Safe Eating: How to Spot Dirty Food and What to Do When You Get Food Poisoned

How seriously does food poisoning affect your health?

1. Short-term effects

• Gastrointestinal upset: This is the most common symptom, including nausea, vomiting, diarrhea, abdominal pain, and bloating. These symptoms usually appear a few hours to a few days after eating contaminated food.
• Dehydration and electrolyte disturbances: Persistent diarrhea and vomiting can cause severe dehydration, leading to fatigue, dizziness, low blood pressure, and even shock due to dehydration.
• Fever and chills: Certain bacteria or viruses can cause high fever along with chills, headache, and fatigue.

2. Long-term effects

• Long-term digestive disorders: Some people after food poisoning may suffer from irritable bowel syndrome or food intolerance for a long time.
• Sepsis: In severe cases, bacteria can enter the bloodstream, causing sepsis, which is life-threatening.
• Impaired liver and kidney function: Certain toxins from contaminated food can damage the liver and kidneys, especially in children, the elderly, and people with weakened immune systems.

3. Impact on special target groups

• Pregnant women: Food poisoning can cause miscarriage, premature birth or stillbirth, especially if contaminated with bacteria such as Listeria.
• Young children and the elderly: Weaker immune systems make them more susceptible to serious effects from food poisoning, and are at higher risk of dehydration and malnutrition.

Therefore, to prevent food poisoning, each person needs to equip themselves with knowledge in recognizing the signs of contaminated food, understanding the causes of poisoning and knowing how to handle this situation when encountering it. This is very important to protect the health of yourself and your family.

I. Signs of contaminated food

Change in color and taste:

• Contaminated food often changes color, becoming darker or showing unusual spots. The smell of the food may also change, becoming foul, sour, or having a strange smell.

Texture changes

• Contaminated food may become soft, slimy, or unusually dry and hard. For example, spoiled fruits and vegetables often become soft and mushy, possibly due to bacterial or mold growth.

Mold appears

• Mold can grow on food when the environment is moist, the temperature is suitable and the storage is not correct. Some types of mold not only spoil the food but also produce toxins that are dangerous to human health.
• Here are some common types of mold that are harmful in food:

1. Aspergillus

• Characteristics: Often found on nuts (peanuts, corn, cashews, etc.), cereals, spices, dried fruits and some dairy products.
• Harmful effects: Some strains of Aspergillus (especially Aspergillus flavus and Aspergillus parasiticus) produce aflatoxin, a toxin that can cause liver cancer, immune system impairment and digestive disorders.
• Identification: Green, yellow or black mold, often grows on the surface of food.

2. Penicillium

• Characteristics: Found in bread, fruits (oranges, apples), nuts and processed foods such as cheese.
• Harmful effects: Some Penicillium species produce ochratoxin A, a toxin that can cause kidney damage, immune suppression, and possibly cancer.
• Identification: Blue, green, or white mold with a smooth or cottony texture.

3. Fusarium

• Characteristics: Mainly appears on cereals such as wheat, corn and rice when infected with fungi during storage.
• Harmful effects: This fungus can produce fumonisin and trichothecene, two toxins that damage the nervous system, liver, kidneys and can cause esophageal cancer. In addition, they can also cause endocrine disorders and affect the reproductive system.
• Identification: Mold is white, pink or red in color, often found on grains or food surfaces.

4. Cladosporium

• Characteristics: Appears on frozen meats, dairy products, breads, and some fruits such as bananas and strawberries.
• Harmful effects: Causes respiratory irritation, allergies, dermatitis, especially dangerous for people with weak immune systems. Although it does not produce strong toxins like Aspergillus or Fusarium, it can still affect health.
• Identification: Mold is black or blue-black in color, often growing as small spots or spreading into patches.

5. Alternaria

• Characteristics: Commonly found on vegetables such as tomatoes, potatoes, eggplants and some fruits such as apples and grapes.
• Harmful: Some strains Alternaria produces alternariol, a toxin that can disrupt hormones, damage DNA, and potentially cause cancer.
• Identification: Appears as black or dark brown spots, spreading over the surface of the food.

