For older people with mild memory problems, taking DHA (a type of omega-3 from fish) might make B vitamins work better to help with memory and thinking, while EPA (another omega-3) seems to help a little but not enough to be sure.

If you're an older adult with mild memory problems, having more DHA (a type of omega-3 found in fish) in your blood might make B vitamins work better to help your brain, and DHA seems to help more than another omega-3 called EPA.

For older people with mild memory problems, taking B vitamins might help their memory get better over time—but only if they already have high levels of a certain omega-3 fat called DHA. If they don’t, the vitamins don’t seem to help.

In older people with early memory problems, those with more DHA (a type of omega-3 fatty acid) in their blood seem to benefit more from B vitamin supplements — only 33% of them got worse over two years, compared to 59% of those who took a placebo. This suggests DHA levels might decide whether B vitamins help stop memory from getting worse.

For older people with mild memory problems, taking B vitamins might help their memory and thinking skills—but only if they already have high levels of a certain omega-3 fat (DHA) in their blood. If their DHA levels are low, the vitamins don’t seem to help at all.

Elderly people with memory problems who eat more fish oil-like fats (DHA and EPA) tend to have less damage from harmful molecules in their blood, which might help protect their brains.