Sharp Brains: Brain Fitness and Cognitive Health News

Neuroplasticity, Brain Fitness and Cognitive Health News


It’s World Mental Health Day today: Let’s review how a healthy diet can promote mental well-being


Should you eat an apple—or a bag of Ore­os? Go to McDonald’s—or the veg­e­tar­i­an restau­rant on the cor­ner?

When we make these every­day food choic­es, many of us think first of our phys­i­cal health and appear­ance. But there’s anoth­er fac­tor we may want to con­sid­er in pick­ing foods: their impact on our men­tal health.

A grow­ing body of research is dis­cov­er­ing that food doesn’t just affect our waist­line but also our moods, emo­tions, and even longer-term con­di­tions like depres­sion. Which makes sense, after all. Our brains are phys­i­cal enti­ties, run­ning on the ener­gy that we put into our bod­ies, affect­ed by shifts in our hor­mones, blood sug­ar lev­els, and many oth­er bio­log­i­cal process­es.

Although there are many unan­swered ques­tions, the research to date can give us some guid­ance when we’re hunt­ing for an after­noon snack. What we know so far can be summed up, more or less, as this: Whole-food diets heavy on the fruits, veg­eta­bles, and unprocessed pro­tein can lift our moods and pro­tect us from depres­sion, while too much junk food and sug­ar may put our men­tal health at risk.

One-third of adults in Amer­i­ca eat fast food on a giv­en day. Many of us see French fries and choco­late cake as treats to cheer us up when we’re feel­ing down. But per­haps our per­spec­tive on food needs an update. With a few sim­ple dietary changes, you might be able to improve both your mind and your mood.

Can your diet protect you from depression?

A paper pub­lished this year in Psy­cho­so­mat­ic Med­i­cine offers one of the most up-to-date snap­shots of diet and men­tal health—specifically, how diet might play a role in depres­sion.

The research team scoured aca­d­e­m­ic jour­nals for exper­i­ments that had asked peo­ple to change their diets and had mea­sured the effects. In all, they found 16 stud­ies with near­ly 46,000 par­tic­i­pants from the Unit­ed States, Aus­tralia, and Europe, rang­ing from ages 21 to 85.

The exper­i­ments were quite diverse, pre­scrib­ing a vari­ety of diets to boost nutri­ent intake, reduce fat intake, or encour­age weight loss. One group went on a veg­an diet, while oth­ers restrict­ed calo­ries; many peo­ple loaded up on fruits and veg­eta­bles while avoid­ing meat and processed foods. Some peo­ple attend­ed nutri­tion class­es togeth­er, while oth­ers got per­son­al­ized coun­sel­ing or sim­ply took home a set of guide­lines. They fol­lowed the diet for any­where from a cou­ple weeks to a few years.

The results? Over­all, adopt­ing a health­i­er diet did lead to reduced symp­toms of depression—less hope­less­ness, trou­ble sleep­ing, and dis­con­nec­tion from others—compared to engag­ing in oth­er self-improve­ment activ­i­ties or going about life as usu­al.

Includ­ing more non-processed foods, more whole foods—fruits, vegetables—is very ben­e­fi­cial in terms of your psy­cho­log­i­cal well-being, par­tic­u­lar­ly mood,” says Joseph Firth, the lead author of the paper and a research fel­low at West­ern Syd­ney Uni­ver­si­ty.

But the results got more inter­est­ing when the researchers start­ed to dig into the details, to see for whom and under what con­di­tions our diet might keep the bad feel­ings at bay.

Who benefits most from a healthy diet?

First off, diet pro­grams tend­ed to work bet­ter for women. Why? Besides dif­fer­ences in hor­mones and metab­o­lism, Firth con­jec­tured, women seem to be in a bet­ter posi­tion to ben­e­fit. They’re more like­ly to be depressed, and, he says, they might have more dis­ci­pline at fol­low­ing diets than men.

Also, the diet pro­grams worked bet­ter if a dietary pro­fes­sion­al admin­is­tered them—probably because the rec­om­men­da­tions were sounder and the par­tic­i­pants (believ­ing in the dietitian’s author­i­ty) were more apt to fol­low them, Firth says. An ear­li­er review of diet stud­ies came to a sim­i­lar con­clu­sion.