6. Rhizopus

• Characteristics: Appears mainly on spoiled bread, fruits and vegetables.
• Harmful effects: Some species can cause serious infections in people with weakened immune systems, leading to mucormycosis, a dangerous infection that can affect the lungs, skin, and brain.
• Identification: Mold is white, gray or black in color and usually grows in long strands.

Important Note: Do not cut off the moldy part and eat the rest, as the toxin may have spread deep into the food and is not visible to the naked eye. Foods that are susceptible to mold, such as dried nuts, bread, cereals, fruits and vegetables, should be stored in a cool, dry place and not left out for too long. If you suspect you have eaten moldy food, monitor for symptoms such as nausea, diarrhea, allergies or difficulty breathing and seek medical attention if there are any unusual signs.

Packaging is swollen or damaged

• This is an important sign that the food inside may be contaminated, spoiled, or no longer safe to eat. 
• Here are some of the main effects of swollen or damaged packaging on food:

1. Signs of contamination or damage

• Bacteria and Microorganism Growth: When bacteria such as Clostridium botulinum, E. coli or Salmonella grow in canned or vacuum-packed foods, they can produce gas, causing the packaging to swell. This is a sign that the food has been contaminated and can cause food poisoning.
• Uncontrolled fermentation: Some foods can be fermented by unwanted yeast or bacteria, producing carbon dioxide gas that causes the packaging to swell. This often happens with milk, juice, processed meats, and canned goods.

2. Food quality deterioration

• Loss of nutritional value: Food that is spoiled by bacteria or exposed to air can decompose, reducing its nutritional content, especially vitamins and proteins.
• Changes in color, taste and texture: Torn or punctured packaging can allow air, moisture or bacteria to enter, causing food to lose its original flavor, develop a foul odor or change its texture (mushy, dry, slimy…).

3. Risk of dangerous toxins

• Botulinum toxin: If canned food is contaminated with Clostridium botulinum, it can produce botulinum toxin, a highly toxic substance that can cause muscle paralysis, difficulty breathing, and even death. This is why bulging cans of food are always warned not to be used.
• Chemicals from damaged packaging: Torn, rusted, or deformed plastic or metal packaging can leach toxic chemicals such as bisphenol A (BPA) or heavy metals into food, causing health problems.

4. Risk of cross contamination

• If the packaging is open or torn, food can be exposed to the outside environment, creating conditions for bacteria, dirt or chemicals to penetrate, leading to the risk of cross-contamination when stored with other foods.

Tips for using packaged foods: Do not use food with packaging that is bulging, torn, dented or rusted. Check the expiry date and storage conditions before purchasing. Do not attempt to open a bulging can of food as the internal pressure may cause contaminated food to escape. Store food properly according to the instructions on the packaging to avoid spoilage.

II. Common causes of food poisoning

1. Bacteria:

• This is a leading cause of food poisoning. Bacteria such as Salmonella, Escherichia coli (E. coli), Listeria monocytogenes and Campylobacter jejuni are commonly found in poultry, eggs, unpasteurized milk and contaminated water. 

2. Virus:

• Norovirus and hepatitis A are two viruses that commonly cause food poisoning. They can be spread through contaminated food or water, especially raw or undercooked seafood. 

3. Parasites:

• Some parasites such as Giardia lamblia can cause food poisoning when people consume food or water contaminated with feces containing the parasite. 

