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Mood & Cognition: What's Food Got To Do With It?

I attended my first virtual conference this summer and my favorite session was about food and the brain. If you're curious about how food affects mental health (depressive disorders and symptoms) or cognitive function, read on to see where the latest research is leading us.

We know that food affects how we feel physically. Think satiated vs overly full. We also know that the way we consistently eat has a compounding effect on our physical health. There's a growing body of evidence that food also affects our mental health and cognition.

Before we dive in, a DISCLAIMER:

This article is not meant to replace professional medical advice. If you're concerned about your health, seek help from a qualified health care provider. If you want to know more about mental health or cognition, check out these resources:

Brain Facts

Our brains:

  • Are always on/hungry - 20% of our calorie intake goes to brain activity

  • Are made up mostly of water - 75%; more than half of the remaining solid matter is made up of fat

  • Change throughout our lives:

in utero - 3 years - reward, emotional and mood systems develop

preschool years - quadruples in size

adolescence - mid 20s - pre-frontal cortex, responsible for self-regulation and self-control, matures

middle adult years - inductive reasoning, problem solving and emotional resilience increase; processing speed and memory decline, but varies among individuals and is exacerbated by stress

70 years + - volume declines, but brain adapts to compensate but varies individually (biological vs. chronological age)

  • Rewire (neuroplasticity) and produce new cells (neurogenesis) throughout life

Because of the brain's make up, water intake is key. Even mild dehydration affects mood, anxiety, energy levels, and ability to focus.

The brain's high rate of metabolism makes it sensitive to oxidative stress which contributes to aging and can lead to disease. This is why nutritionists encourage us to eat omega 3 fats (fish, nuts & seeds) and antioxidant rich foods (berries & dark leafy greens).

Food & Mood

"There is no health without mental health". - World Health Organization

Depression & anxiety are the most common mental health disorders, with higher rates in developed nations and among women. Rates of depression and anxiety are rising and only about 1/3 of people respond to treatment. The pandemic is driving a worldwide increase in feelings of stress, anxiousness, and depression. Can better nutrition help?

Recent studies include reviews of specific nutrients' effects on depression, observational studies of large populations over 5+ years, and randomized control trials. Collectively, they show a relationship between diet and decreasing the risk of depression and depressive symptoms.

Observational studies

The SUN Project has followed over 22,500 people since 1999 and has found higher risk of depression associated with diets high in trans fats, fast food, and commercial baked goods, while a 30% lower risk of depression was associated with diets high in Omega-3s and a Mediterranean based diet (high in vegetables, fruits, whole grains, beans, nut and seeds, and olive oil).

The Whitehall II study was a 5 year study of 4,600 people that found risk of depression increased 158% when diet consisted of processed foods like sweetened desserts, fried foods, processed meats, refined grains, and high fat dairy products. They also found a 26% depression risk reduction for whole food diets.

Randomized Controlled Trials

Recent smaller studies have looked specifically at people being treated for depression and how dietary changes effect their illness and symptoms. The SMILES Trial used nutrition coaching and goal setting and found a significant reduction in symptoms (and a reduction in their weekly food costs). PREDIMED was a study designed primarily to look at reducing cardiovascular disease through the Mediterranean diet (and added nuts), but found reduced risk of depression for participants who had Type II Diabetes. The HELFIMED study provided a Mediterranean based diet and biweekly cooking workshops, and found that participants who ate a variety of (and more) veg, plus nuts, improved mental health scores and had a greater reduction in depression than the control group.

Animal studies are showing promise for the mental health connection between the gut and the brain, but we need more work here.

We still have a long way to go on learning about nutrition and depressive disorders. Solid science is not based on any single study, but the result of sustained and critically evaluated research by multiple investigators through many studies, over many years. On the whole though, eating a healthier diet based on whole foods can help support better mental health and the side effects on our bodies are all good.

Diet & Alzheimer's

“And I have no control over which yesterdays I keep and which ones get deleted. This disease will not be bargained with. I can't offer it the names of the US presidents in exchange for the names of my children. I can't give it the names of state capitals and keep the memories of my husband." - from the book Still Alice, by Lisa Genova

More than 5 million Americans are living with Alzheimer's. If you or someone you love has it, you know the high toll it takes physically, mentally, economically, and emotionally. It kills more seniors than breast and prostate cancers combined, and is the 6th leading cause of death in the U.S. While it's true that cognitive decline is something we all face as we age, there's evidence that we can slow it down significantly with exercise and a better diet.

A group of researchers developed and studied the MIND (Mediterranean-DASH Intervention for Neurodegenerative Delay) diet in 2015. The Mediterranean diet is high in vegetables, fruits, whole grains, and beans, and olive oil is the primary cooking oil. The DASH diet (Dietary Approaches to Stop Hypertension) is similar but also reduces sodium intake and includes low fat or non fat dairy. The researchers found that participants who followed the recommendations could reduce their Alzheimer's risk by half. What's most encouraging is that people didn't have to follow the diet perfectly. The group with the highest compliance (57-83%) cut their risk in half. But even those with moderate compliance (46-53%) still saw a risk reduction of 35%. And what's more, this way of eating also has shown to slow cognitive decline. The group in the top 3rd of compliance had the equivalent of a brain that was 7.5 years younger.

Here are the guidelines for the MIND diet:

None of these recommendations are earth-shattering, and most line up with what we know works for better overall health. What's most encouraging is that people saw brain benefits even when they were eating this way only about half the time. And that feels doable!

Whether you're concerned about mental or cognitive health, eating better only has positive side effects, so why not get started?

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