Mental Health & Nutrition, What Does the Research Say?

In our last blog, we discussed mental health and the role nutrition can play as one piece of the puzzle when it comes to supporting mental well-being. 

This time, we are digging deeper into the research surrounding specific dietary patterns and eating approaches and what the current literature shows about their relationship to mental well-being. 

A quick reminder: there is no single “mental health diet,” and food is not a replacement for mental health treatment. Nutrition can be supportive, but treatment may also include therapy, medication, movement, sleep, relationships, stress-management, and other forms of self-care. With that being said, let’s look at what the research tells us. 

The Mediterranean Diet 

The Mediterranean diet is one of the most studied dietary patterns. Inspired by traditional eating patterns in countries bordering the Mediterranean Sea, it emphasizes a wide variety of plant foods, including vegetables, legumes, whole grains, fruits, nuts, seeds, and herbs and spices. It also includes foods such as seafood, poultry, eggs, dairy, and extra-virgin olive oil, with red and processed meats eaten less frequently. 

This pattern provides plenty of fiber, unsaturated fats, omega-3 fatty acids, vitamins, minerals, and a variety of plant compounds, such as antioxidants and polyphenols. 

So what does this have to do with mental health? 

One of the most frequently discussed studies is the 2017 SMILES trial, a 12-week randomized control trial involving adults with major depression. Participants receiving a dietary improvement intervention based on Mediterranean-style eating experiences greater reductions in depressive symptoms than those receiving social support.¹ 

Most recent reviews of randomized controlled trials have found the Mediterranean-style eating patterns may help reduce depressive symptoms, but the overall certainty of the evidence remains low and studies have varied in both design and quality.² In other words, it’s a promising area of research, but it should be considered as a supportive strategy versus a stand-alone treatment for depression. 

And thankfully, adopting a Mediterranean eating pattern does not require you to move to Greece, learn to make your own olive oil, or develop a sudden obsession with oregano! Think more plants, whole grains, legumes, nuts, seafood and satisfying meals. 

The MIND Diet

MIND stands for Mediterranean-DASH Intervention for Neurodegenerative Delay. It combines elements of the Mediterranean diet and DASH (Dietary Approaches to Stop Hypertension) diet, with particular emphasis on foods thought to support brain health. Such foods include: ● Leafy green vegetables 

● Other vegetables 

● Berries 

● Whole grains 

● Beans and legumes 

● Nuts 

● Fish 

● Olive oil 

It also limits foods such as red and processed meats, butter, high-fat dairy, sweets, pastries, and fried foods.³ 

The MIND diet was developed with cognitive health and dementia prevention in mind, rather than treating mental disorders such as depression and anxiety. And interestingly, the research here is mixed. 

A large 3-year randomized controlled trial published in 2023 compared the MIND diet with a control diet in older adults at risk of cognitive decline. Both groups experienced improvements in cognitive scores, but there was no significant difference between the groups. Brain MRI outcomes were also similar.³ 

This simply means that we don't yet have strong evidence that following the MIND diet specifically prevents cognitive decline. 

Some observational research has also linked greater adherence to MIND-style eating with better mental health outcomes, including lower levels of psychological distress and depression. However, observational research can show associations without proving that one thing caused the other, thus more research is needed. 

What About a Low-Glycemic Diet? 

As we discussed in our previous blog, glucose is an important fuel source for the brain, and the brain has a high energy demand. Carbohydrates are an important source of energy for many people. 

A low-glycemic eating pattern focuses on choosing carbohydrates that produces a slower and more gradual rise in blood glucose. Often referred to as complex carbohydrates, these cars

include sources like beans, lentils, whole grains, oats, vegetables, potatoes, sweet potatoes and fruit. These foods are minimally processed, rich in vitamins and minerals, and packed with fiber. 

The goal isn’t to remove carbohydrates from the overall diet, so you don’t have to worry about breaking up with bread! 

Research examining glycemic index and its impact on depression is mixed. A 2018 systematic review and meta-analysis found some evidence linking higher dietary glycemic index with depression, while results for glycemic load were less consistent.⁴ 

A 2016 randomized crossover feeding study also found that participants consuming a higher glycemic-load reported higher depressive symptom scores and greater overall mood disturbances when compared with lower glycemic-load diets.⁵ It’s important to note that this study had a small sample size and is not conclusive. 

Overall, the relationship between blood glucose, dietary patterns, mood, and mental health is an interesting and still developing area of research. At this point in time, what we can say is that supporting healthy blood glucose through regular meals, adequate carbohydrate intake, high-fiber foods, and balanced meals can be a practical part of overall care. 

And What About “Type 3 Diabetes”? 

You may have heard Alzheimer's disease referred to as “type 3 diabetes” online. This term is sometimes used to describe the relationship between Alzheimer's disease and impaired insulin signaling or insulin resistance in the brain. Researchers have been investigating connections between insulin signaling, glucose metabolism, inflammation, and neurodegeneration for years.⁶˒⁷ 

However, it's important to clarify that “type 3 diabetes” is not an official medical diagnosis. It is a proposed concept used in some research literature, and scientists are still working to understand exactly how metabolic dysfunction and Alzheimer's disease are connected.⁶˒⁸ 

So, while the relationship between metabolic health and brain health is a fascinating and important area of research, we don't want to oversimplify Alzheimer's disease into being caused by eating too much sugar or suggest that a particular diet can prevent or cure it. 

