Study: Dietary interventions can help children with ADHD (especially with proper monitoring and adjustment)

food_pyramidAre dietary inter­ven­tions effec­tive for treat­ing ADHD? This has been a con­tro­ver­sial ques­tion over the years with strong pro­po­nents on both sides of the issue. For many par­ents and pro­fes­sion­als, try­ing to parse through the dif­fer­ent claims about the impact of diet on ADHD has been chal­leng­ing and confusing.

At this point, sub­stan­tial research on how dietary inter­ven­tions impact ADHD has accu­mu­lat­ed and sev­er­al meta-analy­ses of this work have been pub­lished. In a meta-analy­sis, the researcher begins by try­ing to iden­ti­fy all rel­e­vant stud­ies of an issue that meet cer­tain pre­de­fined cri­te­ria, e.g., only stud­ies that are true ran­dom­ized-con­trolled tri­als are includ­ed. Results from stud­ies meet­ing inclu­sion cri­te­ria are ana­lyzed col­lec­tive­ly, so that find­ings across mul­ti­ple stud­ies are syn­the­sized into an over­all result.

The ben­e­fits of this approach are that find­ings are based on many more par­tic­i­pants than from a sin­gle study and typ­i­cal­ly include more diverse pop­u­la­tions as a result. Inte­grat­ing data across stud­ies can also help smooth out the strengths and lim­i­ta­tions of indi­vid­ual stud­ies. Because of this, find­ings that emerge from a well-con­duct­ed meta-analy­sis may be more reli­able than would be the case for any sin­gle study. Recent­ly, a review of sev­er­al meta-analy­ses of dietary inter­ven­tions for ADHD was pub­lished [Research review: The role of diet in the treat­ment of atten­tion-deficit/hyper­ac­tiv­i­ty dis­or­der — an appraisal of the evi­dence on effi­ca­cy and rec­om­men­da­tions on the design of future stud­ies. Jour­nal of Child Psy­chol­o­gy and Psy­chi­a­try]. In this paper, the authors sum­ma­rize find­ings across 6 dif­fer­ent meta-analy­ses of the impact of diet on ADHD to pro­vide a high lev­el sum­ma­ry of the best avail­able evi­dence to date.

Types of dietary interventions

Three types of dietary inter­ven­tions were reviewed — Restrict­ed Elim­i­na­tion Diets (RED), Arti­fi­cial food col­or­ing exclu­sion (AFCE), and sup­ple­men­ta­tion with free fat­ty acids (SFFA). Although oth­er types of sup­ple­ments beyond free fat­ty acids have been inves­ti­gat­ed, the authors felt there was not suf­fi­cient research on any sin­gle approach to include in their summary.

A brief descrip­tion of these dif­fer­ent inter­ven­tions is pro­vid­ed below.

1. Restrict­ed elim­i­na­tion diets (RED) — There are 2 dif­fer­ent approach­es to imple­ment­ing this diet. In one approach, the child is placed on an extreme­ly restrict­ed diet, e.g., rice, turkey, a range of veg­eta­bles (let­tuce, car­rots, cau­li­flower, cab­bage, beets), pears and water; this is some­times referred to as the Few Food Diet. When a reduc­tion in ADHD behav­iors results — this would gen­er­al­ly occur with­in 2–3 weeks if the diet is going to have a pos­i­tive effect — new foods can be added back one at a time to see if they are well-tol­er­at­ed or lead to an increase in prob­lem behav­iors. Alter­na­tive­ly, par­tic­u­lar foods that are sus­pect­ed to exac­er­bate a child’s symp­toms may be removed one at a time to see if the child’s behav­ior improves.

2. Arti­fi­cial food col­or­ing exclu­sion (AFCE)- As the title indi­cates, this involves efforts to remove all arti­fi­cial food col­or­ings from a child’s diet, e.g.,Yellow #6, Yel­low #5, Sodi­um Ben­zoate, Blue #2, etc., and observ­ing whether this is asso­ci­at­ed with a reduc­tion in ADHD behav­iors. Care­ful­ly con­duct­ed tri­als have demon­strat­ed that AFC’s – in amounts chil­dren could typ­i­cal­ly con­sume – can increase ADHD symp­toms in many children.

3. Essen­tial fat­ty acid sup­ple­men­ta­tion — Cer­tain fat­ty acids, e.g., Omega 3 and Omega 6, pro­mote neur­al func­tion­ing. These fat­ty acids are called essen­tial because they are not syn­the­sized in the body and must be ingest­ed. Chil­dren with ADHD may have low­er lev­els of essen­tial fat­ty acids rel­a­tive to peers and sev­er­al stud­ies have demon­strat­ed a link between low lev­els of EFAs and the sever­i­ty of ADHD symp­toms. Stud­ies inves­ti­gat­ing the ben­e­fits of fat­ty acid sup­ple­men­ta­tion for youth with ADHD raise fat­ty acid lev­els by admin­is­ter­ing cap­sules con­tain­ing the fat­ty acids or some­times by intro­duc­ing diets rich in fish products.

