Americans love to designate dietary devils. MSG. Fat. Carbs. Gluten. The latest food to be nominated for devilhood is fructans. And the focus on them came about, in part, because of our collective national obsession with gluten.
Here’s how: We know that many people who follow a gluten-free diet don’t need to for medical reasons, such as having celiac disease. Yet some insist they aren’t going gluten-free because it’s trendy — they’re going gluten-free because it makes them feel better. Many researchers believe these people who think they can’t tolerate gluten are actually sensitive to fructans.
So what exactly is a fructan? Fructans are a type of carbohydrate composed of chains of fructose, the simple sugar found in honey and fruit. Americans encounter fructans most commonly in wheat and onions, but they are also found in rye, oats, barley, artichokes, asparagus, leeks, garlic and lettuce.
The issue seems to be that human beings have a limited ability to digest fructans in the small intestine. That means they’re still intact when they reach the large intestine (colon), where gut bacteria break them down. In some people, this fermentation creates excessive gas and bloating, and sometimes diarrhea. Avoiding these symptoms means limiting daily intake of fructans, although the answer to “how much is too much” varies from person to person.
Now before you break out your magnifying glass and start inspecting and rejecting any label with “fructan” on it, just as we don’t all need to avoid gluten, we don’t all need to avoid fructans. For most people, fructans hae benefits for gut health and general health. Many fructans are prebiotics, which are actually beneficial for gut health, and research is showing that fructans may have antioxidant benefits and contribute to immune system function. And while we’re at it, don’t confuse fructose, a different carbohydrate, with fructans. Some people have developed such an irrational fear of fructose, they decide to shun fruit, despite the fact that it’s a whole, nutrient-rich food.
One difficulty with diagnosing food sensitivities is that the food components that provoke them don’t exist in isolation. They are part of a complex matrix with numerous other food components that could potentially cause an adverse reaction in some individuals. For most people, wheat is a nutritious food. But for the minority who react to wheat, any one or more of the grain’s many components — not just fructans and gluten, for example, but non-gluten proteins — could be the culprit. A second difficulty is that, unlike with celiac disease and wheat allergies, there is no scientifically valid way to test for most food sensitivities.
So how can someone find out whether they’re fructan intolerant? Breath testing is one possible option, but its reliability is uncertain. Some people have luck with eliminating all dietary fructans for a few weeks, then, if symptoms go away, adding back non-wheat sources of fructans. If symptoms return, it’s likely the fructans, not wheat. This is where seeking the guidance of a dietitian who is experienced with food intolerances is helpful, especially because fructans are one of many types of dietary carbohydrates that may cause symptoms in people with irritable bowel syndrome (IBS).
Rather than avoiding a whole class of food, it’s better to determine exactly which food components, and their hidden sources, you need to eliminate to stay symptom-free. The ultimate goal is to enjoy as varied a diet as possible. As in, don’t throw out the baby fructan with the fructan bathwater.
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