Universal Edibility Test

Part of Foraging Edible Plants

When you cannot identify a plant, this systematic protocol lets you test it for safety in stages — each step limiting your exposure before committing to ingestion.

What This Test Is — And What It Is Not

The Universal Edibility Test (UET) is a last-resort protocol adapted from military survival manuals. It works by progressively increasing your exposure to an unknown plant part over approximately 24 hours, watching for adverse reactions at each stage.

What it can detect:

• Contact irritants (rashes, burning, swelling)
• Immediately acting toxins (burning mouth, nausea, cramping)
• Short-acting poisons that cause symptoms within 8 hours

What it cannot detect:

• Cumulative toxins that only cause harm after repeated exposure
• Amatoxins (mushroom toxins) — symptoms delayed 6-12 hours, beyond the test window
• Carcinogens and chronic toxins
• Toxins that require large doses to produce symptoms

Never Use This Test On Mushrooms

The UET was designed for plants. It is dangerously inadequate for mushrooms because the deadliest mushroom toxins (amatoxins) cause no symptoms during the test period. By the time symptoms appear, lethal liver damage has occurred. See Mushroom Dangers for mushroom-specific protocols.

Prerequisites Before Starting

Before testing any plant, eliminate the obvious dangers:

1. Rule out known toxic families — If the plant belongs to a family known to contain deadly species (Apiaceae with purple-blotched stems, Solanaceae with black berries), do not test it. Identification trumps testing.
2. Separate the plant into parts — Roots, stems, leaves, flowers, fruits, and seeds may have different toxicity. Test each part individually.
3. Eat nothing else for 8 hours before beginning the test. An empty stomach ensures that any reaction you experience is from the test plant, not from something else.
4. Have water available — You will need to rinse your mouth and stay hydrated.
5. Have a companion — Someone should know what you are testing and monitor you for symptoms you might not notice (confusion, slurred speech, unsteady gait).

The Complete Test Protocol

Phase 0: Smell Test (5 minutes)

Crush a small piece of the plant part and hold it near your nose. Inhale carefully.

Stop if: The smell is strongly unpleasant, acrid, or produces immediate irritation of the nose or eyes. Plants with volatile toxins (like jimsonweed or some members of the carrot family) may produce warning odors.

Pass criteria: Mild, neutral, or pleasant smell. No irritation.

Phase 1: Skin Contact Test (8 hours)

This is the first real exposure test. See Skin Contact Phase for detailed instructions.

1. Crush or break the plant part to release its juices
2. Place the moist material against the inside of your wrist or the inside of your elbow
3. Secure it in place with a strip of cloth or bandage
4. Leave it in contact with your skin for 15 minutes
5. Remove the plant material and observe the area for 8 hours

Stop if: You develop redness, rash, blisters, burning, itching, swelling, or numbness at the contact site.

Pass criteria: No skin reaction after 8 hours. Proceed to the next phase.

Phase 2: Lip Test (15 minutes)

1. Take a small piece of the prepared plant part
2. Press it against your outer lip
3. Hold it there for 3 minutes
4. Remove and wait 15 minutes

Stop if: Burning, tingling, numbness, or swelling of the lip. Rinse your mouth with water immediately.

Pass criteria: No reaction after 15 minutes.

Phase 3: Tongue Test (15 minutes)

1. Place a small piece on your tongue
2. Hold it there for 15 minutes — do NOT chew or swallow
3. Pay attention to any sensation

Stop if: Burning, extreme bitterness, numbing, soapy taste, or any unpleasant tingling. Spit it out and rinse thoroughly.

Pass criteria: Mild or neutral taste, no adverse sensation.

Phase 4: Chew Test (15 minutes)

1. Chew a small piece thoroughly
2. Hold the chewed material in your mouth for 15 minutes
3. Do NOT swallow — spit it out
4. Wait 15 minutes after spitting

Stop if: Any adverse sensation develops — burning, numbness, nausea, unusual salivation, or throat tightness.

Pass criteria: No reaction after 15 minutes of holding, plus 15 minutes of waiting.

Phase 5: Swallow Test (8 hours)

1. Prepare a small amount of the plant part (approximately 1 tablespoon / 15ml)
2. If the plant requires cooking to be palatable or useful, cook it first using the method you intend to use (boiling, roasting)
3. Chew and swallow the small amount
4. Eat nothing else for 8 hours
5. Monitor yourself (and have your companion monitor you) for any symptoms

Stop if: Nausea, vomiting, diarrhea, cramping, dizziness, drowsiness, difficulty breathing, or any other abnormal symptom. If symptoms appear, induce vomiting (warm salt water) and drink plenty of water.

Pass criteria: No adverse symptoms after 8 hours.