Are these interventions effective?

RED — Three dif­fer­ent meta-analy­ses exam­in­ing the impact of RED on chil­dren with ADHD report­ed sig­nif­i­cant pos­i­tive effects. The mag­ni­tude of this effect var­ied con­sid­er­ably across the dif­fer­ent stud­ies. At this point, I believe the most rea­son­able con­clu­sion to be drawn from avail­able data is that restrict­ed elim­i­na­tion diets, if imple­ment­ed prop­er­ly, have a sig­nif­i­cant effect that is like­ly to be in the small to mod­er­ate range. An aver­age effect in the small to mod­er­ate range reflects the fact that some chil­dren are like­ly to show sub­stan­tial ben­e­fits while many oth­ers may show no ben­e­fits at all.

AFCE — Small but sig­nif­i­cant effects of elim­i­nat­ing AFC’s from chil­dren’s diet have been report­ed. When stud­ies have been restrict­ed to chil­dren with diag­nosed ADHD, sig­nif­i­cant and slight­ly larg­er benefts are report­ed. As with RED, a rea­son­able con­clu­sion at this time is that, on aver­age, chil­dren with ADHD will derive mod­est ben­e­fits when AFCs are removed from their diet. Some chil­dren may show large reduc­tions in ADHD symp­toms while oth­ers may show no dis­cernible reduc­tions at all.

Fat­ty acid sup­ple­men­ta­tion — Results from mul­ti­ple meta-analy­ses con­verge on their being a mod­est but sig­nif­i­cant ben­e­fit of fat­ty acid sup­ple­men­ta­tion on ADHD symp­toms. One com­pli­cat­ing fac­tor is that a wide range of com­bi­na­tion of dif­fer­ent fat­ty acids have been test­ed, mak­ing it dif­fi­cult to derive an aver­age expect­ed ben­e­fit from any spe­cif­ic com­bi­na­tion or dosages. As with RED and AFCE, some chil­dren are like­ly to dis­play sub­stan­tial ben­e­fits from this approach while for oth­ers, the impact on ADHD symp­toms will be min­i­mal or non-exis­tent. Even in these cas­es, how­ev­er, there are gen­er­al health ben­e­fits that may accrue from fat­ty acid supplementation.

Limitations of available studies

Although the con­clu­sions reached above are gen­er­al­ly well sup­port­ed by avail­able data, lim­i­ta­tions to the stud­ies they are based on should be not­ed. First, some stud­ies include chil­dren with ADHD who have been select­ed based on sus­pect­ed food sen­si­tiv­i­ties, rather than a gen­er­al pop­u­la­tion of ADHD youth. Results of dietary inter­ven­tions would be expect­ed to be stronger with this sub­group of ADHD youth; as a result, the impact of such inter­ven­tions on the gen­er­al pop­u­la­tion of youth with ADHD may be some­what overestimated.

Out­come mea­sures have gen­er­al­ly been restrict­ed to par­ent and teacher behav­ior rat­ing scales; keep­ing such raters blind in these stud­ies is chal­leng­ing giv­en their role in admin­is­ter­ing the diet. More objec­tive assess­ments, e.g., com­put­er­ized tests of atten­tion, rat­ings made by observers who are ful­ly blind to treat­ment con­di­tion, would be impor­tant addi­tions to sub­se­quent studies.

Anoth­er impor­tant issue is that the out­comes exam­ined are large­ly restrict­ed to ADHD behav­iors. Exam­in­ing oth­er kinds of behav­iors, and aca­d­e­m­ic func­tion­ing in par­tic­u­lar, would enable more ful­ly informed assess­ments about the ben­e­fits of dietary inter­ven­tions to be made.

One final issue to note is that, to my knowl­edge, stud­ies com­bin­ing dif­fer­ent dietary approach­es have not been con­duct­ed. It is pos­si­ble that elim­i­na­tion diets com­bined with fat­ty acid sup­ple­men­ta­tion would poten­tial­ly have addi­tive effects that would pro­duce larg­er ben­e­fits on aver­age. This seems like an impor­tant pos­si­bil­i­ty to explore.

How should these findings be used to guide intervention?

Exist­ing evi­dence points towards mod­est but sta­tis­ti­cal­ly sig­nif­i­cant ben­e­fits of each dietary inter­ven­tion on ADHD. As indi­cat­ed above, mod­est aver­age ben­e­fits can obscure the fact that some chil­dren show sub­stan­tial gains. If that hap­pens to be your child, the fact that most chil­dren may not real­ize large ben­e­fits would be less relevant.

