With so much focus on lowering the risk of diseases like heart disease and cancer, it’s easy to forget about another important aspect of successful aging – joint health. Joints are the spaces that separate bones from one another and they come in several varieties. The type you find in areas that allow movement, like your knees, are called synovial joints. Keeping these joints healthy is key to good mobility and freedom from joint pain as you age.
Structure of a Joint
If you were to look at a synovial joint, such as your knee, you’d see the outer surface is encased in a thick, fibrous capsule that limits how much the two bones it covers can move. Inside the capsule is a fluid called synovial fluid that lubricates and nourishes the joint. The two bones that the joint capsule encloses and protects is covered in a rubbery layer of cartilage referred to as hyaline cartilage.
Along the outside of the capsule is another type of firm, fibrous cartilage. This more rigid form of cartilage strengthens and reinforces the capsule as it helps the joint absorb shock. This fibrous cartilage is what makes up the ligaments that connect bone to bone and tendons that link bone to muscle. Altogether, these components keep a joint, like the knee joint, stable.
In this article, we’ll focus on damage to hyaline cartilage, the cartilage that covers the ends of bones. Having healthy hyaline cartilage is critical since without it the ends of bones are no longer protected from friction or shock. If you were to lose all of the hyaline cartilage that covers the bones in your knee joint, every time you bend your knee, bone would rub against bone. Needless to say, that wouldn’t feel good. Keeping that layer of cartilage healthy is important for healthy joint function.
How Cartilage Ages
Hyaline cartilage can become damaged from diseases like osteoarthritis or rheumatoid arthritis, from chronic wear and tear, and from sports-related injuries. Cartilage also “ages” along with the rest of your body. The mechanism by which hyaline cartilage ages isn’t clear but oxidative stress, lack of response to growth factors that help maintain healthy cartilage, and aging of chondrocytes, cells that help maintain the collagen matrix are possible factors. Chondrocytes produce proteoglycans, proteins with sugars attached to them that make up the fabric of connective tissue, including hyaline cartilage. Proteoglycans attract water and help keep cartilage tissue and the joint healthy.
When you’re young, chondrocytes easily pump out more proteoglycans. Throughout life, the components of cartilage are “remodeled,” just as bone is remodeled – out with the old and in with the new. As old the old components of the cartilage matrix are broken down, chondrocytes produce new proteoglycans to help rebuild the cartilage matrix, thereby keeping the cartilage healthy and viable.
With age and with osteoarthritis, this process breaks down. The breakdown of old cartilage exceeds the capacity of the chondrocytes to make new proteoglycans and thus fresh cartilage. Inflammation also plays a role in cartilage breakdown. Pro-inflammatory chemicals called cytokines turn on enzymes that break down cartilage.
Does Nutrition Play a Role?
Diet has an impact on almost every aspect of bodily function – what about cartilage? Are there dietary components or supplements that help preserve it? One supplement called glucosamine has shown mixed results in people with arthritis. Glucosamine is a precursor of compounds chondrocytes used to make proteoglycans. As you age, the amount of glucosamine in your body declines. Supplementing with glucosamine helps replenish the precursors your body needs to make new cartilage.
In supplements, glucosamine is often combined with chondroitin sulfate, a substance that helps cartilage hold on to water. Some studies show these supplements offer benefits, including pain relief and a reduction in joint space narrowing due to cartilage loss. Pain relief probably stems from the fact that glucosamine also has anti-inflammatory properties.
With respect to rheumatoid arthritis, an autoimmune form of cartilage destruction, reducing meat and dairy consumption might help. A study published in the journal Rheumatology showed eating a gluten-free, vegan diet improved joint discomfort, swelling, and other signs and symptoms of rheumatoid arthritis.
On the other hand, diets high in omega-3s from sources like fatty fish and fish also ease joint pain and, possibly, slow progression of osteoarthritis and rheumatoid arthritis, thanks to their anti-inflammatory effects. In one study, people with rheumatoid arthritis were able to discontinue non-steroidal anti-inflammatory medications after starting a fish oil supplement.
Just as exciting is the prospect that some herbs and spices may help with joint inflammation. Curcumin, the active ingredient in the spice turmeric, in one study was as effective as a prescription anti-inflammatory for easing the joint symptoms of rheumatoid arthritis. Unfortunately, your body doesn’t readily absorb curcumin. However, if you consume it with black pepper, the piperidine in black pepper helps your body take up and use curcumin.
What about Exercise?
Although sports injuries can damage the joints and accelerate the development of osteoarthritis, regular physical activity is a joint healthy activity. Each time you move a joint through exercise, it delivers more nutrients to cartilage by sending more synovial fluid to the area. There’s even evidence that regular weight-bearing exercise increases cartilage volume. Just as importantly, exercise helps control body weight. That’s critical since obesity is a strong risk factor for osteoarthritis. On the other hand, doing high-impact exercise every day may put too much stress on your joints. Alternate high-impact activities with lower impact ones and reap the benefits of both.