Hyaluronic acid (HA) is a glycosaminoglycan (GAG), which is a substance that attaches to collagen and elastin to form cartilage. HA not only helps keep the cartilage that cushions joints strong and flexible, but also helps increase supplies of joint-lubricating synovial fluid.

HA is the naturally produced water-holding molecule in the connective tissue of the body. Just one gram of HA holds about six liters of water. Think of how the skin of very young babies looks-it won't even create a scar if cut or scratched. That's what HA acid does. It is nature's healing agent and scaffolding or "space filler" for the skin, hair, eyes and joints. It also serves as a barrier against disease.

Research has shown hyaluronic acid to be an effective treatment for both rheumatoid and osteoarthritis, particularly in its injectable form (the only form to date that has been approved for medical use by the FDA). In one study, over 80 percent of participants had significant relief of their painful arthritic symptoms immediately after treatment with HA injections. Pain relief lasted anywhere from nine to 12 months, after which time more injections were needed to maintain results.

Hyaluronic acid is present in every tissue of the body, and it performs many important functions. It helps deliver nutrients to and carry toxins from cells that do not have a blood supply, such as those found in cartilage; without adequate amounts of HA, the joints will become brittle and deteriorate. Not only does it keep joints lubricated, but hyaluronic acid also encourages water retention in other bodily tissues. It is found in large concentrations in the extracellular matrix (ECM), which is the fluid-filled space between cells. HA locks moisture into the ECM, keeping collagen and elastin moist and promoting a youthful appearance.

Hyaluronic acid is gaining popularity in the cosmetic and medical industries. Cosmetic products containing hyaluronic acid claim to hydrate the skin, allowing it to appear smoother and more radiant. Clinical studies have shown that it also helps wounds heal more quickly, and can reduce the appearance of both old and new scars. Injectible hyaluronic acid fillers, such as Restylane, are being to lessen the appearance of lines, sagging and depressions in the skin caused by acne scars or injury. HA eventually breaks down and is absorbed in the body, so both cosmetic and medical applications are not permanent. In most cases, the hyaluronic acid augmentation usually lasts between 6-9 months. Repeat treatments will be necessary.

What is Hyaluronic Acid?
Hyaluronic acid is a substance that is naturally present in the human body. It is found in the highest concentrations in fluids in the eyes and joints. The hyaluronic acid that is used as medicine is extracted from rooster combs or made by bacteria in the laboratory. People take hyaluronic acid for various joint disorders, including osteoarthritis. It can be taken by mouth or injected into the affected joint by a healthcare professional.
The FDA has approved the use of hyaluronic acid during certain eye surgeries including cataract removal, corneal transplantation, and repair of a detached retina and other eye injuries. It is injected into the eye during the procedure to help replace natural fluids. Hyaluronic acid is also used as a lip filler in plastic surgery. Some people apply hyaluronic acid to the skin for healing wounds, burns, skin ulcers, and as a moisturizer.

Hyaluronic acid has been nicknamed by the press as the "key to the fountain of youth" because it has been noted that at least some people who ingest a lot of it in their diets tend to live to ripe old ages. ABC News had a show on a village in Japan and hyaluronic acid entitled, "The Village of Long Life: Could Hyaluronic Acid Be an Anti-Aging Remedy?". (It should be noted that the people in the ABC news show were thought to get high amounts of HA from starchy root vegetables their natural diets.)

Hyaluronic Acid is Found in Synovial Joint Fluid
Our joints (like the elbows and knees) are surrounded by a membrane called the synovial membrane, which forms a capsule around the ends of the bones. This membrane secretes a liquid called the synovial fluid. Basically, the synovial fluid is found in joint cavities. It has many functions, including serving as a lubricant, shock absorber and a nutrient carrier. The fluid protects the joints and bones. Cartilage is immersed in the synovial fluid and is a fibrous connective tissue. Cartilage is avascular, meaning it contains no blood vessels. This is why the synovial fluid is so important. Synovial fluid is the only way in which nutrients can be carried into the cartilage and waste can be removed.

Hyaluronic Acid is a Key Component of Cartilage
Cartilage is a specialized form of connective tissue. Hyaline cartilage is the most predominant form of cartilage in the body. It lends strength and flexibility to the body. A key component of cartilage is hyaluronic acid. Cartilage is also avascular – with no blood vessels. Nutrients are brought by the synovial fluid, which is rich in hyaluronic acid to the cartilage, which is also hyaluronicacid rich.

Hyaluronic Acid is in the Extracellular Matrix
Hyaluronic Acid is found in the extracellular matrix (ECM). The ECM is composed of material (fibrous elements, including glycosamino-glycans) produced by the cells and excreted to the extracellular space with the tissues. All nutrients and metabolic waste are transported through the ECM. Hyaluronic acid is a major constituent of the ECM and serves as an essential structural element of the ECM. Hyaluronic acid locks moisture into the ECM and hyaluronic acid supports the structural integrity of the extracellular matrix.