4. Natural toxins:

• Natural toxins are chemical compounds that occur naturally in foods and can be harmful to health if consumed in large amounts or if not handled properly. These toxins can come from plants, animals, or microorganisms. 
• Here are some common natural toxins in food and their health effects:

Toxins in plants

• Solanine (Sprouted potatoes, green tomatoes)
  • Origin: Found in sprouted potatoes, green potatoes and some unripe tomatoes.
  • Harmful effects: Causes food poisoning with symptoms such as nausea, diarrhea, headache, dizziness, and even nervous disorders if eaten in large quantities.
  • Prevention: Do not eat potatoes that have sprouted or are green. If the potato has signs of small sprouts, cut them off and cook thoroughly before eating.
• Hydrocyanic acid (HCN) – Cassava, fresh bamboo shoots
  • Origin: Found in cassava (especially bitter cassava), fresh bamboo shoots, bitter almonds.
  • Harmful effects: When entering the body, HCN causes poisoning, affects the respiratory system, causes difficulty breathing, headaches, and even death if eaten too much.
  • Prevention: Cassava should be peeled, soaked in water for many hours and boiled thoroughly before eating. Fresh bamboo shoots should be boiled in many waters and the water discarded.
• Lectins (Raw beans, especially red beans, broad beans, kidney beans)
  • Source: Found in raw beans, especially red kidney beans.
  • Harmful effects: Causes digestive disorders, vomiting, diarrhea due to affecting the digestive system and reducing nutrient absorption.
  • Prevention: Soak beans in water for at least 5-6 hours before cooking and cook thoroughly.
• Saponin (raw soybeans, horse chestnut)
  • Sources: Raw soybeans, horse chestnuts, some raw vegetables.
  • Harmful effects: Affects the digestive system, can cause stomach and intestinal irritation if eaten raw.
  • Prevention: Cook food thoroughly before eating.

Toxins in animals

• Tetrodotoxin (Puffer Fish)
  • Origin: Found in pufferfish, some species of blue-ringed octopus, and poisonous frogs.
  • Harmful effects: Is a very strong neurotoxin, causing muscle paralysis, difficulty breathing and can lead to death if not treated promptly.
  • Prevention: Do not eat puffer fish or animals that contain this toxin.
• Saxitoxin (Seafood contaminated with red algae - clams, oysters, mussels, crabs, shrimp)
  • Origin: Appears in clams, mussels, crabs, and shrimp when the sea has a "red tide" phenomenon (toxic algae grow strongly).
  • Harmful effects: Causes nerve paralysis, loss of sensation, and can even cause death if ingested in large quantities.
  • Prevention: Limit seafood consumption during red tide season and choose reliable sources.
• Histamine (Improperly stored tuna, mackerel, anchovies)
  • Origin: Formed in marine fish such as tuna and mackerel when stored improperly.
  • Side effects: Causes allergic reactions such as redness, itching, nausea, headache.
  • Prevention: Store fish at appropriate cold temperature (below 4°C) immediately after catching.

Microbial toxins

• Aflatoxin (Mold in cereals, peanuts, dried seeds)
  • Origin: Aspergillus flavus and mold Aspergillus parasiticus Grows on peanuts, corn, cashews, dried spices.
  • Harmful effects: One of the strongest liver carcinogens, immunosuppressant.
  • Prevention: Keep food dry and away from mold. Check food carefully before use.
• Ochratoxin (Mold on coffee, cereals, wine)
  • Origin: Occurs in cereals, coffee, raisins, and wine when contaminated with Penicillium and Aspergillus fungi.
  • Harmful effects: Causes kidney damage, affects the immune system.
  • Prevention: Buy food from reputable sources and store in a dry place.
• Fumonisin (Fusarium fungus on corn, wheat, rice)
  • Origin: Formed by Fusarium fungus on corn, wheat, barley.
  • Harmful effects: Causes esophageal cancer, affects the nervous system.
  • Prevention: Choose clean grains and avoid eating foods that show signs of mold.

How to avoid natural toxins in food?

• Choose fresh, clean food from reputable sources. Do not use food that shows signs of spoilage or mold.
• Store food properly: Avoid storing food in damp places, refrigerate perishable foods.
• Proper preparation: Remove sprouted parts of potatoes, soak bamboo shoots and cassava in water before processing.
• Cooking foods: Some toxins can be reduced when foods are properly cooked, such as lectins in beans.
• Do not eat poisonous animals or plants: Avoid eating puffer fish, strange mushrooms, or other high-risk foods if you do not know how to prepare them safely.