Phase 6: Larger Portion Test (24 hours)

1. Prepare a larger portion — approximately 1/4 cup (60ml) of the plant part
2. Eat it
3. Wait 24 hours, eating other known-safe foods normally
4. Monitor for any delayed reactions

Pass criteria: No adverse symptoms after 24 hours. The plant part can now be considered provisionally safe for consumption.

Complete Test Timeline

Phase	Action	Duration	Cumulative Time
Pre-test fast	Eat nothing	8 hours	8 hours
Phase 0	Smell test	5 minutes	8h 5m
Phase 1	Skin contact	15 min contact + 8h observation	16h 20m
Phase 2	Lip test	3 min contact + 15 min wait	16h 38m
Phase 3	Tongue test	15 minutes	16h 53m
Phase 4	Chew test	15 min hold + 15 min wait	17h 23m
Phase 5	Swallow small amount	8 hours observation	25h 23m
Phase 6	Larger portion	24 hours observation	49h 23m
Total			~49 hours

Time Investment

The full test takes approximately two full days. Do not rush it. Skipping phases or shortening wait times defeats the purpose entirely. If you are too hungry to wait, you are too impaired to make good decisions about unknown plants — eat something you already know is safe first.

Important Rules

Test One Plant Part at a Time

Never test multiple plants simultaneously. If you react, you need to know which plant caused it. One plant, one part, one test at a time.

Cooking Changes Chemistry

A plant part that is toxic raw may be safe cooked, and vice versa. If you plan to eat a plant cooked, test it cooked. If raw, test it raw. The test result only applies to the preparation method you used.

Example: Stinging nettles are painful raw (urticating hairs) but perfectly safe and nutritious when boiled. Kidney beans are toxic raw (lectin) but safe when thoroughly boiled.

Different Parts May Have Different Toxicity

Many plants have edible parts and toxic parts:

• Rhubarb: stalks are edible; leaves contain lethal levels of oxalic acid
• Elderberry: cooked ripe berries are edible; raw berries, leaves, bark, and roots contain cyanogenic glycosides
• Potato: tuber flesh is edible; green skin, sprouts, and leaves contain solanine
• Tomato: fruit is edible; leaves and stems contain tomatine

Test each part separately. Passing for the leaves does not mean the root is safe.

Reactions That Demand Immediate Action

Symptom	Severity	Action
Skin rash or burning	Low	Wash thoroughly, discontinue test, record plant as skin irritant
Lip or tongue numbness	Moderate	Rinse mouth thoroughly, spit repeatedly, do not proceed
Nausea or cramping after swallowing	High	Induce vomiting with salt water, drink water, rest
Difficulty breathing or throat swelling	EMERGENCY	This may be anaphylaxis; keep airway open, rest in sitting position
Dizziness, confusion, visual disturbance	EMERGENCY	Possible systemic poisoning; induce vomiting, have companion monitor breathing

Record-Keeping

Maintain a written log of every test you perform:

Date: ___________
Plant description: ___________
Location found: ___________
Part tested: ___________
Preparation: raw / boiled / roasted
Phase 0 (smell): PASS / FAIL — notes: ___________
Phase 1 (skin): PASS / FAIL — notes: ___________
Phase 2 (lip): PASS / FAIL — notes: ___________
Phase 3 (tongue): PASS / FAIL — notes: ___________
Phase 4 (chew): PASS / FAIL — notes: ___________
Phase 5 (swallow small): PASS / FAIL — notes: ___________
Phase 6 (larger portion): PASS / FAIL — notes: ___________
RESULT: SAFE / UNSAFE / INCONCLUSIVE

This log becomes your group’s food safety reference. Over weeks and months, you build a reliable database of safe local foods.

Limitations to Accept

Even after a plant passes the full UET:

• It may contain cumulative toxins — comfrey, for example, passes taste tests but contains pyrrolizidine alkaloids that damage the liver over months of consumption
• It may cause allergic reactions in others — your body’s tolerance does not guarantee anyone else’s
• Nutritional value is unknown — a plant may be safe but provide almost no calories or nutrition, wasting foraging effort
• Seasonal variation exists — a plant part that is safe in spring may concentrate toxins by fall

Key Takeaways

• The UET is a last resort, not a first choice — positive identification of known edible species is always safer and faster
• Never use the UET on mushrooms — the deadliest mushroom toxins produce no symptoms during the test window
• The full test takes about 49 hours — shortcuts are not acceptable when your life is at stake
• Test one plant part at a time, prepared the way you intend to eat it
• Keep written records of every test to build a community food safety database
• A passed test is not a guarantee — cumulative toxins and individual allergies remain risks
• If any phase produces a reaction, stop immediately — rinse, spit, induce vomiting as appropriate, and mark the plant as unsafe