One of the strongest stud­ies in the col­lec­tion sug­gest­ed that diet could help peo­ple who were right in the midst of a major depres­sive episode. Researchers recruit­ed 67 depressed peo­ple with poor diets, half of whom were instruct­ed to fol­low a healthy, Mediter­ranean-style diet favor­ing whole grains, fruit and veg­eta­bles, legumes, low-fat dairy, nuts, fish, lean red meat, chick­en, eggs, and olive oil while reduc­ing sweets, refined grains, fried and fast food, processed meats, and sug­ary drinks. Across 12 weeks, they attend­ed sev­en ses­sions with a dietit­ian who helped them set diet goals and stay moti­vat­ed; they also received recipes, meal plans, and a ham­per of food.

The oth­er half attend­ed ses­sions on a sim­i­lar sched­ule. But rather than get­ting diet advice, they sim­ply spent time with a research assis­tant who was trained to be sup­port­ive of them—talking about top­ics they were inter­est­ed in, like sports and hob­bies, or play­ing games with them for an hour.

Despite how ben­e­fi­cial social inter­ac­tion is, the diet group fared bet­ter than the social sup­port group. After 12 weeks, they had reduced their depres­sion and anx­i­ety more—and they were about four times more like­ly to expe­ri­ence a remis­sion from their depres­sion. The more they improved their diet, the more their depres­sion lift­ed.

What about anx­i­ety? In that par­tic­u­lar study, anx­i­ety did go down—but on aver­age, across all 16 stud­ies, health­i­er diets didn’t seem to make peo­ple less anx­ious. That actu­al­ly strength­ens the case that diet can direct­ly affect depres­sion, says Firth. If the results were sim­ply due to peo­ple feel­ing proud and accom­plished with their new healthy habits, you would expect them to feel bet­ter all around, includ­ing less anx­ious. The fact that only their symp­toms of depres­sion shift­ed means that some­thing deep­er may be going on.

What could that be? We don’t know for sure yet, but there are a vari­ety of bio­log­i­cal process­es that seem to be both influ­enced by diet and involved in men­tal health. It’s pos­si­ble that cer­tain diets may increase inflam­ma­tion and oxida­tive stress, and dis­rupt our mito­chon­dr­i­al func­tion and neu­ron pro­duc­tion, in ways that could put us at risk for psy­cho­log­i­cal prob­lems. Our gut microbiome—the colony of microor­gan­isms in our intestines that is increas­ing­ly being stud­ied as a con­trib­u­tor to men­tal health—may inter­act with many of these process­es. Also, says Firth, fol­low­ing a diet can bring us a sense of self-esteem and self-effi­ca­cy, as well as poten­tial weight loss—which can influ­ence our minds, too.

But there are still a lot of unknowns. As Pro­fes­sor Almu­de­na Sanchez-Vil­le­gas of the Uni­ver­si­ty of Las Pal­mas de Gran Canaria points out, the find­ings from diet exper­i­ments are not con­sis­tent. Many of the diet pro­grams in Firth’s review didn’t help alle­vi­ate depres­sion, nor did a new­er one that also includ­ed mul­ti­vi­t­a­mins. Researchers have much more to explore.

Can your diet make you happy?

It’s one thing to say that our diet might pro­tect us from depres­sion and oth­er men­tal health issues. But could the foods we eat actu­al­ly move the nee­dle toward more pos­i­tive emo­tions and hap­pi­ness?

In a 2017 exper­i­ment pub­lished in PLoS ONE, researchers recruit­ed 171 young adults with a diet low in fruits and veg­eta­bles, which meant three or few­er serv­ings per day. These 18 to 25 year olds were split into groups: One got a bas­ket of car­rots, apples, and kiwi or oranges and was told to eat an extra serv­ing of fruit and an extra serv­ing of veg­eta­bles per day; anoth­er didn’t change what they ate.

Every day for two weeks, they answered ques­tions about their feel­ings, mood, and hap­pi­ness. At the begin­ning and the end of the exper­i­ment, they also filled out sur­veys about their anx­i­ety and depres­sion.

The diet group only man­aged to add one extra serv­ing of fruit and veg­eta­bles to their dai­ly diet. But that made a dif­fer­ence: Com­pared to every­one else, they had more ener­gy, curios­i­ty, cre­ativ­i­ty, and moti­va­tion; and they felt more engaged and pur­pose­ful in their lives overall—a greater sense of flour­ish­ing.

Sur­pris­ing­ly, though, the diet didn’t seem to change their mood or their feel­ings of depres­sion and anx­i­ety. That might be because the exper­i­ment was so short, the authors believe; while diet can give us a pos­i­tive boost pret­ty quick­ly, it’s pos­si­ble that men­tal health prob­lems take longer to show up.