5. Chemicals and food additives:

• Excessive or improper use of preservatives, colorants, pesticides or other chemicals in food production and storage can cause poisoning. 

The effects of chemicals and food additives on health

• Benefits: Makes food tastier and lasts longer. Reduces production costs and is convenient for consumers. Some additives such as vitamins C and E are also beneficial for health.
• Harmful effects if abused or used incorrectly: Some preservatives such as nitrite can create nitrosamines - compounds that can cause cancer. Artificial colors can cause allergies or affect behavior in children. Artificial sweeteners such as aspartame can cause digestive disorders or headaches in some sensitive people. Antioxidants BHA, BHT can affect the liver and nervous system if consumed in excess.

How to use food with chemicals and additives safely?

• Read food labels: Check the ingredient list, avoid foods that contain too many artificial additives.
• Limit processed foods: Choose fresh foods with few preservatives.
• Follow food safety regulations: Choose products from reputable brands with quality control.
• Use in reasonable doses: Do not overuse foods containing many chemicals or synthetic additives.

III. How to deal with food poisoning

1. Rehydration and electrolytes:

Water and electrolytes play an important role in sustaining life, supporting physiological functions and ensuring normal body function. Proper hydration and electrolyte replacement helps maintain homeostasis, prevent dehydration, and support the circulatory, nervous and muscular systems.

• Body water: Accounts for about 60-70% of body weight, is the main component of blood, digestive juices, urine and sweat. Supports the transport of oxygen, nutrients, eliminates toxins and maintains body temperature.
• Electrolytes in the body: Electrolytes are minerals found in blood and body fluids that help maintain water balance and perform many important functions. The main electrolytes include:
  • Sodium (Na⁺): Regulates osmotic pressure, retains water, supports nerve conduction.
  • Potassium (K⁺): Helps heart muscle contract and balances water in cells.
  • Calcium (Ca²⁺): Necessary for muscle contraction, blood clotting, nerve conduction.
  • Magnesium (Mg²⁺): Supports muscle and nerve function, stabilizes heart rhythm.
  • Chloride (Cl⁻): Balances body fluids, aids digestion.
• Benefits of rehydration and electrolytes: When suffering from diarrhea, vomiting, high fever, the body loses a lot of water and salt. Electrolytes help prevent dehydration and maintain body fluid balance. Sodium and chloride are needed to produce gastric juice, aiding digestion. Oral rehydration solution (ORS) helps to recover quickly, reducing the risk of shock due to dehydration.
• How to effectively replenish water and electrolytes
  • Drink water properly: Drink small sips, evenly throughout the day, do not drink too much at once. Do not wait until you are thirsty to drink, should maintain about 2-3 liters of water/day.
  • Use ORS (Oresol) rehydration and electrolyte solution: Standard rehydration solution, helps restore water and salt quickly. 

Note when replenishing water and electrolytes: Do not drink too much water in a short time to avoid hyponatremia (dangerous for the brain). When using Oresol, it is necessary to mix the correct ratio according to the instructions to avoid electrolyte disturbances.

2. Rest:

People with food poisoning should rest to give their bodies time to recover. Avoid strenuous activity during this time.

3. Avoid certain foods:

During recovery, avoid foods that are difficult to digest, spicy, greasy, or alcoholic and caffeinated beverages.

4. Consult a doctor:

If food poisoning symptoms last more than 2 days, or there are serious signs such as high fever, bloody diarrhea, severe abdominal pain, go to a medical facility for timely examination and treatment. 

IV. Food poisoning prevention

1. Choosing safe food:

• Buy food from reputable sources, check labels, expiry dates and packaging condition before purchasing. 

2. Store food properly:

• Keep food at the right temperature, avoid leaving food at room temperature for too long. Cooked and raw foods should be stored separately to avoid cross-contamination. 

3. Hygiene in processing:

• Wash your hands thoroughly before and after preparing food. Kitchen utensils such as knives, cutting boards, and dishes should be cleaned after each use. 

4. Cooking food:

• Make sure foods are thoroughly cooked, especially meat, poultry, seafood and eggs.