(CNN) There's no effective treatment for dementia, which affects 50 million people worldwide, but the World Health Organization says there's much can be done to delay or slow the onset and progression of the disease.

In guidelines released Tuesday, WHO issued its first recommendations to reduce the risk of dementia globally. They include regular physical exercise, not using tobacco, drinking less alcohol, maintaining healthy blood pressure and eating a healthy diet -- particularly a Mediterranean one.

The international health body also warned against taking dietary supplements such as vitamins B and E in an effort to combat cognitive decline and dementia.

"While some people are unlucky and inherit a combination of genes that makes it highly likely they will develop dementia, many people have the opportunity to substantially reduce their risk by living a healthy lifestyle," professor Tara Spires-Jones, UK Dementia Research Institute program lead and deputy director of the Centre for Discovery Brain Sciences at the University of Edinburgh, told the Science Media Center.

"The WHO has looked at the available evidence and made recommendations that some lifestyle changes, in particular increasing exercise before any cognitive symptoms are present, can reduce dementia risk," she added.

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