What's trending in the nutrition world this week? Gluten-free diets continue to top the charts. If you have gone gluten-free, are you certain that it is truly gluten that is giving you gastrointestinal (GI) issues? You should definitely have this confirmed by your doctor.

There are two reasons to drop gluten from your diet, celiac disease and Non-Celiac Gluten Sensitivity (NCGS). NCGS is the topic du jour on the Internet these days. In both of these cases, eating a protein in wheat, rye and barley called gluten triggers inflammation in the small intestines. Little is known about NCGS, from how much gluten is needed to trigger symptoms to whether gluten is even the culprit. In the meantime, many who suspect NCGS are eliminating gluten from their diets.

A new study from Melbourne, Australia, noted that 40-50 percent of those who had initiated a gluten-free diet had not gotten necessary testing for celiac disease. Testing by your doctor before you start a gluten-free regimen is important because it's hard to tell if the protein is a problem for you after it's already been eliminated from your system. Self-diagnosis of gluten sensitivity could be mistakenly confused for irritable bowel syndrome or a wheat allergy, which can cause similar symptoms.

Those with true celiac disease (about 1 in 100) must be extremely careful because cross-contamination is everywhere. Gluten can show up in the pot you boil water in, the plate you put your food on or the shelf you use to store groceries. In fact, gluten can show up just about anywhere in our food supply chain. For people with celiac disease, even just a microscopic amount of gluten can cause a reaction and damage the intestines. That is why it is critical for them to establish "gluten-free" zones in the home. Those with NCGS may have a little higher tolerance.

The bottom line: You shouldn't be self-diagnosing a gluten issue. If you think you might have one, ask about the test for celiac disease so you don't have complications down the road. How do you know if you should book an appointment? Here are some symptoms that should prompt you to get tested:

1) Chronic GI symptoms, such as diarrhea, weight loss and abdominal bloating or distension.

2) Deficiencies in iron, folate or vitamin B12. Untreated celiac disease damages certain parts of the intestine where these vitamins are absorbed; deficiencies can be a clue that you may have some issues with gluten.

3) Family history of celiac disease is a huge risk factor, even if you are asymptomatic. You should probably get tested.

Whether you follow a gluten-free diet because of celiac disease or the less-understood gluten sensitivity, consult your doctor for a true diagnosis and a registered dietitian nutritionist to guide you on a lifelong quest to relieve symptoms and improve health.

Dr. SeAnne Safaii, Ph.D., RDN, LD, is an associate professor at the University of Idaho.