Mom Was Right, You Are What You Eat

Why Your Diet Matters to Your Brain

Posted Apr 01, 2019

David Malan/Getty Images
Source: David Malan/Getty Images

In part one of our series on lifestyle risk factors for dementia we talked about how physical exercise and activity are vital to brain health.  For the second part of our series on lifestyle factors that influence dementia risk, let’s turn the spotlight on diet. Medicine is more than pharmaceuticals – medicine is also food. A nutritious and well-balanced diet is an important way to maintain your health and prevent disease.

More often than not, our culture uses the word diet to describe the latest fad or eating strategies of what essentially amounts to food deprivation in order to lose weight. In this article, we are assigning a new, more empowering, and encompassing definition of diet which refers to long-term lifestyle choices and habits of eating that have a profound impact on health.

To determine the best overall diet of 2019, the US News and World Reportanalyzed 41 different diets which included factors like weight loss (short and long-term), ease with which to follow a diet, and how good the diet was for overall health. The Mediterr­anean diet achieved the number one spot by outperforming all other diets. Its benefits were evidence-based and wide-ranging: better cardiovascular health, reduced risk for diabetes, improved cognitive health, and reduced short and long-term risk for dementia.  

What exactly is the Mediterranean diet?

The Mediterranean diet(MeDi) is predominantly plant-based, with an emphasis on limiting saturated fat. In addition to the obvious recommendation of regular physical activity, this diet promotes a high intake of fruits, vegetables, legumes, whole grains, and unsaturated fatty acids such as olive oil and avocado. It also encourages a moderate intake of dairy, red wine, fish, and poultry. Finally, it recommends a low intake of red meats and sweets.

Unlike many fad diets, the MeDi does not advocate for a large restriction of carbohydrates. Instead, the guidelines suggest that healthy carbohydrates are to be consumed—especially those found in vegetables and whole grains. It also does not restrict fat, it just values some types of fats over others. The MeDi focuses on hearty, tasty food and has cultural roots in the traditional foods of Italy, Greece, and Southern France.  

What is the relationship between the Mediterranean diet and brain health?

Studies that support the benefits of the Mediterranean diet on brain health are abundant. Adherence to this well-rounded diet has been linked to better performance in memory, language, visual-spatial perception, and global cognitive functions.3 In a study of approximately 6,000 older adults, researchers found that participants demonstrated a 30-35% lower risk of memory impairment when following a Mediterranean-based diet.4

Given the current scarcity of treatments for Alzheimer’s disease, combined with a rapidly aging population across the globe, these findings carry significant weight. Amyloid beta, one of the main biomarkers for Alzheimer’s, is found to be less apparent in the brains of those that adhere to a Mediterranean diet.5 Furthermore, greater adherence to the MeDi is associated with a slower decline in brain volume overall, implying that the MeDi may be a protective factor against brain atrophy.6

Because diet affects each person in a unique way, it can be difficult to pin down the specificity of what makes the MeDi so beneficial to the brain. One school of thought is that the MedDi is high in antioxidants and anti-inflammatory compounds which combat the oxidative processes that occur within the aging brain. 

Let’s delve deeper into the MeDi’s brain healthy nutrients.

What five healthy nutrients are included in the Mediterranean diet?

Nutritional cognitive neuroscience is an emerging field of research that studies the relationship between nutrients and brain health.An intensive study, from the University of Illinois, examined 32 nutrient biomarker patterns found in the Mediterranean diet and analyzed their influence on the brain. Out of the 32 nutrients evaluated, five were highlighted as promoting cognitive performance: omega-3 and omega-6 polyunsaturated fatty acids (PUFAs), carotenoids, and vitamins B (riboflavin, folate, B12), and D.8

Although fats often receive a bad reputation in the media, they are, in fact, integral to a number of vital biological processes. A careful balance of omega-3 and omega-6 PUFAs is important to maintain neuronal membrane structure and function. This is achieved through several mechanisms including modification of neuronal membrane fluidity and modification of the production of neurotransmitters, to name a few.9

