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Ho recentemente trovato un articolo che dà delle indicazioni particolari sull'assunzione di B12 da parte dei fumatori vegan.

Sembra che la cianocobalamina non sia indicata. Sebbene abbia ridotto il numero di sigarette e sia deciso a smettere, la cosa non è così semplice e, nel frattempo, vorrei almeno assumere la B12 giusta. Attualmente sto prendendo quella sublinguale della Phoenix da 2000 mg. Una compressa alla settimana.
Cosa dovrei invece assumere? Potreste indicarmi anche marca e dosi di un prodotto che posso reperire in Italia? L'articolo di cui parlo è questo: http://www.veganhealth.org/b12/smoke

Appendix: Smokers and Cyanocobalamin

In one study, smokers were found to excrete 35% more B12 than nonsmokers.1 In another study, smokers' sB12 did not differ from nonsmokers', and the Institute of Medicine concluded that "The effect of smoking on the B12 requirement thus appears to be negligible."1

Hydroxocobalamin injections decreased blood cyanide levels by 59% in smokers (1.5-3 packs/day); cyanide was eliminated in the urine as cyanocobalamin.2 This indicates that cyanocobalamin may be actively excreted rather than used in people with elevated cyanide levels. Thus, I am concerned that vegan smokers may not receive much benefit from cyanocobalamin supplementation. Most smokers have an intake of hydroxocobalamin, and other non-cyanocobalamin forms of B12, through animal foods, which can counteract their bodies excretion of cyanocobalamin. Unless vegans take a non-cyanocobalamin supplement, they do not have a non-cyanocobalamin source of B12.

In contrast, I know two vegan smokers whose B12 source has only been cyanocobalamin, and who have not developed overt B12 deficiency in over ten years on the diet. There are probably others. Unfortunately, I could find no studies looking at cyanocobalamin supplementation in smokers, much less in vegan smokers.

To be cautious, I am suggesting that vegan smokers supplement with a non-cyanocobalamin form of B12. The amounts will have to be somewhat arbitrary because of the lack of information on the absorption rates and detoxification action of the various forms of B12 in smokers. I have not seen evidence of oral adenosylcobalamin's effectiveness in counteracting B12 deficiency. Donaldson had success with oral methylcobalamin. I would, therefore, tentatively recommend 500 µg/day, sublingually, of methylcobalamin for vegan smokers. Most tablets are 1,000 µg, so they will need to be broken in half to get 500 µg. At that rate, a month's supply of methylcobalamin should cost about $4.

It could be that the recommendations for vegan smokers need not be any different than those for nonsmokers. At this time, I do not feel that there is enough evidence one way or the other.

There is no evidence that cyanocobalamin is harmful to vegan smokers; including a modest source of cyanocobalamin (e.g., 3-5 µg/day), in addition to methylcobalamin, could serve as insurance.

Risposta a cura della dott.ssa LUCIANA BARONI, Presidente SSNV

Non abbiamo informazioni aggiuntive e più convincenti rispetto a quelle riportate nell'articolo.

Può assumere la B12 sotto forma di idrossicobalamina (come nel Benexol) o di metilcobalamina, ma di solito è associata ad altre vitamine. Non abbiamo un database di prodotti a base di queste forme, quindi non sarebbe serio darle indicazioni di marche o prodotti commerciali.