Researchers followed over 4,000 Japanese adults for 15 years to see if eating foods rich in B vitamins could help prevent dementia. They found that people who ate the most riboflavin (vitamin B2), vitamin B6, and folate had about half the risk of developing serious dementia compared to those who ate the least. The study suggests that getting enough of these B vitamins through your diet—found in foods like eggs, leafy greens, and whole grains—may be one way to protect your brain health as you age.

The Quick Take

  • What they studied: Whether eating enough B vitamins (riboflavin, B6, B12, and folate) could help prevent dementia in older adults
  • Who participated: 4,171 Japanese men and women aged 40-69 years old with no dementia at the start, followed for an average of 15.4 years
  • Key finding: People who ate the most riboflavin had 49% lower risk of developing dementia. Those with highest B6 and folate intake had about 20% lower risk. Vitamin B12 showed a smaller protective effect.
  • What it means for you: Eating foods rich in B vitamins may help protect your brain, though this doesn’t guarantee you won’t develop dementia. This is one piece of a larger brain-health puzzle that includes exercise, social connection, and mental stimulation.

The Research Details

This was a long-term follow-up study where researchers tracked the same group of people over 15 years. At the beginning, they asked participants what they ate in a single day to measure their B vitamin intake. Then they watched to see who developed dementia serious enough to need care under Japan’s national insurance system. The researchers used statistical methods to compare dementia rates between people who ate the most B vitamins versus those who ate the least, while accounting for other factors like age, sex, and overall diet quality.

Following the same people over many years is one of the best ways to understand if something in your diet actually prevents disease. A single day of food recall isn’t perfect, but it gives researchers a snapshot of typical eating habits. Using an official dementia diagnosis system (rather than just asking people) makes the results more reliable.

This study has several strengths: it followed people for a long time, had a large number of participants, and used official medical records to identify dementia cases. However, it only measured diet once at the beginning, so eating habits may have changed over 15 years. The study was done in Japan, so results may not apply equally to other populations with different diets and genetics.

What the Results Show

The strongest finding was for riboflavin (vitamin B2): people eating the most had about half the dementia risk of those eating the least. This difference was very unlikely to happen by chance. Vitamin B6 and folate also showed protective effects, with people eating the most having about 20% lower risk. These findings held true even after accounting for other factors like age, sex, smoking, exercise, and overall diet quality. The protective effect appeared to increase gradually as people ate more of these vitamins—suggesting a dose-response relationship where more is better (up to a point).

Vitamin B12 showed a smaller protective effect that was less clear statistically. The researchers found that the benefits of B vitamins were consistent across different age groups and between men and women. When they looked at different combinations of B vitamins, the protective effect was strongest when people had adequate intake of all three (riboflavin, B6, and folate) together.

Previous research has suggested B vitamins help brain health, but most studies focused on B12 and folate. This study is notable for highlighting riboflavin’s importance, which hasn’t been studied as much. The findings align with the theory that B vitamins help reduce homocysteine (a compound linked to brain damage) and support nerve cell function. The protective effect size is similar to or stronger than what previous studies found for other brain-protective factors.

The study only measured diet once at the start, so researchers couldn’t track how diet changes affected dementia risk over 15 years. They couldn’t prove that B vitamins directly caused the lower dementia risk—only that they were associated with it. The study was done in Japan where diets differ from Western countries, so results may not apply equally elsewhere. People who eat more B vitamins might also exercise more or have healthier overall lifestyles, which could explain some of the benefit.

The Bottom Line

Eat foods rich in B vitamins as part of a healthy diet. Good sources include eggs, fish, chicken, leafy greens (spinach, kale), legumes (beans, lentils), whole grains, and fortified cereals. Most people can get enough through food without supplements. If you’re over 50 or have dietary restrictions, talk to your doctor about whether a B vitamin supplement makes sense for you. (Confidence: Moderate—this is one helpful factor among many for brain health)

Anyone concerned about brain health and dementia prevention should pay attention to this. It’s especially relevant for people over 50, those with family history of dementia, or anyone looking for practical ways to protect their brain. This doesn’t replace other important brain-protective habits like exercise, staying mentally active, managing stress, and maintaining social connections.

Brain health benefits from diet typically take months to years to develop. You won’t notice immediate changes, but consistent eating habits over years may contribute to better brain aging. Start now if dementia prevention is a concern, as the protective effect appears to build over time.

Want to Apply This Research?

  • Track daily intake of B vitamin-rich foods: count servings of leafy greens, eggs, fish, legumes, and whole grains. Aim for at least 2-3 servings daily of B vitamin sources.
  • Add one B vitamin-rich food to each meal: eggs at breakfast, leafy greens in lunch salad, legumes or fish at dinner. Use the app to log these foods and build the habit over 4 weeks.
  • Weekly review of B vitamin food intake patterns. Set reminders for grocery shopping to include eggs, spinach, beans, and whole grains. Monthly check-ins to ensure consistency and adjust based on what works for your lifestyle.

This research suggests an association between B vitamin intake and lower dementia risk, but cannot prove that B vitamins prevent dementia. Individual results vary based on genetics, overall lifestyle, and other health factors. This information is not a substitute for medical advice. Consult your healthcare provider before making significant dietary changes, especially if you take medications or have existing health conditions. If you’re concerned about dementia risk or memory changes, speak with your doctor for proper evaluation and personalized recommendations.