An observational study here at Tufts University has found that a deficiency in vitamin B12 is associated with cognitive decline in older adults, even if that deficiency is mild. Adults over the age of 75 were followed for 8 years, during which time dementia was assessed by screening. The adults that had lower vitamin B12 blood levels were more likely to experience cognitive decline during the 8 years. This is an important finding because older adults have a harder time absorbing vitamin B12 from food, which is found in meats, poultry and eggs. Read more about the study here.