Absorption of Cyanocobalamin, Coenzyme B<sub>12</sub>, Methylcobalamin, and Hydroxocobalamin at Different Dose Levels

Adams, J. F.; Ross, Sheila K.; Mervyn, L.; Boddy, K.; King, Priscilla C.

doi:10.3109/00365527109180702

Cited by 56 publications

(39 citation statements)

References 15 publications

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“…At 25 mg, the whole-body retention of vitamin B 12 was higher after the ingestion of crystalline forms of adenosylcobalamin, hydroxocobalamin and methylcobalamin than cyanocobalamin (37) . Therefore, along with the abovementioned possible interaction with casein, cobalamin forms naturally present in milk could also contribute to explain the increased net PDV flux of the vitamin following ingestion of milk compared with cyanocobalamin.…”

Section: Discussionmentioning

confidence: 99%

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Bioavailability of vitamin B₁₂ in cows' milk

2011

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The natural source of vitamin B 12 in human diets comes from animal products. For example, one glass (250 ml) of milk provides approximately 50 % of the RDA (2·4 mg/d). It was hypothesised that the provision of vitamin B 12 from milk is more efficiently absorbed than the synthetic form used in vitamin supplements. 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. Net flux of vitamin B 12 across PDV after the ingestion of milk was positive, though not influenced by milk enrichment (P. 0·3) or technological processes (P¼0·8) and was greater than after ingestion of equivalent amounts of cyanocobalamin (cyanocobalamin v. all milk, P# 0·003). 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. cyanocobalamin, P¼ 0·7). The cumulative PDV fluxes during the 24 h following ingestion of meals complemented with milk varied from 5·5 to 6·8 mg. These values correspond to an efficiency of intestinal absorption of vitamin B 12 from milk varying between 8 and 10 %. 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.

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Section: Discussionmentioning

confidence: 99%

“…Information on the relative intestinal availability of the different cobalamins is scarce. The only data available compared whole-body retention of crystalline radioactive forms of different cobalamins in human subjects (36,37) .…”

Section: Discussionmentioning

confidence: 99%

Bioavailability of vitamin B₁₂ in cows' milk

2011

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“…To combat this, the synthetic cyano-B12 (CN-B12) is used for supplementation purposes, because it is the least expensive vitamin form and resists aggressive chemicals better than HO-B12. Several studies have documented that both forms are retained alike after oral uptake [9][10][11], but the tissue distributions of the two absorbed vitamins differ. For example, in rats, considerably more B12 is internalized in the liver after ingestion of HO-B12, when compared to an equal dose of CN-B12 [12,13].…”

Section: Introductionmentioning

confidence: 99%

Effect of 8-week oral supplementation with 3-µg cyano-B12 or hydroxo-B12 in a vitamin B12-deficient population

et al. 2017

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Purpose We compare the effect of 8-week oral supplementation with cyano-B12 (currently used in vitamin pills) and hydroxo-B12 (predominant form in the diet) in a population with nutritional vitamin B12 deficiency. Methods Fifty-one healthy Indian adults with baseline serum cobalamin < 200 pmol/L were supplied for 8 weeks with daily oral supplements of 3-µg cyano-B12 (n = 15), 3-µg hydroxo-B12 (n = 16), or a placebo (n = 20). Blood at baseline, and each following week, was examined for total cobalamin, holotranscobalamin, methylmalonic acid, and homocysteine. Results The study groups did not differ at baseline and were characterized by [median (range)] serum cobalamin [128 (68-191)

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“…Here, ADO-B 12 acts as a cofactor for methylmalonyl-CoA mutase in the conversion of methylmalonyl-CoA to succinyl-CoA in the mitochondria. CH 3 -B 12 acts as a cofactor for methionine synthase in the folatedependent methylation of homocysteine to methionine in the cytoplasm (1,2) .Both human and animal studies have demonstrated that synthetic and natural forms of B 12 are absorbed equally (7)(8)(9)(10)(11) . However, our recent data show that HO-B 12 accumulates in the liver to a higher degree than CN-B 12 , but that the patterns are opposite in the brain and plasma.…”

mentioning

confidence: 99%

“…Both human and animal studies have demonstrated that synthetic and natural forms of B 12 are absorbed equally (7)(8)(9)(10)(11) . However, our recent data show that HO-B 12 accumulates in the liver to a higher degree than CN-B 12 , but that the patterns are opposite in the brain and plasma.…”

