If you want to save your brain, focus on keeping the rest of your body well with exercise and healthy habits rather than popping vitamin pills, new guidelines for preventing dementia advise.

About 50 million people have dementia, and Alzheimer’s disease is the most common type. Each year brings 10 million new cases, says the report released Tuesday by the World Health Organization.

Although age is the top risk factor, ‘‘dementia is not a natural or inevitable consequence of aging,’’ it says.

Many health conditions and behaviors affect the odds of developing it, and research suggests that a third of cases are preventable, said Maria Carrillo, chief science officer of the Alzheimer’s Association, which has published similar advice.


Since dementia is currently incurable and so many experimental therapies have failed, focusing on prevention may ‘‘give us more benefit in the shorter term,’’ Carrillo said.

The advice includes exercise; treating other health conditions such as diabetes.

Eating well, and possibly following a Mediterranean-style diet, may help prevent dementia, the guidelines say. But they take a firm stance against vitamin B or E pills, fish oil, or multi-complex supplements that are promoted for brain health because there’s strong research showing they don’t work.