Replacing butter with plant-based oils can significantly lower the risk of early death, according to the study’s findings.cheche22/ISTOCK
Despite much evidence to the contrary, seed oils – which include canola, soybean, corn, sunflower, safflower and grape seed oils – have been portrayed on social media as unhealthy.
Critics claim that consuming these vegetable oils can lead to weight gain, inflammation, heart disease and cancer, among other ills. Healthier alternatives, they contend, are animal fats such as lard, beef tallow and ghee (clarified butter), as well as olive, avocado and coconut oils (which do not come from seeds).
But now, a decades-long study adds to previous evidence that plant-based oils, which include seed oils, are associated with better health. Replacing butter with plant-based oils can significantly lower the risk of early death, according to the findings.
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Here’s what to know.
The latest research
For the study, published this month in the JAMA Internal Medicine journal, researchers investigated the relationship between butter and plant-based oil intake and risk of total mortality, as well as death from cardiovascular disease and cancer.
To do so, they analyzed data collected over 33 years from 221,054 adults who participated in one of three large continuing U.S. studies. Dietary, lifestyle and health information was collected at baseline and every four years during the study follow-up period.
Total butter intake included butter consumed from butter/margarine blends, spreadable butter added to foods, and butter used for frying and baking. Intake of plant-based oils, which included corn, safflower, soybean, canola and olive oil, was estimated based on the type of oil used in frying, sautéing, baking and salad dressings.
Butter versus plant-based oils
Compared with participants whose diets contained little to no butter, those who consumed the most (median daily intake of 2.5 to three teaspoons) had a 15 per cent higher risk of death from all causes. Conversely, participants with the highest (versus lowest) intake of total plant-based oils (median daily intake of five teaspoons) were 16 per cent less likely to die during the study period.
Even when olive oil, well-documented for its cardiovascular health benefits, was removed from the analysis, a higher intake of plant-based oils was still tied to a lower mortality risk. When the researchers looked at specific types of plant-based oils, canola, soybean and olive were each significantly associated with a lower risk of premature death. No significant association was found for corn oil and safflower oils, perhaps because of their low consumption among study participants.
A higher intake of plant-based oils was also associated with a lower risk of death from cancer and cardiovascular disease. Higher butter intake, on the other hand, was tied to a greater risk of cancer death. The researchers estimated that replacing 10 grams of butter (about two teaspoons) each day with an equivalent amount of these plant-based oils would reduce overall mortality and cancer death each by 17 per cent.
To arrive at these conclusions, the researchers controlled for other factors that could influence the findings such as age, body mass index, alcohol consumption, smoking, physical activity, total calorie intake and overall diet quality.
Strengths, caveats
The study is credited for its large sample size, long duration and repeated measurements of diet and other personal and lifestyle factors. The main limitation is that study was observational: It found an association between plant-based oils and lower mortality risk, but it did not prove a causal relationship.
Still, the results are in line with findings from plenty of other studies showing health risks with high intakes of saturated fat and health benefits when they’re replaced with plant-based oils.
How dietary fats may influence longevity
Butter has a high saturated fat content (62 per cent), which has been shown to raise LDL cholesterol in the bloodstream and trigger inflammation. That can contribute to an increased risk of cardiovascular disease and certain cancers. Studies have also revealed that saturated fatty acids can alter hormone activity, which could influence hormone-sensitive cancers such as breast and prostate.
Plant-based oils contain mostly unsaturated fats, a combination of polyunsaturated and monounsaturated fats, which have been shown to help lower LDL cholesterol and reduce inflammation. Olive, canola and soybean oils are also decent sources of vitamin E, an antioxidant that protects against oxidative stress. As well, canola and soybean oils provide alpha linolenic acid, an anti-inflammatory omega-3 fatty acid.
Many plant-based oils are also good sources of the omega-6 fatty acid, linoleic acid, which also has anti-inflammatory effects. There’s evidence that higher intakes of linoleic acid may guard against heart disease and stroke.
Takeaways
These new findings highlight the potential sizeable long-term health benefits that can be achieved by making a simple dietary swap.
If butter is a principal fat in your regular diet, consider swapping some of it for plant-based oils, such as olive or canola oil, in cooking and baking. Even replacing a little butter with plant-based oils could lead to health advantages.
Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan. Follow her on X @LeslieBeckRD
