In last week's article we talked about some of the possible side effects of glucosamine sulfate. These include gastrointestinal problems such as nausea, heartburn, diarrhea, constipation and indigestion. It can also cause drowsiness, skin reactions, and headache. Today's article will discuss two other possible side effects of glucosamine sulfate.
Glucosamine, Blood Sugar Levels, and Insulin Resistance
There have been anecdotal reports of poorer blood glucose control in people with diabetes who take glucosamine. Glucosamine is composed of glucose, a sugar, and the amino acid glutamine. Theoretically, glucosamine sulfate might exacerbate diabetes by increasing insulin resistance and/or decreasing insulin production, resulting in elevated blood glucose levels. Animal research with rats has raised concern that glucosamine desensitizes cell membranes to the effects of insulin. However, these animal studies involved intravenous infusion of glucosamine that results in higher serum concentrations than oral intake. Furthermore, in a large 3-year, placebo controlled trial, published in 1999 in the Lancet, blood glucose levels tended to decline slightly in patients treated with glucosamine; whereas glucose levels remained stable in those receiving a placebo. But to complicate matters further, in an unpublished study announced at the Experimental Biology 2000 conference, non-diabetic subjects taking glucosamine sulfate, 1500 mg per day for 12 weeks, had significantly increased insulin levels compared to those taking a placebo. Additional research to determine the effects of glucosamine on blood sugar levels and insulin is needed.
In the meantime, the possibility that long-term treatment with glucosamine could trigger or exacerbate insulin resistance or elevated blood sugar levels cannot be ruled out. Therefore, diabetics should consult their doctor before taking glucosamine sulfate and have their blood sugar levels monitored regularly if they do take the supplement. This is also something that non-diabetics should do as well. I have a friend who is taking glucosamine sulfate and who is not a diabetic, but she has her blood tested on a regular basis as part of her medical check-ups. A complete blood count includes blood glucose levels. So far hers have been in the normal range. But she will be watchful to see if there is any rise in those levels from her base level.
Glucosamine and Shellfish Allergies
Glucosamine is derived from the shells of crab, lobster, or shrimp. There is, therefore, concern that glucosamine sulfate might cause reactions in people allergic to shellfish, even though glucosamine is not derived from the meaty portion of the shellfish, which is responsible for most allergies. Until more is known, use glucosamine sulfate with caution if you have a shellfish allergy. My friend has such an allergy. She breaks out in hives when she eats shellfish. Thus far, however, she has had no signs of an allergic reaction to glucosamine sulfate in the five years that she has been taking it.
She has decided to continue taking the supplement because she believes it has improved her symptoms through the promotion of cartilage synthesis and repair of damaged joints. She feels that her arthritis have improved rather than deteriorated in the five years she has been taking glucosamine sulfate. Her alternatives are the drugs commonly used to treat osteoarthritis, which suppress symptoms but do nothing to halt the disease process and whose side effects she considers more deleterious.
Mary Lou Williams, M. Ed., is a lecturer and writer in the field of nutrition. She welcomes inquires. She can be reached at 267-6480.