Everything You Need to Know About Buying Oil


Have you ever been confused about which vegetable oils are healthiest? Or which ones to use for what purposes? You’re not alone. Vegetable oils are a slippery minefield. We’ve read it all: Canola oil good. Canola oil bad. Expeller pressed or cold pressed? Refined or unrefined? With so many differing opinions it’s hard enough to figure out what’s healthy and what’s not. Knowing how to use the different oils is another story.

First, a little general information:

Production: Any vegetable oil you buy should be expeller pressed rather than processed through chemical extraction methods. A few types of oils (like olive oil) can be cold pressed. Cold-pressed oils are higher quality because the lower processing temperatures preserve the flavor and characteristics of the oil. There is no regulation for the term, so buy from a trusted producer.

Always buy organic. Two examples why: Most corn and canola oil is genetically modified but organic certification guarantees that it is not (unless it was contaminated by cross-pollination). Peanuts are one of the crops most heavily sprayed with pesticides, so organic is extra important there, too.

Refining: Refined oils are mild to devoid of flavor and have a high smoke point, meaning they can be used for high heat cooking and deep-frying. Unrefined oils are less processed, have more flavor, and are often higher quality, but you have to be careful about using them over very high heat for stir-fries and deep-frying. They also tend to go rancid more quickly.

Mono vs. Polyunsaturated: All vegetable oils are a combination of mono and polyunsaturated fat, so you can’t really choose. I was especially confused about this one as there seems to be more conflicting information about this than any other topic in oils. I asked a trusted source and health care professional over at Gastronicity blog and she said a higher percentage of mono is better. This WebMd article confirms that mono is gaining ground among experts as preferable for protecting against heart disease, though both fats raise good cholesterol in the blood.

The Best Oils for Culinary and Health Properties

Coconut Oil: Mainstream nutritionists will say that coconut oil is bad for you because it’s saturated, but people who believe that saturated fat (even animal fat) isn’t always bad will say that it’s good for you. Some studies have shown that it lowers bad cholesterol. Some people think that the campaign against saturated tropical fats began with the marketers of America’s subsidized mono-crops (canola, soy, and corn). When deciding what to believe, I like to think about what people with pre-industrialized traditional diets ate (food in its most natural state) and go with foods closer to that, rather than highly processed (and marketed) modern foods. Coconut oil is okay in my book. Unrefined is best, but you shouldn’t cook over too high a flame as it will smoke. It also adds a nice flavor.

Palm Oil: Virgin palm oil is supposed to be very healthy like coconut oil, but be careful here as there are some real issues with sustainability. Anything that is billed as sustainable is likely to be very expensive.

Olive Oil: If I could only have one type of oil in my kitchen, this would be it. It’s not always best for high heat cooking, and sometimes you want a different flavor profile. These would be the two biggest reasons to branch out.

Peanut Oil: Unrefined peanut oil has a higher smoke point than most unrefined oils and great flavor. (I like to use it to make popcorn.) Use semi-refined or refined peanut oil for deep-frying or stir-frying, but sparingly. Peanut oil has a fairly high percentage of mono-unsaturated fats.

Sesame Oil: The toasted type is strongly flavored and goes rancid very quickly, so keep in the refrigerator. Regular sesame oil is healthy and has a medium high smoke point, making it a good bet for stir-frying.

Walnut Oil: Delicate, tasty, nutritious, and very perishable. Store in the refrigerator and use for salads, not cooking.

Avocado Oil: Nutritious and full of good fats, and the highest smoke point of all. But very expensive, making it difficult to use for frying and also extremely perishable.

Safflower or Sunflower: According to many people, these are better options than canola for when you want a more neutral tasting oil. They are high in monounsaturated fats and not as highly processed as canola. They’re good all-purpose oils when you don’t want the taste of olive oil.

For smoke points of various oils, refer to this chart from Cooking for Engineers.

A note on storing: Buy oils in opaque containers whenever possible and store in the refrigerator. If the oil isn’t particularly perishable and you use it often, a cupboard is probably fine. Never store out on the counter where the oil is exposed to light. Personally, I keep all my oils in the refrigerator except for my olive oil, which I use daily.

This is the latest installment in Vanessa Barrington’s weekly column, The Green Plate, on the environmental, social, and political issues related to what and how we eat.

Image: Muffet

Vanessa Barrington

Vanessa Barrington is a San Francisco based writer and communications consultant specializing in environmental, social, and political issues in the food system.