Brain on Fire — How Inflammation Damages Mental Health

From depression to dementia: 5 ways to reduce inflammation naturally

Maria Cross
May 17, 2020 · 9 min read
Image: Gerd Altmann/Pixabay

nflammation is often visible and painful. Red, angry swellings make their presence felt. Yet sometimes inflammation is invisible and painless; you would never know it was there. When inflammation flares in the brain, it does so silently.

What is inflammation?

Inflammation is not always detrimental to health — it is a normal immune response to injury or infection and means that the healing process has begun. The body repairs itself or prepares to fight off an intruder. Sometimes, however, things go wrong. The inflammatory process goes on for longer than necessary, or is activated when it is not required.

The response may be either acute or chronic. Acute inflammation is healthy and short-term. It is usually localized and triggered by a wound or an infection. When it begins, inflammatory substances called cytokines are released by the affected tissue to alert and prime the immune system.

The body produces many types of cytokines, including the interleukins IL-1, IL-6, IL-12, IL-18. In the brain, the cytokine TNF-α is also produced.

Chronic inflammation, on the other hand, is systemic and less obvious. Internal organs — the heart, lungs and kidneys — may be affected. It is involved in virtually every chronic disease, including cardiovascular disease, diabetes, metabolic syndrome, rheumatoid arthritis, asthma, and cancer.

With chronic (sometimes called low-grade) inflammation, you won’t see any redness or swelling, and the only way you know it’s there is by testing for something called C-reactive protein (CRP), a marker for inflammation in the blood.

Inflammation in the brain

Chronic, low-grade inflammation in the brain is a factor in the development of many neurodegenerative diseases, including depression and dementia. It is also seen in Parkinson’s disease, multiple sclerosis and Huntington’s disease.


‘Diet-related inflammation can promote depression, and diet-linked depression in turn heightens inflammation.’

Scientists increasingly acknowledge that depression is an inflammatory disorder. Interestingly, it has also been observed that when clinical depression goes into remission, so too does inflammation.

According to data from the National Health and Nutrition Examination Survey, an extraordinary 47% of people with clinical depression also have heightened inflammation.

Inflammatory cytokines are able to induce depression by altering activity in the regions of the brain that control mood, resulting in feelings of negativity and fatigue. This effect has also been seen in cancer therapy. Cytokines are used to treat some cancers and viral infections — and can provoke the onset of major depression in up to 45% of patients.


Inflammation is a common feature of the ageing brain — levels of proinflammatory cytokines increase with age.

Current understanding of the development of Alzheimer’s disease is focussed largely on amyloid-β (Aβ) protein. Deposition of amyloid-β in the brain activates an immune response, including inflammation. If the inflammatory response persists, there may be brain injury and neuronal death, along with dysfunction of the blood-brain barrier, an important protection system which controls what passes in and out of the brain.

Five ways to reduce inflammation naturally

To achieve this, you simply need to remove the causes of inflammation, and increase anti-inflammatory agents. Diet is at the heart of this process. Below is a description of the most common dietary causes of neuroinflammation and how to put them into reverse.

1 Remove sugar, prevent metabolic syndrome

Glucose is pro-inflammatory… A total of 75g glucose intake causes acute oxidative and inflammatory stress’

In 2017, the journal Scientific Reports published a study that examined the link between dietary sugar and depression. The researchers found that men who consumed 67 grams or more of sugar every day were 23% more likely to suffer from depression, over the following 5 years, than men who consumed less than 40 grams of sugar each day.

To get some perspective, consider that just one can of sugar-sweetened soda may contain around 40 grams of added sugar.

In 2016, the US had the highest per capita consumption of sugar in the world, at roughly 126 grams a day. We do comparatively well in the UK, with an average per capita consumption of 93.2 grams a day.

Regular, high intake of sugar can lead to insulin resistance, when the body is no longer able to regulate blood sugar levels normally. Insulin resistance can lead to metabolic syndrome, a condition characterised by high blood pressure, high blood sugar and obesity. Metabolic syndrome puts you at risk of developing cardiovascular disease, stroke, and type 2 diabetes. You are also at risk of developing neurodegenerative disorders.

