As people across the globe grappled with higher levels of
stress, depression and
anxiety this past year, many turned to their favorite
comfort foods: ice cream, pastries, pizza, hamburgers. But studies in recent
years suggest that the sugar-laden and high-fat foods we often crave when we
are stressed or depressed, as comforting as they may seem, are the least likely
to benefit our mental health. Instead, whole foods such as vegetables, fruit,
fish, eggs, nuts and seeds, beans and legumes and fermented foods like yogurt
may be a better bet.
اضافة اعلان
The findings stem from an emerging field of research known as
nutritional psychiatry, which looks at the relationship between diet and mental
wellness. The idea that eating certain foods could promote brain health, much
the way it can promote heart health, might seem like common sense. But
historically, nutrition research has focused largely on how the foods we eat
affect our physical health, rather than our mental health. For a long time, the
potential influence of food on happiness and mental well-being, as one team of
researchers recently put it, was “virtually ignored.”
But over the years, a growing body of research has provided intriguing
hints about the ways in which foods may affect our moods. A healthy diet
promotes a healthy gut, which communicates with the brain through what is known
as the gut-brain axis. Microbes in the gut produce neurotransmitters like
serotonin and dopamine, which regulate our mood and emotions, and
the gutmicrobiome has been implicated in mental health outcomes. “A growing body of
literature shows that the gut microbiome plays a shaping role in a variety of
psychiatric disorders, including major depressive disorder,” a team of
scientists wrote in the Harvard Review of Psychiatry last year.
Large population studies, too, have found that people who eat a
lot of nutrient-dense foods report less depression and greater levels of
happiness and mental well-being. One such study, from 2016, that followed
12,400 people for about seven years found that those who increased their
consumption of fruits and vegetables during the study period rated themselves
substantially higher on questionnaires about their general levels of happiness
and life satisfaction.
Large observational studies, however, can show only
correlations, not causation, which raises the question: Which comes first? Do
anxiety and depression drive people to choose unhealthy foods, or vice versa?
Are people who are happy and optimistic more motivated to consume nutritious
foods? Or does a healthy diet directly brighten their moods?
The first major trial to shed light on the food-mood connection
was published in 2017. A team of researchers wanted to know whether dietary
changes would help alleviate depression, so they recruited 67 people who were
clinically depressed and split them into groups. One group went to meetings
with a dietitian who taught them to follow a traditional Mediterranean-style
diet. The other group, serving as the control, met regularly with a research
assistant who provided social support but no dietary advice.
At the start of the study, both groups consumed a lot of sugary
foods, processed meats and salty snacks, and very little fiber, lean proteins
or fruits and vegetables. But the diet group made big changes. They replaced
candy, fast food and pastries with whole foods such as nuts, beans, fruits and
legumes. They switched from white bread to whole grain and sourdough bread.
They gave up sugary cereals and ate muesli and oatmeal. Instead of pizza, they
ate vegetable stir-fries. And they replaced highly processed meats like ham,
sausages and bacon with seafood and small amounts of lean red meats.
Importantly, both groups were counseled to continue taking any
antidepressants or other medications they were prescribed. The goal of the
study was not to see if a healthier diet could replace medication, but whether
it could provide additional benefits like exercise, good sleep and other
lifestyle behaviors.
After 12 weeks, average depression scores improved in both
groups, which might be expected for anyone entering a clinical trial that
provided additional support, regardless of which group you were in. But
depression scores improved to a far greater extent in the group that followed the
healthy diet: roughly a third of those people were no longer classified as
depressed, compared to 8 percent of people in the control group.
The results were striking for a number of reasons. The diet
benefited mental health even though the participants did not lose any weight.
People also saved money by eating the more nutritious foods, demonstrating that
a healthy diet can be economical. Before the study, the participants spent on
average $138 per week on food. Those who switched to the healthy diet lowered their
food costs to $112 per week.
The recommended foods were relatively inexpensive and available
at most grocery stores. They included things like canned beans and lentils,
canned salmon, tuna and sardines, and frozen and conventional produce, said
Felice Jacka, the lead author of the study.
“Mental health is complex,” said Jacka, the director of the Food
& Mood Centre at Deakin University in Australia and the president of the
International Society for Nutritional Psychiatry Research. “Eating a salad is
not going to cure depression. But there’s a lot you can do to lift your mood
and improve your mental health, and it can be as simple as increasing your
intake of plants and healthy foods.”
A number of randomized trials have reported similar findings. In
one study of 150 adults with depression that was published last year,
researchers found that people assigned to follow a Mediterranean diet
supplemented with fish oil for three months had greater reductions in symptoms
of depression, stress and anxiety after three months compared to a control
group.
Still, not every study has had positive results. A large,
yearlong trial published in The Journal of the American Medical Association (JAMA)
in 2019, for example, found that a Mediterranean diet reduced anxiety but did
not prevent depression in a group of people at high risk. Taking supplements
such as vitamin D, selenium and omega-3 fatty acids had no impact on either
depression or anxiety.
Most psychiatric professional groups have not adopted dietary
recommendations, in part because experts say that more research is needed
before they can prescribe a specific diet for mental health. But public health
experts in countries around the world have started encouraging people to adopt
lifestyle behaviors like exercise, sound sleep, a heart-healthy diet and
avoiding smoking that may reduce inflammation and have benefits for the brain.
The Royal Australian and New Zealand College of Psychiatrists issued clinical
practice guidelines encouraging clinicians to address diet, exercise and
smoking before starting patients on medication or psychotherapy.
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