When comparing sunflower oil and canola oil, both have nutritious components, but the Centers for Disease Control and Prevention doesn't identify any oil as the healthiest. It does, however, recommend canola oil as the best oil for baking.
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Since the body needs fat for various functions, consuming a fat-free diet isn't healthy. You need a certain amount of fat in the diet because it serves as a source of energy and fosters the absorption of vitamins. On the other hand, these foods are calorie-dense, so be careful not to overindulge. Along with olive oil, the CDC includes both canola and sunflower oil in their list of acceptable fat choices.
Sunflower Oil vs. Canola Oil
The main difference between sunflower oil and canola oil involves the type of fat they contain. Sunflower oil is rich in monounsaturated and polyunsaturated fats, which help reduce cholesterol; while canola oil contains omega-3 fatty acids, a type of polyunsaturated that can help decrease high triglycerides.
To avoid weight gain from consuming too much fat, the Mayo Clinic advocates using the oils only in moderation. When selecting fat, the main thing to remember is to reduce consumption of saturated fat foods, such as meat and palm oil. Also, avoid trans fat foods like margarine and shortening, which contain unhealthy hydrogenated vegetable oils.
Like the Mayo Clinic, Harvard Health Publishing recommends replacing saturated fat with liquid fat from oils, but it doesn't say one type of cooking oil is superior to the other. While the institution acknowledges that many experts opt for olive oil, it says other oil choices are also suitable, one of which is canola because it has a high content of monounsaturated oleic acid.
Read more: The Truth About Canola Oil
Comparison of Heat Stability
When evaluating cooking oils, one factor to consider is the smoke point. The Cleveland Clinic defines this as the temperature at which oil begins smoking, which creates toxic fumes and free radicals.
While sunflower oil has a high smoke point, canola oil has a medium smoke point, so of the two oils, sunflower would be preferable for browning and searing. Sunflower is also an appropriate choice for deep-frying, but this method of cooking isn't healthy, so limit it to an occasional treat.
Authors of a May 2018 study published in Acta Scientific Nutritional Health found that smoke point isn't the sole predictor of oil safety when heated. Instead, the amount of polar compounds, which are unhealthy compounds produced during oil degradation, are more accurate indicators of oil stability.
A measurement of the polar compounds of an array of cooking oils showed sunflower oil produced less than canola. Since the oil that produced the least amount was extra-virgin olive oil, the research team concluded it was the safest and most stable option for cooking.
What's High-Oleic Sunflower Oil?
Some manufacturers make high-oleic acid versions of standard oils. The label on these products can show the Food and Drug Administration claim that daily consumption of 1 1/2 tablespoons of high-oleic acid oils may reduce the risk of heart disease. Sunflower oil is one of the oils that come in a high-oleic acid version.
High-oleic sunflower oil contains at least 80 percent oleic acid, explains Tufts University. In contrast, traditional sunflower oil contains 20 percent. Both versions are low in saturated fat, and either is a suitable choice for a diet that promotes cardiovascular health. The high-oleic variety is more stable to use in cooking at high temperatures, and it has a longer shelf life.
Possible Negatives of Sunflower Oil
A possible side effect of consuming sunflower oil is inflammation. The Arthritis Foundation lists sunflower oil among the cooking oils that contain omega-6 fatty acids, and excess consumption of these fats stimulates the production of inflammatory chemicals in the body.
Contributing to the problem, the American diet is plentiful in omega-6 fatty acids. This doesn't mean that the fats should be avoided, but try not to let them dominate the diet.
Chicago's Northwest Community Healthcare states that a normal ratio of omega-6 to omega-3 fatty acids is 4-to-1. Processed foods have high amounts of oils like sunflower oil, and increased consumption can adversely alter this ratio, putting it as high as 10-to-1 or 20-to-1.
An August 2012 study featured in the Journal of Biomedicine & Biotechnology highlights the inflammation-producing potential of sunflower oil. The authors state that the oil has been linked to positive effects on lipids, but it's role in inflammation hasn't been fully explored.
Although the investigation involved mice rather than humans, it's worth mentioning because of the troubling findings. Supplementation of the diet with sunflower oil did, indeed, improve blood lipids; but it showed inflammatory effects.
Possible Negatives of Canola Oil
Research on canola oil also isn't 100 percent positive. A December 2017 study published in Scientific Reports spoke of the recent trend to replace olive oil with canola oil because it's less expensive. Results suggest the oil may have an adverse effect on the pathology in the brain that contributes to Alzheimer's disease.
The Scientific Reports investigation involved mice, but the troubling findings that merit notice. A comparison of the effects of a standard diet with a diet augmented with canola oil showed the latter significantly impaired memory.
It also harmed the integrity of synapses, which are the spaces between neurons where information is transmitted. The authors concluded that the data doesn't support the advisability of replacing olive oil with canola oil to save money.
Another disturbing study published in 2014 in Respiratory Research shows the type of vitamin E contained in canola oil may be contributing to the increasing incidence of lung inflammation and asthma.
The authors said that different forms of vitamin E have different effects. Canola oil has the gamma-tocopherol form, which is linked to reduced lung function; but olive oil and sunflower oils have the alpha-tocopherol form, which is associated with improved lung function. The effects of canola oil could increase breathing difficulty in asthmatics, the authors conclude.
- Centers for Disease Control and Prevention: "Post-Core: Fats – Saturated, Unsaturated, and Trans Fat"
- Mayo Clinic: "Dietary Fats: How to Make Healthy Choices"
- Harvard Health Publishing: "Choosing Oils for Cooking: A Host of Heart-Healthy Options"
- Cleveland Clinic: "Heart-Healthy Cooking: Oils 101"
- Acta Scientific Nutritional Health: "Evaluation of Chemical and Physical Changes in Different Commercial Oils During Heating"
- U.S. Food and Drug Administration: "FDA Completes Review of Qualified Health Claim Petition for Oleic Acid and the Risk of Coronary Heart Disease"
- Tufts University: "What is High-Oleic Sunflower Oil?"
- Arthritis Foundation: "Fats and Oils to Avoid"
- Northwest Community Healthcare: "Ten Tips to Reduce Inflammation"
- Journal of Biomedicine & Biotechnology: "Sunflower Oil Supplementation Has Proinflammatory Effects and Does Not Reverse Insulin Resistance in Obesity Induced by High-Fat Diet in C57BL/6 Mice"
- Scientific Reports: "Effect of Canola Oil Consumption on Memory, Synapse and Neuropathology in the Triple Transgenic Mouse Model of Alzheimer’s Disease"
- Respiratory Research: "The Vitamin E Isoforms α-Tocopherol and γ-Tocopherol Have Opposite Associations With Spirometric Parameters: The CARDIA Study"