Hyaluronic Acid in the Skin
In the skin, the extracellular matrix is composed of hyaluronic acid and other sulfated GAGs, combined with collagen and elastin. Large amounts of water are held in the ECM. When elastin is not bathed in water, it becomes dry and brittle, thus the look of dry, brittle, wrinkled skin.1
Half-life is defined as the time required for one half of the total amount of a particular substance to be consumed, broken down, or depleted. The half-life of hyaluronic acid in the cartilage is 2-3 weeks. But the half-life of hyaluronic acid in the skin is less than 1 day! Hyaluronic acid is present in both the dermis and the epidermis. 50% of the body's naturally produced hyaluronic acid that is found in the epidermis is metabolized and excreted in less than 24 hours. Like hyaluronic acid produced in the body, hyleronic acid taken as a nutritional supplement moisturizes from the dermis to the epidermis - from deeper layers of the skin to the outer layer.

The extracellular matrix fills up the space between the skin cells. This makes the skin soft, smooth and elastic. But as we age, hyaluronic content in the skin changes due to two separate clinically proven factors:

Benefits / uses

The major potential benefit of hyluronic acid is its support on osteoarthritis, skin conditions such as actinic keratose, wrinkles and fold. Let's review its potential medical uses-

1.Osteoarthritis
Hyaluronan preparations have shown to decrease pain but improve the mobility of patients suffered from knee osteoarthritis. The improvement in the condition is possibly related to alternations in the synovial fluid viscoelasticity, cartilage metabolism, and inflammation. Turkish researchers injected high molecular weight hyaluronic acid (Hylan G-F 20) and low molecular weight hyaluronic acid (Orthovisc) to 92 patients suffered from knee osteoarthritis separately at one-week intervals for three weeks. Both hyaluronic acid preparations resulted in a pronounced reduction in pain and improved function, without complications. Physicians have injected hyaluronic acid directly into the synovial fluid in the knee as a treatment for osteoarthritis of the knee for the past 20 years. There are many peer-reviewed articles written on the use of hyaluronic acid extracted from rooster combs for this purpose.

Arthritis and other joint conditions can benefit from more hyaluronic acid which is able to lubricate joints so that they don't become weak. A benefit of the acid is that it can even be used as a supplement to help prevent arthritis.

2.Skin Conditions
HA can help a person to look and feel younger. Hyaluronic acid is able to lock water in to a person's cells and particularly skin cells. This water is needed to maintain good function of elastic and collagen in the skin. Otherwise a person can begin to show their wrinkles and sags. Some women are using supplement forms of hyaluronic acid in an attempt to achieve younger looking skin. Because hyaluronic acid helps to maintain the ideal level of moisture in the skin, overall good skin health can often be one of the hyaluronic acid benefits.

3 Anti-Aging
Hyaluronic acid has been nicknamed by the press as the "key to the fountain of youth" because it has been noted that at least some people who ingest a lot of it in their diets tend to live to ripe old ages. ABC News had a show on a village in Japan and hyaluronic acid entitled, "The Village of Long Life: Could Hyaluronic Acid Be an Anti-Aging Remedy?" (It should be noted that the people in the ABC news show were thought to get high amounts of HA from starchy root vegetables their natural diets. They were not taking supplements.)

Hyaluronic acid (also called Hyaluronan) is a component of connective tissue whose function is to cushion and lubricate. Hyaluronan occurs throughout the body in abundant amounts in many of the places people with hereditary connective tissue disorders have problems such as joints, heart valves and eyes.

Doses
HA is appropriate for adults, age 40 or 50 and up, or anyone who has worn out HA in a particular area. I had a 32-year old piano mover write to me that he was ready to give up his job and undergo knee surgery. He took oral HA and within a month had no pain. The loss of HA can occur early, depending upon wear and tear. Imagine what oral HA supplements could do to extend the career of athletes. I expect Olympic athletes to be using oral HA soon. Oral dosage should be 150 mg per day, with possibly a loading dose for one month of 300 mg per day. More HA is not always better.

Possible Side effects / Precautions / Possible Interactions:
Side effects limited to local pain and swelling. In general, side effects of hyaluronic acid gel include bruising, redness, swelling.
Pregnancy and breast-feeding: Hyaluronic acid is possibly safe when given by injection during pregnancy. However, not enough is known about the safety of hyaluronic acid when taken by mouth or applied to the skin during pregnancy. Stay on the safe side and avoid use.
If you are breast-feeding, don't use hyaluronic acid, even by injection.

Research studies / References