Breast Cancer Awareness Month often focuses on screening, treatment and survivorship, but treatment can also change something we use every day without much thought: Our senses of taste and smell.

For some people undergoing chemotherapy, familiar foods suddenly taste different.

Favourite meals may become unappealing, certain smells may become overwhelming, and foods may develop metallic, bitter or otherwise unfamiliar tastes. These changes can affect appetite, enjoyment of food and the types of foods patients choose during treatment.

There is another important food safety lesson hidden within that experience. Many consumers already rely heavily on their senses to decide whether food is safe. We smell leftovers, taste milk, inspect cooked rice or look at meat and assume that if nothing appears wrong, the food is probably fine.

For someone whose sense of taste or smell has been altered by treatment, that approach becomes even less reliable.

However, the larger truth is that it was never a reliable food safety test in the first place.

Cancer Treatment Can Change Taste and Smell

Taste and smell changes are recognised side effects of some cancer treatments, particularly chemotherapy. A prospective study involving 87 patients receiving chemotherapy for breast cancer or gynaecological cancers found significant reductions in both taste and smell function during treatment. The researchers observed that these changes were generally temporary, with function recovering almost completely three months after chemotherapy.

Another study found that breast cancer patients undergoing treatment often preferred milder and softer foods over fried or oily foods, while other research has documented temporary reductions in taste and smell perception and changes in food preferences during chemotherapy. These changes are important because they can affect appetite and nutrition. However, they also raise another question: If a person’s senses have changed, can smell or taste still be trusted to identify unsafe food? The answer is no. More importantly, even people with perfectly normal senses should not rely on them for that purpose.

Spoiled and Unsafe Food Are Not the Same Thing

One of the most common food safety misconceptions is that dangerous food will announce itself. Consumers expect unsafe food to smell sour, look discoloured, feel slimy or taste unpleasant. Sometimes food does develop obvious signs of deterioration, but those changes are more closely associated with spoilage than with the presence of every foodborne pathogen.

Spoilage microorganisms can produce noticeable changes in odour, flavour, colour and texture.

Those signals may tell us that a food has deteriorated and should not be eaten. Diseasecausing microorganisms are different. Food contaminated with pathogens such as Salmonella, Listeria monocytogenes or certain disease-causing strains of Escherichia coli may still look, smell and taste completely normal. The absence of an unpleasant smell therefore does not prove that the food is safe.

This distinction is critical.

Your nose may tell you that milk has soured. Your eyes may reveal mould growing on bread.

Your tongue may identify an undesirable flavour. However, your senses cannot count bacteria, measure toxin levels or tell you whether a pathogen contaminated the food during preparation, processing or storage. A smell test is therefore a quality assessment, not a microbiological test.

The Dangerous Taste Test

Another common practice is tasting questionable food to decide whether it should be discarded. Someone may take a spoonful of soup, taste yesterday’s rice or sip milk and conclude that the food is safe because it tastes normal. That reasoning is backwards. If the concern is that the food may have been stored improperly or kept for too long, tasting it introduces exposure before the safety question has been answered.

Certain foodborne hazards are particularly good examples of why this practice is unsafe. Rice and other starchy foods can be associated with Bacillus cereus, a spore-forming bacterium capable of causing vomiting or diarrhoeal illness. A 2024 review of research on B. cereus in rice identified improper handling and temperature control during cooking, cooling and reheating as major contributors to risk.

The answer to rice that sat on the stove for hours is therefore not, “Taste it and see.” The more useful question is, “How long was it outside temperature control?”

This principle applies to many other foods, including cooked meat, poultry, soups, gravies, seafood, pasta and leftovers.

Food history is a better safety indicator than food smell.

Refrigeration Does Not Make Food Invincible

Consumers also tend to believe that refrigeration automatically makes food safe. Refrigeration is one of our most important food safety controls because low temperatures slow the growth of many microorganisms. However, refrigeration does not sterilise food, nor does it stop every organism from growing.

Listeria monocytogenes is an important example because it can survive and grow at refrigeration temperatures. This is one reason why Listeria is a concern in refrigerated ready-to-eat foods, including certain prepared meats, deli products and other foods that may be eaten without another cooking step. For someone undergoing cancer treatment who may also have reduced immune defences, this issue is especially important. Yet the lesson extends to every household.

A container of food being cold does not tell you how long it has been stored, whether it was contaminated before refrigeration or whether the refrigerator has actually maintained an appropriate temperature.

Time Tells You More Than Smell

One of the most useful changes consumers can make is to stop asking only, “Does this smell okay?” and start asking, “How long has this been here?” Time and temperature are two of the most important factors governing microbial growth in food.

Cooked foods should be refrigerated promptly rather than being allowed to remain on countertops, stoves or dining tables for extended periods.

Foods prepared in large quantities also need particular attention because large pots of rice, soup, stew or meat can cool slowly, creating conditions that allow bacteria to multiply.

If you cannot remember when it was prepared, how long it remained outside refrigeration, whether the refrigerator was working properly or how many times it has been warmed and cooled, smelling it does not reconstruct that missing information. When storage history is uncertain, the safest decision may be to discard it.

Appearance Can Also Be Misleading

Consumers frequently inspect raw chicken, meat, vegetables and cooked foods for visual signs of danger. Appearance can certainly identify some obvious problems. Visible mould, damaged packaging, leaking containers or unusual physical changes should not be ignored.

However, a normal appearance does not establish safety.

Pathogenic bacteria are microscopic. They do not need to create visible changes before reaching levels capable of causing disease. A beautifully presented salad can still have been crosscontaminated. Cooked chicken may look perfectly normal after being handled with contaminated utensils. Fresh fruit may appear flawless while carrying organisms acquired during production or handling.

The challenge becomes even greater with ready-to-eat foods because there may be no final cooking step between contamination and consumption.

That is why food safety systems are built around preventive controls rather than sensory inspection alone.

What Should Consumers Use Instead?

If sight, smell and taste cannot reliably determine safety, consumers need better decision making tools. The first is time. Know when food was prepared, purchased or opened. Date leftovers when necessary rather than depending on memory.

The second is temperature.

Use refrigerator and food thermometers where appropriate. A thermometer provides information that touch cannot.

The third is storage history.

Ask whether food was refrigerated promptly, whether raw and ready-to-eat foods were properly separated and whether refrigeration was interrupted by a power outage or equipment failure.

The fourth is label information.

Follow storage instructions and pay attention to use-by or expiration information where applicable rather than assuming that an acceptable smell overrides the manufacturer’s instructions.

The fifth is safe preparation.

Prevent cross-contamination, wash hands and food-contact equipment appropriately and cook foods thoroughly.

These practices are far more reliable than sensory judgement because they address the conditions that determine whether pathogens can survive, spread or multiply.

About the Author

Allison Richards is a food safety communicator, certified trainer and the founder of The Food Safety Girl, a consumer awareness platform promoting food safety in Jamaica and the Caribbean. She is the Caribbean Chapter Director for Women in Food Safety (WIFS) and host of The Big Bite Food Safety Show. With over 15 years of experience in food safety regulation, she is committed to public education and consumer empowerment. Through public education initiatives, including free community webinars, she continues to create space for learning, dialogue, and practical food safety awareness.

Allison Richards

thefoodsafetygirlja@gmail.com

Allison Richards | thefoodsafetygirlja@gmail.com.