In the report, WHO also warned against taking dietary supplements, such as vitamins B and E, in an effort to combat cognitive decline and dementia.

The international health body also stated that 10 million new cases of dementia occur every year and warned that the figures might be tripled by 2050.

“The disease is a major cause of disability and dependency among older people and can devastate the lives of affected individuals, their care givers and families.

“The disease also exacts a heavy economic toll, with the cost of caring for people with dementia estimated to rise to $2 trillion annually by 2030,” the report stated.

The 78-page report outlined what WHO believes will and will not help to reduce the risk of dementia, described by campaigners as the biggest health challenge of the current generation.

“The Mediterranean diet is the most extensively studied dietary approach, in general, as well as in relation to cognitive function. Several systematic reviews of observational studies have concluded that high adherence to the Mediterranean diet is associated with decreased risk of mild cognitive impairment and Alzheimer’s Disease, but modest adherence is not,” the report added.

Although the report stressed that social participation and social support are strongly connected to good health and individual well-being, it said there was insufficient evidence linking social activity with a reduced risk of dementia.