For years neu­ro­sci­en­tists have been try­ing to cor­rect the old assump­tion that our minds are reducible to our brains. Research into what is known as the gut micro­bio­me, for exam­ple, has shown that mood and men­tal health are inti­mate­ly linked to the func­tion­ing of an ecosys­tem of microor­gan­isms with­in the diges­tive sys­tem. As researchers write in the Jour­nal of Neu­ro­science, “exper­i­men­tal changes to the gut micro­bio­me can affect emo­tion­al behav­ior and relat­ed brain sys­tems [and] may play a patho­phys­i­o­log­i­cal role in human brain dis­eases, includ­ing autism spec­trum dis­or­der, anx­i­ety, depres­sion, and chron­ic pain.”

Even Parkinson’s Dis­ease has been linked to gut bac­te­ria in stud­ies per­formed by micro­bi­ol­o­gist Sarkis Maz­man­ian, who points out that “70 per­cent of all neu­rons in the periph­er­al ner­vous system—that is, not the brain or spinal cord—are in the intestines, and the gut’s ner­vous sys­tem is direct­ly con­nect­ed to the cen­tral ner­vous sys­tem through the vagus nerve.” Our guts also sup­ply the brain with fuel, and it requires a “con­stant sup­ply,” notes Dr. Eva Sel­hub at the Har­vard Health Blog. “That ‘fuel’ comes from the foods you eat—and what’s in that fuel makes all the dif­fer­ence. Put sim­ply, what you eat direct­ly affects the struc­ture and func­tion of your brain and, ulti­mate­ly, your mood.”

Such find­ings have giv­en rise to the emerg­ing field of Nutri­tion­al Psy­chi­a­try, which you can hear described in the TEDx talk above by clin­i­cal psy­chol­o­gist Julia Ruck­lidge. Ini­tial­ly taught that “nutri­tion and diet were of triv­ial sig­nif­i­cance for men­tal health,” Ruck­lidge, like most of her col­leagues, believed that “only drugs and psy­chother­a­py could treat these seri­ous con­di­tions.” But after encoun­ter­ing evi­dence to the con­trary, she decid­ed to do her own stud­ies. Begin­ning at around 5:30, she presents com­pelling evi­dence for a dra­mat­ic reduc­tion in rates of ADHD, PTSD, depres­sion, and psy­chosis after dietary treat­ments.

That’s not to say that drugs and psy­chother­a­py do not play impor­tant roles in treat­ment, nor that they should be sup­plant­ed by a nutri­tion-only approach. But it does mean that nutri­tion­al treat­ments are shown by many fields of study to be effec­tive and per­haps essen­tial, for rea­sons con­sis­tent with wide­spread knowl­edge about the body and brain. “It is now known,” for exam­ple, as Joyce Cavaye reports at the Inde­pen­dent, “that many men­tal health con­di­tions are caused by inflam­ma­tion in the brain which ulti­mate­ly caus­es our brain cells to die.” Inflam­ma­tion is, in part, caused by “a lack of nutri­ents such as mag­ne­sium, omega‑3 fat­ty acids, pro­bi­otics, vit­a­mins and min­er­als… all essen­tial for the opti­mum func­tion­ing of our bod­ies.”

Diets con­sist­ing pri­mar­i­ly of high­ly processed foods and sug­ars are also a cause of inflam­ma­tion. “Mul­ti­ple stud­ies have found a cor­re­la­tion between a diet high in refined sug­ars and impaired brain func­tion,” Dr. Sel­hub writes. These diets pro­mote a “wors­en­ing of symp­toms of mood dis­or­ders, such as depres­sion.” Processed foods with high car­bo­hy­drate con­tent and few nutri­ents have cre­at­ed an epi­dem­ic of mal­nu­tri­tion among a sig­nif­i­cant por­tion of the pop­u­la­tion who oth­er­wise seem to have plen­ty to eat. The sit­u­a­tion seems to have major­ly con­tributed to the cor­re­spond­ing epi­demics of depres­sion and oth­er men­tal health con­di­tions.

Nutri­tion­al psy­chi­a­try is not a fad or a pro­gram claim­ing to recre­ate the diet of ear­ly humans. While “a poten­tial evo­lu­tion­ary mis­match between our ances­tral past (Pale­olith­ic, Neolith­ic) and the con­tem­po­rary nutri­tion­al envi­ron­ment” mer­its explo­ration, as researchers write in an arti­cle pub­lished at the Jour­nal of Phys­i­o­log­i­cal Anthro­pol­o­gy, many more con­tem­po­rary factors—such as eco­nom­ic devel­op­ment and the rise of sci­en­tif­ic medicine—play a role in how we under­stand diet and men­tal health.

Rather than look to pre­his­to­ry, sci­en­tists have stud­ied the diets of “tra­di­tion­al” soci­eties (those not reliant on mass-pro­duced processed foods) in the Mediter­ranean and Japan. They have found a 25–35% low­er rate of depres­sion, for exam­ple, in those who eat diets “high in veg­eta­bles, fruits, unprocessed grains, and fish and seafood,” writes Sel­hub, with “only mod­est amounts of lean meats and dairy.” There is no per­fect dietary for­mu­la, how­ev­er. Everyone’s gut process­es things dif­fer­ent­ly. Dr. Sel­hub rec­om­mends cut­ting out processed foods and sug­ar and exper­i­ment­ing with adding and sub­tract­ing foods to see how you feel. (Nutri­tion­al exper­i­ments like these are prob­a­bly best car­ried out after con­sult­ing with your doc­tor.)

Just as we will need to change the way we eat if we want to pre­serve our out­er envi­ron­ment, the health of that rich, and no less nec­es­sary, inner world known as the micro­bio­me will require what for many is a dra­mat­ic change in eat­ing habits. Sad­ly, it is not a change every­one can afford to make. But for mil­lions suf­fer­ing from men­tal ill­ness­es, nutri­tion­al psy­chi­a­try may rep­re­sent a life-alter­ing course of treat­ment.

Relat­ed Con­tent:

Stanford’s Robert Sapol­sky Demys­ti­fies Depres­sion, Which, Like Dia­betes, Is Root­ed in Biol­o­gy

Psilo­cy­bin Could Soon Be a Legal Treat­ment for Depres­sion: Johns Hop­kins Pro­fes­sor, Roland Grif­fiths, Explains How Psilo­cy­bin Can Relieve Suf­fer­ing

How Bak­ing, Cook­ing & Oth­er Dai­ly Activ­i­ties Help Pro­mote Hap­pi­ness and Alle­vi­ate Depres­sion and Anx­i­ety

Josh Jones is a writer and musi­cian based in Durham, NC. Fol­low him at @jdmagness