WASHINGTON (Reuters) - Having higher vitamin B12 levels may protect against brain shrinkage in elderly people, according to a study published on Monday.

The researchers called their findings striking, but said more information is needed before recommending that people take vitamin B12 supplements to guard against the loss of brain volume and possibly prevent declines in thinking and memory.

In the study led by David Smith and Anna Vogiatzoglou of the University of Oxford in Britain, people in the upper third of vitamin B12 levels were six times less likely to experience brain shrinkage than those in the lowest third.

The study involved 107 healthy people ages 61 to 87 who underwent scans to measure brain volume and gave blood samples to assess vitamin B12 levels once a year for up to five years.

All of those in the study had vitamin B12 levels classified in what is considered the normal range, the researchers said.

“Our study suggests, but does not prove, that by modifying our vitamin B12 status we might be able to protect our brain and so possibly prevent cognitive decline,” said Smith, who heads the Oxford Project to Investigate Memory and Ageing.

The study, published in the journal Neurology, did not look at whether taking vitamin B12 supplements would slow the rate of brain shrinkage, Smith said. Another study in which he is involved focuses on that question, with the results expected in 2009, Smith added.

“So, we think it is too early to advise people to take B12 supplements to prevent their brains from shrinking,” he said.

“What we can say is that our results suggest that rather than maintaining one’s B12 at a level that is just above the cut-off for deficiency, it might be prudent to aim to keep it higher up the normal range,” Smith said by e-mail.

Smith said that could be achieved by eating plenty of foods that are a good source of vitamin B12 such as milk and other dairy products, fish, meat and fortified breakfast cereals.

Vitamin B12 helps in the formation of red blood cells and is important for the maintenance of the central nervous system. Deficiency can lead to anemia and neurological damage.

Smith said another study from Oxford that came out last year showed that lower vitamin B12 levels -- but still within the normal range -- were linked to cognitive impairment and a higher risk of later cognitive decline.

“More research is needed into the relationship between nutrition and the brain, in particular dementia,” Smith said.

Vitamin B12 deficiency is uncommon in developed countries but is an issue among the elderly due to problems in vitamin absorption and among vegetarians whose dietary intake may be low, the researchers said. But it is a serious problem in less developed parts of the world, Smith said, noting that in India around 70 percent of the people are vitamin B12 deficient.

A separate study led by Harvard University scientists in the journal Nature Genetics showed that common variations of a gene called FUT2 influence B12 vitamin levels in the blood.