Find Information About:

Drugs & Supplements

Get information and reviews on prescription drugs, over-the-counter medications, vitamins, and supplements. Search by name or medical condition.

Pill Identifier

Pill Identifier

Having trouble identifying your pills?

Enter the shape, color, or imprint of your prescription or OTC drug. Our pill identification tool will display pictures that you can compare to your pill.

Get Started

My Medicine

Save your medicine, check interactions, sign up for FDA alerts, create family profiles and more.

Get Started

WebMD Health Experts and Community

Talk to health experts and other people like you in WebMD's Communities. It's a safe forum where you can create or participate in support groups and discussions about health topics that interest you.

  • Second Opinion

    Second Opinion

    Read expert perspectives on popular health topics.

  • Community


    Connect with people like you, and get expert guidance on living a healthy life.

Got a health question? Get answers provided by leading organizations, doctors, and experts.

Get Answers

Sign up to receive WebMD's award-winning content delivered to your inbox.

Sign Up

Osteoarthritis Health Center

Select An Article

Nutritional Supplements and Osteoarthritis

Font Size

Arthritis is a general term that describes inflammation in joints. Osteoarthritis, also called degenerative joint disease, is the most common type of arthritis. It is associated with a breakdown of cartilage in joints and commonly occurs in the hips, knees, and spine. It also often affects the finger joints, the joint at the base of the thumb, and the joint at the base of the big toe.

Common treatment methods don't change the progression of osteoarthritis. However, two nutritional supplements -- glucosamine and chondroitin sulfates -- are being studied to determine if they can relieve pain or perhaps slow the breakdown of cartilage, which is a significant part of osteoarthritis.

What Is Cartilage?

Cartilage is a firm, rubbery material that covers the ends of bones in normal joints (See Figure 1). Its main function is to reduce friction in the joints and serve as a "shock absorber." The shock-absorbing quality of normal cartilage comes from its ability to change shape when compressed.

Cartilage can change shape because it is more than 70% water, which can be redistributed with movement. For example, when force is applied to a knee, as in standing or walking, some water from cartilage enters the joint and coats the cartilage. When the force is no longer present, such as when you sit down, the water is reabsorbed and the cartilage regains its normal shape. Because cartilage does not contain nerves, you do not feel pain when these changes in shape occur.

Osteoarthritis causes the cartilage in a joint to become stiff and lose its elasticity, making it more susceptible to damage. Over time, the cartilage may wear away in some areas, greatly decreasing its ability to act as a shock absorber. As the cartilage wears away, tendons and ligaments stretch, causing pain. If the condition worsens, the bones could rub against each other.

Cartilage is made up of four substances: collagen, proteoglycans, water, and chondrocytes (see Figure 2).

In addition to being a key component of cartilage, the protein collagen is also found in the skin and tendons. Collagen provides cartilage with its strength, and creates a framework that houses the other components of cartilage.

Next Article:

Today on WebMD

elderly hands
Even with arthritis pain.
woman exercising
Here are 7 easy tips.
acupuncture needles in woman's back
How it helps arthritis, migraines, and dental pain.
chronic pain
Get personalized tips to reduce discomfort.
Keep Joints Healthy
Chronic Pain Healthcheck
close up of man with gut
man knee support
woman with cold compress
Man doing tai chi
hand gripping green rubber ball
person walking with assistance