Your Cooking Oil is Harming Your Health and Aging You

Bottle of Olive Oil with Wooden Spoon --- Image by © Radius Images/Corbis
Bottle of Olive Oil with Wooden Spoon — Image by © Radius Images/Corbis

If you open a bottle of cooking oil and take months to finish it, heat, light and air start to break down the oil, making it rancid. At best, it smells and tastes different. At worse – potentially toxic compounds are produced in the oil. In this article, I’ll share how to prevent the introduction of bad compounds, how to choose the right product and store it properly and discuss the difference between regular vs. extra virgin olive oil.

Choose the Right Oil for Cooking & Throw Out Your Deep Fat Fryer

For high heat cooking, choose an oil with a high smoke point. When an oil hits it’s smoke point it breaks down and becomes rancid. Rancid oils may smell or taste bad (though sadly some people are accustomed to this taste as “normal”) and may contain toxic compounds, some of which are believe to contribute to cell aging (1, 2, 3). In general, refined oils have a higher smoke point than those that are unrefined. Refer to the usage instructions on the bottle to find out if it be used for high heat cooking.

Use Type of Oil Smoke Point (3) Greater likelihood of Oxidation (> 50 PUFA %) (4) 
Baking
Cooking
Stir Frying
Almond
Avocado
Canola
Grapeseed
Hazelnut
Peanut
Olive
Palm
Pecan
Safflower
Sunflower
High Almond
Grapeseed
Hazelnut
Safflower
Sunflower
Light sautéing
Sauces
Low-heat baking
Coconut
Corn
Hempseed
Macadamia nut, refined
Sesame, refined
Soybean
Walnut – refrigerate after opening
Medium Corn
Flaxseed
Hempseed
Soybean
Walnut
Dressings
Dips
Sauces
*Refrigerate these after opening
Flaxseed
Pumpkin seed
Wheat Germ
Low

In addition to using the right oil for what you are cooking or baking, throw out your deep fat fryer and quit eating fried foods (or at the very least, throw out the oil after each use). Food manufacturers and restaurants re-use oils over and over for frying. After several days they finally throw it out and replace it with fresh oil (5). Each time the oil is used it loses some of its integrity and the smoke point lowers. And though it may take several uses before it becomes rancid (depending on the type used, frying time, heat and other factors), frying decreases the amount of antioxidants in the oil (greater frying time = fewer antioxidants), changes it’s chemical structure and produces trans fatty acids (repeated heating of oil, prolonged heating and heating in an iron container all increase the formation of trans fatty acids) and volatile compounds (such as aldehydes, triacylglycerol oxidation products including alkoxy, epoxy, keto monomeric compounds, and higher molecular weight oxidation products) (6, 7, 8, 9, 10).

Store it Properly

Store your oil in a cool and dry place away from direct sunlight (some oils should be refrigerated – as noted above). When possible, buy oil in dark glass containers. When monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids in oil react with oxygen they become oxidized and form a variety of chemicals, several of which are toxic (aldehydes, ketones, alkenals). The production of these compounds speeds up when the oil is exposed to heat and light or metals are present. More polyunsaturated fat = greater likelihood of oxidation so check your oil’s PUFA content above and if its high, buy smaller quantities of this oil and smell-check it frequently. If it smells different than when you bought it, toss it in the trash.

What is Extra Virgin Olive Oil vs. Olive Oil?

U.S. Extra Virgin Olive Oil is the oil resulting from the first pressing of olives and is suitable for human consumption without further processing. It has “excellent flavor and odor” (smell).

U.S. Virgin Olive Oil is olive oil obtained by picking and processing olives, or blends of virgin refined olive oil. It has “reasonably good flavor and odor.”

U.S. Olive Oil is a blend of refined and virgin olive oils.

Refined Olive Oil is sold as “Olive oil” or “Pure olive oil” and is the oil obtained from subsequent pressings (after the first pressing) and suitable for human consumption by refining processes which neutralize the acidity or remove particulate. Heating, neutralizing, bleaching and deodorizing may be used (10, 11).

“‘Light olive oil refers only to the flavor and is determined by the amount of extra virgin olive oil added to the refined olive oil.” (12)

Choose an olive oil in a dark glass bottle. California Olive Ranch is a good brand, as are the ones on this list. Or, if you want amazing authentic olive oil from trees that are 2,000 – 3,000 years old, order olive oil from this Masseria in the Puglia region of Italy.

