Chondroitin sulfate facts for kids

Chemical structure of one unit in a chondroitin sulfate chain.

Chondroitin sulfate - an alternate diagram.

Chondroitin sulfate is a special type of sugar chain found naturally in your body. It's made of repeating sugar units, like tiny building blocks. These sugar chains often connect to proteins, forming bigger structures called proteoglycans. Chondroitin sulfate chains can be very long, with over 100 sugars. Each sugar can have a small chemical group called a "sulfate" attached to it in different places.

Chondroitin sulfate is a very important part of cartilage, which is the flexible tissue in your joints. It helps cartilage handle pressure and stay strong. Many people use chondroitin sulfate as a dietary supplement, often with glucosamine, to help with osteoarthritis. This is a condition where cartilage wears down. Chondroitin sulfate for supplements usually comes from shark cartilage.

What is Chondroitin?

When scientists first found chondroitin sulfate, they didn't know its exact structure. So, its name changed over time. Early researchers gave different types of this substance letters to tell them apart.

You might hear the name "chondroitin" without "sulfate." This usually means a type with very little or no sulfate attached. However, not everyone uses this exact difference.

The word "sulfate" in chondroitin sulfate might make you think it's a salt. But it's not. The sulfate is actually strongly connected to the sugar with a chemical bond. Because the molecule has many negative charges, it usually has positive ions (like sodium) nearby. Most chondroitin sulfate supplements are the sodium salt.

How is Chondroitin Built?

Chondroitin sulfate chains are long, unbranched polysaccharides. This means they are long chains made of many sugar units. They are built from two main sugars that repeat: glucuronic acid (GlcA) and N-Acetylgalactosamine (GalNAc). Sometimes, one of the GlcA sugars can change slightly into a different sugar called iduronic acid. When this happens, the chain is called dermatan sulfate.

Connecting to Proteins

Chondroitin sulfate chains connect to specific parts of certain proteins. Scientists are still learning exactly how proteins are chosen for these connections.

The process of attaching the sugar chain starts with four specific sugar units in a fixed order: Xylose - Galactose - Galactose - GlcA. Each sugar is added by a special enzyme. This allows the body to control how these chains are made. The first sugar, xylose, starts attaching to proteins in a part of the cell called the endoplasmic reticulum. The rest of the sugars are added in another part of the cell called the Golgi complex.

Adding Sulfates

Each sugar unit in the chain can have no sulfate, one sulfate, or two sulfates attached. Most often, sulfates are added to positions 4 and 6 of the N-acetyl-galactosamine sugar. Sometimes, they are also added to position 2 of the glucuronic acid. Special sulfotransferase enzymes add these sulfates. Where the sulfates are placed on the chain affects how chondroitin sulfate works in the body.

What Does Chondroitin Do?

The jobs of chondroitin sulfate depend a lot on the larger proteoglycan it's a part of. Its functions can be divided into two main types: structural roles and regulatory roles. Some proteoglycans, like versican, do both.

Structural Role

Chondroitin sulfate is a major part of the extracellular matrix. This is like the "glue" and "scaffolding" that holds cells and tissues together. It's very important for keeping tissues strong and healthy. This structural job is common for large proteoglycans like aggrecan, versican, brevican, and neurocan. These are often called lecticans.

As part of aggrecan, chondroitin sulfate is a key part of cartilage. The sulfate groups on chondroitin sulfate have strong negative charges. These charges push away from each other, which helps cartilage resist being squeezed or compressed. If cartilage loses chondroitin sulfate, it can become weaker. This loss is a big reason why people develop osteoarthritis.

Regulatory Role

Chondroitin sulfate easily interacts with proteins in the extracellular matrix because of its negative charges. These interactions are important for controlling many cell activities.

Lecticans, which contain chondroitin sulfate, are a major part of the brain's extracellular matrix. Here, the chondroitin sugar chains help stabilize normal brain connections, called synapses. They are part of special structures called perineuronal nets. After an injury to the central nervous system (like the brain or spinal cord), the levels of chondroitin sulfate proteoglycans greatly increase. They can actually prevent damaged nerve endings from growing back. While scientists are still learning about all their roles, new functions for chondroitin sulfate proteoglycans are always being discovered.

During the development of the brain's outer layer (the cortex), chondroitin sulfate acts like a "stop sign" for nerve cells moving to their correct places. This helps guide them to form the right layers in the brain.

Medical Use

Chondroitin is found in dietary supplements used as an alternative medicine to help treat osteoarthritis. In Europe and some other countries, it is also approved as a slow-acting medicine for this disease. It is often sold together with glucosamine. Chondroitin and glucosamine are also used to treat animals.

• "Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT)," ClinicalTrials.gov information on a study about glucosamine and chondroitin for arthritis.

See also

In Spanish: Condroitín sulfato para niños