We all know about comfort eating... and it's true, certain foods (such as chocolate!) can actually change your brain chemistry and make you feel better..... maybe just for a while.
But can food make us feel worse?
There is increasing evidence that it can.
One study from Granada shows that people who eat a fast food diet (with a lot of fried and commercially baked food) are 50% more likely to suffer from depression.
Depression Linked to Fast Food Diet
Researchers conducting the study found that risk of depression could be predicted in a dose-dependent manner. Lead study author, Dr. Almudena Sanchez-Villegas commented "the more fast food you consume, the greater the risk of depression." The study found that those participants eating the largest amount of fast food and commercially baked goods are more likely to be single, physically inactive and generally exhibit poor dietary habits. Typically these individuals consumed less fruit, nuts, fish, vegetables, and olive oil, and were more likely to smoke or work more than 45 hours per week.
High consumption of commercially baked goods or fried foods subjected to the oil degradation process known as hydrogenation results in trans-fats that have been shown to dramatically increase heart disease risk in past studies. This current research demonstrates that these misshapen and synthetically processed trans-fats interfere with the proper function of chemical neurotransmitters in the brain and alter normal electrical activity necessary for intercellular signaling.
Can Depression & Anxiety Be Caused By Your Diet?
Another study looks more closely at the mechanism which links diet with depression, anxiety and stress.
Two researchers in Montreal have recently published a study showing that a high-fat diet can cause symptoms of both anxiety and depression, most likely through an addictive process.
After 12 weeks, the rodents were given a series of behavioral tests, including “anxiety” tests measuring how they react to a new environment. Stressed animals tend to freeze, or run off to a corner, rather than explore.
Mice given the high-fat diet were much less active, avoided open areas and did little exploring.
In a swim test used to measure “behavioral despair” — a test also widely used by drug companies to screen new anti-depressants — mice had to swim in a glass cylinder filled with water for six minutes.
“Animals that give up quickly — they stop swimming and just float and stop trying to pull themselves out of the beaker — that’s (a sign of) self-helplessness,” Fulton said.
Mice on the high-fat diet “actually gave up” and attempted fewer escapes, she said.
When the researchers studied the rodents’ brains, they found higher levels of corticosterone, a stress hormone. They also saw a difference in the expression of proteins responsible for signaling among neurons in areas of the brain regulating emotions and reward.
The researchers saw this as evidence that a high fat diet affects the emotion-reward circuits of the brain, thereby causing depression and anxiety.
Animals, including humans, exposed to a stressful situation, or even long-term, moderate stress, “will have a reduced physiological stress response” — meaning they’ll feel a sense of relief — “when given the opportunity to eat high-fat food,” said Fulton, a principal investigator at the Centre Hospitalier de l’Universite de Montreal and a member of the Montreal Diabetes Research Centre.
“In the short-term high-fat food feels comforting, but in the long-term, and with increasing adiposity (fat mass) it is having negative effects on mood. We know that diet is a large contributor to the obesity epidemic throughout the world,” Fulton added.
Foods high in saturated fats and sugar are particularly abundant, she said.
The extra fat given to the mice was mostly saturated fat.
"The type of fat might make a difference," said Fulton. "Other research has shown that food high in saturated fat — such as hamburgers, bacon, pork sausages, cheese, butter, and ice cream — cause inflammation in the body, including the brain, and that this inflammation may lead to 'negative mood states.'"
Fulton’s lab found evidence that rodents consuming the same total amount of fat, but “good fat” like olive oil, experience less anxiety.
Or check out the original reference:
"Diet-induced obesity promotes depressive-like behaviour that is associated with neural adaptations in brain reward circuitry"
S Sharma and S Fulton
International Journal of Obesity, May 2012, doi: 10.1038/ijo.2
From this study we can see that mice fed this high fat diet show symptoms of anxiety and depression, as well as higher levels of stress hormones, when put in stressful situations.
If you wonder whether anxiety and depression can be caused by your diet, the answer has to be "Yes".
So your first step in overcoming anxiety or depression could be to take a close look at your diet, and how it might be affecting your mood.