19 June 2024

How Reused Oil Impacts Our Health Long-Term


Cooking oil is one of the important ingredients in Indian cooking. No one can deny the fact that Indian cuisine is very scrumptious and mouth-watering. We Indians love eating our local cuisine, which a majority of times is made or fried using a large amount of oil. However, we also have a habit of reusing our oil. This is mainly because we want to save our hard-earned money and avoid wastage. Unfortunately, this habit costs us more money in the future. You might be thinking, how? Let me break it down for you so that you will become more cautious regarding your health here on forth.

The Hidden Dangers of Reused Cooking Oil

Formation of Harmful Invisible Contaminants

According to the Food Safety and Standards Authority of India (FSSAI), reheating cooking oil forms harmful contaminants, including free fatty acids, peroxides and polar compounds. When consumed, these substances increase free radicals in the body, which elevate the risk of inflammation and a variety of chronic diseases.

Chemical Reactions in Reused Oil

Repeated frying of moist food in the same oil initiates a series of chemical reactions that significantly impact the composition and properties of the oil. This process leads to the hydrolysis of oil, causing the breakdown of triglycerides into free fatty acids and increasing the oil's acid value. Additionally, the reaction of oil with atmospheric oxygen induces oxidation. These biochemical reactions intensify in the hot frying medium, resulting in the production of degraded chemical compounds like:

  1. Free radicals
  2. Lipid peroxides
  3. Polycyclic aromatic hydrocarbons
  4. Aldehydes
  5. Ketones
  6. Alcohols
  7. Free fatty acids
  8. Alkanes
  9. 4-hydroxy nonenal
  10. Hydro-peroxide volatile compounds
  11. Polymerized triglycerides

Health Risks from Reused Oil

1. Cardiovascular Diseases

Aldehydes present in thermally or oxidatively-stressed frying oils affect the structural modification of the apo B component of low-density lipoprotein (LDL). This process induces the generation of foam cells from macrophages, a hallmark of atherosclerosis (the buildup of fats, cholesterol, and other substances in and on the artery walls). Thus, consumption of polyunsaturated fatty acids-derived oxidation products in the diet represents a hazard to human health, particularly concerning cardiovascular disease.

2. Pro-Inflammatory Properties

Repeated heating of oil increases the oxidation of polyunsaturated fatty acids, resulting in higher concentrations of aldehydic peroxidation products. These products exert powerful pro-inflammatory actions. According to literature, oxidative stress induces a cascade of radical reactions, elevating levels of lipid oxidation products in the knee joint of patients with inflammatory joint diseases, such as rheumatoid arthritis. In addition, peroxidized polyunsaturated fatty acids-derived carbonyl compounds induce significant inflammatory responses.

3. Gastropathic Conditions

The α,β-unsaturated aldehyde 4-hydroxy-trans-2-nonenal, generated from repeated heating of oil at high temperatures, is present in extremely high levels in thermally-stressed polyunsaturated fatty acids-rich cooking oil. This may account for a high fraction of gastropathic conditions in humans, including peptic ulcers.

4. Cancer

The repeated heating of cooking oil increases lipid oxidation, enhancing the peroxidation of membrane macromolecules. This cascade of events significantly increases mutagenic and genotoxic properties, potentially paving the way for carcinogenesis. Polycyclic aromatic hydrocarbons predominantly emerge during the high-temperature cooking process and may cause cancers such as colorectal, lung, stomach, esophagus, prostate, skin, breast, kidney, and pancreas cancer. These health risks may stem from imbalances in omega-3 to omega-6 ratios and the intake of by-products from frying oil.

Why Are Free Fatty Acids (FFAs) in Cooking Oil Bad for Our Health?

What Are FFAs?

Free fatty acids (FFAs) are formed after the breakdown of long-chain fatty acids in oils and fats.

Effects of FFAs on the Body

  1. Immune System Impact: FFAs can change how our immune system works by affecting certain molecules, leading to increased inflammation.
  2. Health Conditions: High levels of FFAs are involved in health issues like obesity, inflammation, and heart disease.

Health Implications of High FFAs

  1. Increased Blood Levels: Consuming oils high in FFAs can raise their levels in our blood, leading to problems like insulin resistance, inflammation, and high blood pressure.
  2. Chronic Diseases: High FFAs are linked to conditions like cancer, heart problems, blood clotting issues, and eye problems.
  3. Cholesterol Imbalance: They affect the levels of "good" and "bad" cholesterol in our blood, contributing to cholesterol buildup in arteries.


    Reusing cooking oil can lead to numerous health issues due to the buildup of contaminants and the formation of harmful contaminants. Prioritizing short-term savings should not come at the expense of our well-being. It is crucial to recognize these dangers and opt for alternative measures, such as using the Purifry power pack, to safeguard our long-term health.