Is it safe to take the Source Naturals NAG with allergies to shellfish, wheat and yeast?

I'll call the manufacturer. The reason I ask is I bought Source Naturals NAG based on the recommendation in LTYG. The bottle says it contains wheat, gluten and shellfish. I wondered if the allergens in each of these substances had somehow been removed.

Listed below is the information from Holistic Health Shoppe. There is a conflicting message. One statement says it contains wheat/gluten and the next statement says that it doesn't. So, I'm very nervous to try the product. I sure would hate to aggravate my Crohn's further. Any help/advice would be appreciated. I called the manufacture and left a message but never heard back.

Source Naturals NAG (N-Acetyl Glucosamine) 500 mg – 60 tablets

$18.50
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Source Naturals NAG (N-Acetyl Glucosamine)
N-acetyl glucosamine, an amino sugar, forms the basis of complex molecular structures that are key parts of the connective tissue and mucous membranes of the body: tendons, ligaments, cartilage, bone matrix, skin, joint fluid, and intestinal lining.

Serving Size: 1 tablet

Amount per Serving: N-Acetyl Glucosamine 500 mg

Other Ingredients: sorbitol, dibasic calcium phosphate, stearic acid, colloidal silicon dioxide and magnesium stearate.

Contains shellfish (shrimp and crab) and wheat/gluten.

Warning: NOTE: If you are pregnant or breastfeeding, consult your health care professional before using this product. Suggested Use: 1 to 3 tablets daily. Contains no yeast, dairy, egg, gluten, soy or wheat. Contains no sugar, starch, salt, preservatives or artificial color, flavor or fragrance.