The vitamin, known as folate helps the body to make healthy red blood cells.
Older people with low levels of vitamin B9 reportedly have a higher risk of dementia.
A study of 60 to 75-year-olds found there was a nearly 3-fold increased risk of dying in those with deficiencies.
The vitamin, known as folate helps the body to make healthy red blood cells and is found in certain foods, like broccoli and spinach.