Liver, calf vitamin

It soon became apparent that the biologically active forms of Vitamin Bj.2 contained the unique Co—C-a-bond, and the instability of these covalent compounds to visible light facilitated observations on the occurrence of functional corrinoids in a number of enzymes. Deoxyadenosyl-cobalamin was found to be the most abundant corrinoid in bacteria (24) and in mammalian liver (25). Methylcobalamin was found in Escherichia coli (26), calf liver and human blood plasma (27), and also in a number of Clostridia (28). 

High vitamin A and procarotenoids content (20,000 76.000 IU./100 grams).1. Carrot, dandelion green, kohlrabi, liver (beef, calf, chicken, pig, sheep), liver oil (cod, halibut, salmon, shark, sperm whale), mint, palm oil, parsley, spinach, turnip greens. 

High vitamin Bn content (50-500 micrograms/100 grains). Brain (beef), kidney (beef, lamb), liver (beef, calf, lamb, pork). 

Every aspea of vitamin B12 amazes It is the active component in the liver that reverses pernicious anemia and it has multiple fimctions in DNA synthesis and intermediary metabolism. Vitamin B12 is synthesized by bacteria (and fungi), is present in soil, and is commonly obtained from meat, milk, eggs, and fish calf liver is a particularly rich source. Bacteria in the human colon synthesize this substance but, ironically, humans cannot absorb their own B12. Ingested vitamin B12 requires adequate intrinsic factor (IF) in gastric juice in order to be absorbed and IF levels tend to decrease with aging. 

It has long been known that vitamin A is stored mainly in liver as retinyl esters, and that the liver is capable of storing large quantities of retinol in ester form. A study of the composition of retinyl esters isolated from the livers of members of a number of vertebrate species (calf, sheep, rabbit, rat, human, frog, trout, and cat) was reported by Futterman and Andrews (1964). In all species examined, except the cat, livers contained substantial stores of retinol, of which 95% or more was present in esterified form. Cat liver contained very little vitamin A, with approximately equal amounts present as bee retinol and as retinyl ester. The palmitate ester was the predominant retinyl ester in all species, comprising 66% of the retinyl esters in the human and 69% in the rat. Retinyl stearate and oleate were the next most common esters together with retinyl palmitate these three esters accounted for approximately 90% of all retinyl esters in the species examined. 

More recently a further series of compounds of the vitamin B12 group has been isolated from natural materials. Unlike the cobalamins, these compounds are not convertible to cyanocobalamin by treatment with cyanide. Wijmenga (1951) announced the isolation from pig feces of a vitamin Bi2-like substance he called vitamin Bi2m, and from ox liver of a further compound he called Factor WR Ford, Kon, and Porter (1951, 1952) found three such compounds—Factors A, B, and C— in calf feces and Pfifiner et al. (1951) found two further compounds, pseudovitamin Bi2 and pseudovitamin Bi2b, in cultures of a rumen anaerobe. 

Cobalt— This mineral, which is an integral part of vitamin B-12—an essential factor in the formation of red blood cells, must be ingested in the form of vitamin B-12 in order to be of value to man hence, a table showing the cobalt content of human foods serves no useful purpose. The oigan meats (liver, kidney) are excellent sources of vitamin B-12 (hence, of cobalt). The vitamin B-12 content, in mcg/100 g, of some rich animal food sources follows beef liver. 111 clams, 98 lamb kidneys, 63 turkey liver, 48 and calf kidney, 25. 

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