Can Molasses Be Toxic? Understanding the Risks and Safe Consumption

January 14, 2026 •

5 min read

According to the Food and Agriculture Organization of the United Nations, fatal food poisoning has been reported in China from consuming moldy sugarcane. This critical fact sets the stage for understanding the circumstances under which molasses—a sugarcane byproduct—can indeed be toxic, posing risks beyond its sugary nature for both humans and animals.

Quick Summary

Molasses is generally safe in moderation but can become toxic due to contamination by mycotoxins from moldy sugarcane or excessive intake leading to nutritional imbalances in animals. Consumers should be vigilant for signs of spoilage and understand the distinct risks for humans and livestock. Proper storage and controlled intake are essential to prevent health complications.

Key Points

Mold Contamination: Moldy sugarcane can produce dangerous mycotoxins, like 3-nitropropionic acid, leading to toxic encephalopathy and potential death if consumed.
Livestock Risk (Molasses Toxicity): Overfeeding molasses to ruminants, especially with insufficient roughage, can cause a severe neurological condition akin to polioencephalomalacia due to thiamine deficiency.
Excessive Intake (Humans): High consumption of molasses contributes to excessive sugar and calorie intake, increasing the risk of obesity, dental issues, and chronic diseases like diabetes.
High Mineral Content: Blackstrap molasses, while nutrient-rich, contains concentrated minerals like potassium, which can be harmful in large quantities, especially for individuals with kidney problems.
Trace Contaminants: Trace amounts of lead and acrylamide can be naturally present in molasses, particularly blackstrap, triggering consumer warning labels in certain regions.
Proper Storage is Crucial: Store molasses in a cool, dry, sealed container to prevent mold and fermentation; discard immediately if there is any visible mold or a sour smell.
Pet Safety: Molasses, especially blackstrap, is safe for dogs in very small, controlled amounts, but high sugar content poses risks like weight gain and digestive issues.

Understanding the Nature of Molasses Toxicity

Molasses is a thick, dark syrup created as a byproduct of sugar refining from sugarcane or sugar beets. While a nutritious alternative to refined sugar in small amounts, its safety is not unconditional. The potential for molasses to become toxic primarily stems from two distinct situations: contamination by mycotoxins and nutritional imbalances caused by overconsumption, particularly in livestock. A common misunderstanding is that molasses is uniformly harmless, but the source, storage, and quantity are critical factors determining its safety.

Contamination from Moldy Sugarcane

One of the most dangerous scenarios involves molasses derived from moldy or improperly stored sugarcane. A specific type of fungus, Arthrinium, can contaminate sugarcane and produce the neurotoxin 3-nitropropionic acid.

Human Risk: Consuming moldy sugarcane or its contaminated byproducts can lead to toxic encephalopathy, causing severe neurological damage, convulsions, and even death. In reported cases, moldy sugarcane poisoning has been linked to extensive damage to the central nervous system, particularly affecting the brain. The key takeaway for human safety is to avoid any sugarcane or molasses with signs of spoilage, such as an unusual color, mold growth, or a fermenting smell.
General Spoilage: Even without mycotoxin contamination, improperly stored molasses can ferment, developing a sour or alcoholic smell. While likely not deadly in small amounts for humans, this indicates that the product's quality and taste have been compromised and it should not be consumed.

Nutritional Risks for Animals and Humans

Molasses is a widely used ingredient in animal feed to increase palatability and energy content. However, high-molasses diets can lead to serious health issues, especially in ruminants like cattle.

For Livestock: Excessive molasses intake, particularly when roughage is restricted, can cause a condition known as molasses toxicity. This syndrome, which causes irreversible brain damage similar to polioencephalomalacia, is linked to an induced thiamine deficiency and an inadequate supply of glucose to the brain. Symptoms in cattle include weakness, lack of coordination, staggering, blindness, and potentially death. Correct feeding practices, including providing adequate roughage, are crucial for preventing this toxicity. In wet conditions, diluted molasses can also ferment and poison cattle.
For Humans: The risk of toxicity from excessive consumption in humans is less severe but still notable. Molasses, despite its nutrient content, remains high in sugar and calories. Overconsumption can contribute to weight gain, dental problems, and an increased risk of chronic conditions like type 2 diabetes and heart disease. Additionally, blackstrap molasses has been found to contain trace amounts of lead and acrylamide, triggering warnings in some regions, though these levels are typically far below harmful thresholds.

