Diet, Inflammation, and Mental Health

DIET, INFLAMMATION, AND MENTAL HEALTH, Angelos Michalopoulos, Unsplash

Is there a link between diet, inflammation, and mental health? You might not have given it much thought before, so you might be surprised by what you’ll learn here. As you likely know, mental health issues have a big impact on our society. In fact, their impact may be larger than any other chronic disease, including heart disease, diabetes, cancer, dementia, and autoimmune diseases.

There are so many factors involved in complex conditions like mental health issues. Interestingly, science is only recently starting to unravel one of these factors – chronic inflammation as it relates to diet.

And the diet, inflammation, and mental health trifecta can be a hard-to-break vicious cycle. Poor diet leads to inflammation, which can lead to mental health issues, which can lead to making poor diet and lifestyle choices, and on and on it goes…Let’s take a deeper look to see what seems to be going on with diet, inflammation and mental health.

First, let’s look at the links between chronic inflammation and mental health (there are a few). Then, we’ll take a look at new research into natural approaches – things like foods, nutrients, and lifestyle changes – and how these factors contribute to increased mental wellness.

What is Inflammation and Why is it bad?

The word inflammation comes from the Latin word “inflammo,” meaning “I set alight, I ignite.”

Inflammation in and of itself is actually a natural process that our body uses to protect against infections, irritants, and damage. Inflammation helps our bodies eliminate damaged cells and tissues, and helps them to repair. If you break your arm, the ensuing inflammation is there to protect you from using that arm. Inflammation that happens in a big way, but for a short time can help the body to heal these injuries and infections. That’s acute inflammation, and that’s a good thing.

However, with poor diet, lack of sleep, or too much stress, to name a few factors, inflammation can stick around longer than necessary. This long-term “chronic” inflammation is what causes damage over time. Often, there are few, if any, signs or symptoms of chronic inflammation. And it’s this chronic inflammation that is linked to many conditions including mental health, heart disease, diabetes, cancer, dementia, and autoimmune diseases.

So as you can see, inflammation isn’t always a bad thing. But because inflammation can become harmful, it has gotten a lot of bad press lately. And it’s that chronic inflammation that we all want to avoid.

Inflammation mostly comes from our immune system’s response to infections and injuries. It also involves our blood vessels (arteries and veins) as well as inflammatory “markers” or molecules like free radicals (oxidants), cytokines, and C-reactive protein (CRP). So, what are the links between diet, inflammation and mental health?

Inflammation Linked to Mental Health Issues

There are many factors known to contribute to mental health issues, including chronic inflammation.

In terms of depression, the link with chronic inflammation was first discovered back in 1991. With respect to bipolar disorder, the link between it and immune dysfunction was proposed as far back as 1981.

While there are many links between chronic inflammation and mental health issues, it’s not the only connection. Others include neurotransmitter issues (e.g. serotonin, dopamine, etc.); reduction in growth factors (e.g. brain-derived neurotrophic factor, BDNF); and even leaky gut (intestinal permeability), which can be a precursor to inflammation.(1)

But new research shows that chronic inflammation may be a factor for about one-third of people with depression. And there seems to be a direct link between diet, inflammation, and mental health. So in this article, we’ll specifically focus on these links between diet, inflammation, and mental health.

Link #1 – Chronic Inflammation and Mental Health

First of all, some mental health issues are associated with increased inflammatory markers like cytokines and CRP. So people with depression tend to have higher levels of cytokines. In fact, some of the inflammatory markers found in the blood are known to reach the brain. And high levels of inflammation may also inhibit recovery in people who experience mental health symptoms.

Research has shown that people with chronic stressed tend to have increased levels of inflammatory markers and lower levels of anti-inflammatory markers. And while inflammation may be part of the cause of mental health symptoms for some people, it may also be a chicken-egg scenario. Mental health issues have been shown to increase some inflammatory markers as well.

