We are what we eat: How food affects our body and brain
Food and Our Brain Health
The scientific research on how food affects the brain is a rapidly growing field, and there is a large body of evidence that demonstrates the important role that diet plays in brain health and cognitive function. Here are some key findings:
Nutrient deficiencies can impair brain function: Several nutrient deficiencies have been linked to impaired brain function, including iron, vitamin B12, and omega-3 fatty acids. Iron is necessary for the formation of myelin, a substance that helps to insulate nerve fibers, while vitamin B12 is essential for the synthesis of neurotransmitters, which are chemicals that transmit signals in the brain. Omega-3 fatty acids are important for brain development and function, and deficiencies have been linked to depression and cognitive decline.
A healthy diet can reduce the risk of cognitive decline: Numerous studies have found that a healthy diet, rich in fruits, vegetables, whole grains, lean protein, and healthy fats, can reduce the risk of cognitive decline and dementia. For example, the Mediterranean diet, which is high in fruits, vegetables, whole grains, and olive oil, has been associated with better cognitive function and a lower risk of dementia.
Specific foods and nutrients can improve brain function: Certain foods and nutrients have been shown to improve brain function and cognitive performance. For example, caffeine, which is found in coffee and tea, can improve attention, alertness, and memory. Blueberries, which are rich in antioxidants, have been shown to improve cognitive function in older adults. And dark chocolate, which contains flavanols, can improve blood flow to the brain and boost cognitive performance.
The gut microbiome plays a role in brain function: The gut microbiome, which is the collection of microorganisms that live in our intestines, has been linked to brain function and cognitive performance. For example, studies have found that the gut microbiome can affect mood, anxiety, and cognitive function. Probiotics, which are beneficial bacteria, have been shown to improve mood and cognitive function in some studies.
Inflammation can impair brain function: Inflammation, which is the body's response to injury or infection, can impair brain function and cognitive performance. Chronic inflammation has been linked to cognitive decline and dementia. A diet that is high in processed foods, sugar, and unhealthy fats can promote inflammation, while a diet that is rich in whole foods and healthy fats can reduce inflammation.
The Gut Bacteria and their effects on Brain Recovery
The gut microbiome has emerged as a promising target for improving neural recovery after brain injury. There is a growing body of scientific literature that suggests that the gut microbiome plays an important role in the regulation of the immune system, which is crucial for neural recovery after brain injury. Here's an evaluation of the current scientific literature on this topic:
Animal studies: Several animal studies have demonstrated the potential of the gut microbiome to promote neural recovery after brain injury. For example, a 2017 study in mice found that treatment with a probiotic (Lactobacillus plantarum) reduced inflammation and improved cognitive function after traumatic brain injury. Another study in rats found that a high-fiber diet increased the abundance of beneficial gut bacteria and improved recovery after stroke.
Human studies: There are fewer human studies on this topic, but some have shown promising results. A 2020 study in humans found that a fecal microbiota transplant (FMT) improved cognitive function in patients with traumatic brain injury. FMT involves transferring fecal material from a healthy donor to a patient in order to restore a healthy gut microbiome. The study found that FMT was safe and well-tolerated, and resulted in improvements in cognitive function and gut microbiome composition.
Mechanisms: The mechanisms by which the gut microbiome affects neural recovery after brain injury are not fully understood, but several hypotheses have been proposed. One is that the gut microbiome influences the immune system, which plays a critical role in the response to brain injury. Another is that the gut-brain axis, which is the communication pathway between the gut and the brain, may be involved. For example, gut bacteria can produce neurotransmitters and other chemicals that can affect brain function.
Limitations: One limitation of the current literature is that most studies have been conducted in animals, and more research is needed in humans. In addition, the optimal strategies for manipulating the gut microbiome to promote neural recovery after brain injury are not yet clear. For example, it is not clear what type of probiotics or prebiotics (substances that promote the growth of beneficial gut bacteria) are most effective.
In summary, the current scientific literature suggests that the gut microbiome may play an important role in neural recovery after brain injury, and that strategies for manipulating the gut microbiome, such as probiotics or FMT, may hold promise for improving outcomes in patients with brain injury. However, more research is needed to better understand the mechanisms involved and to optimize these interventions.
References (for further reading)
Nutrient deficiencies can impair brain function:
Murray-Kolb, L. E. (2013). Iron and brain functions. Current Opinion in Clinical Nutrition and Metabolic Care, 16(6), 703-707.
O'Leary, F., & Samman, S. (2010). Vitamin B12 in health and disease. Nutrients, 2(3), 299-316.
Gómez-Pinilla, F. (2008). Brain foods: the effects of nutrients on brain function. Nature Reviews Neuroscience, 9(7), 568-578.
2. A healthy diet can reduce the risk of cognitive decline:
Morris, M. C., Tangney, C. C., Wang, Y., Sacks, F. M., Bennett, D. A., & Aggarwal, N. T. (2015). MIND diet associated with reduced incidence of Alzheimer's disease. Alzheimer's & Dementia, 11(9), 1007-1014.
Scarmeas, N., Stern, Y., Tang, M. X., Mayeux, R., & Luchsinger, J. A. (2006). Mediterranean diet and risk for Alzheimer's disease. Annals of Neurology, 59(6), 912-921.
3. Specific foods and nutrients can improve brain function:
Nehlig, A. (2010). Is caffeine a cognitive enhancer? Journal of Alzheimer's Disease, 20(s1), S85-S94.
Krikorian, R., Shidler, M. D., Nash, T. A., Kalt, W., Vinqvist-Tymchuk, M. R., Shukitt-Hale, B., & Joseph, J. A. (2010). Blueberry supplementation improves memory in older adults. Journal of Agricultural and Food Chemistry, 58(7), 3996-4000.
Brickman, A. M., Khan, U. A., Provenzano, F. A., Yeung, L. K., Suzuki, W., Schroeter, H., ... & Brown, T. R. (2014). Enhancing dentate gyrus function with dietary flavanols improves cognition in older adults. Nature Neuroscience, 17(12), 1798-1803.
4. The gut microbiome plays a role in brain function:
Mayer, E. A., Knight, R., Mazmanian, S. K., Cryan, J. F., & Tillisch, K. (2014). Gut microbes and the brain: paradigm shift in neuroscience. Journal of Neuroscience, 34(46), 15490-15496.
Dash, S., Clarke, G., Berk, M., & Jacka, F. N. (2015). The gut microbiome and diet in psychiatry: focus on depression. Current Opinion in Psychiatry, 28(1), 1-6.
5. Inflammation can impair brain function:
Heneka, M. T., Carson, M. J., El Khoury, J., Landreth, G. E., Brosseron, F., Feinstein, D. L., ... & Kummer, M. P. (2015). Neuroinflammation in Alzheimer's disease. Lancet Neurology, 14(4), 388-405.
Jacka, F. N., Cherbuin, N., Anstey, K. J., Sachdev, P., & Butterworth, P. (2015). Western diet is associated with a smaller hippocampus: a longitudinal investigation. BMC Medicine, 13(1), 215.
Morris, M. C., Brockman, J., Schneider, J. A., Wang, Y., Bennett, D. A., & Tangney, C. C. (2016). Association of seafood consumption, brain mercury level, and APOE ε4 status with brain neuropathology in older adults. JAMA, 315(5), 489-497.