The best thing about being a dietitian is talking about food with people from all different backgrounds as they parade in and out of my office. In addition to giving me a glimpse into their eating habits, my patients share their guiding beliefs about food and nutrition, assembled from a patchwork of sources: friends, family, magazines, the Internet, and popular lore.
As it turns out, many of these guiding beliefs are actually quite misguided. So, I'm setting the record straight on five of the most common, persistent, and inaccurate nutrition myths I regularly encounter.
1. Bananas are NOT "constipating."
The idea that bananas are constipating likely derives from the observation that bananas can help firm up the stool when one has diarrhea. But bananas do not work their magic by causing constipation. Rather, bananas—particularly the less-ripe ones—are relatively low in fiber and relatively high in a hard-to-digest starch called "resistant starch." This combination seems to contribute to their observed benefits; not too much of the fibrous, idigestible material that could make diarrhea worse, but rather a decent dose of gummy-textured starch that holds its form well in the colon and can soak up some excess fluid. A food that is truly constipating would have to actually slow down the contractions of one's bowel, which bananas most certainly do not do. My best guess as to why people swear that eliminating bananas helps them go to the bathroom may have to do with what's replacing those bananas in the diet. A higher-fiber fruit, perhaps?
2. Brown sugar is NOT healthier than white sugar.
While brown (whole-wheat) bread is indeed healthier than white bread, and brown rice is more nutritious than white rice, this parallel does not hold true when comparing brown sugar (a.k.a. "Sugar in the Raw," or raw turbinado sugar) to white sugar. While marketing would lead you to believe that this sugar is somehow "more natural," it is most certainly no healthier. Raw sugar has just as many calories per teaspoon as more refined white sugar, and your body certainly can't tell the difference when it comes to metabolism. Defenders might argue that brown sugar has more vitamins and minerals than the white stuff, to which my response is: If you're eating enough raw sugar that it's serving as a measurable source of vitamins or minerals in your diet, you should make an appointment to come see me.
3. Enzymes in raw fruits or vegetables DO NOT help you digest them better than cooked vegetables.
As a matter of fact, cooked vegetables tend to be more easily digested than raw ones! Enzymes are revered as magical and omnipotent forces of digestion among nutrition enthusiasts. While I share great awe for the alchemy that takes place along the GI tract, let's be clear about what enzymes are and how they work. Simply, enzymes are proteins whose specific shapes and configurations enable them to complete chemical reactions, such as those needed to break down food. Our bodies secrete numerous different digestive enzymes, starting in the saliva, moving to the stomach, and then from the pancreas to the lining of the small intestine. Each enzyme is activated under very specific conditions. For an enzyme to become active, the pH level (or, the right level of acidity) has to be just right, and in some cases, other compounds, called co-factors, need to be present in order to switch them on. This constellation of circumstances is timed perfectly to coincide as food makes its way through the digestive tract. A healthy, well-functioning human body produces all of the enzymes it needs to fully digest all dietary components except fiber (which, by definition, is indigestible to humans). Any animal or vegetable enzymes present in our food are neither required for—nor enhance—human digestion. Furthermore, any such enzymes we consume with our food will likely face the same fate as other dietary proteins they've been eaten with: they'll be digested. What about supplemental digestive enzymes, like Beano? These may indeed help break down indigestible plant fibers for which humans lack appropriate enzymes. But these enzymes are derived from yeast, not raw veggies or fruit.
4. You CAN eat nuts, seeds, and popcorn if you have diverticulosis.
Diverticulosis is a condition in which small pouches develop along the colon. In 10 percent or more of cases, these pouches can become infected, causing a painful condition called diverticulitis. Traditionally, doctors and grandmothers have cautioned diverticulosis patients to avoid foods like popcorn, nuts, and seeds, under the rationale that tough, indigestible particles from these foods might "get stuck" in a pouch and cause an infection. Alas, actual research has failed to validate this hypothesis time and time again, though countless people continue to avoid these excellent sources of fiber. Since higher dietary fiber intake has been linked to the prevention of complications among those with diverticulosis, this is one nutrition myth that should be laid to rest, once and for all.
5. Lactose from a nursing mother's diet DOES NOT make breast-fed babies colicky.
Unless a baby is born with a rare metabolic disorder, all babies are able to digest lactose, the primary sugar in milk. Even if a nursing mother never eats a drop of dairy in her life, 40 percent of the calories from her breast milk will still derive from lactose. Lactose from a mom's diet is broken down into its component sugars—glucose and galactose—in her intestines before it can be absorbed into her bloodstream. Once these components are absorbed, they do not reassemble; in other words, intact dietary lactose never travels through the bloodstream such that it could make it into a woman's breast milk. Rather, the lactose in breast milk is manufactured from scratch "on location," in the cells of mammary glands. Therefore, if you've got a colicky baby, adopting a lactose-free diet will be of absolutely no benefit.
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Tamara Duker Freuman, MS, RD, CDN, is a NYC-based registered dietitian whose clinical practice specializes in digestive disorders, Celiac Disease, and food intolerances. Her personal blog, www.tamaraduker.com, focuses on healthy eating and gluten-free living.