Is Grass Healthy for the Human Body? The Truth Behind Eating Grass

November 25, 2025 •

3 min read

While ruminants like cows thrive on a diet of grass, the human digestive system is not equipped for the same. Modern humans lack the specialized digestive anatomy of herbivores. So, is grass healthy for the human body? The answer is a clear no when it comes to the blades of your lawn.

Quick Summary

Humans lack the necessary enzymes and digestive system to break down grass's cellulose content, making it nutritionally worthless and potentially harmful. Eating lawn grass can cause digestive distress, damage teeth due to silica, and expose the body to harmful chemicals and pathogens. While concentrated forms like wheatgrass juice offer some nutrients, consuming grass directly is not recommended.

Key Points

Indigestible Cellulose: Humans cannot effectively digest grass due to their inability to produce the enzyme cellulase, which is necessary to break down cellulose in plant cell walls.
Minimal Nutritional Value: Because the body can't digest grass blades, they offer virtually no nutritional benefit to humans and will simply pass through the digestive system.
Dental Damage: Grass is rich in abrasive silica, which would wear down human teeth over time, leading to severe and irreversible dental enamel damage.
Risk of Contamination: Lawn grass is often treated with pesticides and herbicides and can harbor bacteria and parasites from animal waste, posing significant health risks.
Digestive Distress: Ingesting large quantities of indigestible fibers like grass can cause considerable gastrointestinal upset, including vomiting and diarrhea.
Juiced Grass vs. Blades: Some cereal grasses, like wheatgrass and barley grass, can provide concentrated nutrients when juiced, but this is fundamentally different from eating raw grass blades.
Risk of Poisoning: Some grass species contain toxic compounds, such as cyanide, which can be poisonous to humans.

Why the Human Digestive System Fails to Process Grass

The primary obstacle to humans digesting grass is cellulose, a complex carbohydrate in plant cell walls. Unlike ruminants with multi-chambered stomachs and specific gut bacteria, humans lack the enzyme cellulase needed to break down cellulose. Grass offers no nutritional value for humans. This biological difference is why humans don't graze like herbivores.

The Indigestible Components of Grass

Besides cellulose, grass contains lignin, a tough polymer that further impedes digestion and nutrient absorption. These fibers are essentially indigestible filler for humans and can cause significant gastrointestinal issues if consumed in large amounts.

The Abrasive Effects of Silica on Teeth

Grass also has high silica content, making it abrasive. While grazing animals have continuously growing teeth adapted to this, human teeth do not and would suffer significant enamel erosion from chewing grass, leading to severe dental problems.

Significant Health Risks Associated with Eating Grass

Consuming lawn or field grass presents several health risks:

Pesticides and Herbicides: Many treated lawns contain toxic chemicals that can cause serious health problems.
Contaminants: Grass can carry bacteria, parasites from animal waste, dirt, and heavy metals, leading to infections and illnesses.
Toxic Species: Certain grasses, like Johnson grass, can produce poisonous compounds like cyanide upon digestion. Identifying safe grass is difficult for a layperson.
Nutritional Deficiency: Since humans can't extract nutrients from grass, relying on it would cause severe malnutrition, starvation, and dehydration.

The Notable Exception: Processed Cereal Grasses

Processed forms of young cereal grasses, such as wheatgrass and barley grass, differ significantly from lawn grass. These are typically juiced to remove indigestible fiber, and in this concentrated form, they offer some nutritional value, though not as a dietary staple.

Benefits of Wheatgrass and Barley Grass Juice

Nutrient Rich: They contain vitamins A, C, and E, and minerals like magnesium, iron, and calcium.
Amino Acids: These grasses provide essential amino acids.
Antioxidants: They contain antioxidants that may help reduce stress and inflammation.
Chlorophyll: As green foods, they are a source of chlorophyll.

Cereal Grains: Another Form of Edible Grass

Humans also eat the seeds of various grass species, known as cereal grains like wheat, rice, corn, and oats. These contain digestible carbohydrates and proteins and are a staple food source.

Comparison Table: Lawn Grass vs. Cereal Grass


Feature	Lawn Grass (e.g., Fescue)	Cereal Grass (e.g., Wheatgrass)	Cereal Grains (e.g., Wheat, Rice)
Digestibility by Humans	Poor (high cellulose & lignin)	Moderate (juiced or powdered)	High (processed for consumption)
Nutritional Value	Negligible	Moderate (high vitamin & mineral content when processed)	High (primary source of carbs & protein)
Preparation	Ingested whole (not recommended)	Juiced or powdered	Processed, cooked
Health Risks	High (pesticides, contaminants, silica damage)	Minimal (if sourced organically and prepared properly)	Minimal (with proper food safety)
Consumption Method	Unsafe	Juiced to remove fiber	Cooked, baked, milled into flour
Digestive Effect	Gastrointestinal upset, starvation	Concentrated nutrients, can be very potent	Essential macronutrients

Conclusion: The Bottom Line on Eating Grass

Eating lawn grass is unhealthy and carries significant risks like dental damage and exposure to toxins. The human digestive system cannot process its high cellulose content for nutrition. While cereal grains are dietary staples and juiced wheatgrass offers nutrients, consuming common grass blades is unsuitable for humans. A balanced diet of fruits, vegetables, and other digestible foods is necessary for optimal human health.

Live Science: Why Can't Humans Eat Grass?

Frequently Asked Questions

No, humans cannot get meaningful nutrients from eating lawn grass. Our digestive systems lack the enzyme cellulase, which is required to break down the cellulose in grass to access its nutrients.

Yes, eating lawn grass is dangerous. It can be contaminated with harmful pesticides, herbicides, and bacteria from animal feces. The abrasive silica can also damage your teeth.

If a human eats a lot of grass, they will likely experience severe digestive problems, including vomiting and diarrhea. In the long term, attempting to subsist on grass would lead to malnutrition and starvation.

Herbivores like cows are ruminants with specialized multi-chambered stomachs that host symbiotic bacteria. These bacteria produce the enzyme cellulase, enabling the animal to break down and digest grass effectively, a process humans cannot replicate.

No, wheatgrass is not the same as regular lawn grass, and it's consumed differently. Wheatgrass is the young, leafy shoot of the wheat plant, and it is juiced to extract nutrients and remove the indigestible fiber.

No, not all grasses are inedible. Cereal grains like wheat, rice, and oats are seeds from grass species that have been cultivated and processed for human consumption. Other examples include bamboo shoots and lemongrass.

While early human ancestors may have consumed some plant matter, their digestive systems were not adapted to process large quantities of tough, cellulose-rich grasses. Evidence suggests they were omnivores, relying heavily on a varied diet.