![]() For example, vitamin status of vegetarians was positively correlated with their intake of dairy products, especially milk, but not of eggs or seafood ( Reference Miller, Specker and Ho 8 ). However, dietary sources of the vitamin also seem to matter. ![]() Vegetarians had lower vitamin B 12 status than omnivores ( Reference Bor, von Castel-Roberts and Kauwell 7, Reference Miller, Specker and Ho 8 ). ![]() ![]() Vitamin B 12 status is correlated with vitamin B 12 intake in humans ( Reference Tucker, Rich and Rosenberg 5 – Reference Bor, von Castel-Roberts and Kauwell 7 ). Consequently, over the last decade, since folic acid fortification of flour became mandatory in many Western countries, including Canada and USA, there has been a renewed interest in the evaluation of vitamin B 12 status in human populations according to folic acid provision ( Reference Selhub, Morris and Jacques 3, Reference Selhub, Morris and Jacques 4 ). In the presence of vitamin B 12 deficiency, increasing folic acid supply cures anaemia but not neurological symptoms, then, by masking haematological symptoms, it could delay the diagnosis of vitamin B 12 deficiency until neurological damages are irreversible. In humans, vitamin B 12 deficiency affects cell division and may lead to megaloblastic anaemia and neuropathy ( Reference Combs 2 ). Among animal products, those from ruminants are particularly rich in vitamin B 12, the vitamin being naturally synthesised by ruminal microflora using Co as an essential precursor and then absorbed and stored in the liver and muscles (meat) of the host or secreted in its milk ( Reference Combs 2 ). Therefore, in human diets, the sole natural source of vitamin B 12 comes from animal products. As opposed to other B vitamins, it is neither synthesised nor used by fungi and plants ( Reference Martens, Barg and Warren 1 ). This vitamin is produced only by bacteria and archaebacteria if Co supply is adequate. Therefore, vitamin B 12, which is abundant in cows' milk, is also substantially more available than the most commonly used synthetic form of this vitamin.Īmong B vitamins, vitamin B 12 occupies a very special niche. These values correspond to an efficiency of intestinal absorption of vitamin B 12 from milk varying between 8 and 10 %. The cumulative PDV fluxes during the 24 h following ingestion of meals complemented with milk varied from 5♵ to 6♸ μg. In fact, net fluxes of this vitamin were not different from 0 after either cyanocobalamin or the meal devoid of vitamin B 12 (unsupplemented v. Net flux of vitamin B 12 across PDV after the ingestion of milk was positive, though not influenced by milk enrichment ( P>0♳) or technological processes ( P = 0♸) and was greater than after ingestion of equivalent amounts of cyanocobalamin (cyanocobalamin v. Pigs ( n 10) were used as a model for intestinal absorption of vitamin B 12 in humans to compare the net fluxes of vitamin B 12 across the portal-drained viscera (PDV an indicator of intestinal absorption) after ingestion of meals complemented with conventional and vitamin B 12-enriched (via injections to cows) milk (raw, pasteurised or microfiltrated) or with equivalent amounts of cyanocobalamin, the synthetic form used in supplements or unsupplemented. It was hypothesised that the provision of vitamin B 12 from milk is more efficiently absorbed than the synthetic form used in vitamin supplements. ![]() For example, one glass (250 ml) of milk provides approximately 50 % of the RDA (2♴ μg/d). The natural source of vitamin B 12 in human diets comes from animal products. ![]()
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