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What are Cold Pressed Oils?

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What is the best cooking oil? Unrefined, cold-pressed (or expeller-pressed) vegetable oils are the healthiest cooking oils for your kitchen. Learn more about these less-refined vegetable oils in this expert guide.

There used to be a small selection of cooking oils on supermarket shelves, such as corn oil, soybean oil and canola oil – all clear, pale, odorless and tasteless. Then came the popularity of olive oil, which added a flavorful, unrefined, extra virgin oil to the options. But today, the supply of unrefined vegetable oils has increased dramatically. You can find unrefined, cold-pressed avocados, almonds, peanuts, grape seeds, hemp, flax, red palm trees, walnuts, and coconuts in supermarkets — especially health food stores.

It is clear that consumers have a wide range of oils to use in cooking, dressing their salads and toppings on their pasta. But what are the nutritional effects of these unrefined, cold-pressed oils?

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You can find oils made from pumpkin seeds in some markets.

What are unrefined cold-pressed oils?

Refined oils were heated and extracted with chemical solvents to extract the oil and get the best industrial yield from a crop such as soybeans, sunflower seeds, or corn. However, according to Janet Bond Brill, PhD, RDN, FAND, LDN, heart health and dietary fat expert and author of Cholesterol Down, this process results in oils with the poorest quality in terms of health properties. In contrast, unrefined vegetable oils are those that are defined as “virgin,” meaning the oil is mechanically extracted without heat or chemical solvents. “Cold” refers to those oils that do not use heat during the extraction process. When plants like olives are exposed to high temperatures, volatile aromas can be lost, as well as polyphenols, antioxidants and vitamins. “Pressed” refers to being crushed in a mill to extract the oil.

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“Unfortunately, there is no regulation that ensures that unrefined oils are actually unrefined,” says Brill. The only exception is olive oil. In the EU, the terms “cold” and “pressed” are regulated for olive oil, Brill explains, but outside the EU the regulation does not apply to these terms in relation to olive oil, so consumers have no reassurance that any claims made are true . To be safe, Brill suggests looking for olive oil with the highest polyphenol content (over 500), free fatty acid levels of 0.2 percent or less, and peroxides well below 10 meq/kg. Additionally, you can search for certification seals such as Protected Designation of Origin (PDO), Protected Geographical Identification (PGI), Australian Olive Association, California Olive Oil Council, and Association 3E.

What Are the Health Benefits of Unrefined Cold Pressed Oils?

Overall, we know that vegetable oils rich in unsaturated fats, such as sunflower, canola, corn, soybean, and olive oils, are associated with lowering LDL and total cholesterol and triglyceride levels and raising HDL compared to less -Cholesterol levels are linked to healthy fats, like butter. (1) In theory, unrefined vegetable oils should go beyond the mere fatty acid profile benefits as they contain more phytochemicals and micronutrients from the original plant. Unfortunately, there isn’t much scientific evidence on the supply of unrefined vegetable oils on the shelves today to back up this theory, except for the king of unrefined vegetable oils: extra virgin olive oil.

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Extra virgin olive oil pressed from olives has been linked to better health.

The unrefined vegetable oil with the lion’s share of evidence-based benefits is extra virgin olive oil. “The scientific data supporting the health benefits of authentic extra virgin olive oil, along with the existence of olive oil regulatory agencies, make choosing olive oil as the main fat the best choice. At least until the other oils can keep up in terms of data and regulation,” advises Brill. In fact, hundreds of studies have documented the health benefits of extra virgin olive oil, an important part of the Mediterranean diet. In 2018, the International Olive Oil Council gathered world experts at the Robert Mondavi Institute in California to summarize the data on the effects of olive oil consumption on human health. They emphasized the benefits of this oil in cardiovascular disease, breast cancer, Alzheimer’s and diabetes, as well as the lifestyle, taste and cultural benefits of Mediterranean dietary traditions. (2)

Look for unrefined oils made from avocados.

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Another unrefined oil comes from avocado, which has an oil extraction process similar to olive oil, explains Brill, who ranks this oil as her second-best choice after olive oil. Avocado oil extraction involves removing the skin and pit, grinding the pulp into a paste, malaxing (slow stirring) for 40–60 minutes at 45–50°C, and separating with a centrifuge to obtain the oil. That slightly higher temperature doesn’t affect the quality of the oil, says Brill, which is 76% monounsaturated, 12% polyunsaturated, and 12% saturated fat — very similar to olive oil. The main antioxidant is a-tocopherol, with a low presence of d-tocopherol and components such as chlorophyll and carotenoids.

