A vegetable oil is a triglyceride extracted from the seeds of a plant. They can be narrowly defined as referring to substances that are liquid at room temperature. Many vegetable oils are consumed directly, or indirectly, as ingredients in food. They have been used for multiple purposes: as shortening, to separate ingredients (as in finished pasta), to add flavor, or as a flavor base, that is, to carry the flavors of other ingredients that are soluble in oil.
Vegetable (seed) oils are also commonly used as cooking oils, that is, heated to cook other foods. The major cooking oils are soybean oil, Canola oil, corn oil, sunflower, safflower, peanut and cottonseed oil. Today, soybean oil accounts for about half of worldwide edible oil production and about seventy percent of cooking oil in the U.S., although Canola oil use is gaining. Corn oil is also one of the most popular edible oils in the U.S. It is used in salad dressings, margarine, some mayonnaise, prepared foods like spaghetti sauce and baking mixes, and to fry potato chips and French fries.
Most vegetable oils are produced by chemical extraction using a solvent – the most common, petroleum-derived hexane. This technique is used for most of the newer industrial oils such as soybean and corn oil, according to Wikipedia. It “produces higher yields and is less expensive.” The more “traditional” oils, e.g. olive oil and coconut oil, are produced by mechanical extraction. Expeller-pressing extraction is common, and is preferred by most “health-food” customers in the U.S. and Europe. Ghani processing, using a powered mortar and pestle, is common in India.
To replace rendered lard (a saturated animal fat derived from pigs) as a cooking oil, Proctor and Gamble introduced Crisco in 1911. P & G scientists learned how to extract oil from cotton seeds, a waste product of the ginning mills. After chemical extraction and refining, they then partially hydrogenated it (thereby creating trans fats), causing it to be solid at room temperature and thus mimic natural lard. They then canned it under nitrogen gas, and voila, Crisco. It was cheaper than lard, easier to stir into a recipe, and could be stored for two years at room temperature before turning rancid.
Soybeans were an exciting new crop from China in the 1930s. Soy was protein-rich, and this medium viscosity oil was high in polyunsaturates (58%), like cotton seed oil (52%) and corn oil (55%), vs. coconut oil (3%). By the 1950s and ‘60s, soybean oil had become the most popular vegetable oil in the U.S. The Diet Dictorcrats were ecstatic. They love everything PUFA.
In the mid-1970s, Canadian researchers developed a low-erucic-acid rapeseed cultivar. In 1998, a new disease resistant cultivar of biotech canola, an herbicide-tolerant GMO, was developed and now is the fourth most dominant biotech crop globally. Worldwide production increased 17% from 2010 to 2011, with the Canadian share increasing from 94 to 96%. Within the United States, where 90% of the canola crop is grown in oil and gas rich North Dakota, production declined.
Canola oil is lower in polyunsaturated fat (28%), and lower in saturated fat (7%) than soybean (16%) or corn oil (13%), and higher in monounsaturated fat (63%) vs. soybean (23%) or corn oil (28%). It is, however, lower in monounsaturated fat than olive oil (72%). Canola is very thin (unlike corn oil) and flavorless (unlike olive oil), so it is beginning to displace soybean oil, just as soybean oil largely displaced cottonseed oil.
The following paragraphs are extracted verbatim from “Negative health effects” in the Wikipedia entry for “Vegetable Oil:”
“Hydrogenated oils have been shown to cause what is commonly termed the "double deadly effect", raising the level of LDLs and decreasing the level of HDLs in the blood, increasing the risk of blood clotting inside blood vessels.”
“A high consumption of oxidized polyunsaturated fatty acids (PUFAs), which are found in most types of vegetable oil (e.g. soybean oil, corn oil – the most consumed in USA) may increase the likelihood that postmenopausal women will develop breast cancer. A similar effect was observed on prostate cancer and skin cancer in mice.”
“Vegetables oils high in polyunsaturated fatty acids cause inflammation of the cells and may lead to a digestive disease and eventually cancer. The main reason is that the polyunsaturated fatty acids in vegetable oils autooxidize during food processing when exposed to oxygen and/or UV radiation; resulting in the autoproduction of inflammatory peroxides and hydroperoxides from polyunsaturated fatty acids.”So, what is the excuse you still use for continuing to use high Omega-6, polyunsaturated, rancid, oxidized, vegetable oils at home? Are you ready to clean out your pantry? And give up all fried foods in restaurants? And stop buying prepared foods at the supermarket? What will it take? Breast cancer? Prostate cancer? Chronic systemic inflammation? A heart attack?