Is Caramel Color Bad for Kidneys? A Closer Look at Safety Concerns

December 2, 2025 •

4 min read

Food additives like caramel color are among the most commonly used food colorings globally. However, concerns have been raised about specific types of caramel coloring and their potential health effects, particularly relating to kidney function. While the issue of whether caramel color is bad for kidneys is nuanced, research has highlighted potential risks, especially from compounds found in Class III and IV caramel.

Quick Summary

Investigates the safety of caramel color, focusing on potential kidney health implications. Examines the different classes of caramel coloring and the chemical byproducts associated with potential risks to renal function.

Key Points

Not all caramel colors are the same: The four classes of caramel color (I, II, III, and IV) differ based on their manufacturing process and ingredients.
Class III and IV caramel contain 4-MEI: These ammonia-based versions can produce 4-methylimidazole (4-MEI), a potential carcinogen in high doses.
High doses can cause oxidative stress in kidneys: Animal studies have shown that high doses of Class IV caramel color can lead to oxidative stress in kidney tissue, which could potentially cause damage over time.
Regulatory bodies have varying safety assessments: While agencies like the FDA and JECFA have set acceptable daily intakes and deemed current levels generally safe, some experts and organizations maintain concerns about chronic, low-dose exposure.
Minimizing intake is a cautious approach: For those concerned about potential risks, especially with pre-existing kidney conditions, reducing consumption of highly processed foods and beverages containing caramel color is a prudent step.
Reading labels can be difficult: Many products simply list "caramel color" without specifying the class, making it hard for consumers to identify which type they are consuming.
The focus is on chronic, high-level exposure: The most significant potential risks are associated with long-term, high-dose consumption, which is more relevant for heavy consumers of products like soda.
More human research is needed: Most concerning evidence comes from animal studies at very high doses, and more research is necessary to fully understand the long-term effects on human kidneys.

What is Caramel Color and How is it Made?

Caramel color is a family of food additives that are produced by the heat treatment of carbohydrates, such as sugars. The type of caramel color produced depends on the specific reactants used in the process. There are four distinct classes of caramel color, each with different properties and manufacturing methods. These classes are differentiated by the presence or absence of specific reactants, namely sulfite and ammonia compounds.

The Four Classes of Caramel Color

Class I (E150a): Produced by heating carbohydrates alone or with acids or bases. No ammonium or sulfite compounds are used.
Class II (E150b): Prepared by heating carbohydrates with sulfite compounds.
Class III (E150c): Uses ammonium compounds during production, resulting in the formation of specific byproducts.
Class IV (E150d): Made with both sulfite and ammonium compounds, and is commonly found in sodas.

The presence of ammonia in Class III and IV caramel is a key area of concern, as it can lead to the formation of byproducts like 4-methylimidazole (4-MEI) and 2-acetyl-4(5)-tetrahydroxybutylimidazole (THI).

Oxidative Stress and Caramel Color: The Kidney Connection

Several studies, particularly those focusing on animal subjects, have explored the potential impact of high doses of Class IV caramel color on organ health. A 2020 study by Marins et al. investigated the effects of Caramel IV dye (C-IV) on the kidneys of mice. The researchers found that high doses of C-IV promoted oxidative stress in kidney tissue. Oxidative stress occurs when there is an imbalance between free radicals and antioxidants in the body, which can cause damage to cells, proteins, and DNA. For the kidneys, prolonged oxidative stress can impair function and potentially contribute to the development of chronic kidney disease.

The mice study observed increased levels of lipid peroxidation and reactive oxygen species (ROS) in kidney homogenates. These findings suggest a potential cytotoxic effect of C-IV, likely due to the presence of 4-MEI. It is important to note that the doses used in animal studies are often significantly higher than what a human would typically consume. However, the study's authors suggest that daily human doses might still induce substantial oxidative stress damage over time and could contribute to long-term health issues.

The Role of 4-Methylimidazole (4-MEI)

4-MEI is a byproduct of the ammonia-based caramel coloring process (Class III and IV) that has received significant attention. In 2011, the International Agency for Research on Cancer (IARC) classified 4-MEI as a 'possibly carcinogenic to humans' (Group 2B). The state of California also lists 4-MEI as a cancer-causing chemical.

