New Delhi: Leftover food stored in the refrigerator may appear safe to eat, but improper storage or reheating can increase the risk of food-borne illnesses, health experts caution. While refrigeration slows bacterial growth, it does not eliminate harmful microorganisms, making safe food handling essential to prevent illness.

According to the World Health Organization (WHO), unsafe food causes more than 600 million cases of food-borne illness worldwide each year. Experts say leftovers that are left at room temperature for extended periods or stored beyond their recommended shelf life are among the most common causes of food poisoning at home.

Refrigeration is not enough

Dr Mahendra Singh Rajput, Senior Consultant in the Department of Digestive Diseases, Gastroenterology and Hepatology at Amrita Hospital, Faridabad, said many people underestimate how quickly bacteria can multiply in cooked food.

He explained that bacteria such as Clostridium perfringens, Salmonella and certain strains of E. coli can survive or multiply if food is not cooled, stored or reheated properly.

According to Dr Rajput, some bacteria also produce toxins that remain harmful even after the food has been reheated.

Health risks linked to unsafe leftovers

Improperly stored leftovers can lead to several health problems, including:

Food poisoning

Food poisoning is the most common consequence of consuming contaminated leftovers.

Symptoms may appear within hours or several days and commonly include:

  • Nausea
  • Vomiting
  • Diarrhoea
  • Stomach cramps
  • Fever

Most healthy adults recover within a few days, although severe cases may require medical treatment.

Acute gastroenteritis

Contaminated food can inflame the stomach and intestines, leading to acute gastroenteritis.

Common symptoms include persistent diarrhoea, vomiting, abdominal pain, fever and weakness. Severe diarrhoea can also result in dehydration, particularly among children and older adults.

Severe abdominal pain

Certain bacteria release toxins that irritate the digestive tract and cause intense abdominal cramps.

Experts advise seeking medical attention if severe stomach pain develops after eating leftovers.

Dehydration

Repeated vomiting and diarrhoea can rapidly deplete the body’s fluid levels.

Warning signs include:

  • Excessive thirst
  • Dry mouth
  • Reduced urination
  • Dizziness
  • Fatigue

Young children, older adults and people with chronic illnesses are especially vulnerable.

Electrolyte imbalance

Loss of fluids may also reduce essential minerals such as sodium and potassium.

This can result in muscle weakness, fatigue, confusion and, in severe cases, irregular heartbeat.

Some patients may require intravenous fluids to restore electrolyte balance.

Serious bacterial infections

Although many food-borne illnesses are mild, infections can become severe in individuals with weakened immune systems, diabetes, chronic liver disease, cancer or during pregnancy.

These groups are at greater risk of complications and may require hospitalisation.

Worsening of chronic illnesses

Food-borne infections can aggravate existing health conditions, including diabetes, kidney disease, liver disorders and immune-related illnesses, making recovery more difficult.

Safe ways to store leftovers

To minimise the risk of food poisoning, Dr Rajput recommends following these food safety practices:

  • Refrigerate cooked food within two hours of preparation.
  • Store leftovers in clean, covered containers.
  • Consume refrigerated leftovers within three to four days.
  • Reheat food until it is steaming hot throughout.
  • Avoid reheating the same food multiple times.
  • Discard food that has been left at room temperature for several hours.

Do not rely on smell or appearance

Experts emphasise that food which appears, smells or tastes normal may still contain harmful bacteria or toxins.

Dr Rajput advises that food safety should never be judged solely by appearance or smell. Proper refrigeration, timely consumption and thorough reheating remain the most effective ways to prevent food-borne illness.

While leftovers can help reduce food waste and save time, following recommended food storage practices is essential to protect health and reduce the risk of serious infections.