Do B vitamins protect your brain from air pollution? Original paper

Several B vitamins (folic acid, vitamin B₁₂, and vitamin B₆) seem to be important in the prevention of dementia. However, observational evidence has been mixed, and getting more of these vitamins has not been clearly shown to prevent dementia in clinical trials (at best, a small effect is seen). Still, it’s possible that these B vitamins are beneficial in certain contexts. This study explored whether B-vitamin intake is related to dementia risk based on exposure to PM 2.5, a type of air pollution that has been linked to a higher risk of dementia.

This prospective cohort study examined whether B-vitamin intake modifies the association between exposure to PM 2.5 pollution and risk of dementia. The study included 7,183 women (ages 65 to 80). THe participants’ intake of folate, vitamin B₆, and vitamin B₁₂ was estimated using a food frequency questionnaire. The median daily intakes of the vitamins were 500.09 micrograms (μg) for folate, 10.46 μg for vitamin B₁₂, and 2.41 milligrams for vitamin B₆.

The participants’ PM 2.5 exposure was estimated based on their address histories and ranked as higher (>10 μg per cubic meter or m³) or lower (≤12 μg/m³).

Analyses were adjusted for various potential confounders, including age, body mass index, race, region, education, employment, alcohol consumption, physical activity, and history of depression, diabetes, high cholesterol, high blood pressure, and cardiovascular disease. The average follow-up time was 9 years.

Neither exposure to PM 2.5 nor intake of any of the individual B vitamins alone affected dementia risk. However, among participants with a B-vitamin intake lower than the median, higher PM 2.5 exposure was associated with a higher risk of dementia:

• Higher PM 2.5 exposure and lower folate intake: 53% higher risk of dementia
• Higher PM 2.5 exposure and lower B₁₂ intake: 47% higher risk of dementia
• Higher PM 2.5 exposure and lower B₆ intake: 50% higher risk of dementia