A Functional Medicine Perspective on Nutrition and Mental Health

Miranda Moore Stepnitz, M.S.

Functional Medicine Nutritionist & Founder, Awaken Health Nutrition · Shelby Township, MI

September 15, 2025

In recent years, the connection between what we eat and how we feel has gained well-deserved

attention. As rates of anxiety, depression, and cognitive decline continue to rise, a growing body

of research and the lived experiences of patients highlight a key truth: food is not just fuel; it

is information for the body and brain.

From a Functional Medicine perspective, mental health extends beyond the brain, arising

from complex interactions between genetics, lifestyle, gut health, inflammation, and hormone

balance, with nutrition serving as a central and integrative factor.

The Gut-Brain Connection: Where Digestion Meets Emotion

One of the foundational principles of Functional Medicine is the interconnectedness of body

systems. Nowhere is this more evident than in the relationship between the gut and the brain,

often called the gut-brain axis.

The gut is home to over 100 trillion microbes that produce neurotransmitters such as serotonin,

dopamine, and GABA—chemicals responsible for mood regulation, sleep, and focus. In fact, up

to 90 percent of serotonin is produced in the gut.

When the gut microbiome is disrupted by processed foods, antibiotics, chronic stress, or

sugar-heavy diets, it can trigger inflammation that negatively affects brain health and

mood.

A Functional Medicine approach seeks to identify and restore the root causes of gut dysbiosis,

or microbial imbalance, to support both digestive and mental well-being.

Inflammation: The Hidden Culprit

Chronic, low-grade inflammation is increasingly recognized as a key driver of mental health

disorders such as depression and anxiety. The foods we eat can either fuel inflammation or

help calm it.

Pro-inflammatory foods include:

● Refined sugars and flours

● Industrial seed oils such as canola, soybean, and corn oil

● Processed meats

● Artificial additives and preservatives

Anti-inflammatory, brain-supportive foods include:

● Omega-3-rich fatty fish such as salmon and sardines

● Healthy fats such as avocados and olive oil

● Berries, including blueberries, raspberries, and blackberries

● Nuts and seeds, especially walnuts and flaxseeds

● Teas like: green, black, turmeric, and ginger

Functional Medicine practitioners examine dietary triggers, nutrient deficiencies, and

inflammatory markers as part of a personalized approach to improving mental health.

Blood Sugar and Brain Chemistry

Blood sugar instability is another often overlooked factor in mood disorders. Spikes and

crashes in glucose levels can cause irritability, fatigue, brain fog, and anxiety-like symptoms.

Eating a whole foods, nutrient-dense diet that emphasizes protein, fiber, and healthy fats at

every meal helps stabilize blood sugar and supports steady energy and mood throughout the

day.

Key Nutrients for Mental Health

In Functional Medicine, mental health is understood as a reflection of whole-body health.

The foods you eat, your digestive health, nutrient levels, and stress response all influence brain

function and emotional well-being.

One commonly overlooked contributor to depression, anxiety, and brain fog is nutrient

deficiency. Many individuals struggling with mood disorders are unknowingly missing

essential vitamins and minerals that support neurotransmitter production, brain

signaling, and nervous system balance.

Here are some of the most critical nutrients for mental health and why they matter:

Magnesium: The Calming Mineral

Magnesium is essential for a healthy nervous system. It regulates the stress response, calms

overactive nerve signals, and supports restful sleep. Magnesium also plays a vital role in

neurotransmission and muscle relaxation.

Deficiency is widespread due to chronic stress, poor soil quality, and diets high in processed

foods. Low magnesium levels are often linked to anxiety, irritability, insomnia, and low mood.

B Vitamins: Fuel for Brain Chemistry

B vitamins, especially B6, B9 (folate), and B12, are essential for producing mood-related

neurotransmitters such as serotonin, dopamine, and GABA.

● Vitamin B6 supports converting amino acids into serotonin and dopamine.

● Folate is necessary for methylation, a biochemical process influencing mood,

detoxification, and gene expression.

● Vitamin B12 helps maintain nerve cell health and supports energy production.

Deficiency can lead to fatigue, mood swings, irritability, cognitive difficulties, and long-term

neurological issues.

Zinc: Supporting Mood and Mental Clarity

Zinc is a trace mineral important for brain function and immune regulation. It supports the

production of calming neurotransmitters like GABA and promotes neuroplasticity, the brain’s

ability to adapt and form new connections.

Low zinc levels are often associated with depression, difficulty concentrating, and heightened

stress sensitivity.

Iron: Oxygen for the Brain

Iron is vital for delivering oxygen to the brain and synthesizing neurotransmitters. Low iron

levels, particularly low ferritin, the storage form of iron, can cause brain fog, chronic fatigue,

depression, and poor memory.

Iron deficiency is common among menstruating women, people with digestive issues, and those

on vegetarian or vegan diets.

Vitamin D: The Sunshine Vitamin for Mood

Vitamin D functions like a hormone and is essential for mood regulation and immune health. It

interacts with receptors throughout the brain, especially in areas responsible for emotional

regulation and stress resilience.

Low vitamin D levels have been linked to seasonal affective disorder, chronic depression,

anxiety, and weakened immune response.

Why Testing and Guidance Matter

While these nutrients are crucial, supplementing without proper testing and professional

guidance can lead to imbalances or worsen symptoms.

Functional Medicine emphasizes individualized care. Identifying specific nutrient deficiencies

through lab testing and working with a qualified practitioner ensures you receive the correct

forms, dosages, and combinations of supplements tailored to your needs.

For safety reasons, it is essential to consult with a qualified natural health provider before

beginning any supplement regimen. A trained practitioner can accurately assess your individual

needs, recommend appropriate supplements and dosages, and ensure the use of high-quality,

practitioner-grade products. This personalized approach minimizes risks and optimizes

outcomes for your overall health and well-being. Test, don’t guess.

Takeaway: Feed Your Brain, Support Your Mind

Mental health is not just in your head. It is influenced by your cells, digestion, nutrient status,

and daily lifestyle choices. By identifying and addressing key nutrient deficiencies, we can

rebalance the body and support long-term emotional well-being.

If you are struggling with depression, anxiety, or brain fog, consider taking a closer look at your

nutrition and nutrient levels. A Functional Medicine Nutrition approach offers a

comprehensive, root-cause pathway to healing that honors the full picture of your mental and

physical health.

The Functional Medicine Difference

Functional Medicine offers a complementary, root-cause approach. It views mental health not as

a simple chemical imbalance but as a systemic issue influenced by modifiable lifestyle factors.

Through a comprehensive evaluation of nutrition, gut health, inflammation, toxins, sleep, and

stress, Functional Medicine helps patients reclaim their mental wellness from the inside out.

Final Thought: Feed Your Brain, Heal Your Mind

Mental health is not only in your head. It is in your gut, your plate, and your daily choices.

Functional Medicine Nutrition empowers you to explore the deep connections between diet and

mood and supports your mental health with targeted nutrition, personalized care, and a

whole-body perspective.

If you or a loved one is experiencing mental health challenges, consider consulting with a

Functional Medicine Nutritionist in collaboration with your existing mental healthcare providers.

This integrative approach can help uncover the impact of nutrition on mental health and support a personalized path toward healing and long-term well-being.