The Universal Edibility Test, or UET, is a technique created by the United States Army as a way for soldiers in emergency survival situations to identify edible plants. It is often considered a must-know for survivalists and outdoor enthusiasts. The test consists of several steps over the course of 24 hours, with each incremental step intended to trigger a potential warning sign that a plant may be toxic. Despite the popularity of the UET, it is not without its flaws.
Remember: The Universal Edibility Test is a last resort intended for emergency survival situations only. For foraging, please refer to a guidebook or consult an expert to properly identify plants.
The viability of the UET is questioned by some experts, as some plants are toxic enough to cause severe illness or death in miniscule amounts. Not all poisonous plants will cause symptoms with the steps in this test. As such, the UET should always be treated as a last resort. Humans can survive for several weeks without food, so in some circumstances it may be better to go hungry than risky eating a potentially harmful plant.
The Do’s and Don’ts of the UET
- Separate the plant into its basic components – leaves, stems, roots, buds, and flowers. Test only one part of the plant at a time. Just because one part of a plant is edible doesn’t mean other parts are.
- Check for common signs of poisonous plants. These include waxy or shiny leaves; milky sap; an almond or pear-like odor; spines, thorns, or hairy stalks; yellow, white, or green berries; and bulbs, beans, or pods with seeds.
- Remember that poisonous plants come in many varieties, and there is no single rule for identifying them. The common phrase “leaves of three, let it be” only applies to poison oak and poison ivy. On the other hand, salmonberries are safe and delicious but also have three-leaflet compound leaves, yellow berries, and thorns.
- Trust your taste buds. If a plant part tastes soapy or bitter, spit it out and avoid the plant.
- Familiarize yourself with the plants in the area you are visiting. Should you need to use the UET, knowledge of local poisonous and edible plants will drastically reduce the chance of consuming something toxic. Try to positively identify a plant before resorting the UET.
- Don’t assume a plant is safe raw if it safe cooked. Some toxins may be rendered inert by the cooking process, so the same plant may be harmful to eat raw even if it’s safe to eat cooked.
- Don’t use the UET on mushrooms. Mushrooms are fungi, not plants, and are incredibly complex organisms. A poisonous mushroom may not trigger any warnings during the UET until it is too late.
- Don’t speed up the process or skip steps. The UET takes time for a reason. Not allowing enough time between steps can have fatal consequences.
- Don’t assume a plant is safe for your pet if it is safe for you. Humans and animals react differently to plants. The reverse is also true: just because you see an animal chowing down on a plant doesn’t mean it’s safe for you.
- Don’t eat large quantities of a tested plant. Some plants may be “safe” in small amounts, but harmful or deadly in larger amounts. For example, wood sorrel is safe to consume in small amounts but contains oxalic acid – a compound that gives wood sorrel its signature tangy flavor. In large amounts, oxalic acid can harm your digestive tract and kidneys.
- Do not assume the same plant or plant part will affect each person the same way.
Universal Edibility Test
- Do not eat for 8 hours before starting the test.
- For the duration of the test, do not consume anything other than purified water and the plant you are testing.
- Test only one part of one plant at a time. Separate the plant into its basic components – leaves, stems, roots, buds, and flowers. Select a small portion of a single part and prepare it the way you plan to eat it (cooked, boiled, raw, etc.)
- Smell the plant part for strong or acrid odors. Remember, smell alone does not indicate a plant is edible or inedible.
- Test for contact poisoning by placing a piece of the plant part you are testing on the inside of your elbow or wrist. 15 minutes is usually enough time to allow for a reaction, but you can leave it for up to 8 hours. This step can be performed during the 8 hour waiting period. If you feel tingling, burning, itching, numbness, a rash appears, or you experience any other negative reaction, discard and avoid the plant.
- Touch a small portion of the plant part to your lips. Do not put it in your mouth yet. Hold it there for 3 minutes. If you experience any negative reaction, discard, and avoid the plant.
- Place a small amount of the plant part on your tongue. Do not chew or swallow. Hold it on your tongue for 15 minutes.
- If there is no negative reaction to holding the plant on your tongue, thoroughly chew the plant part and keep it in your mouth for 15 minutes. Do not swallow. If the plant part tastes soapy or bitter, spit it out and avoid the plant.
- If no negative reaction occurs, swallow the chewed plant part. Wait 8 hours. If you experience any negative effects in this time, induce vomiting and drink lots of water.
- If you experience no negative effects after 8 hours, prepare and consume ¼ cup of the same plant part. Wait 8 hours. If you experience any negative effects in this time, induce vomiting and drink lots of water. If you feel no side effects, the plant part can be considered safe to consume.