A new study from Penn State has found that if you’re looking for brain benefits from eating fish, it matters not only what type of fish you eat but also how it’s prepared.

The study found that people who ate baked or broiled fish at least once a week retained more gray matter than people who ate fried fish or no fish at all. The researchers surmised that there are 2 reasons for this difference. The first was that the fish that was baked or broiled retained more of the brain-healthy Omega-3 fatty acids when cooked. The fried fish was subjected to a higher heat, which destroyed some of the fatty acids. The second reason is that the types of fish that tend to be baked or broiled are things like salmon and mackerel, which have far more Omega-3s than the types of fish that tend to be fried, like cod.

The good news: Just eating the broiled or baked fish once a week made a difference!

You can view the study abstract at the American Journal of Preventive Medicine.