Hyaluronic Acid: History, Chemical Structure, and its Benefits for the Body
What is Hyaluronic Acid?
Hyaluronic Acid (HA), also known as hyaluronan or hyaluronate, is a carbohydrate, more specifically a mucopolysaccharide
occurring naturally throughout the human body. It can be several
thousands of sugars (carbohydrates) long. When not bound to other
molecules, it binds to water giving it a stiff viscous quality similar
to “Jello”. This viscous Gel is one of the most heavily researched
substances in medicine today with thousands of trials mostly in the
fields of orthopedics and eye surgery. Its function in the body is,
amongst other things, to bind water and to lubricate movable parts of
the body, such as joints and muscles. Its consistency and
tissue-friendliness allows it to be beneficial in skin-care products as
an excellent moisturizer. Because HA is one of the most hydrophilic
(water-loving) molecules in nature with numerous benefits for the human
body it can be described as
"nature's moisturizer".
Hyaluronic Acid Benefits for the Body?
If we compare the joints of the human body to an automobile engine,
the joint fluid in the body mimics the oil in a car engine. At regular
intervals we replace the oil in our car engines because the heat and
friction breakdowns the oils viscosity. The oil becomes thinner and less
able to protect the metal surfaces from excessive wear. Hyaluronic acid
benefits our joints in the same way. As we age the viscosity of the
joint fluid lessens. HA helps to maintain normal joint cushioning.
What is Hyaluronic Acid's Chemical Structure?
It is naturally produced in the human body and is chemically
classified as a Glycosaminoglycan. In the body, hyaluronic acid always
presents itself as a large high molecular weight molecule. The molecule
is made up of a repetitive sequence of two modified simple sugars, one
called glucuronic acid and the other N acetyl gluco
samine. These
compounds are both negatively charged and when put together, they repel
producing an exceptionally long stretched out molecule (high molecular weight). HA
molecules that are long and large in size produce a high viscosity
(lubrication) effect which resists compression and allows our joints and
skin to bear weight.
When was Hyaluronic Acid discovered?
HA was first used commerc
ially in 1942 when Endre Balazs applied for a
patent to use it as a substitute for egg white in bakery products. Its
discovery was very unique. No other molecule had ever been discovered
that has such unique properties to the human body. Balazs went on to
become the leading expert on HA, and made the majority of discoveries
concerning hyaluronic acid benefits.
Where is Hyaluronic Acid located in the body?
Hyaluronic Acid is found naturally in most every cell in the body and
occurs in high concentrations in specific body locations. In each body
location, it serves a different function. Unfortunately, HA also has a
half-life ( the time it takes for the molecule to get broken down and
excreted from the body) of less than 3 days and possibly even as little
as one day in the skin. For this reason, it is imperative that the body
continually replenish itself with HA. Below are some of the areas in the
human body where it is present and critical to anatomical function.
Hyaluronic Acid in Bones and Cartilage
Hyaluronic Acid is found in all bones and cartilage structures throughout the body.
Both
of these structures provide a resilient rigidity to the structure of
the human body. HA is especially found in various forms of cartilage but
none more than the hyaline cartilage. As you've probably guessed it,
hyaline is short for hyaluronic acid. Hyaline cartilage covers the ends
of the long bones where articulation (bending) occurs and provides a
cushioning effect for the bones. The hyaline cartilage has been called
the "gristle cartilage" because its resistance to wear and tear. Hyaline
cartilage also supports the tip of the nose, connects the ribs to the
sternum and forms most of the larynx and supporting cartilage of the
trachea and bronchial tubes in the lungs.
Hyaluronic Acid in Synovial 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 two articulating bones. This membrane secretes a liquid called the
synovial fluid. Synovial fluid is a viscous fluid with the consistency
of motor oil. It has many functions, but none more than providing the
elastic shock absorbing properties of the joint. Its second most
important function in the joint is to carry nutrients to the cartilage
and to also remove waste from the joint capsule.
Hyaluronic Acid in Tendons and Ligaments/Connective tissue
Connective tissue is found everywhere in the body. It does much more
than connect body parts; it has many forms and functions. Its major
functions include binding, support, protection, and insulation. One such
example of connective tissue is the cordlike structures that connect
muscle to bone (tendons) and bone to bone (ligaments). In all connective
tissue there are three structural elements. They are ground substance
(hyaluronic acid), stretchy fibers (collagen and elastin) and a
fundamental cell type. Whereas all other primary tissues in the body are
composed mainly of living cells, connective tissues are composed
largely of a nonliving ground substance, the hyaluronic acid, which
separates and cushions the living cells of the connective tissue. The
separation and cushioning allow the tissue to bear weight, withstand
great tension and endure abuse that no other body tissue could. All of
this is made possible because of the presence of the HA and its ability
to form the gelatinous ground substance fluid.