Because body fat generate cytokines, obesity is itself considered ‘a state of chronic inflammation’, characterised by high IL-6, TNF-α, and CRP levels.

There is a high prevalence of metabolic syndrome in people with psychoneurological disorders, including schizophrenia, bipolar disorder and depression. A systematic review of patients with bipolar disorder found that over 37% had metabolic syndrome.

2 Avoid vegetable oils

Vegetable cooking oils are such a well-established kitchen staple that it is easy to forget that they only entered the culinary landscape a century ago. Sold as healthy alternatives to saturated fat, these novel oils were at the centre of the brave new world of the processed food industry.

The crops most commonly grown to produce these oils are corn, soya, sunflower and canola. The oils extracted from these crops are used liberally in processed foods and ready meals.

These oils all have one common denominator: they are rich in pro-inflammatory, omega-6 polyunsaturated fatty acids (PUFAs). There are two classes of PUFA: omega-6 and omega-3 (n-6 and n-3).

‘Elevated n-6 intakes are associated with an increase in all inflammatory diseases, which is to say virtually all diseases.’

The 2017 U.S. Department of Agriculture report, US Trends in Food Availability, reveals that between 1970 and 2014, salad and cooking oil consumption rose by a staggering 248%.

Both omega-6 and omega-3 PUFAs are metabolised in the body to hormone-like substances called eicosanoids. Generally speaking, omega-6 eicosanoids are pro-inflammatory and omega-3 eicosanoids are anti-inflammatory. Omega-3 eicosanoids work by directly blocking pro-inflammatory omega-6 eicosanoids.

There is nothing intrinsically wrong with omega-6 PUFAs: we need them. They are an essential component of each cell membrane and are involved in brain, reproductive, immune and bone health.

We evolved on, and are genetically adapted to, a diet that provides more or less equal amounts of omega-3 and omega-6. That’s how it was for hundreds of thousands of years.

The problem is that omega-3 and omega-6 fats compete with each other for absorption in the body, including the brain — where excessive omega-6 displaces omega-3.

Now, with the industrialisation of our diets, and the vast quantities of vegetable cooking oils that go into them, the ratio between omega-6 and omega-3 has shifted enormously and we consume up to 25 times more omega-6 than omega-3. This diet reorientation has been described as ‘a total new phenomenon in human evolution.’

‘Diets with high n-6:n-3 PUFA ratios may enhance risk for both depression and inflammatory diseases.’

People with depression have been found to have significantly higher omega-6 to omega-3 ratios, and higher brain cytokines, including TNF-α, IL-6, and sIL-6r levels, than people without depression.

Most trials also report significant improvement in depressive symptoms following supplementation of n-3 PUFAs, compared to controls who are not supplemented.

Instead of vegetable oils, cook with coconut oil, butter, extra virgin olive oil (not a PUFA), lard. And be sure to…..

3 Eat oily fish

Omega-3 PUFAs are found in high amounts in oily fish. Shellfish is also a good source. The two omega-3 fatty acids that are most important to the brain are EPA and DHA EPA is converted to DHA, the most abundant omega-3 fatty acid in the body.

Anti-inflammatory DHA is found abundantly in oily fish, including salmon, mackerel, trout, sardines, herring and fresh (not tinned) tuna. Without regular fish and seafood, it is difficult to obtain sufficient DHA, although meat (and eggs) from animals that are pasture-fed contain small amounts.

If you can’t stomach oily fish, the only vegetarian alternative is micro-algae supplementation. Algae are the original source of DHA, consumed by small fish, in turn consumed by larger fish, and so on up the food chain.

4 Get plant protection

There are two forms of damage to the brain against which certain plant chemicals can offer protection: oxidation and inflammation. One feeds into the other: oxidation leads to inflammation.

Because the brain is 60% fat, it is vulnerable to oxidation, in the same way that oils are vulnerable to rancidity. Substances called free radicals are formed when oxygen is burned to produce energy, but they are also generated by pollution, stress, smoking and certain cooking methods that involve burning food, such as barbecuing.

