Advances in Nutrition review finds some vegetable oils may offer health benefits, but some may pose health risks
Vegetable oils from seeds, nuts, and fruits play a significant role in most diets. In fact, many dietary guidelines recommend the substitution of saturated fats with unsaturated fats, including those found in vegetable oils, to improve health outcomes. Nevertheless, there has been growing controversy over the relationship between the consumption of vegetable oils and health outcomes, including cardiovascular disease, all-cause deaths, and metabolic syndrome. Some randomized controlled trials, for example, have revealed that the benefits of vegetable oils in lowering serum cholesterol concentrations did not translate into better clinical outcomes in terms of disease risk and survival.
Studies have shown that the health effects of vegetable oils are highly dependent on their fatty acid content. Until now, however, there had been no comprehensive overview of studies comparing the various health effects of vegetable oils. Health Effects of Various Edible Vegetable Oils: An Umbrella Review fills this research gap by comparing the distinct health effects of different vegetable oils on health outcomes, including blood pressure, blood lipid concentrations, and glucose concentrations. The results of this scientific review were published in Advances in Nutrition—An International Review Journal, published by the American Society for Nutrition.
To conduct their research, the authors began with a thorough search of the scientific literature, leading them to 48 studies investigating the health effects of vegetable oils. Studies covered olive oil, coconut oil, flaxseed oil, palm oil, canola oil, sesame oil, rice bran oil, and peanut oil.
Overall, the authors noted that “different vegetable oils offer different health benefits, which provide potential primary preventive effects against diseases.” For example, the review’s findings support “the growing body of evidence suggesting vegetable oils rich in monounsaturated fatty acids and polyunsaturated fatty acids, such as canola oil and rice bran oil, have desirable effects in reducing total cholesterol and LDL cholesterol concentrations.” Notably, the authors found that only virgin olive oil, with its higher concentrations of polyphenols, is associated with additional health benefits, including “antioxidant effects, anti-atherosclerotic potential, and anti-inflammatory properties that lower lipid parameters.”
In contrast, the authors found that oils rich in saturated fats, such as coconut and palm oil, tend to increase total cholesterol and LDL cholesterol concentrations. Nonetheless, coconut oil has gained popularity in recent years for its perceived health benefits attributed to the presence of medium-chain triglycerides that are absorbed intact and directly into the liver. However, this review found limited evidence supporting these claims.
The authors found only one study that investigated the link between vegetable oil and cancer. This study indicated that olive oil consumption was associated with a lower risk of developing cancer, including breast and digestive cancers.
The authors stressed that “it is crucial to emphasize that the reported health benefits of these vegetable oils are based on the amounts recommended in dietary guidelines and not by overconsumption and increasing the total amounts of calories consumed daily, as this may lead to weight gain and possibly obesity.”
Finally, due to the limited number of studies, most of the health outcomes reported in this umbrella review were rated as “low-quality evidence.” Given the challenges in evaluating the impact of various vegetable oils independent of other dietary practices, the authors recommend that “upcoming research should prioritize obtaining comprehensive dietary data and concentrate on long-term clinical outcomes such as cardiovascular events and mortality.”
