Natural toxins are chemicals produced by living things like plants, fungi, bacteria, algae, and animals. While these toxins don’t hurt the organisms that produce them, consuming food with natural toxins can sometimes be harmful. When suitable preventive measures are not in place, these toxins can enter the food supply, primarily appearing in fruits, mushrooms, and legumes. They also can be in products that contain these foods as ingredients, such as plant-based beverages.
The FDA monitors domestic and imported foods to help prevent and reduce the chances of people being exposed to these toxins. The FDA has issued regulations to help growers and food producers put hazard controls in place and has developed guidance recommending maximum toxin levels for growers and food producers to follow.
Vegetables, Fruits, Plants and other Foods That Can Contain Toxins
Fish and Shellfish Toxins
Much like with plants, fish and shellfish can contain toxins. When people eat these fish and shellfish, these natural toxins can cause health problems.
Natural toxins are often produced in plants as a defense against predators, insects, or infestation. Below are some examples of vegetables, fruits, plants, and other foods that can sometimes contain a natural toxin.
Please note that these foods can be safe to eat when properly grown, harvested, and/or prepared. This is not a complete list of all the natural toxins that can occur in food.
- Ackee fruit (Hypoglycin A): Hypoglycin A is a heat stable toxin found in high levels in the rinds and seeds of ackee, a tropical fruit that features prominently in Jamaican cuisine. Reactions to hypoglycin A can range from no symptoms, to vomiting, to coma and death. Properly harvested and prepared ackee will have low levels of hypoglycin and is safe to eat.
- Blue-green algae (Microcystins): Produced by Microcystis and other types of blue-green algae (BGA), microcystins are natural toxins that can cause gastrointestinal distress and potentially damage your liver over time. Microcystis cells can contaminate other BGA used in foods, such as wild-harvested Aphanizomenon flos-aquae (AFA). Properly harvested BGA is safe to eat and is used in some dietary supplements and food products.
- Honey (Grayanotoxins): Bees collect nectar from flowers in order to create honey. If those flowers have a natural toxin, that toxin may end up in the honey from that beehive. One example is grayanotoxins, which plants such as rhododendrons and mountain laurel naturally produce. Eating honey with a high amount of this toxin can lead to “mad honey” poisoning, with symptoms such as nausea, vomiting, or dizziness. This type of poisoning is rare.
- Beans (Phytohaemagglutinin): Phytohaemagglutinin (PHA) is a lectin found in raw or undercooked beans. Lectins are proteins that bind to carbohydrates and some plants produce them as a natural defense mechanism. In canned and properly cooked kidney beans, the low levels of PHA won’t affect you. But at high levels in raw beans, PHA can lead to nausea, severe vomiting, and diarrhea. Soaking the beans for a minimum of 5 hours and then boiling them in fresh water for at least 30 minutes will remove and destroy this toxin.
- Mushrooms (Mushroom toxins): It’s well known that some mushrooms are toxic. Depending on the type of mushroom you eat, you could experience milder reactions like nausea or diarrhea. More severe reactions include coma and death.
- Stone fruit, such as peaches or apricots (Amygdalin): Amygdalin, also called laetrile, is a natural chemical found in the seeds of apricots, bitter almonds, apples, peaches, and plums. The chemical is not found in the fruit itself and accidentally eating a seed or pit will not harm you. However, consuming a large amount of the seeds or pits can be problematic because enzymes in your intestines can turn amygdalin into cyanide and cause cyanide poisoning.
Mycotoxins in Foods
Mold or fungus can infect some foods with mycotoxins while the crop is growing or is being stored. Only certain molds and fungi produce mycotoxins that can make you sick if you eat them. Mycotoxins associated with human food include aflatoxins, deoxynivalenol, fumonisin, patulin, ochratoxin A, T-2/HT-2, and zearalenone.
How the FDA Monitors and Tests These Toxins in Foods
Because many of these toxins naturally occur in food, it is often impossible to completely get rid of them. To keep the public safe, the FDA focuses on reducing the amount of toxins in food products and preventing foods with high amounts of toxins from entering the food supply. There are several ways that the FDA protects the food that people eat.
- Testing: The FDA routinely collects food samples to test for potential contamination and health risks. For example, we check for mycotoxins such as aflatoxin M1 in milk or fumonisins in corn-based foods.
- Enforcing industry compliance: If we discover that a food product poses a health risk because of unsafe levels of toxins, we will take steps to remove it from the market. We can work with the manufacturer to recall the product, issue an import alert to prevent the product from entering the United States, and take other actions as needed.
- Research: We conduct ongoing research to develop methods for detecting natural toxins in foods and perform studies that survey whether natural toxins are in particular foods. We regularly publish the results of this research. Please see the individual toxins webpages (listed below) for a list of our publications.
Source: https://www.fda.gov/food/chemical-contaminants-pesticides/natural-toxins-food