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confidence: 99%

The tissue profile of metabolically active coenzyme forms of vitamin B₁₂ differs in vitamin B₁₂-depleted rats treated with hydroxo-B₁₂ or cyano-B₁₂

et al. 2018

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Recent rat studies show different tissue distributions of vitamin B 12 (B 12 ), administered orally as hydroxo-B 12 ) (predominant in food) and cyano-B 12 ) (common in supplements). Here we examine male Wistar rats kept on a low-B 12 diet for 4 weeks followed by a 2-week period on diets with HO-B 12 (n 9) or CN-B 12 (n 9), or maintained on a low-B 12 diet (n 9). Plasma B 12 was analysed before, during and after the study. The content of B 12 and its variants (HO-B 12 , glutathionyl-B 12 , CN-B 12 , 5'-deoxyadenosyl-B 12 (ADO-B 12 ), and methyl-B 12 (CH 3 -B 12 )) were assessed in the tissues at the end of the study. A period of 4 weeks on the low-B 12 diet reduced plasma B 12 by 58 % (from median 1323 (range 602-1791) to 562 (range 267-865) pmol/l, n 27). After 2 weeks on a high-B 12 diet (week 6 v. week 4), plasma B 12 increased by 68 % (HO-B 12 ) and 131 % (CN-B 12 ). Total B 12 in the tissues accumulated differently: HO-B 12 > CN-B 12 (liver, spleen), HO-B 12 < CN-B 12 (kidneys), and HO-B 12 ≈CN-B 12 (brain, heart). Notably, more than half of the administered CN-B 12 remained in this form in the kidneys, whereas HO-B 12 was largely converted to the bioactive ADO-B 12 . Only <10 % of the other cofactor, CH 3 -B 12 , were found in the tissues. In conclusion, dietary CN-B 12 caused a higher increase in plasma and total kidney B 12 but provided less than half of the active coenzymes in comparison to dietary HO-B 12 . These data argue that HO-B 12 may provide a better tissue supply of B 12 than CN-B 12 , thereby underscoring the lack of a direct relation between plasma B 12 and tissue B 12 . ]-coordinating anions. These reactions occur irrespectively of light (6) . All forms of B 12 are metabolically transformed into and CH 3 -B 12 in the cell (3) . Here, ADO-B 12 acts as a cofactor for methylmalonyl-CoA mutase in the conversion of methylmalonyl-CoA to succinyl-CoA in the mitochondria. CH 3 -B 12 acts as a cofactor for methionine synthase in the folatedependent methylation of homocysteine to methionine in the cytoplasm (1,2) .Both human and animal studies have demonstrated that synthetic and natural forms of B 12 are absorbed equally (7)(8)(9)(10)(11) . However, our recent data show that HO-B 12 accumulates in the liver to a higher degree than CN-B 12 , but that the patterns are opposite in the brain and plasma. These observations were based on the administration of acute doses of radiolabelled HO-B 12 and CN-B 12 to rats (10,11) . In accordance with this, acute human studies showed CN-B 12 to cause a 2-3-fold higher increase in the active circulating B 12 , holotranscobalamin, relative to HO-B 12 upon oral administration (12) . These findings Abbreviations: ADO-B 12 ,

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Absorption of Cyanocobalamin, Coenzyme B₁₂, Methylcobalamin, and Hydroxocobalamin at Different Dose Levels

Cited by 56 publications

References 15 publications

Bioavailability of vitamin B₁₂ in cows' milk

Bioavailability of vitamin B₁₂ in cows' milk

Effect of 8-week oral supplementation with 3-µg cyano-B12 or hydroxo-B12 in a vitamin B12-deficient population

The tissue profile of metabolically active coenzyme forms of vitamin B₁₂ differs in vitamin B₁₂-depleted rats treated with hydroxo-B₁₂ or cyano-B₁₂

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Absorption of Cyanocobalamin, Coenzyme B12, Methylcobalamin, and Hydroxocobalamin at Different Dose Levels

Cited by 56 publications

References 15 publications

Bioavailability of vitamin B12 in cows' milk

Bioavailability of vitamin B12 in cows' milk

Effect of 8-week oral supplementation with 3-µg cyano-B12 or hydroxo-B12 in a vitamin B12-deficient population

The tissue profile of metabolically active coenzyme forms of vitamin B12 differs in vitamin B12-depleted rats treated with hydroxo-B12 or cyano-B12

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Absorption of Cyanocobalamin, Coenzyme B₁₂, Methylcobalamin, and Hydroxocobalamin at Different Dose Levels

Bioavailability of vitamin B₁₂ in cows' milk

Bioavailability of vitamin B₁₂ in cows' milk

The tissue profile of metabolically active coenzyme forms of vitamin B₁₂ differs in vitamin B₁₂-depleted rats treated with hydroxo-B₁₂ or cyano-B₁₂