Your ‘gluten’ problem may be fructans
Americans love to designate dietary devils. The latest food to be nominated for devilhood is fructans. And the focus on them came about, in part, because of our 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 doing it because it makes them feel better. Many researchers believe these people who think they can’t tolerate gluten are actually sensitive to fructans.
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.
Humans have 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.
We don’t all need to avoid fructans. Still, some people try to do just that, reasoning that if some people react badly to fructans, perhaps everyone should avoid them. And then there are those who confuse fructose, a different carbohydrate, with fructans. (Fear of fructose also has prompted people to not only eschew corn syrup, but to also shun nutritious fruit.
For most people, fructans have benefits for gut health and general health. Three major types of fructans – inulin, oligofructose and fructo-oligosaccharides – are prebiotics, food components that nourish the beneficial bacteria in our gut. Researchers are also finding that fructans may have antioxidant benefits, and contribute to healthy blood-sugar levels and immune system function.
When you consider that wheat is a major source of gluten, and also contributes about 70 percent of the fructans in the Amer-
ican diet, it’s easy to understand why someone who feels better after eliminating wheat might conclude gluten intolerance. However, avoiding wheat and other gluten sources when fructans are the culprit is an incomplete solution.
One difficulty with diagnosing food sensitivities is that the food components that provoke them don’t exist in isolation but along with numerous components that could affect 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.
People with celiac disease must gluten, which is also found in rye and barley, and people with wheat allergies must avoid wheat, but people with non-celiac gluten/wheat sensitivity are in a gray area. Researchers from Norway randomly assigned 59 people, who did not have celiac disease but were avoiding gluten, to eat baked muesli bars containing gluten, fructans or neither for seven days. The results, published February in the journal Gastroenterology, showed fructans were more likely to produce symptoms than gluten.
So how can someone find out whether they’re fructan intolerant? Breath testing is an option, but its reliability is uncertain. Some people have luck with eliminating all 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 were problematic, not wheat.
Seeking the guidance of a dietitian experienced with food intolerances is helpful, because fructans are one of many types of carbohydrates that may cause symptoms in people with irritable bowel syndrome. Like fructans, fructose, lactose and sugar alcohols such as sorbitol and xylitol are highly fermentable in the large intestine, leading to gas, painful bloating and diarrhea or constipation. These carbs are known as FODMAPs – fermentable oligo-, di- and monosaccharides and polyols (fructans are oligosaccharides).