According to science, our bodies require nutrients from five main groups:

1–    Carbohydrates

2-    Proteins (built from amino acids)

3-    Vitamins

4-    Minerals

5-    Lipids (fats)

We should consume almost all these nutrients daily for optimal health.

While you may consume raw food, cooked food prepared using various methods is often favored. Heating raw materials through cooking alters the nature of most ingredients and generates new ones. Let’s explore this transformation process.

Imagine we have boiling water in a pot, and someone puts their hand in it for 1 minute. What happens to the hand when it’s removed? Now, what if the hand were kept in the boiling pot for half an hour? What would its shape be then? Do you think hot water burns?

We do the same thing to our food ingredients by heating them. In deep frying, instead of 100°C, we heat the ingredients to 250°C. The higher the temperature, the worse the burning.

Cooking and formation of oxidised materials 

When food or nutrients are described as “already Oxidised,” it typically means they have undergone some degree of chemical oxidation, which can alter their structure and potential for use by cells. The ability of a cell to metabolise oxidised food depends on the extent of oxidation and the type of nutrient involved.

1. Oxidised Fats

Effect: Fats can become oxidised when exposed to oxygen, heat, or light, leading to the formation of harmful compounds like lipid peroxides and free radicals.

Metabolism: oxidised fats are less efficient as an energy source and can be harmful to cells. They may contribute to cellular damage and inflammation. Cells may attempt to detoxify these oxidised compounds, but excessive intake of oxidised fats can overwhelm cellular repair mechanisms and lead to oxidative stress.

2. Oxidised Proteins

Effect: Proteins can also undergo oxidation, leading to changes in their structure and function. Oxidised proteins may form cross-links or aggregates that are difficult for cells to break down.

Metabolism: Cells have mechanisms to degrade damaged or oxidised proteins, such as through the ubiquitin-proteasome system or autophagy. However, heavily oxidised proteins may be less useful as a source of amino acids, and their accumulation can be toxic to cells.

3. Oxidised Carbohydrates

Effect: Carbohydrates are less prone to oxidation compared to fats and proteins, but when they do oxidise, it can affect their usability as an energy source.

Metabolism: Oxidised carbohydrates may be less efficient in providing energy through glycolysis and cellular respiration. However, cells can still metabolise them to some extent, depending on the degree of oxidation.

4. Vitamins and Antioxidants

Effect: Certain vitamins, particularly those with antioxidant properties (like Vitamin C and E), can become oxidised. Once oxidised, they lose their effectiveness in neutralising free radicals and may even become pro-oxidants.

Metabolism: Oxidised vitamins are generally less beneficial and may not perform their intended roles in cellular metabolism. Cells cannot easily reverse the oxidation of these nutrients.

5. General Cellular Response to Oxidised Nutrients

Cells have mechanisms to deal with oxidised molecules, such as enzymes that repair or remove damaged molecules (e.g., glutathione peroxidase, superoxide dismutase). Excessive intake of oxidised nutrients can overwhelm these protective systems, leading to oxidative stress, which is associated with various diseases, including cardiovascular diseases, cancer, and neurodegenerative disorders.

Summary

Cells can metabolise some oxidised food components, but they are less efficient and can lead to cellular damage if consumed in large amounts. Oxidised fats, proteins, and vitamins are particularly problematic, as they can contribute to oxidative stress and inflammation. Therefore, it’s generally better for health to consume fresh, un-oxidised foods to support optimal cellular function.

Several studies have shown that cooking, particularly at high temperatures, can lead to the formation of oxidised materials, including oxidised fats and proteins. These oxidised compounds can form through various processes such as oxidation, Maillard reactions, and thermal degradation. Here’s a brief overview of the evidence:

1. Oxidation of Fats:

• High-Temperature Cooking: Cooking methods like frying, grilling, and roasting, which involve high temperatures, can lead to the oxidation of fats, particularly unsaturated fats. This process forms lipid peroxides and other reactive oxygen species (ROS), which can degrade into potentially harmful compounds like aldehydes.
• Study Evidence: Research published in journals like Food Chemistry and Journal of Agricultural and Food Chemistry has shown that prolonged exposure to high temperatures increases the rate of lipid oxidation in cooking oils and fatty foods.

2. Protein Oxidation:

• Formation of Advanced Glycation End Products (AGEs): Cooking proteins, especially at high temperatures, can lead to the formation of oxidised proteins and AGEs. These compounds form when proteins or fats combine with sugars through a process called glycation.
• Study Evidence: Studies published in journals such as Free Radical Biology and Medicine and The American Journal of Clinical Nutrition have demonstrated that cooking methods like grilling and frying increase the concentration of AGEs and Oxidised proteins in food.

3. Oxidation of Carbohydrates:

• Maillard Reaction: This reaction between reducing sugars and amino acids during cooking, particularly under dry heat, can lead to the formation of browning and oxidised compounds.
• Study Evidence: Research has shown that the Maillard reaction, while contributing to flavour and colour, can also produce potentially harmful oxidised compounds, as documented in journals like Critical Reviews in Food Science and Nutrition.

4. Formation of Harmful Compounds:

• Heterocyclic Amines (HCAs) and Polycyclic Aromatic Hydrocarbons (PAHs): These are formed when meat is cooked at high temperatures, such as grilling or barbecuing. Both HCAs and PAHs are products of protein and fat oxidation and are considered potential carcinogens.
• Study Evidence: Numerous studies, including those published in Carcinogenesis and Food and Chemical Toxicology, have identified the formation of HCAs and PAHs during high-temperature cooking as a health concern.

