Time to rethink your vegetable oil?

March 7, 2016

Risk of heart disease and diabetes may be lowered by a diet higher in a lipid found in grapeseed and other oils, but not in olive oil, a new study suggests.

Researchers at The Ohio State University found that men and women with higher linoleic acid levels tended to have less heart-threatening fat nestled between their vital organs, more lean body mass and less inflammation.

And higher linoleic acid levels also meant lower likelihood of insulin resistance, a precursor to diabetes.

This finding could have obvious implications in preventing heart disease and diabetes, but also could be important for older adults because higher lean body mass can contribute to a longer life with more independence, said Ohio State's Martha Belury, a professor of human nutrition who led the research.

But there's a catch. Low-cost cooking oils rich in linoleic acid have been disappearing from grocery shelves, fueled by industry's push for plants that have been modified to produce oils higher in oleic acid.

"Vegetable oils have changed. They're no longer high in linoleic acid," said Belury, an expert in dietary fats and part of Ohio State's Food Innovation Center.

The research appears online in the journal Molecular Nutrition & Food Research.

The research team also looked at the health effects of oleic acid, found in and some other , as well as long-chain omega-3 , found in fatty fish including salmon and tuna.

Though inflammation decreased as blood levels of those fatty acids rose, higher levels of oleic acid or long-chain omega-3s did not appear to have any relationship to body composition or signs of decreased diabetes risk despite longstanding recommendations that people eat more of these "healthy" fats.

"It really kind of popped out and surprised us," Belury said.

Previous research found that taking linoleic acid supplements increased lean body mass and lowered fat in the midsection. As little as a teaspoon and a half was all it took, Belury said. The current study is the first study to examine linoleic acid alongside body composition and other health markers in people who hadn't been given supplements or prescriptive diets, she said.

Because of previous research showing cardiovascular benefits of linoleic acid, the American Heart Association in 2009 recommended people take in at least 5 to 10 percent of their energy in the form of omega-6 fatty acids, which includes linoleic acid.

But U.S. consumption of linoleic acid is declining because of genetic modification of plants for food manufacturers seeking oils higher in oleic acid, Belury said.

There's been a pronounced shift in the last five years, she said, and it is linked to the push against trans fats. When linoleic acid is made solid (hydrogenated) for processed foods, it is more likely to convert to trans fat than its oleic cousin.

So oils, notably safflower, sunflower and soybean, now routinely contain less linoleic acid - it often makes up less than 20 percent of the fatty acids in commonly purchased oils, based on food labels and confirmed by testing in her lab, Belury said.

Grapeseed oil for now remains an excellent source of linoleic acid, which constitutes about 80 percent of its fatty acids, she said. Corn oil also remains a decent source, she said.

The team used data from two previous studies that focused on stress and included 139 people. In those studies, researchers assessed body composition using DXA scanning, an advanced way of measuring fat and muscle mass.

They tested blood drawn after the men and women fasted for 12 hours, calculating the amount of linoleic acid (and other fatty acids) in red blood cells. All of the linoleic acid in our bodies comes from food sources.

They also evaluated the blood for insulin resistance and two markers of inflammation that are connected with disease.

Then they plotted results for each health category against the group's results for each of the three fat categories: linoleic acid, oleic acid and long-chain omega-3 fatty acids.

Belury said the study doesn't explain the apparent interplay between linoleic and measures of risk for and diabetes. It shows an association between those things, but not a cause and effect. And its power is limited because it relied on looking back on two previous research efforts and those involved middle-aged men and women who were slightly healthier on average than the general population.

The study participants lived in and around Columbus, Ohio. It's possible that the results would have been different in a population with diets that tend to be higher in omega-3 rich fatty fish, Belury said.

Explore further: Some 'healthy' vegetable oils may actually increase risk of heart disease

Related Stories

Some 'healthy' vegetable oils may actually increase risk of heart disease

November 11, 2013
Some vegetable oils that claim to be healthy may actually increase the risk of heart disease, and Health Canada should reconsider cholesterol-lowering claims on food labelling, states an analysis in CMAJ (Canadian Medical ...

Omega-3 fatty acids may play role in bipolar disorder

December 7, 2015
(HealthDay)—There may be a link between levels of omega-3 fatty acids and bipolar disorder, according to a small study published in the November issue of Bipolar Disorders.

Fatty acid composition in blood reflects the quality of dietary fat and carbohydrates in children

April 7, 2014
Recently published research in the University of Eastern Finland found that fatty acid composition in blood is not only a biomarker for the quality of dietary fat but also reflects the quality of dietary carbohydrates. For ...

Vegetable oil IS good for you, researcher says

June 7, 2013
A typical American consumes approximately 3 or more tablespoons of vegetable oil each day. Vegetable oils, like those from soy, corn and canola, are a significant source of calories and are rich in linoleic acid (LA), which ...

Replacing saturated fat with polyunsaturated fat linked with lower risk of heart disease

October 28, 2014
People who swap 5% of the calories they consume from saturated fat sources such as red meat and butter with foods containing linoleic acid—the main polyunsaturated fat found in vegetable oil, nuts, and seeds—lowered their ...

Intake of the right fatty acids can help to prevent heart attacks

June 30, 2011
There is much confusion at present about the importance of fatty acids in preventing heart attacks. Recent studies have questioned the need to reduce the intake of saturated fatty acids in the diet and to increase that of ...

Recommended for you

Study finds being in a good mood for your flu jab boosts its effectiveness

September 25, 2017
New research by a team of health experts at the University of Nottingham has found evidence that being in a positive mood on the day of your flu jab can increase its protective effect.

New tool demonstrates high cost of lack of sleep in the workplace

September 25, 2017
Sleep disorders and sleep deficiency are hidden costs that affect employers across America. Seventy percent of Americans admit that they routinely get insufficient sleep, and 30 percent of U.S. workers and 44 percent of night ...

Maternal diet could affect kids' brain reward circuitry

September 25, 2017
Researchers in France found that rats who ate a junk food diet during pregnancy had heavier pups that strongly preferred the taste of fat straight after weaning. While a balanced diet in childhood seemed to reduce the pups' ...

Breathing dirty air may harm kidneys, study finds

September 21, 2017
Outdoor air pollution has long been linked to major health conditions such as heart disease, stroke, cancer, asthma and chronic obstructive pulmonary disease. A new study now adds kidney disease to the list, according to ...

Excess dietary manganese promotes staph heart infection

September 21, 2017
Too much dietary manganese—an essential trace mineral found in leafy green vegetables, fruits and nuts—promotes infection of the heart by the bacterium Staphylococcus aureus ("staph").

Being active saves lives whether a gym workout, walking to work or washing the floor

September 21, 2017
Physical activity of any kind can prevent heart disease and death, says a large international study involving more than 130,000 people from 17 countries published this week in The Lancet.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.