Hyaluronic Acid and Vision

Hyaluronic acid is synthesized within the human eye and is secreted into both tears and the aqueous humor of the eye in its non-acidic form, hyaluronidate. On the ocular surface, tears with normal hyaluronidate content exhibit greater lubrication during blinks. Yet while the eyelid is still, hyaluronidate maximizes the thickness of the protective fluid covering the surface of the eye – another reflection of the special properties of hyaluronidate. Within the eye itself, hyaluronidate forms part of a web of large molecules that confer structural stability to the retina and help keep it attached to the underlying cell layers.

Both advancing age and dry eyes reduce tear production and the amount of hyaluronidate that is secreted in tears; complaints about burning, itching, a sensation of the presence of a foreign body, redness and heaviness of the eyelids are common. Hyaluronic acid replacement, via drop form, can promote normal eye functions, as shown by the results of a study published in the British Journal of Ophthalmology, which assessed the effects of eye drops containing hyaluronic acid.5

Research consistently demonstrates that the insertion into the eyes of drops containing sodium hyaluronidate several times daily decreases burning, dryness, “foreign body” sensation, itching and mucous discharge. At the same time, tear formation is increased. These tears help protect the cornea from environmental insults, indicating that hyaluronic acid acts both on the surface of the eye and within the eye. The chemical process of vision produces a number of oxidizing by-products.6 The gradual steady accumulation of oxidative damage interferes with the functions of all parts of the eye. The hyaluronic acid in tears acts as a powerful antioxidant that preserves the structure and function of the visual apparatus.7

References:
5. Aragona P, Papa V, Micali A, Santocono M, Milazzo G. Long term treatment with sodium hyaluronate-containing artificial tears reduces ocular surface damage in patients with dry eye. Br J Ophthalmol 2002;86:181-184.
6. Rotstein NP, Politi LE, German OL, Girotti R. Protective effect of docosahexaenoic acid on oxidative stress-induced apoptosis of retina photoreceptors. Invest Ophthalmol Vis Sci 2003;44:2252-2259.
7. Debbasch C, De La Salle SB, Brignole F, Rat P, Warnet JM, Baudouin C. Cytoprotective effects of hyaluronic acid and Carbomer 934P in ocular surface epithelial cells. Invest Ophthalmol Vis Sci 2002;43:3409- 3415.

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How Does Oral Hyaluronic Acid Work?

Traditionally, hyaluronic acid has been used as an injectable to promote joint health and support joint structure. There have also been questions regarding the absorbability of hyaluronic acid when taken orally. Research shows that oral hyaluronic acid is in fact absorbed and that it functions in at least three important ways. Hyaluronic acid is a large molecule with repeating subunits that, when taken orally, naturally goes through the process of digestion in the digestive tract. Studies show that 1) A portion of the hyaluronic acid is absorbed intact, 2) A portion of it is broken down into its component sugars and absorbed in this way (providing building blocks the body can use to remanufacture hyaluronic acid, and 3) Hyaluronic Acid acts to stimulate the growth of beneficial bacteria in the digestive tract, which promote immune system health and lead to overall health of the joints, skin and connective tissue throughout the body. These three unique and distinctly separate mechanisms of activity illustrate the ability of oral hyaluronic acid to benefit and support the body’s connective tissue.

To reaffirm the efficacy of oral hyaluronic acid for joint support, let’s look at the results of an important Japanese study. This study, which was published in 2008, was carried out to assess the efficacy of oral hyaluronic acid in promoting healthy joint function and mobility. Fifteen individuals with achy knees were supplemented with 240 mg of highly purified hyaluronic acid daily for twelve weeks. Positive results were evident after 4 weeks of supplementation as the individuals had significant improvements in knee joint function and comfort. The benefits continued throughout the duration of the study, showing that oral hyaluronic acid supplements are effective for promoting healthy joint function.11

Now that we know that studies affirm the effectiveness of oral hyaluronic acid, let’s look at evidence supporting the three mechanisms of activity. Bioavailability studies in animals show that hyaluronic acid taken orally reaches joint tissue. Radioactively-labeled particles of hyaluronic acid were found to reach the skin, bone and joints of rats after oral administration, showing that a percentage of orally administered hyaluronic acid is absorbed intact.12 A further percentage of hyaluronic acid taken as supplements is digested and broken down into its component molecules. These components are absorbed into the bloodstream, providing the body with the building blocks necessary to produce hyaluronic acid on its own, allowing it to replenish its own stores. Finally, a very interesting study was carried out in which rats were administered hyaluronic acid orally. Researchers found that the orally administered nutrient was fermented by gut bacteria as a source of nutrition. Hyaluronic acid was shown to act as a prebiotic, as it increased the level of Lactobacillus and Bifidobacterium species in the intestinal tract.13 Taking these important studies into account, we can see that oral hyaluronic acid supplements have both direct and indirect effects in supporting the health of our joints, skin and connective tissue. Given its broad range of potential benefits, hyaluronic acid is a crucial and important nutrient for healthy aging.

