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Clearly, refined flour doesn’t do our health any favors. Increasingly, research indicates that it significantly increases the risk for many health conditions, including weight gain and obesity, metabolic syndrome, diabetes, hypertension, heart disease, cognitive decline, food addiction, depression, cancer, and acne.
The United States is suffering from an obesity epidemic, with two-thirds of American adults currently classified as overweight or obese. (10) Refined flour is a key contributor to this epidemic, as its consumption promotes fat in the body and impairs fat oxidation, the process by which the body “burns” fat for fuel. Refined flour may also promote an inflammatory gut microbiota, or inflammation caused by bacteria in the gut, a condition that fosters metabolic dysfunction and weight gain.
Currently, metabolic syndrome afflicts 35 percent of the U.S. population, and 100 million Americans have either prediabetes or full-blown type 2 diabetes. Refined carbohydrate intake is an established risk factor for insulin resistance, the most powerful predictor of metabolic syndrome and diabetes. In fact, the odds of having metabolic syndrome are 41 percent higher among people who eat the most refined carbohydrates, compared to those who eat the least.
While the U.S. dietary guidelines recommend switching out refined grain products for whole grains to reduce the risk of metabolic syndrome and type 2 diabetes, research indicates that this change leads only to minute improvements in blood sugar.) A far more effective strategy for managing blood sugar is to remove grains from the diet altogether (i.e., consuming a Paleo diet), thereby inhibiting the development of an inflammatory gut microbiota and the insulin resistance and metabolic dysfunction with which it is associated.
One of the most significant contributors to high blood pressure (hypertension) is insulin resistance. The consumption of refined carbohydrates—which behave like sugar in the body—can disrupt the relationship between glucose and insulin and ultimately could lead to the development of high blood pressure or worsen existing hypertension. Cutting out refined carbohydrates such as refined flour should be the first step in hypertension treatment. Indeed, diets low in refined carbohydrates lead to significant reductions in blood pressure.
For decades, dietary fat was wrongly blamed for causing cardiovascular disease, a mistake that led to the development of the United States’ infamous low-fat, high-carb dietary guidelines. Unfortunately, we now understand that these guidelines, which led Americans to consume more refined carbohydrates, may have exacerbated the cardiovascular disease epidemic.
A 2017 article published in The Lancet, one of the world’s most prestigious medical journals, demonstrates that high carbohydrate intake is associated with higher total mortality from cardiovascular disease, whereas total fat and types of fat are not associated with cardiovascular disease, myocardial infarction, or cardiovascular death. This finding is supported by many more studies indicating a strong association between refined grain intake and cardiovascular disease risk.
How exactly do carbohydrates such as refined flour contribute to heart disease? The serious blood sugar imbalances caused by refined carbohydrates promote systemic inflammation, damage the vascular system, and negatively impact blood lipids (increasing “bad” LDL cholesterol while lowering “good” HDL levels), thereby compromising the cardiovascular system. A low intake of refined carbohydrates, on the other hand, significantly reduces cardiovascular disease risk factors.
The connection between dietary carbohydrates and cancer was dismissed by the medical community until 2017, when an article in PLOS Biology published internal documents indicating that evidence of a link between sugar and cancer was purposely covered up by the sugar industry decades ago.
There is also research that supports evidence of a link between processed carbohydrates, such as refined flour, and cancer risk. A high intake of refined carbohydrates is associated with a moderate, but statistically significant, increased risk of breast, colon, and endometrial cancers. This effect is likely mediated by the increased release of insulin-like growth factor 1 (IGF-1), which triggers cell division induced by refined carbohydrate intake. The impact of refined carbohydrates on cancer risk may be even more pronounced when combined with the other unhealthy components of the Standard American Diet, such as industrial seed oils and food additives.
It is increasingly clear from research that insulin resistance and chronic elevated blood sugar are major risk factors for cognitive impairment, Alzheimer’s disease, and Parkinson’s disease. Insulin resistance promotes brain dysfunction by impairing glucose transport to the brain, inducing neuroinflammation, altering synaptic plasticity (which harms the brain’s ability to learn and memorize), and stimulating the production of harmful compounds called advanced-glycation end products in the brain. A diet high in refined carbohydrates is associated with an increased concentration of beta-amyloid protein in the brain, a characteristic feature of Alzheimer’s disease, while also raising the risk of mild cognitive impairment and dementia.
Refined carbohydrates are known to trigger food addiction, a condition in which certain foods—including refined flour products loaded with excess salt or sugar and bad fats (think doughnuts or pretzels)—are consumed in amounts that exceed the body’s energy needs. Food addiction also features binge eating behavior, cravings, and lack of control around foods.
A diet high in refined carbohydrates is associated with an increased risk of depression.While the relationship between these two variables is bidirectional—depressed individuals tend to “self-medicate” their depression with high-carbohydrate foods—refined flour may also contribute to depression by promoting systemic inflammation and inducing mood-altering blood sugar swings.
While dermatologists have long disputed the role of diet in acne, it is now well established that refined carbohydrates contribute to the development and progression of this frustrating skin condition. Interestingly, acne is nonexistent among hunter–gatherer societies consuming diets devoid of refined carbs, but it is exceedingly common in industrialized societies subsisting on a Western diet.
The consumption of refined carbohydrates triggers excessive insulin secretion; elevated insulin increases sebum production in skin follicles, leading to obstruction of the follicles and the development of inflamed skin lesions, i.e., pimples. Some researchers have gone so far as to call acne a “metabolic syndrome” of the hair follicle due to the pivotal role insulin plays in the condition’s pathogenesis. Conversely, a diet low in refined carbohydrates can significantly improve acne by increasing insulin sensitivity and decreasing inflammation.
Aside from its high carbohydrate density, refined flour is also a source of another potentially problematic ingredient—gluten. The term “gluten” refers to a family of proteins found in wheat, rye, barley, and triticale that are responsible for the elastic texture of dough. Gluten is perhaps most well known for its harmful effects in people with celiac disease, a condition in which the body launches an immune response to gluten, resulting in significant damage to the small intestine.
However, celiac disease is a response to just one member of the gluten protein family—alpha-gliadin—and to one gluten-digesting enzyme in the gastrointestinal tract, tissue transglutaminase-2 (tTG-2). It’s entirely possible to be sensitive to other components of wheat and gluten in the absence of celiac disease. This condition, called non-celiac gluten sensitivity (NCGS), is a distinct clinical condition supported by a substantial body of scientific literature.
It’s important to note that gluten isn’t a problem for everyone. While it’s true that gluten intolerance is far more common than was previously believed, statistics suggest that, at most, one in 10 people are affected. That said, most of the foods that contain gluten—bread, crackers, cookies, cakes, and other processed and refined foods—are high in calories and low in nutrients and should thus be minimized in the diet even if you do tolerate gluten.
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