How food affects mood and psyche ?
Scientists are gathering more and more evidence that diet can influence the psyche and even alleviate the symptoms of many diseases.
The gut communicates with the brain through the gut-brain axis, a signaling system between organs. Microbes in the gut produce neurotransmitters such as serotonin and dopamine that regulate our mood and emotions. A growing body of research shows that nutrition can affect mental health through these mechanisms.
As psychiatrist Drew Rumsey says, this is good news for all of us: “We can’t control our genes, we can’t choose our parents and whether traumatic events happen to us. But we can control what we eat and thus take care of our brain daily.”
Of course, Ramsey’sRamsey’s words cannot be completely relied upon: a person cannot always control his diet, if only because of financial problems. In addition, research on the relationship between microbes in the gut and the brain has its limitations. For example, it is unknown whether the relationship between nutrition and the brain is causal or correlational. Does the microbiome influence the mental state or vice versa? More research is needed before psychiatric organizations give clear diet recommendations to maintain mental health. Nevertheless, the first conclusions can already be drawn.
Here are some of the conclusions reached by scientists in recent studies.
A Mediterranean diet may reduce symptoms of depression.
This is not even a diet but a whole cuisine based on familiar products for Greece, Italy, and Spain inhabitants. Instead of animal fats – vegetables, preferably olive oil. Instead of pork and beef – chicken and fish. Plus plenty of legumes, whole grains, fruits, vegetables, and dairy products. Studies show that people with depression on the Mediterranean diet recover from it faster.
Here’s how it was tested: American scientists collected 67 people with clinical depression and divided them into two groups. One group began to consult a nutritionist: he taught the participants the principles of the Mediterranean diet. The second group was a social support worker who gave no dietary advice. All participants continued to take antidepressants if they were prescribed.
The dietitian’s group has seriously changed the diet. They ate muesli and oatmeal, small amounts of lean meat and fish, and plenty of vegetables, fruits, and grains. They also gave up pizza, sugary cereal, sausages, and ham.
After 12 weeks, all participants were tested for their level of depression. In both groups, there was a decrease in the symptoms of the disease. But in the nutritionist group, progress was more noticeable: 30% of participants stopped experiencing symptoms of depression. In the second group, there were only 8% of them.
This is not the only positive effect that participants observed. Before switching to the diet, they spent an average of $138 per week on food, and after – $112. The hamburgers, pizza, and sweets they had eaten before were more expensive.
Later, other studies showed the effectiveness of the Mediterranean diet for depression. But exactly how it works is still unknown. Perhaps the point is tryptophan, an amino acid-rich in many “Mediterranean” foods: cheese, nuts, Yogurt, fish, soybeans, and vegetables. The brain needs this amino acid to produce serotonin.
At the same time, apparently, it is not necessary to switch to the Mediterranean diet completely for a positive effect: even small changes will have an effect. One study tracked the mental state of 12,400 people over six years after they increased their fruit and vegetable intake. After two years of the experiment, almost all participants rated their satisfaction with life as significantly higher. But it was important how much they ate fruits and vegetables. The greatest positive effect on the psyche was when respondents ate eight servings daily.
Excess Sugar Can Affect Productivity and Concentration
WHO recommends reducing the amount of added sugar in the diet, especially sweets and soda. But it’s not just about the risks of obesity and caries.
The main carrier of calories in sugar is glucose. Our cells use it in combination with oxygen to generate energy. But on their own, glucose molecules cannot penetrate cell membranes; for this, the hormone insulin is needed – it gives the cells a command to let in glucose from the blood. If too much glucose is supplied with food, then the body does not have time to produce enough insulin, and excess glucose continues to circulate in the blood. According to one hypothesis, this, among other things, leads to inflammation. And inflammation can negatively impact cognition.
In 2019, Chinese scientists analyzed the effects of added sugar on children aged 6 to 12. Tests showed that students who drank soft drinks or tea with sugar twice a week or more often performed 1.62 times worse on school assignments than their peers who avoided such drinks. In addition, sweet lovers are more likely to suffer from attention deficit hyperactivity disorder.
In another experiment, the scientists fed rats a standard diet and a diet high in sugars. Those who were fed sweets showed signs of inflammation in the hippocampus. The same mechanism operates in humans.
But, at least up to a certain point, these changes are reversible if a person switches to a low-sugar diet, such as the Mediterranean one. The participants in the experiment who switched to this type of diet and began to play sports significantly improved their cognitive abilities and especially their memory in three years. But the effect can come even faster. Some researchers have pointed out that even seven weeks without added sugar improves memory.