Link #2 – Inflammatory Illnesses and Mental Health

Inflammatory illnesses like allergies and autoimmune diseases, and metabolic conditions (e.g. heart disease, diabetes, and obesity) are associated with higher rates of mental health symptoms. And this link also goes both ways – people with mental health symptoms are more likely to develop metabolic-related conditions too.

Link #3 – Inflammatory Medications and Mental Health

People who take certain inflammatory medications (including antibiotics, statins, and chemo) are at increased risk of developing mental health symptoms. On the other hand, some medications used to treat depression (e.g. SSRIs) reduce levels of some inflammatory markers.(2)

Link #4 – Inflammatory diets and mental health

There is growing evidence that people who eat a high-quality diet tend to have not only better physical health but also better mental health as well. This includes better moods and lower stress. And certain anti-inflammatory diets have shown lower rates of mental health issues.(3)

Studies also show links between unhealthy eating patterns and mental health issues too. Inflammatory diets (which we’ll go into more detail below) are associated with higher rates of mental health symptoms.

Food and Mood

Have you ever thought about how food affects your mood? As a Holistic Health Coach, I always have my clients keep a Food & Mood Journal to track this. You may have experienced being “hangry”, or that mood crash after a high-sugar snack. It seems like common sense: if you fuel your car with bad gas, it will run poorly. The same goes for our physical and mental health. Garbage in equals garbage out.

Ironically, scientific evidence linking what we eat to how we feel is fairly new. The first research studies to be published on this were as recent as 2009. This new area is called “nutritional psychiatry.”(4)

The relationships between food and mood, or mental health are complex, and we’re just starting to understand them. As an example, one study concluded(5):

“Our data support the hypothesis that high dietary quality is associated with good emotional well-being.”

What foods are associated with worse moods? These inflammatory dietary patterns found in the Standard American Diet (S.A.D.) include higher intakes of:

  • Saturated fat
  • Processed meats
  • Refined sugars and starches
  • Fried foods
  • Processed foods

People who eat this way, tend to report more mental health symptoms than those who eat a healthier diet. And recent studies have shown poor eating habits to be a risk factor for some mental health issues. There is also increasing evidence to link poor diet with the potential for committing crimes and incarceration.(6)


Unhealthy Foods Linked to Inflammation

Not surprisingly, these not-so-healthy foods are also linked with higher inflammatory markers like CRP. And several studies show that improving the diet can reduce levels of CRP. In fact, studies have even shown that the higher the “inflammatory factor” of the diet, the higher the risk for mental health issues. So it would appear that food really can affect your mood as well as your overall health.

One dietary pattern that’s been studied a lot is the Mediterranean diet. This diet includes a lot of vegetables, fruits, whole grains, legumes, fish, and olive oil. It also contains a lot of nutrients and fiber. Eating a Mediterranean-style diet is associated with lower levels of inflammatory markers and a reduced risk of mental health issues.

This complex association between diet, inflammation, and mental health can also go both ways. Mental health symptoms can influence appetite and food choices. And it’s likely that other factors such as obesity, lack of exercise, food insecurity, and use of alcohol and tobacco affect mental health as well.(7)

Nutrition can impact how our immune system functions, and this can affect levels of inflammation and mental health issues. Lack of necessary nutrients can also cause inflammation, as can an out of balance gut microbiome (microbiota-gut-brain axis). And intestinal permeability (leaky gut) is known to cause inflammation as well.

Better Foods for Better Moods

A recent clinical study found that when people start eating a healthier diet, they can actually reduce some of their mental health symptoms! This study, called the SMILES trial, is particularly interesting.

What makes the results from the SMILES trial so strong is that it was an interventional experiment. It didn’t just ask people what they ate, measured their inflammatory markers, and what their symptoms were. People agreed to actually change the way they ate.

