A once questionable cooking product, vegetable oil can now be considered a diet-friendly source of beneficial nutrients, according to a new study. Pure vegetable oil was found to be the healthiest kind of oil, one that should be incorporated into our daily diets. Researchers from the University of Missouri and the University of Illinois are now confirming that a heart-healthy diet can be achieved by consuming soybean, canola, corn, and sunflower oils, instead of cooking with animal-based fats.

Vegetable oils do account for a significant source of calories, but they are also rich in linoleic acid (LA), an essential nutrient that can help lower the risk of heart disease. Recently, among experts, there has been controversy surrounding the suggested quantity of LA, claiming that Americans could be consuming too much of a good thing. The typical American consumes approximately three or more tablespoons of vegetable oil each day, and the newest study, "Effect of Dietary Linoleic Acid on Markers of Inflammation in Healthy Persons: A systematic Review of Randomized Controlled Trials," approves of that quantity.

Vegetables oils are easier to digest and help the body preserve important vitamins and natural properties of olives. According to the American Heart Association, they aid in lowering low-density lipoprotein (LDL), which is known as "bad" cholesterol levels, while raising high-density lipoprotein (HDL), also known as the "good" cholesterol. These two different types of lipids, along with triglycerides, which is another form of fat made in the body, and a genetic variation of LDL known as LP(a), all make up an individual's total cholesterol count.

This is not to be confused with hydrogenated vegetable oils, such as shortening or margarine, which, when consumed in large and frequent quantities, can easily become a negative contributor to an otherwise healthy diet. When vegetable oil is hydrogenated, it is chemically altered from a liquid to a solid state, which in turn changes natural and healthy fatty acids into unwanted trans fatty acids. In fact, trans fatty acids can lead to heart disease, clogged arteries, heart attack, or stroke. They are neither easily digestible nor advantageous to include in any diet.

"Consumers are regularly bombarded with warnings about what foods they should avoid," University of Missouri researcher Kevin Fritzsche said. "While limiting the overall fat intake is also part of the current nutrition recommendations, we hope people will feel comfortable cooking with vegetable oils."

Given that linoleic acid is a major component of vegetable oils, researchers tested vegetable oil consumption in nearly 500 adults to understand the effect it would have on their bodies. After 15 reviewed clinical trials of a diet high in linoleic acid (between two to four tablespoons), no links to inflammation of the body were found.

Those who struggle with high cholesterol or heart disease in their family should evaluate and consider revising their diets. Replacing margarine or butter with vegetable oil can be a step towards a healthier life. According to the Centers for Disease Control and Prevention (CDC), a healthy and desirable total cholesterol level is less than 200 mg/dL (milligrams per deciliter). People with a high total cholesterol level run twice the risk of heart disease compared to those with healthy cholesterol levels.

Approximately 71 million Americans, or 33.5 percent of the total population, have high LDL levels. When too much LDL circulates in the blood, fat can slowly build up along the inner walls. Eventually a blood clot will form if the levels are maintained or increased to high levels. The fat that forms is a thick, hard plaque deposit, and results in a condition called atherosclerosis, which can lead to a heart attack or stroke. Cholesterol levels can be checked with a blood screening. According to the CDC, 96 million doctor visits included a cholesterol test in 2009; however that only accounted for 9.2 percent of all visits.

Linoleic acid is an omega-6 fatty acid, commonly found in almonds and Alaskan salmon. Omega-6 plays an vital role in cell growth that triggers immune responses, and encourages brain and muscle development, which explains why it is a sought-after nutrient for top athletes and body builders. However, like overall vegetable oil consumption, it is only healthy in moderation. Researchers suggest up to four tablespoons of vegetable oil daily are within a healthy range.

"We're not saying that you should just go out and consume vegetable oil freely," Fritzsche said.