Oxidised foods and the impact on cellular health- The information provided about the metabolism of oxidised foods and the impact on cellular health is based on well-established biochemical and nutritional principles. While the explanation is drawn from general scientific knowledge, I can summarise key points and provide references to support the discussion.

Key Concepts and References

Oxidised Fats:

Impact on Health: Oxidised fats, particularly those containing lipid peroxides, can lead to oxidative stress and inflammation. These compounds are known to be harmful and contribute to various diseases, including atherosclerosis.

References:

Halliwell, B., & Gutteridge, J. M. C. (2015). Free Radicals in Biology and Medicine (5th ed.). Oxford University Press.

Kanner, J. (2007). Dietary advanced lipid oxidation end products are risk factors to human health. Molecular Nutrition & Food Research, 51(9), 1094-1101.

Oxidised Proteins:

Cellular Handling: Oxidised proteins can be recognised and degraded by cellular mechanisms like the ubiquitin-proteasome system or autophagy. Accumulation of oxidised proteins is linked to aging and various diseases.

References:

Stadtman, E. R. (2006). Protein oxidation and aging. Free Radical Research, 40(12), 1250-1258.

Levine, R. L., & Stadtman, E. R. (2001). Oxidative modification of proteins during aging. Experimental Gerontology, 36(9), 1495-1502.

Oxidised Carbohydrates:

Metabolic Impact: While carbohydrates are less prone to oxidation, the presence of oxidised sugars (e.g., advanced glycation end products) can negatively affect cellular function and contribute to conditions like diabetes.

References:

Ramasamy, R., Vannucci, S. J., Yan, S. S., Herold, K., Yan, S. F., & Schmidt, A. M. (2005). Advanced glycation end products and RAGE: a common thread in aging, diabetes, neurodegeneration, and inflammation. Glycobiology, 15(7), 16R-28R.

Oxidised Vitamins and Antioxidants:

Nutritional Role: Antioxidant vitamins, such as Vitamin C and E, lose their protective effects when oxidised. This can diminish their role in preventing oxidative damage to cells.

References:

Traber, M. G., & Atkinson, J. (2007). Vitamin E, antioxidant and nothing more. Free Radical Biology and Medicine, 43(1), 4-15.

Carr, A. C., & Frei, B. (1999). Toward a new recommended dietary allowance for vitamin C based on antioxidant and health effects in humans. The American Journal of Clinical Nutrition, 69(6), 1086-1107.

General Cellular Response to Oxidative Stress:

Protective Mechanisms: Cells use enzymes like glutathione peroxidase and superoxide dismutase to neutralise oxidative damage. However, excessive oxidative stress can overwhelm these systems, leading to cell damage and disease.

References:

Sies, H. (1997). Oxidative stress: oxidants and antioxidants. Experimental Physiology, 82(2), 291-295.

Droge, W. (2002). Free radicals in the physiological control of cell function. Physiological Reviews, 82(1), 47-95.

Lipid Oxidation and Free Radical Formation:

Study: A study published in Food Chemistry (2016) investigated lipid oxidation in various cooking oils when exposed to high temperatures.

Findings: The researchers found that heating oils, especially at high temperatures like those used in frying, leads to the formation of lipid peroxides and free radicals. These compounds are responsible for oxidative stress, which can contribute to various health issues when consumed.

Effects of Cooking on Meat

Study: Research published in the Journal of Agricultural and Food Chemistry (2008) examined the formation of free radicals in different types of meat (beef, chicken, pork) during cooking.

Findings: The study showed that cooking methods such as grilling, broiling, and frying produced more free radicals in meat compared to boiling or steaming.

The formation of free radicals was linked to the oxidation of fats and the Maillard reaction (a chemical reaction between amino acids and sugars that gives browned food its distinctive flavor).

Antioxidant Degradation in Vegetables:

Study: A study in the Journal of Food Science (2009) analysed the effect of various cooking methods on the antioxidant content and free radical scavenging ability of vegetables.

Findings: High-temperature cooking methods, like frying and roasting, significantly reduced the levels of antioxidants such as vitamin C and phenolic compounds in vegetables. The loss of these antioxidants was associated with an increased potential for free radical formation.

Formation of Reactive Oxygen Species (ROS) in Fried Foods:

Study: A paper in Food and Chemical Toxicology (2010) investigated the formation of reactive oxygen species (ROS) during the frying process.

Findings: The research demonstrated that frying oils, especially after repeated use, produced significant amounts of ROS, which are a type of free radical. These ROS were shown to increase oxidative stress in the body when the fried foods were consumed.

Cooking Oil Stability and Free Radical Formation:

Study: Research published in Food Research International (2017) focused on the stability of various cooking oils under heat and their tendency to form free radicals.

Findings: The study found that oils with a high content of unsaturated fats (like sunflower and corn oil) were more prone to oxidation and free radical formation when heated, especially at high temperatures. Saturated fats, like those in coconut oil, were more stable under heat but still produced free radicals to some extent.

Antioxidant Loss: The degradation of antioxidants like vitamins C and E during cooking can reduce the food’s ability to neutralise free radicals, indirectly contributing to oxidative stress.

Free radicals in biology and medicine” (Halliwell and Gutteridge, 2007) is a widely cited book that explores the role of free radicals in various diseases, including CVD and cancer. Review articles and meta-analyses, such as “Oxidative stress in atherosclerosis: The role of oxidised LDL and noxious radicals” (American Journal of Physiology, 1993), provide comprehensive insights into the role of oxidative stress in cardiovascular diseases.

What do you think? is it burning or cooking? Share your thoughts in the comments below! ⇓