Media Releases

“Healthy” vegetable oils may actually increase risk of heart disease, researchers say

November 11, 2013

Calling on Health Canada to reconsider health claim for omega‑6 oils on food labels

TORONTO, ON — Healthy eat­ing just got a lit­tle more com­pli­cat­ed.

New research from the Uni­ver­si­ty of Toron­to shows cer­tain veg­etable oils that claim to be healthy may actu­al­ly increase the risk of heart dis­ease.

And the results mean Health Cana­da should recon­sid­er cho­les­terol-low­er­ing claims on food labelling, says Dr.Richard Bazinet, lead author of the new study which is avail­able online now at the Cana­di­an Med­ical Asso­ci­a­tion Jour­nal.

“This is impor­tant infor­ma­tion for peo­ple buy­ing cer­tain foods because of the heart ben­e­fits when real­ly, that’s not accu­rate,” says Bazinet, of U of T’s depart­ment of nutri­tion­al sci­ences. “While most of these foods are a good choice, there are a few notable excep­tions.”

Bazinet and his team report that replac­ing sat­u­rat­ed ani­mal fats with polyun­sat­u­rat­ed veg­etable oils had become com­mon prac­tice for con­sumers, based on the under­stand­ing that such oils reduce serum cho­les­terol lev­els and help pre­vent heart dis­ease. Since 2012, Health Canada’s Food Direc­torate has allowed the food indus­try to use a label on the oils – and foods con­tain­ing the oils – claim­ing “a reduced risk of heart dis­ease by low­er­ing blood cho­les­terol lev­els.”

But researchers say it’s more com­pli­cat­ed than the label sug­gests – and the prob­lem lies in the ratio of two kinds of polyun­sat­u­rates fat­ty acids found in the oils.

“Care­ful eval­u­a­tion of recent evi­dence, how­ev­er, sug­gests that allow­ing a health claim for veg­etable oils rich in omega‑6 linole­ic acid but rel­a­tive­ly poor in omega‑3 α‑linolenic acid may not be war­rant­ed,” write Bazinet and Michael Chu, Law­son Health Research Insti­tute and Divi­sion of Car­diac Surgery at West­ern Uni­ver­si­ty in Lon­don, Ontario.

Corn and saf­flower oil, which are rich in omega‑6 linole­ic acid but con­tain almost no omega‑3 α‑linolenic acid, are not asso­ci­at­ed with ben­e­fi­cial effects on heart health, Bazinet says.

The authors cite a study pub­lished ear­li­er this year in Feb­ru­ary 2013 in which “…the inter­ven­tion group replaced sat­u­rat­ed fat with sources of saf­flower oil or saf­flower oil mar­garine (rich in omega‑6 linole­ic acid but low in omega‑3 α‑linoleic acid). They found that the inter­ven­tion group had serum cho­les­terol lev­els that were sig­nif­i­cant­ly decreased (by about 8%–13%) rel­a­tive to base­line and the con­trol group, which is con­sis­tent with the health claim.”

How­ev­er, rates of death from all caus­es of car­dio­vas­cu­lar dis­ease and coro­nary artery dis­ease sig­nif­i­cant­ly increased in the treat­ment group, says Bazinet.

“When the new results were added to a meta-analy­sis, the net result was a bor­der­line 33 per cent increase in heart dis­ease risk for oils rich in omega‑6 and poor in omega‑3, with absolute­ly no evi­dence of a ben­e­fit as is implied by the health claim,” Bazinet says.

In Cana­da, omega‑6 linole­ic acid is found in corn and saf­flower oils as well as foods such as may­on­naise, creamy dress­ings, mar­garine, chips and nuts. Canola and soy­bean oils, which con­tain both linole­ic and α‑linolenic acids, are the most com­mon forms of oil in the Cana­di­an diet.

“We sug­gest that the health claim be mod­i­fied such that foods rich in omega‑6 linole­ic acid but poor in omega‑3 α‑linolenic acid be exclud­ed,” con­clude the authors.

(Read the research arti­cle in CMAJ.)

-30-

For more infor­ma­tion, please con­tact:

Michael Kennedy
Media Rela­tions Offi­cer
Tel: 416–946-5025
m.kennedy@utoronto.ca

Media Rela­tions
Uni­ver­si­ty of Toron­to
Tel: 416–978-0100
media.relations@utoronto.ca