Encyclopedia of Diets - A Guide to Health and Nutrition

A typical dosage of glucosamine is 1,500 milli-

grams per day. The two most commonly sold forms

are glucosamine sulfate and glucosamine hydrochlor-

ide. Glucosamine is often sold in combination with

other supplements such as chondroitin sulfate (a sul-

fated glycosaminoglycan composed of a chain of alter-

nating sugars) and methylsulfonylmethane (MSM, an

organic sulfur compound within the chemical class of

sulfones).

When glucosamine is taken orally into the body

(as a pill), according to conclusions from scientifically

based animal studies, it is absorbed into the small

intestine. It then travels into the liver where most of

it is metabolized. Based on these studies, some of it

does apparently go to cartilage; however, it is not

known how much is actually transmitted to joints. It

is primarily removed from the body through urine.

Precautions

Clinical studies have consistently showed that glu-

cosamine is safe when used as directed. However,

according to the National Institutes of Health (NIH),

side effects may include drowsiness, headache, upset

stomach, insomnia, skin reactions, light sensitivity,

and nail toughening. Rare symptoms include abdomi-

nal pain, appetite loss, vomiting, nausea, intestinal gas,

heartburn, and diarrhea.

The National Institutes of Health recently spon-

sored a large, multi-institutional clinical trial to test

the effects of chondroitin sulfate, glucosamine, and

the combination of the two on knee osteoarthritis.

(Chondroitin is a carbohydrate that is a component

of cartilage. It is thought to help promotewaterreten-

tion and elasticity in cartilage and help prevent

enzymes from destroying cartilage.) The study is the

largest of its kind to date with respect to research into

the two substances.

The four-year study, known as Glucosamine/

chondroitin Arthritis Intervention Trial (GAIT),

involved almost 1,600 participants and 16 research

facilities. It was funded by the National Center for

Complementary and Alternative Medicine and the

National Institute of Arthritis and Musculoskeletal

and Skin Diseases. The lead researcher in the study

was Daniel O. Clegg from the University of Utah,

School of Medicine (Salt Lake City). Five different

treatments were given daily for 24 weeks: glucosamine

alone (1,500 mg), chondroitin sulfate alone (1,200

mg), glucosamine and chondroitin sulfate combined

(same doses), a placebo, or celecoxib (200 mg) (a

FDA-approved drug for osteoarthritis pain, and

branded in the United States as CelebrexÒ).

According to the resulting 2006 article ‘‘Glucos-

amine, chondroitin sulfate, and the two in combination

for painful knee osteoarthritis’’ in theNew England

Journal of Medicine, the six-month trial found that

patients taking glucosamine, chondroitin sulfate, or a

combination of the two had no significant decrease in

their major osteoarthritis symptoms compared to

patients taking a placebo. Patients who took celecoxib

had a significant decrease in the severity of their symp-

toms. However, glucosamine and chondroitin sulfate

together seemed to help people with pain classified as

moderate-to-severe. With people in the mild pain

group, glucosamine and chondroitin sulfate together

or alone did not provide substantial relief.

Interactions

For the most part, glucosamine does not show any

contraindications with other drugs; that is, medical

studies have not shown that it is harmful to users.

Scientific studies have shown that the use of glucos-

amine (as directed) does not produce any serious,

permanent problems.

Glucosamine is derived from the shells of shell-

fish. People with shellfish allergies oriodinehyper-

sensitivity may not want to take it. It is important to

note that people with shellfish allergies are usually

allergic to the skin (protein) of shellfish, and not to

the actual shells (chitin). According to a 2004 article

from theJournal of Allergy and Clinical Immunology,

most people with shellfish allergies can safely take

glucosamine. However, it is always wise to ask a

KEY TERMS

Antihistamine—Drugs that treat allergies.

Autism—Condition that causes disturbances in

psychological development within children such

as problems in relationships; perceiving, interpret-

ing, and reacting to stimuli, and using language.

Diabetes—Medical problem that affects blood

sugar levels and causes the body to produce urine

in excessive amounts.

Fetus—Unborn offspring.

Gastrointestinal—Relating to the stomach and

intestines.

Sedative—Medicines that increase drowsiness and

calmness.

Tranquilizer—Medicines that reduce anxiety and

tension.

Glucosamine