by Katherine J. Wu

As an aging and increasingly cynical graduate student, I’ve found that my ability to keep up with the hip lingo has been waning in recent years. But even I know that “gluten” has become the dirty culinary word of the decade. One in five adults now avoid or completely eliminate gluten from their diets; in millennials, the fad is even more prevalent. But here’s the (g)rub: only about one in twenty of these gluten-avoiders actually need to be limiting themselves.

Let’s back up. Although gluten is most commonly associated with certain grains and the carbohydrates contained within, gluten itself is actually a kind of protein. It’s found in wheat, barley, rye, and the bastard child of wheat and rye, triticale (who knew?), and is responsible for that chewy, elastic texture characteristic of wheat breads. Gluten proteins prefer to avoid interacting with water – a property called “hydrophobicity” – and glom together to minimize their contact with the liquid in dough. As a result, they form a strong matrix that takes on the properties of a balloon as yeasted dough releases carbon dioxide, allowing bread to rise. Some bakers will actually add gluten to their bread doughs to increase volume or stability. And if you’ve ever had the meat alternative seitan, you’ve eaten the end product of wheat-based dough rinsed free of most of its starch and fiber, leaving behind a mass of sticky, chewy gluten. Pro tip, if you haven’t caught on already: seitan is not gluten-free. (For some extra irony, chew on the fact that buckwheat is.)

So gluten itself sounds relatively harmless. And in the vast majority of cases, it is. One exception is when a person suffers from celiac disease, a genetic disorder that gradually destroys the small intestine when the body is exposed to gluten. Celiac disease is a classic case of autoimmunity, in which the immune system raises inappropriate alarm bells in response to the presence of harmless substances like gluten, eventually attacking the body’s own cells. Subsequent damage to the surface of the small intestine prevents proper absorption of nutrients, leading to malnutrition, anemia, fatigue, and, in children, potential developmental delays.

Technically, even though patients with celiac disease react to gluten, they don’t have an allergy to gluten, in which the immune system directly targets the gluten protein itself. While celiac disease is a chronic illness that can take a long time to take effect, gluten allergies typically cause immediate and potentially life-threatening reactions that range from hives to anaphylaxis.

The only treatment for celiac is following a very strict gluten-free diet. In addition to having to avoid bread, pasta, cake, beer, cereal, and many other wheat-based products, these patients have to carefully read labels to avoid using and ingesting products with gluten contamination. This latter list contains some surprising culprits, including soy sauce, pickles, jelly beans, and even certain beauty products, toothpastes, and medications.

Celiac disease and gluten allergies are the only medical reasons to completely eliminate gluten from the diet. However, allergies to other components of wheat exist, in which reactions are raised against the other proteins in the grain, seeds, and pollen of these plants. In these cases, patients may need to avoid grains, and end up cutting out gluten as a result.

More amorphously, there also exist gluten and wheat intolerances. These diagnoses involve physical discomfort upon ingestion of wheat or gluten by patients in whom a doctor has ruled out both celiac disease and gluten or wheat allergies.

Only a handful of quality studies have been done so far on these intolerances, but it seems that a major difference between them and celiac disease or an allergy is how the body responds. Gluten and wheat intolerances often don’t involve the immune system at all, and can instead occur because the body lacks an enzyme to digest certain molecules in wheat-based products, leading to gas, bloating, discomfort, and other symptoms.

At the end of the day, however, these miscellaneous sensitivities to gluten and wheat are poorly defined, poorly understood, and contested. While a small percentage of individuals, including those who suffer from irritable bowel syndrome or chronic pain conditions, do indeed receive diagnoses of gluten/wheat sensitivity from their doctors, millions more across the globe have chosen to forsake gluten without any medical input.

There are a lot of people out there who swear by gluten-free diets, saying the change helps them lose weight, feel more energetic, and more. But often the culprit isn’t actually gluten itself. For example, in some cases, the gluten-free rule is more of a tool to help dieters cut out unhealthier foods that also happen to contain wheat, like pizza, baked goods, and processed or packaged snacks. Alternatively, there is some evidence that other carbohydrates – a group called FODMAPs – may actually be to blame for some people’s gastrointestinal distress. In these cases, it’s really not about the gluten, but rather, who it hangs out with – and poor gluten ends up the scapegoat. In a vacuum, gluten isn’t a mystery chemical or dangerous additive: it’s a naturally-occurring protein that adds nutrition to many grains.

At the end of the day, this is the fact that so many have forgotten: gluten can, and often should, be a part of a healthy diet. Barring celiac disease, gluten is a source of nutrition and unlikely to cause side effects on its own in most individuals. Swapping muffins for gluten-free muffins is probably not going to yield the health benefits many think it will – and many foods marketed as gluten-free are actually less healthy than their counterparts. To compensate for the lack of gluten protein in their products, manufacturers will add more sugar, saturated fat, salt, and additives to mimic the texture and flavor of traditional goods, or use alternative gluten-free flours that contain more heavily processed carbohydrates. In fact, for people who don’t have celiac disease, going gluten-free can actually negatively affect overall health, including increasing the risk of heart disease, weight gain, and insufficient vitamin and mineral intake. Findings like these are very preliminary and should absolutely be approached with caution – but it’s worth considering that eliminating so many grains from the diet also removes the benefits we can reap from fiber, vitamins, and minerals naturally found in these plants.

What’s more, because of the extra steps required to manufacture them – and, let’s face it, due to the hype – gluten-free versions of our favorite snacks tend to be more expensive. So, if you’re considering going gluten-free, be sure it’s worth the swap first.

Katherine Wu is a graduate student at Harvard University and Co-Director Emeritus of Science in the News.

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