For most people, choosing a cooking oil depends on taste preferences, intended use or health considerations. Richly flavored oils like extra virgin olive oil or unrefined coconut oil are best saved for uses where that flavor shines through, while more refined options, like canola, are useful for things like frying, inclusion in baked goods, or other times you don’t want to impart too much flavor to the food. People worried about saturated fat might avoid butter, lard, coconut and palm oil, and instead turn to oils like olive, avocado or flaxseed for their heart-healthy omega-3 and omega-6 fatty acids.
But while we’re used to thinking about cooking oils in terms of culinary value or health, we’re less used to thinking about their sustainability. This is a big gap, considering how much land is used for growing the seeds that most oils are derived from: in 2022, 337 million hectares of cropland worldwide were devoted to oil crops, just over 20 percent of the world’s total cropland.
Like all foods, oils come with a carbon footprint, but that’s not the only dimension of sustainability that matters. Depending on the scale of production, oils come with a number of other impacts on biodiversity and land use, soil health, water quality and more.
With the exception of butter, most animal fats are becoming less popular in cooking than they used to be. This is partially the result of health concerns — with lard and tallow (rendered fat from pigs and cows) being high in saturated fats that most health experts recommend limiting — and partially the result of their relatively high cost compared to plant-derived options. As a result, most of the cooking oils we use today in the U.S. are vegetable oils.
That name, which might suggest broccoli, carrots or other fresh veggies as the source material, is actually just an umbrella term for plant-based oils, most of which come from oil-rich fruits or seeds. While you can extract oils from almost any plant, most cooking oils come from three kinds of crop: tree crops (like olive and avocado), tropical palms (like coconut and oil palm) and row crops (like corn, canola, sunflower and soybean).
Tree crops: high demand but low production
Compared to other vegetable oils, oils from tree crops like olives and avocados tend to be expensive and in high demand, especially for the flavor and nutrient-rich virgin oils that come from the first cold pressing of fruit. These are typically labeled as extra virgin, virgin, cold pressed or unrefined, depending on exactly how they were pressed. More refined oils are usually extracted from the fruit paste after the first press, and these are often better suited for uses like frying because they are milder in taste and have high smoke points. Tree nuts, like almonds, walnuts and pecans, can also be pressed for oil, though the high cost and rich flavor of these oils means they’re mainly used as flavor enhancers rather than cooking oils.
Tree crops represent a major investment in time, water and land as they get established, but the upside is that groves can be productive for decades or — in the case of olives — centuries after they’re established. Trees often require little supplemental care after they’ve reached maturity if they’re planted in an appropriate location. While the oil yield from olives and avocados tends to be lower than that of palms or tree crops, they can succeed on land that’s too hilly or too dry for other crops to succeed. Groves can be well integrated into their surrounding environment and be minimally disruptive to other species, particularly in situations where chemical use is low.
However, the sustainability of tree crops is ultimately scale-dependent: the explosion of demand for avocados worldwide has led to extensive deforestation in Mexico, and even helped destabilize local weather patterns. If groves are too extensive and break up too much of the natural environment, they can also put significant strain on local water supplies.
Demand for avocado oil is high, but demand for olive oil is even higher. This means it outpaces the fairly low production of olive oil generally, which makes up less than 2 percent of global oil production. This means that while olive oil may be a great choice to consume in limited quantities, there’s simply not enough of it to make it a reliable everyday choice for everyone. Much of the lower-quality olive oil on the market today is fraudulently blended with other oils.
Palm-derived oils: efficiency vs. biodiversity
Because oil crops take up so much space, efficiency — how much oil we can expect out of an acre of the crop — is an important factor in assessing sustainability. On this basis, palm oil comes out on top, producing nearly four times as much oil per acrethan the closest competitor, canola. But there’s a problem here: not all land is created equal.
Oil palms thrive in the tropics, and their expanding footprint has led to extensive deforestation and biodiversity loss in some of the most ecologically sensitive rainforests on earth, especially in Southeast Asia. So while canola, sunflower and other oils may take up more space than oil palms, they aren’t displacing such sensitive land. This doesn’t mean that they don’t also have impacts on biodiversity, which suffers under any monoculture (one crop being grown in huge tracts), but because biodiversity in tropical forests is so high, oil crops in temperate areas simply aren’t harming as many species.
Deforestation is also responsible for the high carbon footprint of palm oil (as well as Brazilian soybeans and other crops that farmers cut down tropical forests to grow): Because tropical forests store so much carbon, converting them to farmland releases an enormous amount of carbon dioxide back into the atmosphere, driving up the footprint of these commodities.
Palm oil, particularly the refined palm oil that’s common in processed foods, isn’t especially common as a cooking oil in the U.S., though the less refined red palm oil is a common pantry ingredient in West African cuisine. While it may originate with the same crop, red palm oil’s use predates the industrially scaled palm oil plantations that have become so widespread in the last few decades. As food writer Yewande Komolafe has pointed out, given that the demand for refined palm oil in the industrial food system is what’s driven the deforestation associated with palm oil production, it would be unfair to narrow in on the small amount that’s used by West African cooks as a traditional ingredient, especially when there are regeneratively sourced options for red palm oil. When it comes to industrially produced palm oil, the best way to limit your intake is to limit your consumption of ultraprocessed foods that rely on it as their main source of fat, like packaged cookies and snacks.