Is Canola Oil Harmful?

If you’ve heard that canola oil is harmful, read this post for a good explanation of oil processing techniques.

There are plenty of oil choices depending on your desire for taste and a temperature you are using.

References
1 J Oleo Sci. 2008;57(3):153-60.
2 Toxicol Mech Methods 2006;16(5):267-74.
3 Deep Fat Frying and Food Safety. USDA.
4 Food Nutr Res. 2011;55:10.5
5 Nahrung 2002;46(6):420-6.
6 Food Chem 2007;104(4):1740–1749.
7 Eur J Lipid Sci Tech 2002;104(12):785–791.
8 J Food Sci Technol 2014;51(6):1076-84.
9 Chem Phys Lipids 2012;165(6):662-81.
10 J Sci Food Agric 2012;92(11):2227-33.
10 Guidance for Industry: A Food Labeling Guide (12. Appendix D: Qualified Health Claims). U.S. Food and Drug Administration.
11 United States Standards for Grades of Olive and Olive-PomaceEffective October 25, 2010. USDA.
12 Grading Manual for Olive and Olive-Pomace. USDA. Effective May 2012.

 

Food Fraud: Is Your Food Adulterated?

By: Gisselle Marie Rosa, UGA MS student & Dietetic Intern

As consumers, we put our trust in food companies to be honest about their food products. You go to the grocery store and spend and exorbitant amount on 100% pure Italian olive oil expecting that it comes from the finest olive crops in Italy. Yet that dark glass bottle with the scenic picture of an olive farm in Tuscany may contain olive oil mixed with lower quality vegetable oil. Then you see news reports bombarding the media about honey that is diluted with less expensive syrups and “wild” salmon that was actually farm-raised in another continent. It makes you wonder why food companies would risk lying to their consumers about the quality of the food they are selling and how you can avoid buying these products at all.

Food Adulteration for Economic Gain (Saving Cash)

Food fraud, or economically motivated adulteration, refers to defrauding buyers of food or ingredients for economic gain. There are generally three types of fraud: complete or partial replacement of a food or ingredient, the addition of a substance to mask the quality of the food product, and removal of a component of the food product. Unfortunately, no one really knows exactly how common these practices are. Most instances of food fraud do not pose a public health risk, so they are easy to get away with. There are some instances, however, where certain foods or ingredients are adulterated with potential allergens or toxic ingredients that could harm the consumer. Some examples are as benign as injecting shrimp with gelatin, while others are as dangerous as adding melamine to infant formula to make the protein content of the formula seem higher. The latter example led to thousands of infant illnesses and the death of 6 infants in China.

Unintentional Food Adulteration

However, not all cases of food adulteration are intentional. An example is selling bruised fruit, where mishandling could have led to decreased quality of the produce item and potential exposure to contamination.

It is pretty evident that food fraud can be deceiving and even dangerous. So how can you become a more informed consumer?

The U.S. Pharmacopeial Convention (USP) has an online database that provides food ingredient fraud reports. In this database, you can find past reports from the media and scientific journals about food fraud cases. Additionally, the United States Department of Agriculture website  posts the most recent food recalls, many of which are due to food adulteration.

According to the Congressional Research Service, some of the most common food categories with reported cases of food fraud include: olive oil, fish and seafood, milk and milk-based products, honey, fruit juice, coffee and tea, spices, and organic foods. Curious to see how these foods have been adulterated in the past? If you are curious about food fraud, check out this Food fraud database.

Just remember: a smart consumer is a safe consumer. While there is no need to be skeptical about every food product you buy, it is important to understand that food fraud exists. So the next time you go to the store to buy fresh red snapper, make sure that the fish you are buying is authentic and not a cheaper, lower quality fish.

Resources:

Johnson, R. Food Fraud and “Economically Motivated Adulteration” of Food and Food Ingredients. Congressional Research Service 2014. Internet: https://www.fas.org/sgp/crs/misc/R43358.pdf

U.S. Pharmacopeial Convention. USP’s Food Fraud Database 2015. Internet: http://www.usp.org/food-ingredients/food-fraud-database

United States Department of Agriculture. Recalls and Public Health Alerts, 2014. Internet: http://www.fsis.usda.gov/wps/portal/fsis/topics/recalls-and-public-health-alerts/