Why you should throw away that vegetable oil in your kitchen

Ever wonder how cooking oil is made? It seems pretty obvious, right? You take the seed/fruit/nut, crush it and then squeeze/press out the oil, or rinse it in hot water to separate the oil out. At least that’s how our grandparents used to get palm oil and coconut oil. These days oil production is way more advanced than that.

“Over time extracting vegetable oils has become more and more efficient. The very earliest methods of pressing the vegetable matter probably obtained, at best, 10 percent of the oil available. On the other hand, more modern methods involving solvent extraction can extract all but 5 to 2 percent of the oil.”

Quoted from here

Getting more oil out sounds great, doesn’t it? But as with many things, technological improvement of something that wasn’t broken in the first place tends to create problems. Modern solvent extraction methods leave us with a substance that is highly unnatural and seriously harmful to our health: refined oil. Considering that even virgin oil is not good for us, we should be running very far away from its refined cousin.

Unlike virgin oil which is simply cold pressed, the refined oil we use for frying is produced using destructive processes such as neutralising, bleaching and deodorising. Honestly the process looks more like how you make petrol from crude oil.

How refined oil is made

Step 1: Pressing and solvent treatment

The oil seeds (often from plants genetically engineered to be immune to pesticides) are cleaned, ground up, heated to very high temperatures and pressed to release oil. The resulting residue is treated with a hydrocarbon solvent (usually hexane, a petrochemical) to dissolve any remaining oil. The solvent is then removed by boiling the oil with steam, leaving a very small amount in the oil (which manufacturers claim is harmless).

“Note: Hexane is produced by the refining of crude petroleum oil…Inhalation of high concentrations produces first a state of mild euphoria, followed by sleepiness with headaches and nausea. Chronic intoxication from hexane has been observed in recreational solvent abusers and in workers in the shoe manufacturing, furniture restoration and automobile construction industries where hexane is used as a glue. The initial symptoms are tingling and cramps in the arms and legs, followed by general muscular weakness. In severe cases, atrophy of the skeletal muscles is observed, along with a loss of coordination and problems of vision. In 2001, the U.S. Environmental Protection Agency issued regulations on the control of emissions of hexane gas due to its potential carcinogenic properties and environmental concerns.”

Quoted from here

Step 2: Neutralising

Free fatty acids and waxes in the extracted oil promote oxidation and discoloration so they are removed using caustic soda. The resulting liquid is lighter in colour and less viscous.

Step 3: Bleaching

The oil is then bleached to remove unwanted colours. This is done by treating heated oil with activated carbons, fuller’s earths or activated clays which absorb ‘impurities’ such as chorophyll, vitamins and the natural antioxidants in the oil. This strips away any nutritional value left in the oil and leaves it highly susceptible to oxidation.

Step 4: Deodorising

The final step is removing unwanted odours by treating the oil with pressurised steam at very high temperatures.

While all the steps appear damaging and unhealthy for the oils (neutralization, bleaching, etc.), this last step of deodorization and heating in the process may be the most damaging of all as it severely weakness the fatty acids, leaving them less structurally sound as the high heat carries with it a hefty dose of free radicals. These free radicals wreak havoc on the structure of the fats and are very oxidizing.

Quoted from here

The final product is an unnaturally clear liquid made of pure fat that can withstand very high cooking temperatures. It has zero nutritional value and definitely does not belong in your food. Considering that we often heat this oil to very high temperatures when cooking which introduces cancer causing free radicals, it is probably the most dangerous thing in your kitchen. For the sake of you and your family’s health, please throw away that vegetable oil.

If you must cook with oil, try to use a cold pressed oil from a reputable source. The only oils that can be cold pressed are sesame seed and olive oil. All other oils require heat to extract them. Real cold pressed oils tend to be pricey as they are made in such small quantities, so if the oil is cheap it has likely been adulterated or the manufacturer is being dishonest. Cold pressed oils also tend to be more viscous/thick than refined oils, and they will not be odourless.

22 May 2016 edit: I found what seems like a pretty good test for real olive oil here: apparently if it is cheaper than $10 per litre, it is probably fake. This make sense because vegetable oils are generally much cheaper than $10 per litre, and the real olive oil I have encountered always costs more than that.


Read more about the production of refined vegetable oil here and here

Photo credit – vconnect


2 thoughts on “Why you should throw away that vegetable oil in your kitchen

  1. Hi Itua,
    I’m absolutely turned off vegetable oil at this point. I can eat it in parties because foodie for life, but I’d like to change the oil I use at home. Which do you use?


    1. Hello, thanks for reading! I use cold pressed olive oil at home. Check the bottle to see whether it says ‘extra virgin, cold pressed’. Sometimes they say just ‘virgin’ but that doesn’t mean it hasn’t been exposed to heat. Usually when it comes to oils, the more expensive, the better the quality. Just remember you will be using it sparingly so you will definitely get the value for your money.

      I also use coconut oil, but not in food any longer. I use it on my skin and hair, and for oil pulling.


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