Is it time to ditch seed oils?

You’re probably hearing a lot about the danger of consuming seed oils and that could be confusing as it is only maybe 30 years ago that we were being urged to cut out animal-based oils and fats in favour of vegetable or seed oils.

That was because of research that linked high cholesterol and heart disease with the consumption of traditional animal fats like butter and lard which are high in saturated fat. Since then, however, doubt has been cast on the voracity of these findings and indeed new concerns have been raised over the inflammatory effects of certain seed oils. “Eat this, not that,” is a constant refrain from food media, but it can’t be denied that a sudden and significant upswing in many major illnesses across the Western world also coincided with concerted efforts to feed seed oils into the food supply chain into virtually every product you can buy today.

Here is a list of seed oils, describing what they are, what they are generally used for, and whether to avoid using them in your own kitchen.

Corn oil

Corn or maize oil is an oil extracted from the germ of the corn plant and is one of the most widely used oils both domestically and commercially. The extraction process can involve both mechanical and chemical techniques using a solvent like hexane. The oil then goes through a series of refinement stages designed to remove contaminants that could affect the oil's flavour. The downside is that this process consists of degumming, neutralising, washing/drying, bleaching, dewaxing and deodorising. This makes it a highly processed product that removes much of the corn’s beneficial nutrients and while the oil has a high smoke point, making it perfect for frying and deep-frying, it has a high omega-6 to omega-3 ratio which makes it inflammatory. Corn oil is not an intrinsically bad product, but it is highly processed, and while using it every now and then is not the worst thing in the world, it shouldn’t be a staple in your kitchen and you should avoid it when possible.

Canola (rapeseed) oil

Canola oil is a rebranding of rapeseed oil, which fell out of favour for obvious reasons. The name is a combination of the words ‘Canada’ and ‘oil-low-acid’. Canola oil has a bad reputation because, like corn oil, it is highly processed and goes through bleaching and deodorising phases which often include solvents like hexane. With a high smoke point, it is a good choice for frying and its bad reputation maybe be unfair as it is low in saturated fat and high in omega-3 fatty acids. But, while canola oil may not be the worst seed oil out there, use of it should be limited where possible, substituting for healthier oils like olive oil and avocado oil where possible.

Soybean oil

Soybean oil is extracted from the seeds of the soybean plant. After the seeds are cleaned and dried, they are cracked and the husk is removed. The bean is then flattened and washed with a solvent to remove the oil, which then goes through bleaching and deodorising phases. Because it’s cheap to make and has a neutral flavour, it has become the most widely used seed oil in the US and is found in a huge number of processed foods. With a high smoke point soybean oil may have some cholesterol-lowering characteristics and may promote heart health, but it is highly processed and contains little nutritional value. Soybean oil is best avoided both as a cooking ingredient and as an ingredient in processed foods.

Cottonseed oil

Extracted from the seeds of the cotton plant, this oil is not commonly used in home kitchens but it is widely used in processed foods and in restaurant kitchens for frying. Once the oil is extracted from the seeds, a process of bleaching, deodorising and refining is carried out, principally to remove gossypol, a toxic polyphenolic compound that the plant uses to repel insects. Originally used for making soap it became a widely used cooking ingredient in the early 20th century. Cottonseed oil is high in unsaturated fats which may help lower cholesterol, however, the highly processed nature of the product, the pro-inflammatory characteristics and fact that the production often involves pesticides and genetic modification, mean that it is probably best avoided.

Sunflower oil

Pressed from the seeds of the sunflower, this oil is one of the most recognisable and widely used oils in home and restaurant kitchens. The oil has a high smoke point making it well suited to frying. High in Vitamin E, sunflower oil is high in pro-inflammatory omega-6 fatty acids and low in anti-inflammatory omega-3 fatty acids. Again, moderation is the key in using this oil, so if you must have a seed oil in your kitchen, it is not the worst choice.

Safflower oil

Coming from the seeds of the safflower, a member of the sunflower family, this oil has very similar qualities to sunflower oil. It is often used in the production of potato chips or crisps and for frying French fries (chips) in fast food restaurants. These foods are in general best consumed in moderation.

Grapeseed oil

A by-product of the winemaking industry this oil comes from discarded seeds of grapes. Grapeseed oil contains high levels of vitamin E, but it also contains nasty polycyclic aromatic hydrocarbons. Grapeseed oil has some health benefits but as with all seed oils, moderation is advised.

Sesame oil

Derived from sesame seeds, sesame oil is one of the oldest known seed oils used in cooking and is a well-integrated ingredient in Eastern cuisines. Mass production is limited because it is relatively expensive to produce. It has a long history of use in Chinese cooking and in traditional Chinese medicine – it is thought to improve circulation, warm the body and nourish hair. Sesame oil is a relatively harmless seed oil with some benefits but negative effects may be weight gain, danger for allergy sufferers and interference with blood pressure medication. Use this oil in moderation, when cooking Asian cuisine at home.

Peanut oil

Derived from the seeds of the peanut plant, this widely used oil has some benefits to health such as being rich in vitamin E. Its healthy fat factor benefits heart health when substituted for saturated fats in the diet. However, you guessed it, it is a pro-inflammatory, and a peanut allergy can be a potentially fatal condition, so always handle with care. Peanut oil is pretty much like all other seed oils, best in moderation and when possible, choose a healthier alternative like olive, avocado or coconut oil.