Scientists have long known that what we eat affects our bodies, but growing evidence suggests our diets also have a major impact on the brain.
Foods that are high in fat and added sugar have been linked to obesity, diabetes, heart disease, and poor brain health. Researchers are now trying to find out whether the brain can fully recover after people switch from an unhealthy diet to a healthier one.
A new study led by the University of Technology Sydney explored this important question. The research was published in the journal Nutritional Neuroscience.
Instead of carrying out a single experiment, the team reviewed the findings from many earlier studies to look for clear patterns.
The researchers performed a systematic review and meta-analysis of 27 controlled animal studies. The studies involved rodents that were first fed diets high in fat, high in sugar, or a combination of both.
The animals were then switched to healthier diets so scientists could see whether their memory and other brain functions improved.
Lead author Dr. Simone Rehn said the results showed that eating healthier did help memory. However, the recovery was only partial. Even after several weeks of healthy eating, the animals’ memory did not return to the same level as animals that had always eaten a healthy diet.
The researchers found that the type of unhealthy diet made a difference. Animals that had eaten mainly high-fat diets showed noticeable improvements after changing to healthier food. In contrast, animals that had eaten diets high in added sugar, or diets rich in both fat and sugar, showed little evidence that their memory fully recovered.
The team also examined other behaviors, including anxiety-like behavior, depression-like behavior, general activity, and motivation to seek food. They did not find consistent improvements in these areas after the diet change. This suggests that the strongest effect of the healthier diet was on memory rather than overall behavior.
The memory tests mainly measured the function of the hippocampus, an area of the brain that plays a key role in learning and forming memories. The hippocampus is also involved in controlling appetite and food intake. Previous studies have suggested that this part of the brain is especially sensitive to the effects of unhealthy diets.
Senior author Dr. Mike Kendig said animal studies are valuable because they allow researchers to study the effects of diet without other factors getting in the way. In people, changing eating habits often happens together with changes in exercise, stress, sleep, and daily routines, making it difficult to know which factor is responsible for any improvement.
The findings challenge the common belief that the effects of unhealthy eating can always be completely reversed. The researchers say improving diet quality is still one of the best steps people can take for their health. However, avoiding long-term exposure to diets high in added sugar may be just as important as adopting healthy eating later in life.
This study has important strengths because it combined results from many experiments instead of relying on a single study.
However, the research was carried out in animals, so the findings may not fully apply to humans. More human studies are needed, but the results add to growing evidence that protecting brain health may begin with healthy eating habits early in life.
If you care about health, please read studies about how Mediterranean diet could protect your brain health, and the best time to take vitamins to prevent heart disease.
For more health information, please see recent studies that olive oil may help you live longer, and vitamin D could help lower the risk of autoimmune diseases.
Source: University of Technology Sydney.
