A new study goes deeper in understanding the connection between good nutrition and a healthy brain. Previous studies have linked individual vitamin deficiencies to cognitive decline. But new research looks at a wider range of vitamins, and even better, it uses biomarkers in the blood to correlate vitamins with brain health, both good and bad.

People who had higher levels of B family vitamins, as well as vitamins C, D, and E, had higher scores on cognitive tests than people with lower levels. The same positive relationship was found for omega-3 fatty acids.

Many studies exploring the relationship between nutrition and cognitive health rely on people’s personal reports of their diets – a notoriously unreliable way to gather personal nutritional information. For this reason, the researchers behind the current study decided to use a more objective means of studying the nutrition-brain link: they looked at biomarkers in the blood to measure the vitamin levels in 104 participants. They also had participants take tests to measure thinking and memory function, and 42 participants had MRI scans to measure their brain volume.

The researchers found some striking connections between nutrition and brain health. People who had higher levels of B family vitamins, as well as vitamins C, D, and E had higher scores on cognitive tests than people with lower levels. The same positive relationship was found for omega-3 fatty acids, which have previously been linked to better brain health.

On the flipside, people with higher levels of trans fats in their blood had poorer performance in thinking and memory tests. Their MRI scans also revealed more brain shrinkage than people who had lower trans fats levels. Trans fats are found in a variety of junk foods, like fried, packaged, and fast foods.

The researchers also determined the portion of the cognitive test scores the participants’ nutrient statuses accounted for. They found that nutrient biomarkers accounted for 17% of the variation in the tests of thinking and memory function. Other variables, like age, education, and having high blood pressure accounted for more: 46%. But for brain volume, the role of nutrition was larger, accounting for 37% of the variation.

Author Gene Bowman said that the team’s findings “need to be confirmed, but obviously it is very exciting to think that people could potentially stop their brains from shrinking and keep them sharp by adjusting their diet.”

More and more research is showing that there’s a lot of truth to the old adage “you are what you eat” – and the same goes for the brain, since after all, it is an organ, too. Genetic and environmental factors also play a role in the development of disease, but we can do our best to give our brains the nutrients they need for good cognitive health.

The study was carried out at the Oregon Health & Science University in Portland, and is published in Neurology.