Antioxidants are the antidotes that disarm those free radicals and reduce the inflammation they create. It is this effect that links them to lower risk of a number of chronic diseases, including Alzheimer’s and depression.

The most effective of those protective chemicals in the brain are the carotenoids.

Carotenoids are made by plants and consumed by animals. Therefore, many plant foods, and some animal-source foods, provide good levels of this phytochemical.

Carotenoids are found in red, yellow and orange plant foods such as carrots, tomatoes, sweet potato, squash, peaches and apricots. They are also found in leafy green vegetables such as spinach and kale (the orange pigment is hidden by the dominant green).

At least 600 carotenoids have been identified, most famously beta carotene. But when it comes to the brain (and eye, an extension of the brain), the most important that we know of is lutein, found in spinach, kale, broccoli, carrots, pumpkin, squash, yellow and red peppers. These are also found in egg yolk.

Muscle meat can be a good source of carotenoids, but only meat from pasture-reared animals. You can see this by the colour of the fat, which tends to be more yellow than that of animals given concentrate feed. Grass-fed steers incorporate significantly higher amounts of total carotenoids in their meat and livers than their grain-fed counterparts.

Lutein works predominantly in the central nervous system. It is concentrated across all brain areas and appears to play a role in protecting cognitive function. During the early stages of Alzheimer’s, there is increased oxidation of fat and increased levels of inflammatory markers. Lutein has been found to be significantly lower in people with mild cognitive impairment, the pre-dementia stage.

5 Deal with dysbiosis

The inflammation that leads to brain dysfunction may be triggered by alterations in the composition and activity of the gut microbiome — the collection of bacteria and other microorganisms that live in your digestive system. Disturbance of the healthy microbiome is called dysbiosis, and dysbiosis causes inflammation and damage to the gut lining, the barrier between your gut and your bloodstream.

Dysbiosis and alterations of the gut microbiome composition have been shown to contribute to the development of several diseases in humans, such as inflammatory bowel disease, type 2 diabetes, metabolic syndrome, obesity, allergies, colorectal cancer, and Alzheimer disease’

Bacteria belong in the gut, where they normally either stay put or move out.

However, when the gut is damaged it can become permeable. Bacteria are able to move into the blood (‘translocation of bacteria’), releasing toxins that trigger an immune response. This response includes the production of cytokines and a substance called lipopolysaccharide (LPS). There is growing evidence that these cytokines and LPS can trigger clinical depression (also known as major depression, or MDD).

The depression-gut highway operates both ways. Just as inflammation is involved in the progression of depression, it has been observed that when clinical depression goes into remission, so too does inflammation.

‘Limited data from human subjects suggest that selected probiotics may reduce depressive symptoms as a result of their anti-inflammatory properties’

Dealing with dysbiosis means altering the composition of the microbiome, increasing the number and activity of friendly bacteria, or probiotics. Probiotics have an anti-inflammatory effect and can restore gut integrity.

For more details of how to increase and feed the friendly bacteria in your gut, see the article:

This gut inflammation can also contribute to the development of dementia. It has been suggested that dementia begins the gut, and that altering the gut microbiome ‘will probably become a new treatment for AD’.

‘Abnormalities in the composition of the intestinal microbiome have also been found in many neurodegenerative diseases, including Alzheimer’s neurodegeneration.’

Diet is key to reducing inflammation and the risk of developing neurodegenerative disease. However, sometimes you need to look at other lifestyle factors that contribute to the inflammatory response, including stress. For further information, see the following articles.

Feed Your Brain

Feed Your Brain explores the link between diet and mental…

Maria Cross

Written by

MSc. Registered nutritionist, specialising in diet and mental health. Visit AllYouCanEat.Org.UK for free brain food guide, or to book a consultation

Feed Your Brain

Explores the link between diet and mental health, and how food influences brain function. How what you eat can change the way you feel, sharpen your focus, and affect your memory.

Maria Cross

Written by

MSc. Registered nutritionist, specialising in diet and mental health. Visit AllYouCanEat.Org.UK for free brain food guide, or to book a consultation

Feed Your Brain

Explores the link between diet and mental health, and how food influences brain function. How what you eat can change the way you feel, sharpen your focus, and affect your memory.

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