Are dietary inter­ven­tions some­thing that par­ents should try and that pro­fes­sion­als should rec­om­mend? In think­ing about this, sev­er­al issues are impor­tant to con­sid­er. First, the eas­i­est of the 3 dietary inter­ven­tions to imple­ment would be fat­ty acid sup­ple­men­ta­tion. This does not requir­ing restrict­ing chil­dren’s food intake in any spe­cif­ic way, can have gen­er­al health ben­e­fits regard­less of how it impacts ADHD behav­iors, and places much more lim­it­ed demands on chil­dren and par­ents. When known food allergies/sensitivities are not present, this approach seems as like­ly to be help­ful as restric­tive diets that are more dif­fi­cult to imple­ment. It thus seems like a rea­son­able ini­tial alternative.

It is impor­tant to rec­og­nize that restrict­ed elim­i­na­tion diets can be dif­fi­cult to imple­ment and sus­tain — efforts to sig­nif­i­cant­ly lim­it the foods a child eats may lead to con­flicts that cre­ate impor­tant prob­lems in their own right. Unless food aller­gies are present, a diet restrict­ing only AFCs may be a bet­ter choice as this would be eas­i­er to imple­ment than a few foods diet. How­ev­er, giv­en the ubiq­ui­tous nature of arti­fi­cial food col­or­ings and dyes, this can also be challenging.

Intro­duc­ing restrict­ed diets in ways that focus on secur­ing the coop­er­a­tion and agree­ment of the child is an impor­tant goal. Real­is­ti­cal­ly, main­tain­ing a child on a restrict­ed diet over long peri­ods would be vir­tu­al­ly impos­si­ble with­out such coop­er­a­tion and sus­tain­ing a child’s coop­er­a­tion over time is like­ly to prove chal­leng­ing. Enlist­ing the help of a pro­fes­sion­al with this aspect of the inter­ven­tion should cer­tain­ly be considered.

Although par­ents might try to imple­ment such diets on their own, dietary inter­ven­tions should be car­ried out under the super­vi­sion of a nutri­tion­ist or oth­er pro­fes­sion­al who is expe­ri­enced in these approach­es. In par­tic­u­lar, restrict­ed elim­i­na­tion diets, e.g., few foods diet, should be over­seen by a prop­er­ly qual­i­fied pro­fes­sion­al to avoid nutri­tion­al defi­cien­cy. Such a pro­fes­sion­al should also be able to assist in iden­ti­fy­ing pos­si­ble food allergies/sensitivities that would both increase the chances of a pos­i­tive out­come and help deter­mine which foods are most impor­tant to avoid.

Because par­ents ini­ti­at­ing dietary inter­ven­tion may have strong expec­ta­tions of ben­e­fit, and the place­bo effect may also be oper­at­ing, there should be a sys­tem­at­ic plan in place to mon­i­tor chil­dren’s response. Ide­al­ly, behav­ior rat­ings would be obtained week­ly from par­ents and teach­ers that would include assess­ments of ADHD symp­toms, oth­er behav­ior prob­lems, and the quan­ti­ty and qual­i­ty of school work com­plet­ed. If the teacher can be kept unaware of the inter­ven­tion, so much the bet­ter as this would remove a poten­tial source of bias in his/her ratings.

Obtain­ing these rat­ings should begin sev­er­al weeks before start­ing treat­ment so that a reli­able base­line can be estab­lished; once the inter­ven­tion begins they should be col­lect­ed week­ly. Review of these rat­ings reg­u­lar­ly by the pro­fes­sion­al over­see­ing the treat­ment is the best way to learn whether things real­ly are get­ting bet­ter, and even if they are, what prob­lems are per­sist­ing that need to be addressed via oth­er means. If the diet — or fat­ty acid sup­ple­men­ta­tion — has been care­ful­ly fol­lowed for at least 4 weeks and no reli­able ben­e­fits are dis­cerned, it would be time to con­sid­er oth­er treat­ments. This type of mon­i­tor­ing approach is not spe­cif­ic to dietary inter­ven­tions but is an impor­tant com­po­nent of any treat­ment for ADHD.

One uncom­pli­cat­ed and sen­si­ble inter­ven­tion that all par­ents can imple­ment is mak­ing sure their child eats a good break­fast that has ade­quate amounts of pro­tein. Research has shown that this can play an impor­tant role in help­ing all chil­dren — not just those with ADHD — main­tain bet­ter atten­tion lev­els across the morning.

Rabiner_David– Dr. David Rabin­er is a child clin­i­cal psy­chol­o­gist and Direc­tor of Under­grad­u­ate Stud­ies in the Depart­ment of Psy­chol­ogy and Neu­ro­science at Duke Uni­ver­sity. He pub­lishes the Atten­tion Research Update and is teach­ing the upcom­ing online course  How to Nav­i­gate Con­ven­tional and Com­ple­men­tary ADHD Treat­ments for Healthy Brain Devel­op­ment (May 2015; reg­is­tra­tion open).

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