London: Want to stave off dementia as you age? Have vitamin B daily, for a new study says it can fight memory loss and even protect against Alzheimer's disease.

Researchers at Oxford University have carried out the study and found that daily dose of vitamin B can dramatically combat memory loss in old age and protect against Alzheimer's disease, the British media reported.

More than 250 people took part in the study, including people with mild cognitive impairment who were aged 70 years or older. They were given vitamin B -- found naturally in food such as beans, meat, wholegrains and bananas -- or a placebo over a two-year period.

Taking the food supplement appeared to help maintain mental processes, such as planning, organising and recalling information.

The researchers found that people taking the pill had lower levels of a brain protein known to lead to a rise in the risk of dementia. They found it also slowed mental decline in older people who have slight problems with their memory.

The study suggested dementia could be treated with a food supplement rather than by taking complicated medicines. In fact, an earlier study showed B vitamins slowed the rate of brain shrinkage compared with a group receiving a placebo.

Dr Carrie Ruxton of the Health Supplements Information Service was quoted as saying, "The findings from these two reports should be of interest to clinicians."