A Weight-Neutral Approach to Nutrition 

A weight-neutral or weight-inclusive approach focuses on supporting health behaviors without making body size or weight the primary measure of success. 

This may include:

● Building a positive relationship with food 

● Practicing body acceptance 

● Eating regularly and adequately 

● Reducing food guilt and rigid food rules 

● Learning to recognize hunger and fullness cues 

● Practicing mindful or intuitive eating 

● Supporting enjoyment and satisfaction from food 

This approach can be particularly helpful for individuals who have a history of dieting, body dissatisfaction, disordered eating, or a difficult relationship with food. 

Research on intuitive eating has found associations with lower eating pathology and body image concerns, as well as higher self-esteem and psychological well-being.⁹ Longitudinal research has also found that greater intuitive eating is associated with better psychological health and fewer disordered eating behaviors over time.¹⁰ 

Intuitive eating provides another way to view nutrition that considers both physical and mental well-being. 

Nutrition Isn't the Whole Story 

Lifestyle factors can also play an important role in supporting mental well-being, including: 

● Physical activity: Exercise has been associated with improvements in depression and anxiety symptoms. Walking, dancing, yoga, strength training, gardening, or any form of movement can count.¹¹ 

● Sleep: Consistent sleep and good sleep hygiene can support mood, cognitive function, and overall well-being. 

● Social connection: Time with supportive friends, family, community, or loved ones can be an important part of mental health. 

● Creative activities: Art, music, writing, cooking, crafting, and other creative pursuits can provide enjoyment, expression, and connection. 

● Regular routines: Having some consistency around meals, sleep, movement, and daily activities can provide structure, especially when mental health symptoms make everyday life feel a little less predictable. 

And, of course, professional mental health support can be an incredibly important part of the picture. 

The Bottom Line 

When it comes to nutrition and mental health, we're learning more every year, but there is still more to learn.

The Mediterranean and MIND diets are interesting areas of research, particularly because they emphasize a wide variety of nutrient-dense foods. Research into glycemic patterns and mental health is also evolving. At the same time, weight-neutral and intuitive eating approaches remind us that how we eat and how we feel about food matter, too. 

Your nutrition needs to fit your culture, preferences, budget, schedule, medical needs, relationship with food, and most importantly, your actual life. 

At 360 Nutrition Consulting, we're passionate about helping you build a positive relationship with food and your body that is sustainable for YOU. If you're looking for a personalized, weight-neutral approach to nutrition, contact us to schedule your initial consultation at (805) 738-5700. Our passionate dietitians are ready to help you find an approach that feels sustainable, supportive, and uniquely yours. 

Written by: Lexi Underhill, RDN 

Original piece written by the author, with AI assistance for editing and refining format and sentence structure. 

References 

1. Jacka FN, O'Neil A, Opie R, et al. A randomised controlled trial of dietary improvement for adults with major depression (the “SMILES” trial). BMC Med. 2017;15:23. doi:10.1186/s12916-017-0791-y. 

2. Solis M, et al. The impact of the Mediterranean diet on alleviating depressive symptoms in adults: a systematic review and meta-analysis of randomized controlled trials. Nutr Rev. 2024. doi:10.1093/nutrit/nuad176. 

3. Barnes LL, Dhana A, Liu X, et al. Trial of the MIND diet for prevention of cognitive decline in older persons. N Engl J Med. 2023;389(7):602-611. 

doi:10.1056/NEJMoa2302368. 

4. New England Journal of Medicine. Salari-Moghaddam A, Saneei P, Larijani B, Esmaillzadeh A. Glycemic index, glycemic load, and depression: a systematic review and meta-analysis. Eur J Clin Nutr. 2019;73(3):356-365. doi:10.1038/s41430-018-0258-z. 

5. Breymeyer KL, Lampe JW, McGregor BA, Neuhouser ML. Subjective mood and energy levels of healthy weight and overweight/obese healthy adults on high- and low-glycemic load experimental diets. Appetite. 2016;107:253-259. doi:10.1016/j.appet.2016.08.008. 

6. Kciuk M, et al. Alzheimer's disease as type 3 diabetes: understanding the link and implications. Int J Mol Sci. 2024;25(22):11955. doi:10.3390/ijms252211955. de la Monte SM, Wands JR. Alzheimer's disease is type 3 diabetes-evidence reviewed. J Diabetes Sci Technol. 2008;2(6):1101-1113.

7. Fu W, et al. Shared pathophysiology and therapeutic repurposing in Alzheimer's disease and type 2 diabetes: a critical review of convergent mechanisms and clinical challenges. Bioorg Chem. 2026. doi:10.1016/j.bioorg.2026.110044. 

8. Linardon J, Mitchell S. Rigid dietary restraint, flexible dietary control, and intuitive eating: a meta-analysis. J Eat Disord. 2021. [Research on intuitive eating and psychological correlates.] 

9. Hazzard VM, Telke SE, Simone M, Anderson LM, Larson NI, Neumark-Sztainer D. Intuitive eating longitudinally predicts better psychological health and lower use of disordered eating behaviors: findings from EAT 2010-2018. Eat Behav. 2020;39:101437. 

10. Noetel M, Sanders T, Gallardo-Gómez D, et al. Effect of exercise for depression: systematic review and network meta-analysis of randomised controlled trials. BMJ. 2024;384:e075847. doi:10.1136/bmj-2023-075847.