Is eating burnt toast good for you? What the science says about acrylamide

November 5, 2025 •

4 min read

In 2002, Swedish scientists discovered that a substance called acrylamide forms when starchy foods, like toast, are cooked at high temperatures. This revelation sparked widespread concern and debate about whether eating burnt toast is bad for your health and potentially linked to cancer.

Quick Summary

Examines the health implications of consuming burnt toast, focusing on the formation of acrylamide during high-heat cooking. Clarifies the scientific evidence regarding potential health risks, including cancer, and outlines practical strategies for reducing exposure to this chemical in your diet.

Key Points

Acrylamide Formation: Burnt toast and other starchy foods cooked at high temperatures contain acrylamide, a chemical linked to cancer in animal studies.
Not a Direct Cause: Human studies have not definitively proven a link between dietary acrylamide and cancer, but regulatory bodies advise caution.
Minimize Exposure: It is best to minimize exposure to acrylamide by avoiding heavily burnt or charred food.
Scrape or Aim for Golden: When toasting, aim for a light golden-brown color. If you accidentally burn it, scrape off the darkest parts to reduce acrylamide intake.
Vary Cooking Methods: Consider boiling or steaming starchy foods instead of frying or roasting them at high temperatures to avoid acrylamide formation.
Store Potatoes Safely: Avoid storing raw potatoes in the refrigerator, as this can increase acrylamide formation when they are later cooked at high heat.
Nutritional Loss: The burning process destroys some vitamins and nutrients in the food, reducing its nutritional value.

The Maillard Reaction: How Burnt Toast Is Created

When bread is toasted, a chemical process known as the Maillard reaction occurs, which is responsible for giving the toast its appealing brown color and distinct flavor. This reaction happens when the amino acid asparagine in the bread reacts with sugars under high heat. The browning is a desired effect, but if the process continues too long or at too high a temperature, it leads to burning and the creation of a potentially harmful byproduct: acrylamide.

Acrylamide is also used in various industrial processes, but high exposure has been shown to be toxic to the nervous system in animals and humans. While the levels in burnt food are typically lower than those experienced by industrial workers, the cumulative effect of consuming it over a lifetime is a key area of concern for food safety authorities.

The Cancer Controversy: What the Research Shows

The link between acrylamide and cancer has been a subject of extensive study and public discussion. The International Agency for Research on Cancer (IARC) classifies acrylamide as a "probable human carcinogen" based on studies in animals. These animal studies have shown that high doses of acrylamide can increase the risk of certain types of tumors.

However, studies on the effects of acrylamide on human cancer risk have produced mixed results. A review of 32 studies concluded that dietary acrylamide was not associated with a higher risk of the most common types of cancer. This has led to inconsistent evidence regarding its definite carcinogenicity in humans. Still, the general consensus among health organizations is to minimize exposure as a precautionary measure.

Other Potential Health Risks

Beyond the cancer concern, there are other potential health implications associated with eating burnt food:

Loss of nutrients: The intense heat required to burn toast can destroy vitamins and other beneficial molecules. While the nutritional loss from one piece of burnt toast is likely insignificant, consistent burning of food can degrade its overall nutritional value.
Unpleasant taste: The charred bits of burnt toast offer no nutritional benefit and have a bitter, unpleasant taste. This is because the high-heat process breaks down the food molecules into non-nutritive compounds like carbon char.
Formation of other harmful chemicals: When meat is charred, other potentially harmful chemicals like polycyclic aromatic hydrocarbons (PAHs) and heterocyclic amines (HCAs) can also form. This is another reason to avoid regularly consuming heavily charred foods.

How to Reduce Acrylamide in Your Diet

Fortunately, there are several simple strategies to significantly reduce your exposure to acrylamide from toast and other starchy foods. The key principle is to avoid overcooking and charring.

Aim for a golden color: When toasting bread, aim for a light golden-yellow color rather than a dark brown. The darker the toast, the higher the concentration of acrylamide.
Scrape off burnt parts: If you do accidentally burn a piece of toast, scraping off the excessively dark or burnt areas can help reduce your acrylamide intake.
Adjust cooking time and temperature: Using a lower setting on your toaster or cooking for a shorter duration can prevent the bread from burning.
Vary your cooking methods: While roasting and frying produce acrylamide, cooking methods like boiling or steaming do not. Incorporating more of these cooking styles can help reduce your overall intake of the chemical.
Store potatoes properly: Storing raw potatoes in the refrigerator can increase acrylamide formation during cooking. It is best to store them in a cool, dark place outside the fridge.

Comparison: Optimal Toast vs. Burnt Toast


Feature	Optimal Golden Toast	Heavily Burnt Toast
Acrylamide Content	Low	High
Nutritional Value	Intact, minor vitamin loss	Significant vitamin loss
Taste	Pleasant, nutty flavor	Bitter, burnt, unpleasant
Carcinogenic Risk	Unlikely to increase risk	Potential concern with regular, heavy consumption
Appearance	Light, evenly browned	Dark brown to black, charred
Primary Reaction	Desirable Maillard reaction	Maillard reaction leading to charring

Conclusion

While the occasional piece of burnt toast is unlikely to cause significant harm, regularly consuming heavily charred foods is not a healthy practice. The primary concern is acrylamide, a chemical formed during high-heat cooking of starchy foods, which is classified as a probable human carcinogen based on animal studies. Although human studies have not provided conclusive evidence of a direct link to cancer at typical dietary levels, food safety agencies like the Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA) still advise minimizing consumption as a precautionary measure. By adopting simple cooking practices like aiming for a light golden color and scraping off any black parts, you can significantly reduce your acrylamide exposure and prioritize a healthier diet.

World Cancer Research Fund offers more insights on the evidence connecting burnt toast and cancer risk.

Frequently Asked Questions

Yes, occasionally eating a piece of slightly burnt toast is unlikely to cause significant harm. The main concern is regular, long-term exposure to high levels of acrylamide, the chemical found in heavily charred foods.

Acrylamide is formed through the Maillard reaction, which happens when the amino acid asparagine reacts with sugars at high cooking temperatures, creating the brown color and distinct flavor of toast.

Yes, scraping off the heavily charred parts of burnt toast can significantly reduce your exposure to acrylamide. The darker, more burnt areas contain the highest concentration of the chemical.

Food safety agencies, like the FDA, recommend toasting bread to a light golden-yellow color rather than a dark brown. This minimizes the formation of acrylamide.

Acrylamide is primarily found in starchy foods like bread, potatoes, and cereals when they are cooked at high temperatures. Burnt meat, on the other hand, can produce other harmful chemicals like HCAs and PAHs.

Acrylamide is classified as a "probable human carcinogen" by the IARC based on animal studies, but human studies have not provided conclusive evidence of a direct link at typical dietary levels.

Safer cooking methods that do not produce acrylamide include boiling and steaming. For starchy foods like potatoes, roasting or frying at lower temperatures for shorter durations is recommended.