Fish liver oil

Two molecules of vitamin A are formed from one molecule of -carotene. Vitamin A crystallizes in pale yellow needles m.p. 64 C. It is optically inactive. It is unstable in solution when heated in air, but comparatively stable without aeration. Vitamin A is manufactured by extraction from fish-liver oils and by synthesis from / -ionone. The role of vitamin A in vision seems to be different from its systemic function. See also relincne and rhodopsin. 

Retinoids are alcohols and accordingly soluble in ethanol, isopropanol, and polyethylenglycol. Major sources of natural retinoids are animal fats, fish liver oil (retinylesters) and yellow and green vegetables (carotenoids). Ingested retinylesters (RE) are hydrolyzed to retinol by enteral hydrolases in the intestine. ROL and carotenoids are absorbed by intestinal mucosa cells. 

Small amounts of the precursor for l,25(OH)2-D3 synthesis are present in food (fish liver oil, egg yolk), but... 

The active vitamins are produced by conversion of provitamins by ultraviolet light. Ergosterol, a yeast sterol, is converted to its active form, ergocalciferol (vitamin D2), and 7-dehydrocholesterol, which is found in many natural foods and is also synthesized in man, is converted to cholecalciferol (vitamin D3). Fish liver oils are virtually the only source of vitamin D3 in nature. The most active form of vitamin D3 is 1,25-dihydroxycholecalciferol and this is produced by the hydroxylation of cholecalciferol at position 25 in the liver and then at position 1 in the kidney. 

Vitamin D comes in many formulations, including multivitamin preparations, fish liver oils with or without vitamin A, combinations with calcium salts, and vitamin D preparations alone. Most forms of vitamin D contain either cholecalciferol (D3) or ergocalciferol (D2). 

Vitamin A (8.52, retinol) occurs in plants as the provitamin carotene it is a highly unsaturated terpenoid, with all of its double bonds trans (E) to one another. Fish liver oils. 

The major dietary sources of retinol are dairy products, eggs and liver, while important sources of /3-carotene are spinach and other dark-green leafy vegetables, deep orange fruits (apricots, cantaloupe) and vegetables (squash, carrots, sweet potatoes, pumpkin). The richest natural sources of vitamin A are fish liver oils, particularly halibut and shark. 

Squalene 287 Fish liver oils Yeast lipids and higher >2.0 Colon, Lung [30,37,46,89]... 

Members of the vitamin D family are extremely difficult to isolate and identify in pure form from any source. Fish liver oils are rich sources, and vitamins D2 and D3 have been isolated from them. Most ordinary foods are such poor sources in terms of amounts present, that the presence of D vitamins in them has not been demonstrated. Sterols that can be converted into some form of vitamin D by ultraviolet light are, however, widespread, and it may be inferred tlial D vitamins are often present even when their presence has never been demonstrated. 

Commercial vitamin D dietary supplements are prepared by the irradiation of ergosterol. 7-dchydrocliolesterol or by extraction of fish liver oils. 

Either native winterized or concentrated whole-body fish oils or fish liver oils have been utilized in most studies as dietary source of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The physiological effects and possible health benefits of administered fish oils generally have been attributed to either EPA or DHA alone or to a synergistic effect between the two. As a result, there has been controversy over the contribution of individual fish oil constituents to particular pharmacological actions and the optimal dosages required for achieving established and/or suspected beneficial effects. The predominant marine triglyceride-derived m-3-fatty acids are all-cA-5,8,11,14,17-eicosapentaenoic acid (C20 5i3, EPA) and all-ci.v-4,7,10,13,16,19-docosa-hexaenoic acid (C22 6,3, DHA). 

The liver of meat animals is a rich source of vitamin A, for this organ is the body s main storage site of the vitamin. Fish liver oils, particularly halibut liver oil, are incredibly rich in the vitamin and are too potent to be consumed as foods. Typical food sources of vitamin A (in /ag retinol equivalents/100 g) are sheep and ox liver, 15,000 butter, 830 cheese, 320 eggs, 140 herring and... 

It is found in fortified milk and butter, egg yolks, fatty fish and fish-liver oils. It is also made by... 

A number of geometric isomers of retinol exist because of the possible cis-trans configurations around the double bonds in the side chain. Fish liver oils contain mixtures of the stereoisomers synthetic retinol is the all-trans isomer. Interconversion between isomers readily takes place in the body. In the visual cycle, the reaction between retinal (vitamin A aldehyde) and opsin to form rhodopsin only occurs with the 11 -cis isomer. 

Supplemental vitamins shall originate from geminated grains, fish liver oil, or brewing yeast. When natural vitamin sources cannot be provided, synthesized vitamin products can be used if they are approved by OFDC. 

The USP XX (30) and the Official Methods of Analysis of the Association of Official Analytical Chemists (AOAC) (44) describe in detail the curative method more commonly known as the rat line method. This method is not applicable to products offered for poultry feeding. For poultry feeds, and fish liver oils and their extracts, the AOAC (44) also describes in detail the chick bone ash method. In addition to the above two methods, there is a method based on the comparative measurement of serum calcium in rats referred to as Intestinal Calcium Transport Assay and another method based on the comparative amounts of calcium absorbed by control and test chicken referred to as Calcium Absorption Test. These methods are described by DeLuca and Blunt (45). 

This method is applicable with suitable modifications to biological samples like fish liver oils, fortified milk, etc., but the colorimetric procedures are being replaced when possible by more specific instrumental methods, usually HPLC. 

Prior to the availability of synthetic vitamins Dg and D3, fish liver oils were the primary sources of vitamin D3. The commonly used oil is that from... 

Vitamin A A fat-soluble compound found in fish-liver oils, milk, green and yellow vegetables, and egg yolk. It is required for cell growth and development, epithelial tissue growth and protection, and normal vision. 

Vitamin D A fat-soluble compound found in milk and fish-liver oils that is required for tooth and bone growth. 

Vitamin A is found in nature and is available in several forms. Retinol (vitamin A) is an unsaturated alcohol containing an ionone ring and can be obtained from fish liver oil (Table 13-2), egg yolk, milk, and butter. Vitamin A2 (dehydroretinol) is present in freshwater fishes. /3-carotene, a carotenoid, is the most important precursor of this vitamin. 

Yeast and hen s egg for ergos-terol animal products for 7-dehydrocho-lesterol irradiated ergos-terol for vitamin D2 fish liver oil, milk, egg yolk, irradiated 7-dehy-drocholes-terol for vitamin D,. 

In the absence of inadequate endogenous synthesis, vitamin D must be obtained from dietary sources or from supplements. Few foods contain vitamin D except for the flesh of fatty fish (salmon, mackerel, sardines), fish liver oils, and eggs from hens fed feed enriched with vitamin D. In the United States, all commercially produced milk is fortified with vitamin D2 at a level of 400 IU/L (1 IU = 0.025 fig of vitamin D3). Therefore, in the United States (and other economically advanced countries) most dietary vitamin D is obtained from milk and other vitamin D2-fortified foods. Both vitamin D2 and vitamin D3 are converted at the same rate to 25-hydroxyvitamin D by a hydroxylase in the liver and are equally active as a prohormone. Because dietary uptake of vitamin D is dependent on normal fat absorption, conditions in which fat malabsorption is present can result in vitamin D deficiency. Because breast milk contains little vitamin D, vitamin D deficiency can occur in infants who are solely breastfed, are not exposed to adequate sunlight, and are not receiving vitamin D supplements. The adequate intake of vitamin D for children is 5 pg/day (200 IU/day) (Table 30-2). 

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