Vitamin B12 May Reduce Alzheimer’s Risk

Two new studies point to the importance of vitamin B12 for brain function, for old and young alike.

A new study appearing in the medical journal Neurology shows that vitamin B12 may protect against Alzheimer's disease, adding more evidence to the scientific debate about whether the vitamin is effective in reducing the risk of memory loss.

"Our findings show the need for further research on the role of vitamin B12 as a marker for identifying people who are at increased risk of Alzheimer's disease," said study author Babak Hooshmand, MD, MSc, with Karolinska Institutet in Stockholm, Sweden. "Low levels of vitamin B12 are surprisingly common in the elderly. However, the few studies that have investigated the usefulness of vitamin B12 supplements to reduce the risk of memory loss have had mixed results."

For the seven-year study, researchers took blood samples from 271 Finnish people age 65 to 79 who did not have dementia at the start of the study. During that time, 17 people developed Alzheimer's disease. Blood samples were tested for levels for homocysteine, an amino acid associated with vitamin B12, and for levels of the active portion of the vitamin, called holotranscobalamin. Too much homocysteine in the blood has been linked to negative effects on the brain, such as stroke. However, higher levels of vitamin B12 can lower homocysteine.

The study found that for each micromolar increase in the concentration of homocysteine, the risk of Alzheimer's disease increased by 16 percent, whereas each picomolar increase in concentration of the active form of vitamin B12 reduced risk by two percent.

The results stayed the same after taking into account other factors, such as age, gender, education, smoking status, blood pressure and body mass index. The addition of folate did not appear to raise or lower the risk of Alzheimer's disease.

"More research is needed to confirm these findings before vitamin B12 should be used solely as a supplement to help protect memory," said Hooshmand. 

Autistic children

Meanwhile, researchers at The Children's Hospital of Philadelphia have found that autistic children with severely limited diets may be at risk for vision loss due to vitamin B12 deficiency.

The Children's Hospital study, which appears in the journal Pediatrics, looked at three boys with autism who exhibited behaviors that indicated vision loss, such as groping for items or bumping into walls. Further evaluation and tests revealed optic nerve damage and low levels of B12.

The researchers administered a shot of intramuscular vitamin B12 and visual behavior improved modestly in each case after normal levels were reached. All three patients, ages 6, 7 and 13, ate almost no meat or dairy products, important sources of vitamin B12.

"To the best of our knowledge, these are the first three reported cases of vision loss related to a vitamin B12 deficiency related to poor diet in children with autism," said Stacy Pineles, M.D., lead author of the study. She conducted the research as a fellow at Children's Hospital and is now at Ronald Reagan UCLA Medical Center. "Clinicians should have a high index of suspicion for vitamin deficiencies and questions about diet should be part of routine history-taking in this population."

There have been many associations between autism and feeding difficulties, with diet-related deficiencies causing such illnesses as rickets, scurvy and dry eyes. With such patients, the researchers said, parents should also be advised to seek evaluation by a pediatric ophthalmologist or neuro-ophthalmologist who can perform a careful examination to rule out optic nerve damage. 

"Children who refuse foods from animal sources, such as meat and dairy products, are specifically at a higher risk for vitamin B12 deficiency," said Grant T. Liu, M.D., senior author of the study and a neuro-ophthalmologist at Children's Hospital. "In our experience, B12 deficiency optic neuropathy in autism is a recognizable, treatable, and at least partially reversible disorder."

Vitamin B12 can be found in fish, poultry and other meat products.