Is starch found in plants or animals? The Definitive Answer

December 12, 2025 •

3 min read

Approximately one-third of the human diet consists of starchy foods. While animals consume these plant-based carbohydrates, a common misconception is that they also produce starch. This article will clarify whether starch is found in plants or animals and explain the critical biological differences.

Quick Summary

Starch is produced and stored exclusively by plants as an energy reserve, while animals store their energy in a similar but more highly branched molecule called glycogen.

Key Points

Plant Exclusive: Starch is produced and stored only by plants as their primary energy reserve through photosynthesis.
Animal Equivalent: Animals store energy in a different molecule called glycogen, which is more highly branched than starch.
Structural Differences: Starch is a mix of linear (amylose) and branched (amylopectin) components, while glycogen is extensively branched, enabling faster energy release for animals,.
Dietary Source: Animals consume starch from plants, which is then broken down into glucose and converted into glycogen or used for immediate energy.
Storage Locations: Starch is stored in plant plastids (like chloroplasts), while glycogen is stored primarily in animal liver and muscle cells,.
Digestive Process: Animals possess enzymes like amylase to break down starch into glucose, which is then utilized or stored as glycogen.

What Is Starch?

Starch is a complex carbohydrate, or polysaccharide, composed of long chains of glucose units joined by glycosidic bonds. It is a white, tasteless, and odorless powder that is insoluble in cold water. There are two main types of starch molecules found in plants: amylose and amylopectin. Amylose consists of linear, unbranched chains of glucose, while amylopectin is a larger, branched molecule. The specific ratio of amylose to amylopectin can vary between different plant species, which influences the starch's properties.

Starch Is Exclusively Found in Plants

All green plants produce starch as a means of storing energy. This process is directly linked to photosynthesis, where plants convert light energy into glucose. Any excess glucose that the plant does not immediately need for metabolism is converted into starch for storage. This stored energy can then be used by the plant later, such as at night when photosynthesis is not occurring, or during periods of growth and reproduction.

Starch storage occurs in specific locations within the plant:

Leaves: Transitory starch is stored in chloroplasts during the day and is broken down at night.
Storage Organs: Large quantities of starch are accumulated in specialized storage parts like roots, seeds, tubers, and fruits.

Common examples of starchy plants that form a major part of the human diet include grains such as wheat, rice, and maize, as well as root vegetables like potatoes and cassava.

Why Animals Don't Produce Starch

Animals, including humans, do not produce or store starch. Instead, they store excess glucose as a different polysaccharide called glycogen. Glycogen is synthesized mainly in the liver and muscle cells. This structural difference between starch and glycogen is crucial to meeting the energetic demands of an active organism. Glycogen's more highly branched structure allows for faster enzymatic breakdown and mobilization of glucose for immediate use.

When animals consume starchy plants, their digestive systems break down the starch into its component glucose monomers using enzymes like amylase. This glucose is then absorbed into the bloodstream. Once in the body, the glucose can be used immediately for energy or converted into glycogen for short-term storage in the liver and muscles. Any remaining glucose can be converted to fat for long-term energy reserves.

A Comparison of Starch and Glycogen

To understand the fundamental difference, it is helpful to compare the key characteristics of starch and glycogen.


Feature	Starch (in Plants)	Glycogen (in Animals)
Primary Function	Long-term energy storage.	Short-term energy storage.
Organism	Produced by green plants.	Produced by animals and fungi.
Structure	Composed of amylose (linear) and amylopectin (branched).	More extensively branched than amylopectin.
Storage Location	Plastids (chloroplasts, amyloplasts).	Liver and muscle cells.
Mobilization	Slower due to less dense branching and semicrystalline structure.	Faster due to dense branching, allowing rapid access to glucose.
Solubility	Insoluble in water.	More soluble in water.

The Dietary Importance of Starch for Animals

For animals, starch is a vital source of dietary carbohydrates that provides the glucose needed for cellular functions. The breakdown of dietary starch into glucose powers metabolic processes in the body. Starchy foods also provide other essential nutrients and fiber. The fiber component of some starches, known as resistant starch, passes through the small intestine undigested and acts like dietary fiber, promoting gut health.

The ability of animals to effectively digest and utilize starch is a crucial adaptation that allows them to benefit from the energy stored by plants. However, the fundamental difference remains: plants are the producers and storers of starch, while animals are the consumers who then convert the glucose into their own energy storage form, glycogen.

Conclusion

In summary, the presence of starch is a defining characteristic of plants, where it functions as a primary energy reserve created through photosynthesis. Animals do not produce starch; they use a different, more highly branched polysaccharide called glycogen for short-term energy storage in their liver and muscles. While animals are dependent on plant-based starches as a significant source of dietary energy, the process of digestion and energy storage in animals relies on converting that starch into a form suitable for their specific metabolic needs. Understanding this fundamental biological distinction clarifies the unique energy strategies of different kingdoms of life. For further reading on the intricate process of starch formation within plant cells, consult the scientific literature.

Frequently Asked Questions

No, animals cannot create starch. Instead, they synthesize and store energy in the form of glycogen, particularly in the liver and muscles.

Starch functions as the main energy reserve for plants. It is synthesized from excess glucose produced during photosynthesis and is stored in granules for later use, especially during periods without sunlight,.

While both are complex carbohydrates made of glucose, glycogen is more highly branched than starch. This allows for more rapid mobilization of glucose to meet an animal's immediate energy needs,.

When humans consume starch, digestive enzymes like amylase break it down into glucose. The body then uses this glucose for energy or converts excess into glycogen and fat for storage,.

Starch is abundant in many plant-based foods, including grains (rice, wheat, corn), legumes (beans, lentils), and root vegetables (potatoes, cassava),.

The highly branched structure of glycogen offers many points for enzymatic action, meaning it can be broken down into glucose and released into the bloodstream much faster than starch. This is crucial for the mobile, high-energy lifestyle of animals.

Chemically, both are glucose polymers using similar linkages. However, their physical structure and branching density differ, which impacts their properties like solubility and storage efficiency.

Plants store starch in specialized organelles called plastids. These are found in chloroplasts in leaves for temporary storage and amyloplasts in storage organs like roots, tubers, and seeds,.