Seeds Highest in Lectins
Soybeans contain the highest lectin levels among seeds, with raw soybean seeds containing 692.8 HU/mg (hemagglutinating units per milligram), which is substantially higher than all other investigated seeds. 1
Lectin Content by Seed Type
Highest Lectin Seeds
- Soybeans: 692.8 HU/mg in raw seeds, representing the highest lectin content among all investigated legume seeds 1
- Common beans (Phaseolus vulgaris): 87.69-88.59 HU/mg, making them the second-highest lectin-containing seeds after soybeans 1
Moderate to Lower Lectin Seeds
- Other pulses (peas, lentils, chickpeas, fava beans): 2.73-11.07 HU/mg, representing significantly lower lectin levels compared to soybeans and common beans 1
- Cereal grain embryos (wheat, rye, barley): Contain wheat-germ-agglutinin-like lectins, though specific quantitative levels are lower than legume seeds 2
Important Clinical Context
The high lectin content in raw or improperly processed beans, particularly common beans containing phytohemagglutinin, constitutes a genuine food safety risk. Consumption of inadequately processed beans has been documented to cause outbreaks of gastroenteritis, nausea, and diarrhea 3. This represents a direct impact on morbidity and quality of life when these seeds are consumed without proper preparation.
Processing Effects on Lectin Levels
- Soaking in distilled water: Reduces lectin content by only 0.11-5.18%, which is insufficient for safety 1
- Cooking: More effective at reducing lectin levels in most seeds, though the specific reduction varies by seed type 1
- Critical caveat: Soaking alone does not adequately reduce lectins to safe levels; proper cooking is essential for food safety 1
Practical Implications
Legume seeds, particularly soybeans and common beans, accumulate lectins especially in their seeds at relatively high amounts depending on genetic and environmental factors 3. The detection limit for lectin in soybean samples using modern analytical methods is 35.5 μg/g 4, allowing for precise quantification in both raw materials and processed products.