How the SMILES Trial Worked

The SMILES trial recruited 67 people with depression and poor dietary quality to a trial for 12-weeks. These were people who reported a high intake of sweets, processed meats, and salty snacks; and a low intake of vegetables, fruits, lean protein, and dietary fibre.

Half of them were asked to:

  • Eat more vegetables, whole grains, fruit, legumes, low-fat unsweetened dairy, raw and unsalted nuts, fish, lean red meat, chicken, eggs and olive oil; and
  • Eat fewer sweets, refined grains, fried food, fast food, processed meats, and sugary drinks; and,
  • Drink no more than 2 glasses of wine per day (with meals, preferably red wine).

And half of those participants who upgraded their diet also received seven professional nutrition counseling sessions.

The other half of the people in the SMILES trial were given social support. They were “befriended” and discussed sports or news, or played cards or board games. There was no nutrition support, nor any dietary recommendations given to people in this group.

The researchers found that in 12-weeks the people who improved their diet also significantly improved their mental health symptoms!(8) They said:

“We report significant reductions in depression symptoms as a result of this intervention… The results of this trial suggest that improving one’s diet according to current recommendations targeting depression may be a useful and accessible strategy for addressing depression in both the general population and in clinical settings.”

Hopefully, more clinical trials will continue to confirm the links between diet, inflammation, and mental health. In the meantime, eating a healthier diet is helpful for overall health and well being, not just mental health conditions!

Better Nutrition Equals Better Moods

So is there something special in these foods that may help with moods?

We know the brain needs enough of all essential nutrients in order to function properly. And insufficient levels are linked with the stress response and the immune response. Eating nutrient-dense foods is the best way to get nutrition. Foods are complex combinations of nutrients. Supplementing with individual nutrients is not the same as eating a healthy diet. But sometimes it’s necessary to take supplements too, as people age.

Now let’s look at a few key nutrients to benefit better moods.

B-Vitamins Including B6, B9 (Folic Acid), and B12

People who tend to be low in B-vitamins, like vegetarians and vegans, are more likely to have mental health issues. Conversely, higher intakes of vitamin B6 (pyridoxine) and B12 (cobalamin) may reduce the risk of mental health issues.

With folic acid in particular, the connection may be due to its different forms. “Folic acid” is the inactive form of vitamin B9. Our bodies naturally converted it into the active form (called L-methylfolate) by the enzyme methylenetetrahydrofolate reductase (MTHFR).

Once folic acid has been activated, it goes to the brain and is used to make neurotransmitters like serotonin, melatonin, dopamine, epinephrine, and norepinephrine. However, as much as 40% of the population may have one or two genetic mutations that inhibit the body’s ability to convert folic acid into its active form of L-methylfolate.(9)

The MTHFR gene mutations could be one cause of mental health issues. Luckily for people with one or both genetic mutations (determined by a simple blood test for the MTHFR genes), they can supplement with a pre-methylated form of L-methylfolate like 5-MTHF from Thorne.

One study tested supplementing with L-methylfolate for people with mental health issues. While some had moderate improvement, the people who also had inflammation (higher levels of CRP markers) had the most improvements. If you suspect you have chronic inflammation, your doctor can do a blood test for C-reactive proteins, and cortisol levels. If you have high CRP or cortisol, it might be a good idea to be tested for the MTHFR gene mutations as well. Also if you’re considering getting pregnant, knowing if you have the MTHFR gene mutation will enable you to take the right form of folic acid for your body.

Vitamin D

Vitamin D is well known to help absorb calcium for strong bones but has many other functions too. In terms of immunity, vitamin D can reduce inflammatory molecules in people with certain infections and inflammatory diseases. Vitamin D has a number of roles within the brain. It plays a role in circadian rhythms and sleep, and influences the growth of nerve cells in the developing brain. Vitamin D has also been shown to be very beneficial in helping to fight cancer.

