrated to have beneficial effects on psoriasis, [10] and daily supplementation has been shown to be correlated with lower rates of high-severity depression. [11]
A tablespoon (13.6 g) of cod liver oil contains 136% of the UL for preformed vitamin A (retinol). [12] [13] Vitamin A accumulates in the liver, and can reach harmful levels sufficient to cause hypervitaminosis A. [7] Pregnant women may want to consider consulting a doctor when taking cod liver oil because of the high amount of retinol. [14]
Fatty acid oxidation and environmental toxins content are reduced when purification processes are applied to produce refined fish oil products. [15]
In Newfoundland, cod liver oil was sometimes used as the liquid base for traditional red ochre paint, the coating of choice for use on outbuildings and work buildings associated with the cod fishery.
In Tübingen, Germany, drinking a glass of cod liver oil is the punishment for the loser at the traditional Stocherkahnrennen, a punting boat race by University of Tübingen groups.
In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food.
Omega−3 fatty acids, also called omega−3 oils, ω−3 fatty acids or n−3 fatty acids, are polyunsaturated fatty acids (PUFAs) characterized by the presence of a double bond three atoms away from the terminal methyl group in their chemical structure. They are widely distributed in nature, being important constituents of animal lipid metabolism, and they play an important role in the human diet and in human physiology. The three types of omega−3 fatty acids involved in human physiology are α-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). ALA can be found in plants, while DHA and EPA are found in algae and fish. Marine algae and phytoplankton are primary sources of omega−3 fatty acids. DHA and EPA accumulate in fish that eat these algae. Common sources of plant oils containing ALA include walnuts, edible seeds, and flaxseeds as well as hempseed oil, while sources of EPA and DHA include fish and fish oils, and algae oil.
Rickets, scientific nomenclature: rachitis, is a condition that results in weak or soft bones in children and is caused by either dietary deficiency or genetic causes. Symptoms include bowed legs, stunted growth, bone pain, large forehead, and trouble sleeping. Complications may include bone deformities, bone pseudofractures and fractures, muscle spasms, or an abnormally curved spine.
Vitamin A is a fat-soluble vitamin that is an essential nutrient. The term "vitamin A" encompasses a group of chemically related organic compounds that includes retinol, retinyl esters, and several provitamin (precursor) carotenoids, most notably β-carotene (beta-carotene). Vitamin A has multiple functions: growth during embryo development, maintaining the immune system, and healthy vision. For aiding vision specifically, 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.
Essential fatty acids, or EFAs, are fatty acids that are required by humans and other animals for normal physiological function that cannot be synthesized in the body. As they are not synthesized in the body, the essential fatty acids – alpha-linolenic acid (ALA) and linoleic acid – must be obtained from food or from a dietary supplement. Essential fatty acids are needed for various cellular metabolic processes and for the maintenance and function of tissues and organs. These fatty acids also are precursors to vitamins, cofactors, and derivatives, including prostaglandins, leukotrienes, thromboxanes, lipoxins, and others.
Margarine is a spread used for flavoring, baking, and cooking. It is most often used as a substitute for butter. Although originally made from animal fats, most margarine consumed today is made from vegetable oil. The spread was originally named oleomargarine from Latin for oleum and Greek margarite. The name was later shortened to margarine.
Cholecalciferol, also known as vitamin D3 or colecalciferol, is a type of vitamin D that is produced by the skin when exposed to UVB light; it is found in certain foods and can be taken as a dietary supplement.
β-Carotene (beta-carotene) is an organic, strongly colored red-orange pigment abundant in fungi, plants, and fruits. It is a member of the carotenes, which are terpenoids (isoprenoids), synthesized biochemically from eight isoprene units and thus having 40 carbons.
Oily fish are fish species with oil (fats) in soft tissues and in the coelomic cavity around the gut. Their fillets may contain up to 30% oil, although this figure varies both within and between species. Examples of oily fish include small forage fish such as sardines, herring and anchovies, and other larger pelagic fish such as salmon, trout, tuna, swordfish and mackerel.
Linoleic acid (LA) is an organic compound with the formula HOOC(CH2)7CH=CHCH2CH=CH(CH2)4CH3. Both alkene groups are cis. It is a fatty acid sometimes denoted 18:2 (n−6) or 18:2 cis-9,12. A linoleate is a salt or ester of this acid.
Fish oil is oil derived from the tissues of oily fish. Fish oils contain the omega−3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), precursors of certain eicosanoids that are known to reduce inflammation in the body and improve hypertriglyceridemia. There has been a great deal of controversy in the 21st century about the role of fish oil in cardiovascular disease, with recent meta-analyses reaching different conclusions about its potential impact.
Eicosapentaenoic acid (EPA; also icosapentaenoic acid) is an omega−3 fatty acid. In physiological literature, it is given the name 20:5(n−3). It also has the trivial name timnodonic acid. In chemical structure, EPA is a carboxylic acid with a 20-carbon chain and five cis double bonds; the first double bond is located at the third carbon from the omega end.
Raw feeding is the practice of feeding domestic dogs, cats, and other animals a diet consisting primarily of uncooked meat, edible bones, and organs. The ingredients used to formulate raw diets vary. Some pet owners choose to make home-made raw diets to feed their animals but commercial raw diets are also available.
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.
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.
Vitamin A deficiency (VAD) or hypovitaminosis A is a lack of vitamin A in blood and tissues. It is common in poorer countries, especially among children and women of reproductive age, but is rarely seen in more developed countries. Nyctalopia is one of the first signs of VAD, as the vitamin has a major role in phototransduction; but it is also the first symptom that is reversed when vitamin A is consumed again. Xerophthalmia, keratomalacia, and complete blindness can follow if the deficiency is more severe.
Cat skin disorders are among the most common health problems in cats. Skin disorders in cats have many causes, and many of the common skin disorders that afflict people have a counterpart in cats. The condition of a cat's skin and coat can also be an important indicator of its general health. Skin disorders of cats vary from acute, self-limiting problems to chronic or long-lasting problems requiring life-time treatment. Cat skin disorders may be grouped into categories according to the causes.
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.
In general, cognitive support diets are formulated to include nutrients that have a known role in brain development, function and/or maintenance, with the goal of improving and preserving mental processes such as attentiveness, short-term and long-term memory, learning, and problem solving. Currently, there is very little conclusive research available regarding cat cognition as standardized tests for evaluating cognitive ability are less established and less reliable than cognitive testing apparatus used in other mammalian species, like dogs. Much of what is known about feline cognition has been inferred from a combination of owner-reported behaviour, brain necropsies, and comparative cognitive neurology of related animal models. Cognition claims appear primarily on kitten diets which include elevated levels of nutrients associated with optimal brain development, although there are now diets available for senior cats that include nutrients to help slow the progression of age-related changes and prevent cognitive decline. Cognition diets for cats contain a greater portion of omega-3 fatty acids, especially docosahexaenoic acid (DHA) as well as eicosapentaenoic acid (EPA), and usually feature a variety of antioxidants and other supporting nutrients thought to have positive effects on cognition.