Heavily processed foods may increase the risk of depression.
A diet commonly referred to as a Western diet – high in refined foods, processed foods, and saturated fats – increases the risk of many mental disorders, including depression. Many studies have already confirmed this with large samples.
For example, French scientists tracked the fate of 27,000 people who did not have depression when the study began. Participants were required to submit three daily nutrition reports every six months. According to them, scientists have identified typical patterns of eating behavior. Separately, they paid attention to heavily processed food – with various flavor enhancers and sauces, pizza, burgers, sweets, instant noodles, and ready-made meals from the supermarket that need to be warmed up.
As a result, 8% of the participants were diagnosed with depression during the experiment. And many of them ate mainly processed food. Researchers say that the chance of having depressive symptoms increases by 21% for every 10% increase in the amount of processed food in the diet. Still, the study has limitations. For example, scientists cannot completely exclude the influence of other factors on the development or reduction of symptoms of depression. They could have been triggered by events in the participants’ lives, not their diet.
But, as usual, scientists do not fully understand why processed food can harm health. One of the main hypotheses is that the body lacks important nutrients and disrupts the processes in which these substances are involved. Zinc deficiency creates problems in the transport of dopamine, which affects a person’s mood and mental stability.
Another problem is the non-nutrients used in cooking, such as emulsifiers and molecules that form when food is heated to high temperatures. They impoverish the gut microbiome and cause inflammation, which can ultimately affect the functioning of the central nervous system and cause symptoms of depression.
Boredom can lead to obesity.
When a person is doing boring, uninteresting work, he often takes breaks for a snack. The same thing happens with people whose lives are monotonous and boring. If a person is apathetic, he is not interested in anything; he is looking for meaning in food.
Why is this happening? The fact is that to maintain a good mood, a person needs dopamine, which the body produces at the time of receiving a subjectively pleasant experience.
If you are interested in the work that you are doing and you enjoy it, then the process of work itself stimulates the production of dopamine. If you do not like your job, then you will look for this incentive on the side. The easiest way to have fun is delicious food.
The result is an increase in body weight. Scientists from Ireland and England argue that obesity is more common among those who regularly experience boredom than other negative emotions. The researchers asked the participants to write daily in a diary for a week about how easy it was for them to focus on work today and whether they had a good day. The degree of satisfaction was required to be assessed in points. At the same time, it was necessary to evaluate positive and negative emotions over the past day and keep a food diary.
It turned out that with an increase in the level of boredom by about 1.3 times, the participants in the experiment consumed 100 kilocalories more per day.
Of course, a week is too short a time to draw far-reaching conclusions, but these scientists’ other small experiments confirmed these conclusions. In one of them, 44 students took part, who were divided into two groups: one was shown a sad film, the other a boring video clip. And they offered to eat sweet crackers or cherry tomatoes while watching. Those who watched the boring video were likelier to choose cookies than cherry tomatoes. That is, boredom causes a desire to eat “harmful” food, which gives pleasure, and not “healthy,” which in itself is rated as “boring.”
The microbiome may influence the feeling of fear.
A key element of gut health is a rich microbiome, a wide variety of bacteria living in it. Monotonous and highly processed food leads to the impoverishment of the microbiome. And this, in turn, can greatly affect the mental state and, as recent studies show, the feeling of fear.
The study was carried out on mice. Some had a normal microbiome, while others had a depleted microbiome. Scientists scared the mice: they turned on a sound signal, followed by an electric shock. But soon, they stopped using the current and just turned on the signal. Mice with a normal microbiome quickly stopped responding to it, while mice with a depleted microbiome continued to freeze when they heard the sound.
Then the researchers looked at what the medial prefrontal cortex looks like in these mice: she is responsible for fear reactions. In those with a depleted microbiome, some neurons looked different: they had fewer special spikes associated with learning. The scientists speculated that microbe-depleted mice could not learn not to be afraid.
Later, a small study on children confirmed these results. Scientists tracked how one-year-old children reacted to the appearance of a stranger in a mask. Children who had a depleted microbiome at the age of one month were more afraid of it.
More research is needed to confirm a pattern between microbiome diversity and childhood fear and to rule out the influence of other factors on a child’s reactions.
The study people think this fear can lead to depression, anxiety, and trouble expressing feelings.
The baby’s microbiome depends on many factors, including the mother’s diet during pregnancy and breastfeeding. Yogurt, kefir, kimchi, and sauerkraut help maintain a diversity of bacteria in the gut. This diversity can benefit a child’s health, from an efficient immune system to a reduced risk of psychological disorders. And, of course, it can increase the stress resistance of the mother.