There is growing evidence that people who tend to be low in vitamin D also tend to have more mental health symptoms. In fact, some (but not all) studies show that vitamin D supplementation can improve mood scores and reduce mental health symptoms. And most people living above Latitude 37 rarely get enough vitamin D from the sun. (10) So it might be a good idea to talk with your health care provider about supplements.

Vitamin D is the most commonly deficient nutrient in Western countries. It’s known as the “sunshine vitamin” because our skin makes it when exposed to sunlight. It is also found in a few foods and as a supplement. If you live in the northern hemisphere, especially north of Latitude 37, getting a blood test to check for vitamin D levels might be a good idea. When I lived in Seattle my levels were dangerously low. And even now living in Mexico and exposed to the sun almost daily, my levels are still at the low end of normal. This is one vitamin you do not want to be low in, for a variety of reasons.

Minerals (Calcium & Selenium)

Low intake of calcium is associated with mental health symptoms, while high intake is associated with lower rates of mental health symptoms. Vegans often don’t get enough calcium. However, you can easily get enough calcium from a plant-based diet by eating foods like dark leafy greens: collard greens, kale, spinach, and Swiss chard; sesame seeds; molasses; Brazil nuts; broccoli; and flax seeds. In order for calcium to uptake properly, it needs to be eaten with vitamin C, so squeeze some lemon juice on your dark leafy greens, or snack on other citrus fruits with your nuts and seeds.

Depression has also been linked to low blood levels of the essential mineral selenium.(11) Brazil nuts are one of the few plant-based foods with high amounts of selenium. Selenium also found in most meats, so here again, vegetarians and vegans may be low in selenium.


Omega-3 oils are healthy fats found in many foods such as seafood, nuts, legumes, and leafy greens. They have been shown to reduce inflammation and reduce the incidence of mental health issues.(12)

Many studies suggest that omega-3 fats, specifically those found in fish and fish oil, have mental health benefits. Wild-caught, cold-water fish like salmon, sardines, and mackerel are all high in omega-3. Beware of eating farmed fish, as it’s not only environmentally unfriendly to the planet, but it’s also much lower in nutritive value and may contain antibiotics and artificial coloring which are inflammatory.

One big concern with low omega-3s is that omega-3 and omega-6 fatty acids need to be in a ratio of about 3:1 in the body. While omega-6s are an important nutrient too, these days they are most often found in processed and fried foods. And when people eat the S.A.D. diet, the ratio gets flipped to about 1:26 or more in favor of omega-6, instead of the other way around.(13) This out-of-balance ratio of omega-3 to omega-6 can lead to inflammation too.

Diet, Inflammation, and Mental Health Conclusions

The link between diet, inflammation and mental health issues is thought to go both ways – diet can contribute to inflammation, which can contribute to mental health issues, and vice versa. Conversely, eating a nutrient-dense, anti-inflammatory diet, and getting regular exercise and quality sleep can help to reduce inflammation, and improve mental health as well as overall health.

Inflammation is one of several factors that is linked to mental health issues. And it may be a factor for up to one-third of people who suffer from these.(14)

It’s an exciting area of research that will continue to answer more questions about the link between diet, inflammation, and mental health as more studies are done. In the meantime, eating a healthier (anti-inflammatory) diet, and getting enough nutrients, exercise, and sleep benefits everyone with no downsides.

While eating a mostly plant-based, whole-foods diet is always ideal, sometimes supplementation is necessary to ensure all the nutrients you need. If you’re looking for quality supplements, I highly recommend Thorne. I’ve been taking Thorne brand supplements myself for over 30-years, and you can save money when you order through my online Thorne dispensary.

NOTE: This information is not a substitute for professional medical advice. If you have any of these conditions, make sure you’re being monitored regularly by a licensed healthcare professional.

Thanks for reading! Please share this article with friends and family who might benefit. And leave a comment to know your takeaway, or how you plan to implement some of these suggestions?



Photo credit: Angelos Michalopoulos (top) and Robin Stickel,

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