Giving the mineral in its typical vanadyl sulphate form to mice before exposure to a pathogen had a significant effect on how they fought off the disease, reported a team from the University of Illinois at Urbana-Champaign this week.
They also saw a benefit in diabetic mice, which could be important if the same results are demonstrated in people. Diabetics tend to have lingering tiredness and apathy long after many infections end. And the incidence of diabetes is rising in many parts of the world.
The researchers, Daniel Johnson, a doctoral student, and Dr Gregory Freund, head of the pathology department at Urbana-Champaign's medical college, do not suggest adding vanadium supplements to everyday diets. But their findings could add to the little knowledge on vanadium's nutritional role.
The body is thought to need an estimated 10 to 20 micrograms of the mineral each day, obtaining it mostly from plant material. Its use for building muscles has not been confirmed, according to the US scientists, but vanadium has improved insulin sensitivity and reduced blood sugar in diabetics.
However the trace element is not currently on the list of permitted nutrients of the new European food supplements directive, prompting some supplement makers such as UK-based Boots to remove the ingredient from its products in recent months.
Some companies will keep vanadium supplements on the market through a special process that allows them to continue using an ingredient already available in supplements if a scientific dossier on it has been submitted to the European food authorities.
Potential new applications revealed by the US study underscores the importance of keeping little-known nutrients on the market.
The trial, reported in the early online edition of the Proceedings of the National Academy of Sciences (10.1073/pnas.0507191102), tested a vanadium dose comparable to that found in nutritional supplements.
The researchers gave a low dose of lipopolysaccharide (LPS), a molecule present on E. coli and other gram-negative bacteria, to both diabetic and non-diabetic mice after they had been given insulin-like growth factor (IGF-1), which vanadium mimics.
Non-diabetic mice recovered more quickly than diabetic mice, suggesting an insulin resistance state in the diabetic animals, said Johnson.
Then experimental mice were pre-treated with vanadyl sulphate before exposure to LPS. Recovery after illness of the vanadium-treated mice, diabetic or not, was 50 per cent faster than that of the untreated control mice.
"With vanadyl sulphate being like IGF-1, we expected to see resistance in the diabetic animals, but we didn't see that," Johnson said. "We saw similar improvement. Thus it must have been acting through a different pathway than do IGF-1 or insulin."
The researchers believe that this effect on recovery may be down to vanadium's metal-related shape or its ability to inhibit tyrosine phosphatases, which help to modulate signaling proteins, in the immune system.
Freund and colleagues last year documented a connection between serine phosphorylation and anti-inflammatory cytokines.
"This research implies that metals that are trace elements may have more importance than we realise to human health, not only in preventing diseases but also in making you feel better," said Freund.
The researchers suggest that taking vanadyl-sulphate supplements two weeks before possible exposure to gram-negative organisms might help speed recovery from subsequent infection.
Dossiers The forms of vanadium for which dossiers have been submitted in the UK to support their continued availability in European supplements include vanadium amino acid chelate, vanadium ascorbate, vanadium aspartate, vanadium citrate, vanadium glycinate, vanadium oxide, vanadium pentoxide, vanadium picolinate, vanadium sulphate, vanadium-enriched yeast, vanadyl sulphate, bio-transformed vanadium, glycinato oxo vanadium and bis maltolato oxo vanadium.