Refined cooking oil & their dangerous effects on health

Highly refined cooking oils are oils which have become a household name in every home in India. Also, sometimes referred to as plastic oils are mainly chosen over pure oils because they have been largely advertised to be of high quality and good for health. But this is untrue.

Research has found that refined oils are highly dangerous for our body and regular consumption of highly refined cooking oils can bring forth many debilitating diseases like cancer, heart attacks, osteoporosis etc. To understand why refined cooking oils are dangerous for our body, let us try to understand what the main manufacturing process of these oils. These oils pass through three refining methods. These are neutralization, bleaching, and deodorization and then the final light golden colour oil is usually called NBD Palm Oil or refined vegetable oil.

Below mentioned are the step by step processes which are adapted to extract the oil out of seeds, nuts, pericarps which then goes to the markets.


Once the oil is extracted from the seeds, it then follows the chemical process to get refined, which involves the treatment of the crude oil with a lye solution to reduce the free fatty acid (FFA) content to 0.05 percent. This method is adopted to prevent spoilage—so that the shelf life of the oil is extended to a considerable amount of time. Along with this, other impurities in the oil, such as gums, phosphatides, pigments, and other oxidation products, are removed from the oil. This is done because, evidently if not done so, it would ‘impair’ the taste, odour, shelf life, and other such properties which makes the oil more appealing to the masses. This neutralization process is accomplished by means of phosphoric acid and more lye.


Once the oil is neutralized, it is mixed with bleaching earth which activates the carbon in it to give the oil a lighter colour. The final purification process includes filters, presses, and polishing filters. Post that, the oil is pumped into storage filters for distribution.


All edible oils and fats contain certain compounds that give the particular oil its identifiable taste and smell. In refined and other commercial oils, these properties are removed to make the oil neutral. This process is called deodorization. It involves very high temperatures and thus is very damaging to the properties of oil, which in turn damages our health.

Refined oil after bleaching is first transferred to a de-aerator operating under a vacuum for removal of any air in the oil. The oil is then subjected to a series of heaters, where the temperature is raised high enough for efficient steam distillation and deodorization. This results in a change of the fundamental chemical structure of the oil into a different form of fatty acid. This process is called isomerization. The newly changed structure of oil is not beneficial to the human body. The high heat also results in the formation of trans fatty acids and we all know that trans fatty acids are highly impervious to our health. In the final step, steam is blown into the oil to remove any residue odour and taste of the oil. The fully deodorized, tasteless, and refined oil is then put through a cooler and polishing filter basket which removes any fine suspension.

The final product

What’s left of the oil is a tasteless, colourless and odourless product which can be stored on the shelf for years. But in actuality, this refined oil has no beneficial quality which was originally present in the seed or nut. It is now a ‘plastic fat,’ fundamentally changed in structure and is quite harmful to the human body. All of the beneficial phytochemicals which are a part of the original raw oil, and which are useful for the body to keep it healthy, have been removed.

Refined cooking oil and their dangerous effects on health

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