Common grass is generally not suitable for human consumption. While many plants are botanically classified as “grass,” typical lawn varieties are not viable food sources. Certain edible grasses, however, differ fundamentally from the fibrous blades covering most lawns.
Why Common Grass Isn’t Human Food
Humans cannot effectively digest common grass due to its high cellulose content. Cellulose is a complex carbohydrate that forms the structural component of plant cell walls, giving grass its rigid texture. Humans lack the necessary digestive enzymes, such as cellulase, to break down cellulose. Our digestive system is designed to break down starches and simple sugars, not these more resilient plant fibers.
Unlike herbivores, humans do not possess specialized digestive structures or symbiotic bacteria required to break down cellulose. Consequently, when humans ingest common grass, its nutrients remain locked within the indigestible cellulose. The grass simply passes through the digestive tract largely undigested, providing minimal nutritional value and serving primarily as insoluble dietary fiber.
When “Grass” Is Edible
Despite the indigestibility of common lawn grass, many plants botanically classified as grasses are staple foods. Cereal grains, including wheat, rice, corn, barley, and oats, are the edible seeds of various grass species. Only the nutrient-rich grains are consumed, not the leafy green stalks. Sugarcane, another grass, is cultivated for its sweet juice, which is processed into sugar.
Bamboo shoots, the young, tender sprouts of giant bamboo grass, are widely consumed after cooking. Wheatgrass and barley grass, derived from young cereal grasses, are typically juiced or powdered. This allows for the absorption of concentrated vitamins, minerals, and simple sugars before the plants develop a high content of indigestible cellulose.
Risks of Consuming Lawn Grass
Consuming common lawn grass carries several health risks. Many lawns are treated with pesticides and herbicides. These chemicals can be harmful to humans, with potential links to neurological disorders, certain cancers, and reproductive issues. Residues from these treatments can persist on grass blades, posing a risk if ingested.
Lawn grass can also be contaminated with pathogens from animal waste, including bacteria like E. coli, Salmonella, and Campylobacter, as well as viruses and parasites. Ingesting such contaminants can lead to serious gastrointestinal illnesses. The fibrous and abrasive nature of grass blades, which contain silica, can cause physical irritation or minor damage to the digestive tract and may contribute to dental wear over time. Its indigestibility can also lead to digestive upset, including nausea, vomiting, or, in severe cases, intestinal blockages.