It’s hard to talk about carbs without talking about wheat, and it’s hard to talk about wheat without talking about gluten. Gluten is not a carbohydrate; it’s a mix of proteins found in wheat and its close relatives (including spelt, kamut and farro), as well as in barley and rye. It’s what gives bread its elasticity, but it also sets off the immune system of people with celiac disease, damaging the small intestine and sometimes producing painful and unpleasant symptoms.
Even some people who don’t have celiac disease feel better when they don’t eat wheat. They may assume that they have gluten sensitivity, but some researchers believe that it’s not the gluten they’re sensitive to. Instead, it’s fermentable oligosaccharides, disaccharides, monosaccharides and polyols, or FODMAPS.
Never was a group of molecules more desperately in need of an acronym. FODMAPs are a group of carbohydrates that don’t get broken down and absorbed in the small intestine. Instead, they pass through to the large intestine, where they draw water into the gut and start to ferment. The process by which FODMAPs are broken down and fermented can cause gastrointestinal distress: diarrhea, bloating, pain, flatulence and constipation. Wheat and rye are high in FODMAPs, as are onions, garlic, apples, stone fruit, pistachios and many other foods.
Research by Peter Gibson, a professor of gastroenterology at Australia’s Monash University, has found that some people who believed they were gluten-sensitive were, instead, FODMAP-sensitive. A low-FODMAP diet eased their symptoms, as it does for about 70 percent of people who suffer from irritable bowel syndrome, a condition that causes abdominal pain and bowel changes. Gibson estimates that, overall, about 10 percent of the population may be FODMAP-sensitive.
But there’s a problem with a low-FODMAP diet. The fermentation that is painful to that 10 percent is good for your gut because it stimulates growth of the kind of bacteria associated with digestive health. “Following strictly the low-FODMAP diet is associated with changes in the microbiota that many would not equate with good health,” says Gibson, who stresses that a low-FODMAP diet should be used to reduce specific symptoms, not as a way to improve health.
If your gut can handle FODMAPs, foods that contain a lot of them can be very good choices — partly because the fermentation helps your gut biome and partly because the way FODMAPs are digested means you’re absorbing fewer calories than indicated on a FODMAP-rich product’s label. Unless you have specific symptoms that a low-FODMAP diet alleviates, Gibson says, “enjoy your FODMAPs!”
But are carbs really so bad?
Science makes the answer pretty clear: no. While bread, pasta and sugar are hard-to-resist sources of calories without much in the way of nutrition, other carbohydrate-heavy foods — whole grains, legumes and fruit — are nutrient-rich. Carbohydrates can play a healthful role in your diet or they can be your undoing, depending on which, and how many, you eat.
“Carbs aren’t the enemy,” says Julie Jones, a professor emeritus of food and nutrition at St. Catherine University in St. Paul, Minn. “Overconsumption, of anything, is the enemy.”
Even so, the good-or-bad notion gets traction. “It’s easier for a lot of people to cut off whole categories of food than to eat moderately,” says Marion Nestle, a professor in New York University’s department of nutrition, food studies and public health. And a lot of people report that they feel better and lose weight when they cut out sugar and refined carbohydrates, she says. Yet there’s no reason, she adds, that bread, pasta and plain old sugar should be completely off-limits, as some popular diets recommend. In moderation, they’ll do you no harm.
Carbohydrates run the gamut from very simple molecules that your body breaks down easily to very complex molecules that your body breaks down more slowly, or not at all. Since carbohydrates that you eat are mainly converted to glucose, the sugar that every cell of your body can use for energy, the faster the carbohydrate is digested, the quicker it’s turned into blood sugar.
There are questions about possible negative health effects of some carbs, such as fructose, which is found in sugar and high-fructose corn syrup, and galactose, which is found in milk. But the question of how carbs affect health is mostly focused on how quickly and efficiently the body can break the molecule down and deliver glucose to the bloodstream.
Simple-carb foods are those that your body breaks down quickly and easily, such as sweeteners (sugar, honey, maple syrup) and refined grains (white flour, pasta, white rice). These are the carbs that tend to get the bad rap because they cause spikes in blood sugar. Complex-carb foods, which include whole grains and legumes, have large, complex molecules that are more difficult to digest and consequently don’t cause the same rapid increase in blood sugar.
The simple/complex classification isn’t perfect. Many fruits and vegetables contain both types of carbohydrates: Some get broken down quickly, others more slowly. And it’s not always true that whole foods are digested slowly while refined foods are digested quickly. Potatoes, for example, have lots of carbohydrates in the form of starch, which is broken down quickly.