`Mediterranean Diet with Olive Oil or Nuts Improves Cognitive Function

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Mediterranean Diet with Olive Oil or Nuts Improves Cognitive Function

May. 26, 2015
Sukhsatej Batra

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Results of a ran­dom­ized clin­i­cal trial, pub­lished ear­lier this month in the JAMA Inter­nal Med­i­cine, revealed that long-term con­sump­tion of the Mediter­ranean diet sup­ple­mented with either extra vir­gin olive oil or nuts improved cog­ni­tive func­tion in older adults.

Although pre­vi­ous obser­va­tional stud­ies reported a pos­i­tive rela­tion­ship between adher­ence to the Mediter­ranean diet and improved cog­ni­tive func­tion, they com­pared intake of a con­trol diet ver­sus intake of a Mediter­ranean diet with­out a base­line eval­u­a­tion of the sub­jects before and after con­sump­tion of the Mediter­ranean diet.

In con­trast, find­ings of the new study are based on repeated neu­ropsy­cho­log­i­cal assess­ment of the sub­jects who con­sumed a con­trol diet or a Mediter­ranean diet sup­ple­mented with either EVOO or nuts over a four-year period.

Con­ducted on a small sub-sam­ple of Span­ish sub­jects enrolled at the Barcelona-North PREDIMED cen­ter, the study started with 447 cog­ni­tively healthy sub­jects who had either Type 2 dia­betes or risk to car­dio­vas­cu­lar dis­ease in 2003. How­ever, only 344 sub­jects com­pleted the study in 2009. The objec­tive of the study was to inves­ti­gate the effect of an antiox­i­dant-rich Mediter­ranean diet on cog­ni­tive func­tion of the sub­jects.

The enrolled sub­jects were ran­domly assigned to one of the three diets: a Mediter­ranean sup­ple­mented with one liter of extra vir­gin olive oil per week; a Mediter­ranean sup­ple­mented with intake of 30 grams mixed nuts that included 15 grams of wal­nuts, and 7.5 grams each of almonds and hazel­nuts; or a con­trol diet with advice to reduce fat intake.
See more: The Health Ben­e­fits of Olive Oil
Cog­ni­tive func­tion of the sub­jects, whose aver­age age was 67 years, was assessed by sev­eral neu­ropsy­cho­log­i­cal tests that were car­ried out at the begin­ning of the study to pro­vide base­line data and again, at the end of the study. Three cog­ni­tive com­pos­ites were con­structed from the neu­ropsy­cho­log­i­cal tests that included mem­ory com­pos­ite (based on the Rey Audi­tory Ver­bal Learn­ing Test and the Welch­ler Mem­ory Scale); frontal com­pos­ite that mea­sured atten­tion, cog­ni­tive flex­i­bil­ity and work­ing mem­ory; and global com­pos­ite that assessed changes in all neu­ro­log­i­cal tests con­ducted.

At the end of the study, results revealed that sub­jects on both vari­a­tions of the Mediter­ranean diet had improved cog­ni­tive func­tion while those on the con­trol diet showed a decline in cog­ni­tive func­tion. Fur­ther­more, the inves­ti­ga­tors found that the observed changes were con­sis­tent in all sub­jects irre­spec­tive of fac­tors such as gen­der, age, energy con­sump­tion, and other vari­ables.

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More specif­i­cally, results showed a sig­nif­i­cant increase in mem­ory com­pos­ite in the group who con­sumed a Mediter­ranean diet sup­ple­mented with nuts, while those on the Mediter­ranean diet with olive oil improved frontal and global cog­ni­tion com­pos­ites.

Increased intake of antiox­i­dant and anti-inflam­ma­tory agents that are nat­u­rally present in the Mediter­ranean diet may be respon­si­ble for improv­ing cog­ni­tive com­pos­ites of the sub­jects, accord­ing to the authors of the study.

In addi­tion, the phe­no­lic-rich com­pounds in extra vir­gin olive oil and nuts may also be pro­tec­tive against neu­rode­gen­er­a­tion as they act as antiox­i­dants, increase blood flow to the brain and increase neu­ron syn­the­sis.

In spite of sev­eral draw­backs of the study such as a small sam­ple size recruited from a larger study with dif­fer­ent objec­tives, results of the study showed that the Mediter­ranean diet sup­ple­mented with olive oil or nuts pro­tected against cog­ni­tive decline.

In an inter­view for JAMA Net­work, Emilo Ros, MD, PhD, senior con­sul­tant at the Endocrinol­ogy Depart­ment, Hos­pi­tal Clinic de Barcelona, said, The two Mediter­ranean diets coun­ter­acted age-related cog­ni­tion decline com­pared to the con­trol diet.”

Ros fur­ther empha­sized the impor­tance of this study as the first ran­dom­ized clin­i­cal trial and sug­gested that inter­ven­tion with Mediter­ranean diet sup­ple­mented with EVOO or nuts at the pre-clin­i­cal stage would be ben­e­fi­cial before the onset of devel­op­ment of mem­ory com­plaints and car­dio­vas­cu­lar health prob­lems.



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