As the holidays approach, you might find more and more guests letting you know that they have a gluten allergy or intolerance, but what exactly is it?

Gluten is a mixture of two proteins. Generally, bakers want gluten in their dough to help it keep its shape. It’s found in rye, barley and wheat. Wheat includes wheatberries, durum, emmer, semolina, spelt, farina, farro, graham, KAMUT khorasan wheat and einkorn, according to the Celiac Disease Foundation.

Symptoms of Celiac's Disease or an intolerance to gluten can range from stomachaches to hives to vomiting. Talk to your doctor if you think you have a problem when consuming gluten.

Cutting out gluten doesn’t mean avoiding bread, cake and pasta forever (thank goodness). It just means that the food products can’t contain the above ingredients. Gluten-free alternatives are made with flour from rice, corn, nuts, quinoa and more. Gluten-free bakers will often combine several different flours as well as other ingredients like starches to get a consistency closer to that of products with gluten.

What is gluten?
Doughnuts have gluten when they are made with wheat flour. These desserts are pictured on Oct. 18, 2014 in New York City. Noam Galai/Getty Images for NYCWFF

Those who learn they have any sort of gluten intolerance should get used to checking labels, and they should read beyond just the ingredient list. Watch out for labels that say the food was processed on the same equipment as wheat, rye or barley products. Items certified gluten-free are best.

Remember that even foods that people don’t think of as using wheat, rye or barley can be troublesome. Many prepackaged foods use wheat starch to thicken sauces or barley malt to color food.

People should also check their medicines and vitamins to make sure they’re gluten-free as well.

There are plenty of naturally gluten-free foods. Gluten is not found in meat, fish, poultry, dairy, fruits or vegetables. However, those looking to recreate their favorite gluten-free foods have plenty of options. Against All Grain, Eating Bird Food and My Gluten-Free Kitchen are just a few of the sites that can help you make your holiday favorites without gluten.