Coconut oil also comes from palms, though its current status as a cure-all in both traditional medicines and modern wellness circles (as well as its popularity in the keto diet) lends it a much better reputation than palm oil. Ultimately, however, coconuts occupy essentially the same acreage worldwide as oil palms. And because coconut palms thrive in similar regions as oil palms, they have similar problems: one study has indicated that coconut oil production could be just nearly as damaging to biodiversity as palm oil, though these claims have stirred some debate in the scientific community. Coconut palms might be markedly less efficient at producing oil (yielding less than 10 percent as much oil per acre as oil palms), but that’s not their only use — coconut plantations are also a source of coconut milk and meat, as well as industrial fiber, so oil isn’t the only thing coming from that land. They’re also less likely to be cultivated in complete monocultures than oil palms, which diffuses their impact on surrounding ecosystems. Still, given these concerns, it’s a good idea to consume coconut oil in moderation.
Oils from row crops: sustainable on paper, problematic in practice
After palm oil, the most popular cooking oils worldwide all come from row crops, which are planted, grown and harvested by machine on an industrial scale. The most-produced vegetable oils from row crops are soybean, canola (also called rapeseed), and sunflower. But a host of other row crops are also used as a source of oils, including cotton, corn, safflower, peanut and flax. The generic “vegetable oil” you find at the supermarket is usually just soybean oil, but it may contain a blend of other oils that varies based on price and availability. Sometimes these oils are also collectively called seed oils, reflecting the fact that they’re extracted from the seeds of these crops.
These crops are generally grown in monocultures, large stands of a single species of plant. Large-scale monocultures make mechanized farming easier and efficient, and this means that row crops often carry a relatively low carbon footprint: canola and sunflower oil offer lower footprints than other choices, especially crops that are tied to deforestation like palm oil and Brazilian soybean oil.
But that nominally low footprint doesn’t tell the whole story : industrial monocultures don’t support the same amount of biodiversity that smaller-scaled operations do, and maintaining them generally takes large amounts of synthetic fertilizers and pesticides. When used in excess, those fertilizers can run off into waterways and cause algae blooms, impairing water quality and hurting wildlife. They can also leach into groundwater and present potential health issues. In the Upper Midwest, where corn and soy are king, public and private wells are extensively contaminated with excess nitrates from chemical fertilizers and animal manure that’s been applied to farmland. These nitrates limit blood’s ability to carry oxygen, and can present a serious risk of cardiovascular issues for infants and other vulnerable people, as well as potentially increasing risk for some cancers.
For a few oils, one herbicide is a particular concern. The vast majority of soy, corn and canola in the U.S. comes from plants that have been genetically modified to resist the herbicide glyphosate, the main ingredient in Roundup. This modification allows farmers to spray entire fields with glyphosate, leaving the crop unharmed. The ease and popularity of this method of weed control made glyphosate the world’s most popular herbicide, but it’s also had some unintended effects: the widespread use has sped the evolution of herbicide-resistant “superweeds”that can withstand glyphosate, leading farmers to turn to other, more dangerous herbicides like dicamba and paraquat. Glyphosate overuse also has negative impacts on soil bacteria, lowering the number of species in agricultural soils, as well as potentially disrupting the lifecycles of soil-dwelling animals like worms and insects.
Organically produced seed oils do partially sidestep these problems, since synthetic pesticides and fertilizers are not allowed under the USDA’s organic rules. This forces growers to maintain fertility more naturally with crop rotation and other practices, which at least helps to ensure that the land isn’t in a constant monoculture year after year. But some of the problems of farming at this scale, particularly issues like soil erosion and limited biodiversity, still persist even under organic management.
Are seed oils bad for you?
And if you’ve been on social media in the last year or so, it’s quite likely you’ve seen someone — usually an alternative medical influencer with dubious accreditation — warning about the dangers of consuming seed oils. There are currently claims that seed oils cause cancer, gut issues and depression, or can leave you with chronic inflammation or make you more vulnerable to sunburns. But how much of this is accurate?
There may be some room to be concerned about the chemicals that can be left behind by the processing that seed oils undergo during extraction (though these are generally accepted by the FDA as not enough to be a concern). But most of the ire directed at seed oils has to do with the theory that the fats they contain, omega-6s, cause inflammation. But there’s simply not good enough evidence to support this; while it’s true that one compound produced as your body breaks down omega-6s, arachidonic acid, is linked to inflammation, other breakdown products actually help fight inflammation. Overall, provided your omega-6 intake is balanced with omega-3s — the heart and brain-boosting fats found in fish, nuts, flax and more — the wide consensus among nutritionists remains that seed oils are a healthy fat when eaten in moderation.
Of course, this is complicated by the reality that inexpensive vegetable oils are frequently included in foods that are fried, ultraprocessed or otherwise unhealthy, which lends the anti-seed oil narrative some believability. And given the environmental impact of industrial row crop production, there’s a sustainability angle for moderating your intake as well. But it’s worth noting that warnings about seed oils usually go arm in arm with the suggestion that animal fats like tallow or lard are the healthiest option, something that — in addition to being something few nutrition experts would endorse — dovetails neatly with the reality that many anti-seed oil campaigners also profit off of by selling carnivore diet plans and supplements.
All cooking oils come with tradeoffs, so using a variety of oils (preferably organic when possible) is a good way to incorporate diverse fats into your diet without doubling down on the environmental problems associated with any one oil.
