Flour is hard to sidestep come mealtime. Breakfast brims with toast, bagels, cereal, pancakes. Lunch is built around sandwiches, wraps, pasta, pizza. And dinner may come with its very own breadbasket.
Flours are produced by crushing grains into fine powders. And those powders form the basis not just for breads and buns, but for a huge variety of processed foods, from cereals, crackers and pizza dough to cookies, cakes and ice cream cones. As a result, the average American now eats 10 servings of refined grains each day.
Are Refined Grains Bad for You?
As our national appetite for flour has inched up, so has the incidence of diet-related ills, such as obesity, heart disease and diabetes. Coincidence? Many nutrition experts don’t think so. When they weigh the evidence linking food choices and disease, they see the white, dusty fingerprints of flour everywhere.
“Now that trans fats are largely out of the food supply,” says David Ludwig, MD, PhD, director of the New Balance Foundation Obesity Prevention Center at Children’s Hospital Boston, “refined carbohydrates, including refined grain products, are the single most harmful influence in the American diet today.”
Flour started out as an ingenious fix to a vexing problem. Grass seeds were plentiful, but the tough outer shell (the husk) made the seeds difficult to chew and digest. Early humans outsmarted the seeds by grinding them between stones, crushing the outer layers to get at the goodness inside. The result — a coarse powder — was the first whole-grain flour.
The downside was spoilage. Crushing the germ released its oils, which quickly turned rancid when exposed to air. With the advent of industrial milling in the late 1800s, machines began filtering out the germ and pulverized the remaining endosperm into a fine, white powder that lasted on the shelf for months. And so all-purpose white flour was born — along with a host of health problems.
Beneath their rigid architecture, whole-kernel grains conceal an array of vitamins, minerals, phytonutrients and fiber. But when machines pulverize kernels into flour, even whole-grain flour, what’s left behind is a starchy powder capable of wreaking havoc on the body.
What Is the Difference Between Whole Grains and Refined Grains?
Flour, as opposed to whole-kernel grains, is easy to overconsume because most flour-based foods require little chewing and go down rather quickly. “It is so much easier to overconsume any food where the work of chewing or digesting or separating fiber from starch has been done for us,” says functional nutritionist Julie Starkel, MS, MBA, RD.
Overconsuming flour can lead to a number of problems in the body, including:
Blood-Sugar Blues. Smashing a whole-kernel grain to smithereens means it digests faster. Rapid-fire digestion causes blood sugar to spike, which causes a rise in insulin. The result? Not only are you hungry two hours later, but you are also paving the way for insulin resistance and diabetes. “The difference between a whole-kernel grain and a processed grain all boils down to the glycemic index, which is how quickly the body turns food into fuel, or glucose,” says Gerard Mullin, MD, FACN, director of integrative gastroenterology nutrition at Johns Hopkins Hospital in Baltimore, Md., and coauthor of The Inside Tract: Your Good Gut Guide to Great Digestive Health (Rodale, 2011). Foods made with wheat flour are particularly damaging. A carbohydrate in wheat, called amylopectin A, is more easily converted to blood sugar than just about any other carbohydrate. Two slices of bread made with whole-wheat flour raise blood sugar higher than six teaspoons of table sugar and higher than many candy bars.
“If we were evil scientists and we said, ‘Let’s make the most perfect poison,’ it would be wheat,” says preventive cardiologist William Davis, MD. (For more on why Davis advises against eating any kind of wheat — including even whole-kernel grains — check out his book, Wheat Belly: Lose the Wheat, Lose the Weight and Find Your Path Back to Health (Rodale, 2011).)
Food Cravings. Over the past 50 years, the amber waves of grain our grandparents enjoyed have been replaced with modern, high-yield dwarf strains of wheat that produce more seeds and grow faster. The result is a dietary wild card, says Davis: “Agricultural geneticists never asked if these new strains of wheat were suitable for human consumption. Their safety has never been tested.” One of the biggest changes in modern wheat is that it contains a modified form of gliadin, a protein found in wheat gluten. Gliadin unleashes a feel-good effect in the brain by morphing into a substance that crosses the blood-brain barrier and binds onto the brain’s opiate receptors. “Gliadin is a very mind-active compound that increases people’s appetites,” says Davis. “People on average eat 400 more calories a day when eating wheat, thanks to the appetite-stimulating effects of gliadin.”
Caloric Overload. By definition, a refined grain packs more calories than a whole-kernel grain because it is more concentrated. And foods that are high in grains also tend to be high in sugar and industrialized fats. These are the foods, say many experts, that are causing our obesity and diabetes epidemic.
Metabolic Slowdown. Research shows that the body may shift nutrients into fat storage and away from muscle burning in the presence of high-glycemic-index foods. In 2004, Ludwig and his colleagues at Harvard conducted a study, published in the journal Lancet, in which they fed rats diets with identical nutrients, except for the type of starch. By the end of the study, rats in both groups weighed roughly the same, but those eating a high-glycemic diet had 71 percent more fat than the low-glycemic-index group.
Inflammation. A diet high in grains stokes inflammation. When blood sugar spikes, glucose builds up in the blood like so many standby passengers on a flight. When glucose loiters in the blood, it gets into trouble by attaching itself to nearby proteins. The result is a chemical reaction called glycation, a pro-inflammatory process that plays a role in a host of inflammatory diseases — everything from cataracts to arthritis to heart disease.
GI Disorders. Studies show that the lectins in grains inflame the lining of the gut and create fissures between cells. Also, when whole-kernel grains are refined, 80 percent of the fiber is lost, and gut health suffers. “Without the fiber, you end up with rapid-release carbs in these grains, which is a bad thing for the gut,” says Kathie Swift, MS, RD, coauthor (with Mullin) of The Inside Tract. Plus, fiber helps sweep the gut of debris and supports the body’s critically important elimination and detoxification processes, which also play a role in keeping high cholesterol and inflammation at bay.
Food Allergies/Intolerances. Wheat, in particular, is one of the biggest dietary triggers of food allergies and intolerances. While the exact reason is unclear, many experts blame the higher gluten content of modern wheat varieties. A type of protein found in many grains, including wheat, gluten gives dough elasticity, trapping air bubbles and creating a soft texture. Because soft is considered desirable, wheat today is bred to have more gluten than ever before.
Acid-Alkaline Imbalance. The body has an elaborate system of checks and balances to keep its pH level at a steady 7.4. A diet high in acidic foods, such as grains, forces the body to pull calcium from the bones to keep things on an even keel. When researchers looked at how the diets of more than 500 women affected their bone density, they found that a diet high in refined grains, among other nutrient-poor foods, was linked to bone loss. A highly acidic diet also chips away at our cellular vitality and immunity in ways that can make us vulnerable to chronic disease. “Grains are the only plant foods that generate acidic byproducts,” says Davis. “Wheat, in particular, is among the most potent sources of sulfuric acid, a powerful substance that quickly overcomes the neutralizing effects of alkaline bases.”
This article has been updated. It originally appeared as “A Grain of Truth” in the July/August 2012 issue.