Can an Anti-Inflammatory Diet Help Depression?

Depression affects more than 150 million people worldwide, making it a leading cause of losing healthy years of life as a result of disability. By 2020, depression may be second only to heart disease as the leading cause of healthy years of life lost. Why is depression so common? Well it’s said, “Nothing in Biology makes sense except in the light of evolution.” But why would we evolve to get depressed?

Depression presents a baffling evolutionary puzzle. Despite its negative effects, it remains common and heritable, meaning a large part of the risk is passed through our genes. Presumably, there must be some kind of adaptive benefit or it would have been naturally selected against. Could depression be an evolutionary strategy to provide a defense against infection?

Infection has been the leading cause of mortality throughout human history, making it a critical force in natural selection. Indeed, because of infections, our average life expectancy before the industrial period was only 25 years, and it was not uncommon for half of our children to die without reaching adulthood.

When we become infected, there is a surge of inflammation as our body mounts a counter attack. Our body responds by feeling lousy, sick, weak, tired, and slow. We don’t want to socialize. The only thing we do want to do is sleep. These symptoms are similar to the ones we experience during depression and are great for fighting infection. Slowing down not only helps us conserve energy to put up a good fight, it also reduces social contact so we don’t infect others. We see this protective phenomenon in other social animals, like honeybees and mole rats, who feel compelled to crawl off and die alone to reduce the risk of infecting the rest of their community. Humans have even evolved to think poop and decaying flesh don’t smell good to keep us safe from infection.

To explore the relationship between inflammation and mental health, we have to look back to 1887, when this connection was first noted by Dr. Julius Wagner-Jauregg, the only psychiatrist to ever win the Nobel Prize. What evidence have we accumulated in the past century that inflammation causes depression? We know that people who are depressed have raised inflammatory markers, such as C-reactive protein and that inflammatory illnesses are associated with greater rates of major depression. Indeed, we find depression in even more benign inflammatory conditions such as asthma and allergies. This is important as it suggests that the mood symptoms may be directly tied to the inflammation and are not simply the result of “feeling bad about having a terrible disease.”

We also know that you can induce depression by inducing inflammation. For example, when we give interferon for certain cancers or chronic infection, up to 50 percent of people go on to suffer major depression. Even just giving a vaccine can cause enough inflammation to trigger depressive symptoms. Taken together, these studies “are strongly suggestive of inflammation being a causative factor of mood symptoms.”

Can an anti-inflammatory diet help prevent depression? We didn’t know until researchers followed the diets of about 43,000 women without depression for approximately 12 years. Those who ate a more inflammatory diet, characterized by more soda, refined grains and meat, became depressed. “This finding suggests that chronic inflammation may underlie the association between diet and depression.”

Normally, we think of omega-3s as anti-inflammatory, but researchers found fish to be pro-inflammatory, associated with increased C-reactive protein levels. This is consistent with recent findings that omega-3s don’t seem to help with either depression or inflammation. As I discuss in my video, the most anti-inflammatory diet is a plant-based diet, which is capable of cutting C-reactive protein levels by an impressive 30 percent within two weeks, perhaps because of the anti-inflammatory properties of the antioxidants found in plants.

When free radicals cause oxidative damage, it may cause an autoimmune response in the body by changing the chemical structures of otherwise ubiquitous molecules to generate new structures that the body attacks as foreign. For example, when LDL cholesterol gets oxidized, our body creates antibodies against it that attack it. Likewise, clinical depression can be accompanied by increased oxidative stress and the autoimmune inflammatory responses it creates. Free radicals may thus lead to autoimmune inflammation.

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations—2015: Food as Medicine: Preventing and Treating the Most Dreaded Diseases with Diet, and my latest, 2016:How Not to Die: The Role of Diet in Preventing, Arresting, and Reversing Our Top 15 Killers.

Related:

Fighting Depression With Antioxidants
Exercise vs. Drugs for Depression
Boost Serotonin Naturally

92 comments

Margie FOURIE
Margie FOURIEabout a month ago

Thank you

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Carol M
Carol Mabout a month ago

I stopped reading after "humans have even evolved to think poop and decaying flesh smell bad..."

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Kay M
Kay Mabout a month ago

noted.

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Lorraine A
Lorraine Andersenabout a month ago

A very good reason for one to change their diet. Thanks for posting

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Karren S.
Karren S.about a month ago

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Elaine W
Elaine Wabout a month ago

Very good to know.

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Lisa M
Lisa Mabout a month ago

Noted.

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Lisa M
Lisa Mabout a month ago

Noted.

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Melissa DogLover
Melissa DogLoverabout a month ago

noted... thx

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Donna T
Donna Tabout a month ago

thank you

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