Molasses Toxicity Comparison Table: Human vs. Animal Risks


Aspect of Toxicity	Human Risk	Livestock Risk (Ruminants)
Cause	Primarily from consuming mycotoxin-contaminated (moldy) molasses or excessive sugar intake.	Excessive intake, high sugar content, low roughage diet, and diluted/fermented molasses.
Mechanism	Mycotoxins (e.g., 3-nitropropionic acid) cause neurological damage. Excess sugar contributes to metabolic issues.	High sugar shifts rumen fermentation, leading to thiamine deficiency and insufficient glucose for the brain.
Symptoms	Neurological damage, convulsions, dizziness, vomiting. Metabolic issues from excess sugar.	Staggering, incoordination, weakness, blindness, and brain damage.
Prevention	Avoid any molasses with signs of spoilage; consume in moderation, especially with conditions like diabetes.	Strict control of intake, ensuring adequate roughage, and preventing fermentation.
Contamination Risk	Yes, from contaminated raw materials (sugarcane).	Yes, from improperly stored or diluted molasses.
Other Considerations	Trace levels of lead and acrylamide can be present. High potassium in blackstrap is a risk for those with kidney disease.	Potassium excess, bloat, and diarrhea can occur with high intake.

Different Types of Molasses

Molasses is not a single product. Different types have varying levels of nutrients and sugar, which can affect their potential for harm, particularly for animals.

Light Molasses: Resulting from the first boiling, it is the sweetest and contains the most sugar. Its high sugar content means it should be used in moderation for humans and is not the best choice for pets due to potential blood sugar spikes.
Blackstrap Molasses: A product of the third boiling, it is the most concentrated and contains the highest levels of vitamins and minerals. It is also the lowest in sugar and has a more bitter taste. Due to its mineral content, excessive intake can lead to high potassium levels, which is a concern for individuals with kidney issues. Trace elements like lead and acrylamide are also concentrated here.
Sulfured vs. Unsulfured: Sulfured molasses contains sulfur dioxide as a preservative. While not inherently toxic, some people may have a sensitivity or allergy to sulfites. For this reason, unsulfured molasses is often recommended for both human and animal consumption.

Practical Safety Measures for Storage and Use

To prevent molasses from becoming toxic, whether for human or animal use, safe handling and storage are paramount. Molasses, with its high sugar content and low moisture, is naturally resistant to many types of spoilage, but it is not immune.

Preventing Mold Contamination: Always store molasses in a tightly sealed container in a cool, dark place away from heat and moisture. Any visible mold, a sour smell, or signs of fermentation means the product must be discarded immediately. For animal feed, ensure all storage areas are dry and the molasses is not diluted by rain, which could trigger fermentation.
Controlled Intake: For livestock, intake must be carefully controlled, especially when combined with low-fiber diets. Providing sufficient roughage is the most effective preventative measure against molasses toxicity in ruminants. For humans, moderation is key, especially for those with conditions like diabetes.
Awareness of Contaminants: While trace amounts of lead and acrylamide in blackstrap molasses are low, awareness of their presence is important for consumers, especially in regions with stringent labeling laws like California's Proposition 65.

Conclusion

Can molasses be toxic? The answer is nuanced. While high-quality, properly stored molasses is generally safe for humans in moderation and for animals in controlled amounts, several factors can introduce toxicity. The most serious risk comes from mycotoxins produced by moldy sugarcane, which can cause severe neurological damage. For livestock, overconsumption without adequate roughage can induce a specific toxicity syndrome. Furthermore, excessive sugar intake and high mineral concentrations in blackstrap molasses pose additional health considerations for humans. Responsible consumption, proper storage, and awareness of the specific risks for both humans and animals are essential to prevent the potential for molasses toxicity.

Learn more about safe livestock feeding practices by reading up on animal nutrition and feed management.

Frequently Asked Questions

Poisoning from consuming normal, store-bought molasses is highly unlikely if it is properly stored and free of mold. The primary risk is from consuming molasses contaminated by mycotoxins from moldy sugarcane, which is prevented by quality control and proper storage.

Signs of spoiled molasses include visible mold growth (fuzzy spots), an unpleasant or sour smell suggesting fermentation, and an abnormal or bad taste. If you notice any of these, the molasses should be discarded.

Blackstrap molasses is not inherently toxic, but it contains higher concentrations of minerals and sugar compared to lighter varieties. Excessive intake can be harmful, especially for individuals with diabetes or kidney disease due to its potassium content. Trace contaminants like lead may also be present, although usually at very low levels.

For dogs, molasses is generally safe in very small amounts but can cause digestive upset and blood sugar spikes due to its high sugar content. It should be avoided for pets with diabetes or obesity. Cats should typically not be given molasses due to their different dietary needs and sensitivity to sugar.

In livestock, especially ruminants, molasses toxicity can occur with high-intake diets, particularly those low in roughage. It leads to neurological disorders like brain damage due to a thiamine deficiency and insufficient glucose for brain function.

Some blackstrap molasses products carry a California Prop 65 warning because of trace amounts of naturally occurring lead and acrylamide. The warning is based on specific state regulations, not necessarily because the product is unsafe at typical consumption levels.

If molasses becomes diluted with water, it can rapidly ferment into alcohol. For livestock, this can be fatal if large quantities are consumed. For human consumption, fermented molasses will have an off-flavor and should be discarded.