References:
11. Sato T, Iwaso H. An Effectiveness Study of Hyaluronic Acid (Hyabest® (J)) in the Treatment of Osteoarthritis of the Knee. J New Rem & Clin 2008;57(2):128-137.
12. Balogh L, Polyak A, Mathe D, Kiraly R, Thuroczy J, Terez M, Janoki G, Ting Y, Bucci LR, Schauss AG. Absorption, uptake and tissue affinity of high-molecular-weight hyaluronan after oral administration in rats and dogs. J Agric Food Chem 2008 Nov 26;56(22):10582-93.
13. Ishibashi G, Yamagata T, Rikitake S, Takiguchi Y. Digestion and Fermentation of Hyaluronic Acid. Journal for the Integrated Study of Dietary Habits 2002; 13(2): 107-111.

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Hyaluronic Acid and Keeping Skin Healthy Longer

This is part of our ongoing The Best Kept Secrets to Healthy Aging spotlight. Each day, we will be posting some of the great information that’s packed into our book, The Best Kept Secrets to Healthy Aging.

Today’s topic:
Keeping Skin Healthy Longer with Hyaluronic Acid

Aging skin is characterized by a significant loss of elasticity coinciding with a reduced content of hyaluronic acid.8 Because hyaluronic acid is the most abundant water-binding glycosaminoglycan in healthy skin, loss of hyaluronic acid results in decreased water content and loss of elasticity. In addition, loss of hyaluronic acid is accompanied by increased compaction of collagen fibers. Skin depleted of hyaluronic acid takes on a dry and wrinkled appearance, much like joints depleted in hyaluronic acid lose their ability to retain moisture, and thus have decreased cushioning and shock-absorbing ability.

In contrast, enrichment of the dermal layer of the skin with hyaluronic acid optimizes collagen organization (“packing”). Hyaluronic acid also has been shown to promote intercellular communication, allowing cells to cooperate more efficiently in organizing the collagen they produce. Hyaluronic acid contributes to the organization and structure of the skin by increasing the amount of water that is bound into the structure of the skin – the better hydrated the skin, the more flexible it is.9 In addition, hyaluronic acid enrichment supports the ability of new skin cells to replace old, further facilitating the restoration and maintenance of healthy skin.

When the skin is exposed to oxidizing chemicals or conditions (such as sunlight), the lipid structures of cell membranes are susceptible to increased rates of oxidative peroxidation.10 Skin cells with membranes that have been oxidized shrink and deform, losing cell-to-cell contact and “leaking” increased amounts of evaporative water from the abnormal spaces between cells, causing dehydration of the skin and reducing its flexibility.10

As reported in a paper published recently in the Journal of Pharmacology and Pharmaceutical Science hyaluronic acid is a powerful antioxidant within the skin that acts to maintain skin health by preventing lipid peroxidation and by maintaining the normal level of hydration within the skin.10 These properties of hyaluronic acid promote flexible and supple skin, making hyaluronic acid a vital component of your healthy skin preservation program.

Next Best Kept Secrets to Healthy Aging topic:
How Does Oral Hyaluronic Acid Work?

References:
8. Guinot C, Malvy DJ, Ambroisine L, Latreille J, Mauger E, Tenenhaus M, Morizot F, Lopez S, Le Fur I, Tschachler E. Relative contribution of intrinsic vs extrinsic factors to skin aging as determined by a validated skin age score. Arch Dermatol 2002;138:1454-1460.
9. Toole BP. Hyaluronan is not just a goo! J Clin Invest 2000;106:335-336.
10. Trommer H, Neubert RH. Screening for new antioxidative compounds for topical administration using skin lipid model systems. J Pharm Pharm Sci 2005;8:494-506.

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Hyaluronic Acid and Joint Mobility

This is part of our ongoing The Best Kept Secrets to Healthy Aging spotlight. Each day, we will be posting some of the great information that’s packed into our book, The Best Kept Secrets to Healthy Aging.

Today’s topic:
Hyaluronic Acid and Joint Mobility

Batches of hyaluronic acid are synthesized and assembled into long chains before being secreted by articular chondrocytes (cartilage cells) and synoviocytes (cells that live in the synovial lining of the joint capsule). Regardless of its source, hyaluronic acid can be incorporated into the load-bearing sugar/protein mats of joint cartilage.

As shown in research recently published in the Journal of Physiology the unique properties of the special sugars that make up hyaluronic acid attract water and are responsible for the cushioning properties of healthy joint cartilage.3 Because the synthesis of its component sugars slows with age, the replenishment of hyaluronic acid within a joint also slows with age, creating an inevitable imbalance in the cartilage’s replenishment/replacement cycle. As the contact surfaces of the joint cartilage become depleted of hyaluronic acid, they become chronically dehydrated and lose their vital cushioning hydrostatic properties.

A large volume of published scientific research has demonstrated that adequate availability of hyaluronic acid can promote joint health and function. These conclusions have been echoed most recently in a mathematical analysis of the body of published research, itself published in the Journal of Family Practice.4 The strength of the evidence certainly argues in favor of adding hyaluronic acid to your personal joint health program.