The accu­mu­la­tion of fac­tors such as low vital­i­ty, reduced moti­va­tion, and poor­er socio-emo­tion­al flour­ish­ing may pre­cip­i­tate the devel­op­ment of psy­cho­log­i­cal ill-being over time,” write researcher Tam­lin S. Con­ner and her col­leagues.

Sim­i­lar­ly, in a short pilot study from 2011, a Mediter­ranean diet seemed to boost people’s feel­ings of contentment—but didn’t improve their depres­sion or anx­i­ety.

Twen­ty-five women were sur­veyed on their feel­ings of depres­sion, anx­i­ety, anger, calm, and con­tent­ment. Some con­tin­ued eat­ing as usu­al for 10 days, while the rest adopt­ed a Mediter­ranean diet (this time with no red meat). After anoth­er round of sur­veys, the researchers found that the women on the Mediter­ranean diet felt more con­tent.

The nutri­ents con­sumed in every­day diets are impor­tant for indi­vid­u­als’ mood,” write Lau­ra McMil­lan and her col­leagues.

Of course, this was a very small study—and the women may have sim­ply felt sat­is­fied about doing some­thing good for their health. Indeed, in a few oth­er stud­ies, a healthy diet didn’t make peo­ple hap­pi­er. For exam­ple, fol­low­ing a Mediter­ranean diet for 12 weeks didn’t seem to boost people’s mood, well-being, or sense of self-effi­ca­cy com­pared to receiv­ing social sup­port.

Despite how catchy it sounds, it might be too ear­ly to say that any par­tic­u­lar diet is going to bring us hap­pi­ness.

Eating for well-being

So, how should all this research inform our gro­cery list?

Most researchers are only will­ing to say that diet does seem to influ­ence our men­tal health in some way, although they’re not sure exact­ly how. “There’s no real evi­dence to sug­gest that one diet works bet­ter than anoth­er,” says Firth.

How­ev­er, the big pic­ture is rea­son­ably clear: Try to get enough fruits and vegetables—and avoid junk food.

Sup­port­ing that per­spec­tive, one paper reviewed the results of anoth­er 16 stud­ies and found no dif­fer­ences between two rel­a­tive­ly healthy diets. Peo­ple who were eat­ing a typ­i­cal West­ern diet of fast food, salty snacks, desserts, and soft drinks became more depressed over time. But eat­ing a clas­sic healthy diet high in fruit and veg­eta­bles, seafood, and whole grains or a more Mediter­ranean diet—which includes lots of olive oil and more legumes, meat, dairy, and alcohol—both seemed to pro­tect against depres­sion.

Since many of the research find­ings are stronger for women, Firth does have one fur­ther tip.

If you’re female, then you will ben­e­fit from adopt­ing a health­i­er diet in gen­er­al and you don’t need to wor­ry about what type of spe­cif­ic diet you’re adopt­ing,” he says. “If you’re a man and you’re not over­weight, prob­a­bly don’t both­er.”

In oth­er words, at least as far as our men­tal health goes, we can stop obsess­ing about hav­ing a per­fect­ly con­sis­tent diet—or whether we should go paleo or keto—and instead focus on cul­ti­vat­ing healthy but sus­tain­able eat­ing habits. That’s the area where Firth wants to see more research, too, to fig­ure out how to help peo­ple make lifestyle changes that last.

It’s more impor­tant to actu­al­ly stick to any healthy diet than it is to try and go for some aspi­ra­tional per­fect one that’s ulti­mate­ly unfea­si­ble or dis­gust­ing for you to stick to,” he says.

– Kira M. New­man is the man­ag­ing edi­tor of Greater Good. Based at UC-Berke­ley, Greater Good high­lights ground break­ing sci­en­tif­ic research into the roots of com­pas­sion and altru­ism. Copy­right Greater Good.

Relat­ed arti­cles:

Leave a Reply...

Loading Facebook Comments ...

Leave a Reply

Categories: Cognitive Neuroscience, Health & Wellness

Tags: , , ,

Search in our archives

About SharpBrains

As seen in The New York Times, The Wall Street Journal, BBC News, CNN, Reuters,  SharpBrains is an independent market research firm tracking how brain science can improve our health and our lives.

Follow us and Engage via…

RSS Feed

Watch All Recordings Now (40+ Speakers, 12+ Hours)