Concerns about 4-MEI and its impact on kidneys are primarily linked to the oxidative stress pathway. While the FDA and other regulatory bodies have stated that current levels of 4-MEI in food do not pose an immediate risk, the cumulative effect of chronic exposure is still under review. Some studies have also observed potential reproductive and developmental effects in animals exposed to very high doses of 4-MEI. This raises questions about potential long-term, low-dose exposure effects that are not yet fully understood.

Regulatory Landscape and Risk Assessment

Regulatory bodies worldwide have evaluated the safety of caramel colors and established acceptable daily intakes (ADI). The Joint FAO/WHO Expert Committee on Food Additives (JECFA), for example, has established ADIs for the different classes. The FDA continues to review data on 4-MEI and its safety profile.

There is a debate between industry-backed research, which often concludes that current intake levels are safe, and independent studies that raise more significant concerns. This highlights the need for continued, independent research to fully understand the long-term impacts of caramel color consumption, especially for vulnerable populations or individuals with pre-existing kidney conditions.

Navigating Caramel Color in Your Diet

For most people, the occasional consumption of foods and beverages containing caramel color is not considered a major health risk. However, for those with pre-existing kidney issues or who are concerned about potential long-term effects, reducing intake of products with Class III and IV caramel color might be prudent. Since labels often just list “caramel color,” it can be challenging to distinguish between the classes. Focusing on whole, unprocessed foods is a reliable way to minimize your consumption of all food additives, including caramel color.

Comparison of Caramel Color Classes and Kidney Health


Feature	Class I Caramel	Class II Caramel	Class III Caramel	Class IV Caramel
Reactants Used	Acids or bases	Sulfite compounds	Ammonium compounds	Sulfite and ammonium compounds
Key Byproduct	None of concern	None of concern	THI, some 4-MEI	THI and 4-MEI
Oxidative Stress Concern	Minimal risk	Minimal risk	Moderate potential (THI)	Highest potential (4-MEI, THI)
Regulatory ADI	Not Specified	0–160 mg/kg bw	0–100 mg/kg bw	0–200 mg/kg bw
Kidney Impact	No identified risk	Low risk	Potential for high-dose effects	Potential for oxidative damage at high doses

Conclusion: Making Informed Dietary Choices

While definitive evidence directly linking typical human intake of caramel color to kidney damage is still developing, the available research, particularly on Class IV caramel and its 4-MEI byproduct, suggests that high consumption could contribute to oxidative stress in the kidneys. Regulatory bodies maintain that current intake levels are generally safe, but there is an acknowledged need for further investigation into long-term, low-dose exposure.

Ultimately, consumer awareness and informed dietary choices are paramount. Reading ingredient labels, moderating intake of highly processed foods and sugary drinks, and prioritizing whole foods can help mitigate any potential risks. For individuals with existing kidney conditions, it is especially important to discuss dietary concerns with a healthcare provider. Staying informed on ongoing research will also help you make the best decisions for your health. One authoritative link for further reading is the FDA's Q&A on 4-MEI.

Frequently Asked Questions

Class IV caramel color is of the most concern because its manufacturing process uses both sulfite and ammonia compounds, leading to the formation of byproducts like 4-methylimidazole (4-MEI), which has been linked to oxidative stress in animal studies.

4-Methylimidazole (4-MEI) is a chemical compound that can form during the production of Class III and IV caramel color. It has been classified as a potential carcinogen based on high-dose animal studies, though regulatory bodies state that levels in food do not pose an immediate risk.

It is often impossible to tell from the label alone, as FDA regulations only require the ingredient to be listed as "caramel color" or "color added". The best way to reduce exposure is to minimize consumption of highly processed foods and beverages, especially brown-colored sodas, where it is most commonly found.

For most people, moderate consumption of caramel color is considered safe. However, individuals with specific health concerns, such as pre-existing kidney conditions, should monitor their intake and consult a healthcare provider.

Oxidative stress is an imbalance of free radicals and antioxidants that can lead to cell damage. A mouse study showed that high doses of Class IV caramel caused oxidative stress in kidney tissues, suggesting a potential risk for renal damage over time, though this was with extremely high doses.

No, the risk is not the same across all classes. Class I, for example, is produced without ammonia or sulfites and does not carry the same concerns as Class III and IV. The level of potential risk is directly related to the manufacturing process used.

While completely avoiding it might be overly restrictive, minimizing your intake, especially of Class III and IV caramel color, is a prudent approach. Focus on consuming whole foods and discuss your diet with a renal dietitian or nephrologist.