Carotenoids, the next highlighted nutrient, provides a number of neuroprotective benefits. For example, carotene acts as an antioxidant, removing harmful free radicals in the brain tissue.10

Vitamins B, specifically folate, riboflavin, and B12, are additional MeDi nutrients that impart brain health benefits. Riboflavin is integral to the metabolism of fatty acids in the brain and also acts as an antioxidant. Deficiencies in folate and B12 are associated with significant brain-related issues including affective disorders, behavior changes, psychosis, and cognitive decline, which includes Alzheimer’s and vascular dementia.11

The last featured brain healthy nutrient is vitamin D. In a mouse study of the effects of vitamin D, researchers found that a deficiency of vitamin D increased the number of amyloid beta plaques in the mice’s brains. They also noted that this deficiency decreased the overall production of neurons.12

To learn which foods have the highest amounts of these brain-healthy nutrients, refer to the table below.

Savonix
Source: Savonix

While the Mediterranean diet might not be a feasible choice for everyone, it is something to consider given the weight of evidence linking this diet to improved health. In the end, our moms were right: We are what we eat.  

References

1. US News and World Report. (n.d.). 2019 Best Diets Overall. Retrieved from https://health.usnews.com/best-diet/best-diets-overall

2. Willett, W. C., Sacks, F., Trichopoulou, A., Drescher, G., Ferro-Luzzi, A., Helsing, E., & Trichopoulos, D. (1995). Mediterranean diet pyramid: a cultural model for healthy eating. The American journal of clinical nutrition, 61(6), 1402S-1406S.

3. Anastasiou, C. A., Yannakoulia, M., Kosmidis, M. H., Dardiotis, E., Hadjigeorgiou, G. M., Sakka, P., ... & Scarmeas, N. (2017). Mediterranean diet and cognitive health: Initial results from the Hellenic Longitudinal Investigation of Ageing and Diet. PloS one, 12(8), e0182048.

4. McEvoy, C. T., Guyer, H., Langa, K. M., & Yaffe, K. (2017). Neuroprotective diets are associated with better cognitive function: the health and retirement study. Journal of the American Geriatrics Society, 65(8), 1857-1862.

5. Matthews, D. C., Davies, M., Murray, J., Williams, S., Tsui, W. H., Li, Y., ... & de Leon, M. J. (2014). Physical activity, Mediterranean diet and biomarkers-assessed risk of Alzheimer’s: a multi-modality brain imaging study. Advances in molecular imaging, 4(4), 43.

6. Luciano, M., Corley, J., Cox, S. R., Hernández, M. C. V., Craig, L. C., Dickie, D. A., ... & Deary, I. J. (2017). Mediterranean-type diet and brain structural change from 73 to 76 years in a Scottish cohort. Neurology, 88(5), 449-455.

7. Zamroziewicz, M. K., & Barbey, A. K. (2016). Nutritional cognitive neuroscience: innovations for healthy brain aging. Frontiers in neuroscience, 10, 240.

8. Zwilling, C. E., Talukdar, T., Zamroziewicz, M. K., & Barbey, A. K. (2019). Nutrient biomarker patterns, cognitive function, and fMRI measures of network efficiency in the aging brain. NeuroImage, 188, 239-251.

9. Yehuda, S. (2003). Omega-6/omega-3 ratio and brain-related functions. In Omega-6/omega-3 essential fatty acid ratio: the scientific evidence (Vol. 92, pp. 37-56). Karger Publishers.

10. Johnson, E. J. (2002). The role of carotenoids in human health. Nutrition in clinical care, 5(2), 56-65.

11. Kennedy, D. (2016). B vitamins and the brain: Mechanisms, dose and efficacy —A review. Nutrients, 8(2), 68.

12. Morello, M., Landel, V., Lacassagne, E., Baranger, K., Annweiler, C., Féron, F., & Millet, P. (2018). Vitamin D Improves Neurogenesis and Cognition in a Mouse Model of Alzheimer’s Disease. Molecular neurobiology, 1-17.