Does eating grass have any health benefits for humans?

November 26, 2025 •

3 min read

Unlike ruminant animals like cows, humans lack the necessary enzymes to break down the tough, fibrous cellulose that makes up grass. This fundamental biological difference is the primary reason why, contrary to popular assumption, eating grass has virtually no health benefits for humans and can actually be harmful.

Quick Summary

Humans cannot derive nutrition from eating grass due to an inability to digest cellulose. It poses risks from chemicals and abrasives, unlike processed wheatgrass juice.

Key Points

Indigestible Cellulose: Humans lack the enzymes to break down the cellulose in grass, making it indigestible and nutritionally worthless.
Chemical and Parasite Risks: Eating lawn grass can expose humans to harmful pesticides, herbicides, parasites, and bacteria.
Dental Damage: The silica content in grass is abrasive and can wear down human tooth enamel over time.
Digestive Upset: Consuming large amounts of grass can cause stomach pain, bloating, vomiting, and diarrhea.
Wheatgrass Exception: Concentrated, processed wheatgrass juice offers nutrients by removing indigestible fiber, unlike eating raw grass.
Herbivore vs. Human Digestion: Herbivores have multi-chambered stomachs and symbiotic bacteria to ferment and break down cellulose, a system humans lack.

The Human Digestive System: Not Built for Grazing

For herbivores like cows and sheep, a grass-heavy diet is both natural and nutritious. Their complex, multi-chambered stomachs are specifically adapted to ferment and break down tough plant fibers. Humans, on the other hand, are omnivores with a single, less specialized stomach. This difference is crucial to understanding why eating grass is a bad idea for people.

The Problem with Cellulose and Lignin

At the core of the issue is cellulose, a complex carbohydrate that forms the structural cell walls of plants. Animals like ruminants and some other herbivores host symbiotic microbes and have specialized digestive anatomy that produces the enzyme cellulase, which breaks down cellulose into usable sugars. Humans do not have this enzyme, and as a result, cellulose passes through our system largely undigested, offering no nutritional value. Mature grass also contains lignin, a woody protein that can further disrupt the digestion of other fibrous material.

The Health Risks of Eating Lawn Grass

Beyond the lack of nutritional benefit, eating grass from your lawn or other uncultivated areas poses several health risks:

Chemical Contamination: Lawn grass is often treated with pesticides, herbicides, and fertilizers, which are toxic to humans. Ingesting these chemicals can cause serious health problems, including potential long-term issues like cancer and birth defects with prolonged exposure.
Digestive Upset: Since the human body cannot properly process grass, consuming it in large quantities can lead to significant digestive discomfort. Symptoms can include bloating, gas, stomach pain, vomiting, and diarrhea, which can lead to dehydration.
Dental Damage: Grass contains silica, a hard, abrasive mineral. Grazing animals have teeth adapted for constant wear and tear, but for humans, chewing grass can cause significant damage to tooth enamel over time.
Exposure to Parasites and Bacteria: Grass is a natural habitat for various parasites, bacteria, and other organisms from the soil. Consuming grass can expose you to harmful pathogens and increase your risk of illness.

The Difference: Lawn Grass vs. Wheatgrass Juice

It is important to differentiate between ordinary lawn grass and certain cultivated 'cereal grasses,' such as wheatgrass and barley grass. These are often processed into juices or powders and are popular health supplements. The key difference lies in the method of consumption, which bypasses the human inability to digest cellulose.

Comparison of Raw Lawn Grass vs. Wheatgrass Juice


Feature	Raw Lawn Grass	Processed Wheatgrass Juice
Digestibility	Indigestible due to cellulose and lignin content	Highly digestible; nutrients are extracted from fibers
Nutritional Value	Virtually zero nutritional benefit for humans	Rich in vitamins, minerals, antioxidants, and amino acids
Health Risks	Potential for pesticide contamination, parasites, and digestive upset	Generally considered safe, but potential for bacterial contamination if not prepared properly
Preparation	No preparation needed, but poses risks	Juiced or powdered, which separates the digestible components from indigestible fiber
Taste	Often bitter and unpleasant	Distinctive, strong, and 'earthy' taste

Potential Benefits of Wheatgrass

When harvested at a young stage, before significant cellulose develops, and processed correctly, wheatgrass is known for its nutritional density. The juicing process effectively breaks down the plant's cells, making the nutrients bioavailable to the human digestive system.

Here are some of the potential nutritional benefits of wheatgrass juice:

Rich in vitamins: Contains vitamins A, C, E, K, and B6.
Packed with minerals: A good source of magnesium, calcium, iron, and potassium.
High in antioxidants: Helps combat oxidative stress.
Contains amino acids: Provides the building blocks for proteins.
Source of chlorophyll: The pigment that gives plants their green color is said to have various health properties.

Conclusion

While the sight of a cow happily grazing might spark curiosity, the answer to the question, "Does eating grass have any health benefits?" is a definitive no for humans when it comes to the unprocessed plant itself. Our digestive system is not equipped to handle the high cellulose content, and the health risks of eating common lawn grass—from chemical exposure to parasites—far outweigh any theoretical gains. The only way to derive potential nutritional benefits from certain types of grass is by consuming specially prepared products like wheatgrass juice, which bypasses our natural digestive limitations. For those seeking plant-based nutrition, a diverse diet of fruits, vegetables, and whole grains remains the safest and most effective approach.

For more detailed information on the difference between herbivore and human digestive systems, see this article from Live Science: Why Can't Humans Eat Grass?.

Frequently Asked Questions

Humans lack the necessary enzymes, specifically cellulase, to break down the complex carbohydrate cellulose, which is the main structural component of grass.

Eating grass will likely pass through the human digestive system largely undigested, potentially causing digestive upset like gas, bloating, and diarrhea. In the worst case, contaminated grass could lead to sickness.

Yes, eating grass can be dangerous. Besides the indigestibility, lawn grass is often treated with toxic chemicals like pesticides and herbicides, and can harbor bacteria or parasites.

Grazing animals like cows are ruminants with multi-chambered stomachs that, along with symbiotic bacteria, can ferment and break down cellulose, a digestive process that humans cannot perform.

No, wheatgrass is the young, sprouted leaves of the wheat plant, which is different from common lawn grass. Most importantly, it is consumed as a juiced or powdered supplement, which extracts the nutrients from the fiber.

Wheatgrass juice is known to be rich in vitamins, minerals, amino acids, and antioxidants. Because it is juiced, the nutrients are made accessible to the human body without the need to digest the tough fiber.

Yes. Grass contains silica, an abrasive mineral that can wear down the enamel on human teeth over time. Grazing animals have teeth that have evolved to continually grow to counteract this.

While it is technically non-toxic, eating grass will not provide meaningful sustenance in a survival situation and may cause more harm than good due to digestive issues and dehydration. It is not a viable food source.