What makes a person clever and happy? Popular ideas suggest that it’s all about a family life, lifestyle choices and even their genes. Some say it’s even about their openness to new ideas and people. But science is starting to suggest that the types of food we eat could also have an important role to play in our mood and memory. Could it be true?

Well, our brain and our stomach are very closely connected. Hormones and proteins can easily move from the stomach to the brain and vice versa (see ‘What is a gut reaction?’). Scientists believe that the type of food you eat, and how your body reacts to that food, can affect how efficiently your brain works and particularly effect your mood, learning and memory.

Readers digest-ing

When you eat, or even just think of food, your body releases hormones and proteins to get your stomach ready to breakdown that food and use it for energy. These breakdown chemicals, travel in the blood (it’s the most popular public transport system for hormones and proteins). And while most of them head to the stomach, some of the chemicals make a side trip to your brain. Once in the brain, hormones can influence how efficiently your neurons communicate with each other. If neurons are moving quickly, and communicating with each other effectively, learning and memory is improved. Also, the actual chemicals found in the food can affect how well our brain functions. So what are the best chemicals to eat?

The Big O

Omega-3 polyunsaturated fatty acid (more marketable as just omega- 3 and even more marketable as “eat a fish”) is science’s golden girl for the theory that eating the right food makes us happy and clever. Omega-3 is an important ingredient in cells, and a type of omega 3 called DHA, is prominently found in cells of the brain. DHA is particularly important for brain functioning, and a deficiency of it in humans has been associated with an increased risk of mental disorders such as attention-deficit disorder, dyslexia, and depression. We aren’t 100 percent sure why, but having DHA supplements has been shown to increase hormonal levels in the brain that get our neurons into action.

The human body isn’t too efficient at making DHA, so we rely on eating it in our diet. A study from the UK found that giving omega-3 supplements to children with developmental disorders improved their reading, spelling, and teaching-rated behaviour. Another study found that giving a drink of omega-3 and other nutrients (including iron, zinc, folate and vitamins A) to 396 children in Australia and 394 children in Indonesia over 12 months improved test scores measuring verbal intelligence and learning in both the boys and girls in Australia, and the girls in Indonesia.

Other components in food have also been shown to have a positive effect on our memory. Eating flavonols, which are found in some fruits (such as apples and oranges), cocoa, and beans, also improves memory, and gets blood vessels in our brain reproducing faster than usual. This means that we can get oxygen around our brain faster.

Foods that don’t make you smarter

On the other hand, eating junk food, with high levels of fats and sugars, overtime can decrease our brain function because they make our neurons less efficient at communicating with each other. Studies have found that after giving junk food diets to rodents for 3 weeks they made fewer hormones that improved memory and learning, and their brain function declined.

What about chemicals from inside our body, how do they affect our mood?

Leptin is a chemical that gets sent to the brain to tell us to stop eating. Like all hormones, leptin can only affect the brain if there is a special receptor for it to latch onto. (Think of hormones as a weird-shaped baseball that needs the right shaped glove to fit into it.) These special leptin-shaped receptors are usually found all around the brain. So when the leptin fits into its receptor it reduces our appetite, and also improves learning and memory.

Studies show that genetically obese rats develop dysfunctional leptin receptors. As a result, their body keeps making leptin, trying to tell the rats to stop eating, but there is nothing in the brain for leptin to hold onto, so the brain doesn’t get the message. These obese rats just keep on eating, or wanting to eat. Dysfunctional leptin receptors in these fatty rodents also lead to many of the rats getting depression and suffering from learning difficulties. Although I’m not too sure what a depressed rat would be like, I’m guessing they didn’t speed around the wheel as fast as they usually would, or cook ratatouille as well as expected. (Actually the study looked at brain scans of the rats for the composition of chemicals that usually relate to depressive behaviour.)

So there you have it, science does it again. Our mood and our food, are all related (dude).

Foods to eat to improve your memory

• Foods rich in DHA are the key. Fish, particularly fatty fish, such as salmon mackerel, lake trout, herring, sardines, and albacore tuna, is the best source of omega 3. It is recommended that people eat these fish at least twice a week. For people who don’t eat enough fish you could try fish oil supplements.
• Vegetarians aren’t completely out of the loop. Studies from CSIRO in Melbourne found that marine plants also make DHA. Vegetarians can take algae oil supplements to get DHA, or whole grains, fresh fruits and vegetables, fish, olive oil, garlic which also contain omega 3.