Other unrefined oils, such as hemp and flaxseed, may have potential benefits related to their plant-based omega-3 content. Hemp oil contains 2 grams of omega-3 fatty acid per tablespoon and flaxseed oil contains about 7 grams per tablespoon. However, these oils are often used as dietary supplements rather than cooking oils.

Hemp oil is becoming increasingly popular.

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Not all cold-pressed oils are created equal

Just because the oil is unrefined doesn’t mean the oil has a healthy lipid profile. “My two favorite nuisances are coconut oil and palm oil,” says Brill. She stresses that the claim that coconut oil is a healthy food is based on the misconception that coconut oil contains mostly medium-chain triglycerides (MCTs), so the oil is thought to have a neutral effect on blood LDL cholesterol levels. Additionally, the high levels of lauric acid in coconut oil are thought to increase HDL cholesterol. “That’s just not the case,” says Brill, who reports that more than 40 years ago, the saturated fatty acids lauric acid, myristic acid, and palmitic acid were shown to be hypercholesterolemic. (3) “Approximately 92% of the fat in coconut oil is saturated and consists primarily of the three big saturated fatty acids: about 49% lauric acid, 18% myristic acid, and 9% palmitic acid.”

While marketed as another unrefined, healthy oil, red palm oil is also high in saturated fat—about 50% of total fatty acids are saturated, with high levels of palmitic acid (44%). (4) “The high level of hypercholesterolemic saturated fat in palm oil clearly makes it a poor choice for heart health, regardless of how it’s processed,” says Brill.

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What is the end result of these oils? “Claiming that the oil is unrefined does not automatically make it a healthy food. Just because it comes from a plant doesn’t make it a healthy oil,” says Brill.

Walnut oil is good for baking.

In the kitchen

One of the most important culinary benefits of unrefined vegetable oils is the aroma and flavor that are still present in the oil. So if you want your pan to taste like peanuts, add unrefined peanut oil. If you want your cookies to taste like walnuts, use unrefined walnut oil. The flavor attributes you can achieve in numerous dishes such as salad dressings, marinades, savory recipes, baked goods, stir-fries, side dishes and pasta dishes are limitless.

But how do unrefined vegetable oils fare in the kitchen? “The more refined the oil, the higher the smoke point,” says Brill. This means that unrefined oils can degrade as the cooking temperature increases. In fact, some unrefined oils have fairly low smoke points – flaxseed oil is around 225 F. However, many have higher smoke points. For example, olive oil’s smoke point is 410 F, which should cover most cooking operations in a home kitchen.

Unrefined vegetable oils often come at a high price point, highlighting the possibility of using these oils as a specialty culinary ingredient rather than replacing all of the fat in a traditional recipe. The high price and sensitivity of many unrefined oils may make them a better choice for non-heat culinary uses, such as cooking. While we wait for the science, use extra virgin olive oil as the best cooking oil and other heart-healthy options to round out the health and flavor of a plant-based diet.

For recipes using healthy unrefined oils, check out the following:

Prime tomato and aubergine pasta sauce
Fresh cranberry beans with pasta and vegetables
Balsamic Butternut Squash and Brussels Sprouts with Farro
Homemade Pistachio Butter
Quinoa Waldorf Salad with Walnut Vinaigrette

References:

  1. Schwingshackl L, Bogensberger B, Bencic A, Knuppel S, Boeing H, and Hoffman G. Effects of oils and solid fats on blood lipids: a systematic review and network meta-analysis. Journal of Lipid Research. 59(9): 2018 1771-1782. Retrieved from: http://www.jlr.org/content/early/2018/07/13/jlr.P085522.full.pdf
  2. Visioli F, Franco M, Toledo E et al. Olive oil and chronic disease prevention: summary of an international conference. Nutrition, metabolism and cardiovascular diseases. 2018. 28(7):649-656. Retrieved from: https://www.sciencedirect.com/science/article/pii/S0939475318301261.
  3. Mensink RP. Effects of stearic acid on plasma lipids and lipoproteins in humans. lipids. 2005. 40 (12): 1201-1205.
  4. Mancini A, Imperlini E, Nigro E, et al. Biological and nutritional properties of palm oil and palmitic acid: health implications. molecules. 2015. 20(9):17339-17361. Retrieved from: https://www.ncbi.nlm.nih.gov/pubmed/26393565.

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