Next Best Kept Secrets to Healthy Aging topic:
Vision and Hyaluronic Acid

References:
3. Scott JE, Stockwell RA. Cartilage elasticity resides in shape module decoran and aggrecan sumps of damping fluid. Implications in osteoarthrosis. J Physiol 2006; Mar. 31. doi: 10.1113/ jphysiol.2006.108100 (http://jp.physoc.org/cgi/content/abstract/jphysiol.2006.108100v1).
4. Modawal A, Ferrer M, Choi HK, Castle JA. Hyaluronic acid injections relieve knee pain. J Fam Pract 2005;54:758-767.

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Hyaluronic Acid: The Molecule of Youth

This is part of our ongoing The Best Kept Secrets to Healthy Aging spotlight. Each day, we will be posting some of the great information that’s packed into our book, The Best Kept Secrets to Healthy Aging.

Today’s topic:
Hyaluronic Acid – The Molecule of Youth

Relatively new as a dietary supplement ingredient, hyaluronic acid has now been available for more than ten years. However, it has been used much longer than that as an injectable for supporting joint structure. Of course, the nutrient is indigenous to our bodies and present in connective tissues, nerves, brain tissue, and the skin. Hyaluronic acid is a complex molecule made up of two special sugars, N-acetyl-glucosamine and glucuronic acid. Hyaluronic acid disaccharides are produced and secreted in nearby tissue by cells in joint cartilage, synovial membranes, the cornea of the eye, tear ducts and skin. Wherever hyaluronic acid occurs it plays vital roles in maintaining the hydration and lubrication of that tissue.

Joints, Cartilage, Mobility and Nutrition

The cartilage tissue that covers the contact surfaces of joints is made up of mats of interwoven strings of special sugars and proteins. The electrical charges on these mats makes them very attractive to water molecules (water is highly charged – that’s why it conducts electricity so well). Cartilage is spongy because its sugars attract water, which makes the mats swell. When the swollen tissue is squeezed, it absorbs the shock by releasing water into the joint space. Remove the pressure and the water streams back in, restoring the size and shape of the fully hydrated tissue.

Because they are subject to so much wear and tear, the mats are replaced regularly – each one lasts a little under a month in a young adult. In order to maintain balance, an old mat must be removed before a new one can replace it. Once our joints stop growing, they have to adjust their replenishment/replacement cycle in order to stabilize the amount of cartilage covering their contact surfaces. As we age, our cartilage becomes less and less able to adjust and this replenishment cycle goes out of balance. The result is that the mats begin dissolving earlier and earlier. In addition, new replacements are not made quickly enough. As the insertion of new mats falls behind the rate of removal of old mats, joint surfaces can normally become thinner as a result of the aging process and more susceptible to mechanical breakdown from normal everyday activity. Replenishing the joints with the nutrition they need to stay healthy becomes absolutely critical.

The Wear and Tear on Our Joints

You don’t need to be unhealthy or be diagnosed with a medical condition to experience joint discomfort – just continue doing what you always do and eventually one of your joints will get cranky from the effects of normal wear and tear. Or perhaps you over-exert yourself during a sports activity or day-hike and feel it in your knees later that night. That didn’t use to happen. However, now you’re getting older. Things change with age. Whatever the case, this usually signals the need for extra care and supportive measures to maintain healthy joints – joints whose nutrients are not replenished or replaced on a regular basis eventually may not be able to catch up and function as well as they used to. Welcome to the process of normal aging.

There are two ways to help your joints last as long as possible – exercise and nutrition. Becoming more active helps maintain healthier joints as activity stimulates the renewal of connective tissue, bone and cartilage. Two recently published human studies have confirmed the roles of physical activity in joint health. One of these studies showed that if you don’t use your joints, their cartilage covering tends to thin out on its own.1 A second study showed that moderate exercise increases the thickness of joint cartilage and improves joint performance.2 Active individuals have active (well-functioning) joints.

Just as important is to remember to nourish your joints. Joints are known to benefit from regular “feedings” (through eating well and through dietary supplementation) with fish oils, glucosamine, chondroitin sulfate and hyaluronic acid. You can think of hyaluronic acid as the cement that holds things together. Hyaluronic acid thus supports the normal structure of joint tissue. Feed your joints hyaluronic acid and they will reward you.

Next Best Kept Secrets to Healthy Aging topic:
Hyaluronic Acid and Joint Mobility

References:
1. Eckstein F, Lemberger B, Gratzke C, Hudelmaier M, Glaser C, Englmeier KH, Reiser M. In vivo cartilage deformation after different types of activity and its dependence on physical training status. Ann Rheum Dis 2005;64:291-295.
2. Roos EM, Dahlberg L. Positive effects of moderate exercise on glycosaminoglycan content in knee cartilage: A four-month, randomized, controlled trial in patients at risk of osteoarthritis. Arthritis Rheum 2005;52:3507-3514.

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