Hyaluronic Acid in Scalp Tissue and Hair Follicles
Structurally the scalp is identical to the skin tissue located
throughout the body except it also contains about 100,000 hair follicles
that give rise to hair. Actually the hair and the hair follicle are a
derivative of skin tissue. There are two distinctive skin layers, one,
the epidermis (outer layer) which gives rise to the protective shield of
the body and the other, the dermal layer (deep layer) which makes up
the bulk of the skin and is where the hair follicle is located. This
dermal layer is composed of connective tissue and the connective tissue,
with its gelatinous fluid like characteristics provides support,
nourishes and hydrates the deep layers of the scalp. The result is
healthy lustrous hair and a moisturized scalp. Again, all of this is
made possible because of the presence of HA in the scalp.
Hyaluronic Acid in
Lips
The lips are a core of skeletal muscle covered by skin tissue. The
dermal layer of the lips is composed primarily of connective tissue and
its components hyaluronic acid and collagen that give the structure
(shape) and plumpness to the lips. The HA binds to water creating a
gelatinous fluid that hydrates the surrounding tissue and keeps the
collagen (responsible for keeping the skin tight) nourished and healthy.
The result is healthy well hydrated and plump lips that are well
protected from the environment.
Hyaluronic Acid in Eyes
Hyaluronic acid is highly concentrated inside the eyeball. The fluid
inside the eye called the vitreous humor is composed almost completely
of hyaluronic acid. The HA gives the fluid inside the eye a viscous gel
like property. This gel acts as a shock absorber for the eye and also
serves to transport nutrients into the eye. HA has been directly
injected into the eye during procedures to help maintain the shape of
the eye during surgery. It has been said that after the 5th decade of
life, our eyes stop producing the much needed hyaluronic acid resulting
in various eye needs.
Hyaluronic Acid in Gum Tissue
The Gums (gingivoe) are composed of dense fibrous connective tissue
(ligaments) which secure the teeth to the aveloar bone (jaw bone). Once
again, connective tissue is composed of a fibrous tissue surrounded by
hyaluronic acid (extra-cellular matrix). Without the presence of HA, the
gum tissue becomes unhealthy. If it is present it helps to provide the
tensile strength of the ligaments that secure the tooth in place by
providing hydration and nourishment. The result is a healthy set of
gums.
Skin
Although Hyaluronic Acid (HA) can be found naturally in most every
cell in the body, it is found in the greatest concentrations in the skin
tissue. Almost 50% of the bodies HA is found here. It is found in both
the deep underlying dermal areas as well as the visible epidermal top
layers. Young skin is smooth and elastic and contains large amounts of
HA that helps keep the skin stay young and healthy. The HA provides
continuous moisture to the skin by binding up to 1000 times its weight
in water. With age, the ability of the skin to produce HA decreases.
ECM (ground substance)
The extracellular matrix (ECM) is a gelatinous (gel-like) fluid that
surrounds almost all living cells and is essential to life. It gives
structure and support to the body and without it, we would just be a
trillions cells without a shape or function. It is essentially the
mortar between the bricks. The skin, bones, cartilage, tendons and
ligaments are examples where the ECM is located in the body. The ECM is
composed of material (fibrous elements) called elastin and collagen
surrounded by a gelatinous substance (Hyaluronic Acid). HA's roles in
the ECM is to help the stretchy fibers in the body from overstretching
and drying out by continually bathing them in this nutritious water base
gelatinous fluid. It also serves as a wonderful medium through which
nutrients and waste are transported to and from the cells of these
structures. This fluid would not exist if it was not for the ability of
the HA molecule to bind up to 1000 times its weight in water.
Hyaluronic Acid in the skin
The skin is the largest organ in the body comprising about 15% of the
body weight. Roughly 50% of the Hyaluronic Acid in our body is found in
the skin. HA and Collagen are vital to maintaining the skin’s layers
and structure. It is the collagen that gives the skin its firmness but
it is the HA that nourishes and hydrates the collagen. Imagine the
collagen as the stretchy fibers that restore the skin back to shape when
stretched. Collagen is like a rubber band but stretch that rubber band a
million times, like what we do with our skin and without any moisture.
Eventually that rubber band gets overstretched (saggy) and dried out and
will most likely break. This is much the same way the collagen in our
skin reacts leaving our skin in need of moisture. Now imagine that same
rubber band stretched a million
times while under water the whole time.
Chances of that rubber band drying out and breaking are minimal.
Consider the Hyaluronic Acid as the water that keeps the collagen moist
and elastic. Collagen is continuously surrounded and nourished by the
gelatinous HA substance. Young skin is smooth and highly elastic because
it contains high concentrations of Hyaluronic Acid, which helps skin
stay healthy. As we grow older, the body loses its ability to maintain
this same concentration in the skin. With decreasing levels of HA in the
skin, so goes the ability of the skin to hold water. The result, the
skin becomes drier and loses its ability to maintain it's hydration.
Hyaluronic acid acts as a space filler by binding to water and thus
keeping the skin wrinkle-free.