"The scientists studied 107 people between the ages of 61 and 87 without memory or thinking problems. The average age of participants was 73, and 54% were women.
The researchers collected blood samples to check the levels of vitamin B12, a nutrient found in meat, fish, and milk. Participants underwent yearly brain scans using magnetic resonance imaging (MRI), memory testing, and physical exams.
None of the people in the study had a vitamin B12 deficiency.
When the researchers compared the results, they found that people who had higher vitamin B12 levels were six times less likely to experience brain shrinkage compared with those who had lower levels of the vitamin in their blood."