Carmine Pariante may be the most important scientist you’ve never heard of. He is a professor of biological psychiatry at King’s College, London, as well as being warm, charming, Catholic by upbringing and an Italian originally from Naples. For the past decade, his research has been at the cutting edge of the science of happiness. In particular, his work on the links between inflammation and depression is fascinating for those, like me, who have a history of anxiety.

The jury is still out as to the exact causes of depression, but some scientists like Prof Pariante are questioning the simplistic explanation that blames “a chemical imbalance in our brains” and low levels of serotonin in particular. While serotonin has some role to play, exactly what is happening when we succumb to the Black Dog may be more nuanced and different for each of us and is now thought to affect the whole body rather than just the brain.

One new explanation is that those who suffer from low mood may also experience high levels of chronic inflammation throughout the body as well as in the brain. This new explanation is particularly encouraging for the 30 per cent of patients who do not respond to currently available antidepressants, as they may benefit the most from novel antidepressant treatments that decrease inflammation. Prof Pariante is examining a range of such potential new treatments in his research programme.

Processed foods and trans fats increase inflammation and create more fatty or adipose tissue, which is also a source of inflammation – a vicious cycle. Stress can be to blame for inflammation too: studies show that if you stress mice, for example, you also create a stressed and inflamed digestive system.

Evidence from animal studies suggests that when our guts are inflamed it can affect our mood. Some of the compounds produced by the bacteria in our gut can also increase inflammation, and if too many of them escape into the rest of the body from the gut, they may cause inflammation elsewhere, eventually leading to depression.

Yet there may be a delightfully simple nutritional answer. Prof Pariante’s study in 2014 followed 152 patients who were at risk of depression because of the high levels of inflammation. He found that omega-3 fatty acids reduced the rates of depression.

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