The question of whether grass is a probiotic is a common one, stemming from the increasing public awareness of gut health and the role of microorganisms within it. Understanding the key differences between probiotics and prebiotics is crucial to clarifying this topic. Probiotics are live, beneficial microorganisms found in fermented foods and supplements, while prebiotics are specific types of dietary fiber that serve as food for these microorganisms. Grass contains prebiotics, but due to human digestive limitations, it cannot be effectively used as a probiotic source.
What are Probiotics? The Scientific Definition
According to the International Scientific Association for Probiotics and Prebiotics (ISAPP), probiotics are defined as “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host”. To meet this definition, the microorganisms must be scientifically tested and proven to offer a specific health benefit at a specific dosage. Examples of true probiotics include the bacteria strains found in products like yogurt, kefir, and many dietary supplements.
Characteristics of Probiotics
- Live Organisms: They are living bacteria or yeast. Crucially, they must be alive and viable when consumed to confer their benefits.
- Strain-Specific Effects: The health benefits of probiotics are often strain-specific. For example, one strain of Lactobacillus may help with a certain digestive issue, while another may not.
- Examples: Common probiotic strains come from genera such as Lactobacillus, Bifidobacterium, and the yeast Saccharomyces boulardii.
What are Prebiotics? Feeding the Gut Flora
Prebiotics are non-digestible dietary fibers that act as a food source for the beneficial bacteria already living in the gut, effectively fertilizing the microbiome. By nourishing these existing microorganisms, prebiotics help support a healthy and balanced gut environment.
The Prebiotic Power of Plants
Many plant-based foods are excellent sources of prebiotic fiber, including:
- Garlic
- Onions
- Leeks
- Asparagus
- Bananas (especially unripe ones)
- Oats
- Barley
- Chicory root
Grass for Humans: The Digestibility Issue
The primary reason grass is not a probiotic and offers limited nutritional value to humans is our inability to digest cellulose.
The Human Digestive System vs. Herbivores
- Lack of Enzyme: Humans lack the enzyme cellulase, which is necessary to break down the tough cellulose fibers that make up the cell walls of grass and other plants.
- Different Anatomy: Unlike ruminant animals such as cows, which have specialized multi-chambered stomachs and host the necessary symbiotic bacteria to ferment and break down cellulose, humans have a single-chambered stomach and a much shorter intestinal tract.
- Acting as Fiber: For humans, consuming regular grass simply means the cellulose passes through the digestive system largely undigested, adding roughage but not providing any meaningful nutrition.
Grass-Based Products with Added Probiotics
It is important to differentiate between whole grass and grass-based products that have been modified or supplemented. Some manufacturers add beneficial bacteria to grass-derived products to create probiotic-enhanced supplements.
- Amazing Grass Superfoods: Products like Amazing Grass's Supergreens Powder combine greens with added digestive enzymes, prebiotics, and probiotics to support gut health. The probiotics are added externally, and the product is a blend, not pure grass.
- Animal Feed: In agricultural applications, studies have shown that grass meal enriched with specific probiotic bacteria can benefit animals like chickens and carps. In these cases, the probiotic effect comes from the added bacteria, not the grass itself.
- Bermuda Grass Juice: Research has been conducted on incorporating Lactobacillus Acidophilus into Bermuda grass juice to increase its health benefits and shelf life. The probiotic properties are due to the added bacterium, not the grass juice naturally containing probiotics.
Probiotics vs. Prebiotics: A Comparison Table
| Feature | Probiotics | Prebiotics |
|---|---|---|
| Nature | Live microorganisms (e.g., bacteria, yeast) | Non-digestible fibers (food for bacteria) |
| Function | Colonize the gut and offer direct health benefits | Feed and stimulate the growth of existing beneficial gut bacteria |
| Source Examples | Yogurt, kefir, kombucha, specific dietary supplements | Onions, garlic, bananas, barley, oats, chicory root |
| Human Digestibility | Administered and intended to survive passage through the digestive system | Pass largely undigested through the human small intestine to the colon |
The Misconception of Pets Eating Grass
Many pet owners observe their dogs or cats eating grass and assume it is for a specific health benefit, such as probiotics. While canines are omnivores and may derive some fiber from grass, the reasons are more complex and not related to probiotic intake.
Why Do Dogs Eat Grass?
- Fiber Intake: A key reason is to increase fiber in their diet, which helps with digestion and bowel regularity.
- Induced Vomiting: Some dogs may eat grass to induce vomiting when they feel nauseous.
- Instinctual Behavior: For others, it's simply an instinctive, natural behavior that provides no ill effects.
- Addressing the Cause: As some research notes, a dog's persistent desire to eat grass could be a sign of a gut microbiome imbalance, which might be addressed with a specific probiotic supplement—but the grass itself is not the probiotic.
Conclusion
To be clear, grass is not a probiotic. While it contains prebiotic fiber that can potentially nourish beneficial bacteria in the gut, humans lack the necessary enzymes to digest it effectively. Therefore, relying on grass as a source of gut-benefiting microorganisms is unfounded. For those seeking to support their gut health, a diet rich in prebiotic foods like onions and oats, or the consumption of fermented products like yogurt that contain true, live probiotics, is the scientifically supported approach. Always consult a healthcare provider before making significant dietary changes. A balanced diet and lifestyle are fundamental to maintaining a healthy gut microbiome.
