Cooking methods affect inflammation and the gut barrier

How we choose to prepare our food has a direct impact on systemic inflammation and the function of the intestinal barrier. The health effects of a meal are determined not only by the quality of the raw ingredients. But also by the chemical alterations that occur when food is subjected to heat. Research demonstrates that the choice of cooking method can either attenuate or exacerbate inflammatory processes in the body (Bengmark, 2007; Rodríguez-Ayala et al., 2022).

By understanding how high temperatures alter food and affect the gastrointestinal tract, it becomes easier to make informed choices in everyday life.

 

Heat-induced toxins – impact of high temperatures on food

When food is exposed to high temperatures, particularly exceeding 120–130 °C, chemical processes occur that result in the formation of harmful compounds. These substances are frequently referred to as heat-induced toxins, with the most well-documented groups abbreviated as AGEs (Advanced Glycation End-products) and ALEs (Advanced Lipoxidation End-products). They form when food develops a heavily fried, grilled, or roasted surface, such as on chips, grilled meat, or darkly toasted bread. These compounds are absorbed by the body and contribute to increased inflammation (Bengmark, 2007; Bengmark, 2009).

Clinical studies indicate that a diet rich in highly heat-treated food has distinct negative effects on health:

• Triggers Inflammation: Heat-induced toxins are absorbed in the gut and activate processes in the body that elevate inflammatory markers (Bengmark, 2009; Birlouez-Aragon et al., 2010).
• Impaired Metabolic Balance: Research indicates that the body’s ability to manage blood glucose and insulin decreases after a period of consuming highly heat-treated food, compared to a diet based on steamed food (Birlouez-Aragon et al., 2010).
• Loss of Vitamins: High heat destroys the natural protective compounds in food. Studies show that vitamin levels in the blood decrease significantly when consuming food prepared at high temperatures (Birlouez-Aragon et al., 2010).

Concurrently, research shows that gentle preparation methods, such as consuming raw ingredients, boiling, or steaming, are associated with significantly lower inflammatory markers in the body (Rodríguez-Ayala et al., 2022).

 

How cooking affects the intestinal tract

When the gut is burdened with high concentrations of heat-induced toxins, the barrier function is negatively affected. The intestinal wall normally functions as a tight barrier designed to prevent harmful substances from entering the systemic circulation. Consuming a large proportion of highly heat-treated food creates stress that can weaken this defence. Increased intestinal permeability may allow harmful substances to leak into the body, which in turn maintains and drives systemic inflammation (Bengmark).

 

Recommendations for anti-inflammatory cooking

To protect the intestinal tract and manage inflammation in the body, the primary focus lies in how we choose to prepare our food and what we place on the plate.

• Choose Gentle Cooking Methods: Utilise boiling, steaming, and oven-baking below 100 °C as the foundation of the daily diet. When cooking in the oven or on the hob, avoid burning the food and remove any darkened sections (Bengmark).
• Focus on Fresh Ingredients: Aim to consume a portion of vegetables completely raw to preserve sensitive enzymes and antioxidants (Bengmark).
• Utilise the Effect of Cooled Food: A practical method is to boil potatoes or root vegetables in advance and allow them to cool in the refrigerator before consumption. As the starch cools, retrogradation occurs, forming resistant starch which serves as excellent nutrition for the gut microbiota (Bengmark).

Supplements as a complement

A fibre-rich synbiotic supplement serves as a valuable support for the gut microbiota, particularly during periods when the diet has placed extra strain on the gastrointestinal tract. However, it is important to emphasise that supplements cannot replace an otherwise healthy lifestyle. They should always be viewed as a complement to a varied, fibre-rich, and anti-inflammatory diet.

 

References

Bengmark, S. (2007). Vår tids kost bakom inflammation och sjukdomsutveckling. Upphettning av mat ger dysfunktionella proteiner som ansamlas i kroppen. Läkartidningen, 104(51), 3873-3877.

Bengmark, S. (2007). Advanced glycation and lipoxidation end products – amplifiers of inflammation: the role of food. JPEN. Journal of Parenteral and Enteral Nutrition, 31(5), 430-440.

Bengmark, S. (2009). AGE, ALE, RAGE and disease – a foods perspective. In: Handbook of Prebiotics and Probiotics Ingredients. CRC Press, Taylor and Francis Group.

Birlouez-Aragon, I., Saavedra, G., Tessier, F. J., Galinier, A., Ait-Ameur, L., Lacoste, F., Niamba, C. N., Alt, N., Somoza, V., & Lecerf, J. M. (2010). A diet based on high-heat-treated foods promotes risk factors for diabetes mellitus and cardiovascular diseases. The American Journal of Clinical Nutrition, 91(5), 1220-1226.

Moreno-Franco, B., Rodríguez-Ayala, M., Donat-Vargas, C., Sandoval-Insausti, H., Rey-García, J., Lopez-Garcia, E., Banegas, J. R., Rodríguez-Artalejo, F., & Guallar-Castillón, P. (2021). Association of Cooking Patterns with Inflammatory and Cardio-Metabolic Risk Biomarkers. Nutrients, 13(2), 633.

Rodríguez-Ayala, M., Banegas, J. R., Ortolá, R., Gorostidi, M., Donat-Vargas, C., Rodríguez-Artalejo, F., & Guallar-Castillón, P. (2022). Cooking methods are associated with inflammatory factors, renal function, and other hormones and nutritional biomarkers in older adults. Scientific Reports, 12, Article 16483.