When it comes to carbs, the pendulum has swung dramatically in the past three decades, from eating them without discretion, to avoiding them altogether—and finally, to a new appreciation for the healthiest sources. In the 80s and 90s, it was all about low-fat diets. As health experts cautioned people to cut back on fat, food manufacturers responded by making low-fat everything, including cookies and snacks. But they typically ramped up the refined carbohydrates from white flour and sugars to make up for the taste. We splurged on way too many of these foods, which showed in the nation’s rising rates of obesity and type 2 diabetes. The next diet to make it big was the low-carb, high-protein diet, courtesy of Dr. Atkins, which launched a nation of dieters who avoided carbs like the plague. This diet was difficult to follow for the long term and not optimal for health, and petered out around 2005.
Fast forward to the present and studies now reveal that it’s the type of carbohydrate that may be more important for optimal health. A diet focusing on highly refined carbohydrates—a hallmark of the typical American diet—such as white bread, sugary beverages, snack foods, and baked items—has been linked with health problems. A number of epidemiological studies have found that higher intake of such carbohydrates is linked with a greater risk of type 2 diabetes and ischemic heart disease, while diets high in minimally processed carbohydrate sources, such as whole grains, vegetables, fruits, and legumes, have been linked with a lower risk. In a 2010 Danish study of more than 53,000 participants, published in The American Journal of Clinical Nutrition (AJCN), replacement of saturated fat with high glycemic index (GI) carbohydrates significantly increased the risk of heart attack, whereas replacement with low-GI carbs showed a lowered risk.
Which are the healthy carbs? Carbohydrates, a major group of macronutrients that includes starches and sugars, have many key roles in your body. They provide energy, help make you feel full and satisfied, control your blood glucose and insulin metabolism, promote proper elimination, and foster fermentation in your gut, which promotes normal digestion and the growth of friendly bacteria. But not all carbohydrates are created equal.
We used to qualify “good” versus “bad” carbohydrates through terms such as “complex” (which included starches like potatoes and bread) and “simple”—meaning sugars, such as sucrose. But now we know that these descriptions don’t fully portray the qualities of carbs. More useful indicators include the amount and type of fiber, the amount of processing, and the GI and glycemic load (GL), reported Harvard researcher Frank Hu, M.D., Ph.D. in a 2010 article in AJCN.
“Typically, the best choices are the whole foods or minimally processed foods. Fruits, vegetables, beans and lentils, barley, wheat berries, quinoa—these are examples of carbohydrate-rich whole foods, and they are all very nutritious,” says Jill Weisenberger, M.S., R.D., C.D.E., dietitian and author. These foods have higher amounts of fiber, so they are more slowly digested and absorbed into the bloodstream, and provide other benefits, such as lower risk of heart disease and certain cancers. Minimally processed carbohydrate foods also contain health-protective phytonutrients, according to Andrew Weil, M.D., Director of the Arizona Center for Integrative Medicine, who spoke at the 10th Annual Nutrition and Health Conference in Seattle on May 13, 2013.
Glycemic index as indicator of carb quality. Strong evidence suggests that after eating high-GI foods, such as heavily refined carbohydrate foods, including white bread, refined cold cereals, and sugary foods, blood sugar levels rise more so than after eating low-GI foods, such as whole grain kernels, dairy foods, beans and most vegetables. This spike in blood sugar may increase your susceptibility for type 2 diabetes, heart disease, or overweight. This was confirmed in a consensus statement of the International Scientific Consensus Summit on Glycemic Index, Glycemic Load, and Glycemic Response released in June of this year. The statement was drafted by an international panel of experts, including David Jenkins, M.D., Ph.D., Ds.C., Canada Research Chair in Nutrition and Metabolism at the University of Toronto and the originator of the GI concept.
Which are the carbs to limit? Weil recommends decreasing your consumption of refined, processed, high-glycemic-load carbohydrate foods, including sugars and refined grains, due to their pro-inflammatory action and lack of protective phytonutrients. For example, grains which have been ground to reduce particle size and remove the outer bran and germ, found in bread, rolls, pizza crust, white rice, and ready-to-eat cold cereals—are more rapidly absorbed into the blood stream.
Excess added sugar intake (including table sugar, high fructose corn syrup, cane sugar, beet sugar, honey, and maple syrup) in processed foods, baked goods, dairy products, desserts, and beverages is linked with higher risk of cardiovascular disease and metabolic conditions, according to the American Heart Association. In particular, the intake of sugar-sweetened beverages shows even more potential for weight gain and health risk.
But don’t worry about the sugars that are found naturally in foods. “When we eat the sugar that comes naturally in fruit, milk, yogurt and vegetables, we are getting the whole package of nutrients, which includes vitamins, minerals, sometimes protein, sometimes fiber, and health-boosting phytochemicals,” says Weisenberger.
Putting it into practice. Weisenberger suggests that if you make room for three servings of dairy (or dairy substitute), and at least 2 cups of fruits, 1½ cups vegetables, and three servings of whole grains every day, you can allow yourself a treat. “If you accomplish this most days, you can enjoy the amount of highly processed foods that allows you to stay within your calorie needs,” she adds. The Dietary Guidelines suggests that you make at least half of your grain servings whole grains (about three servings daily for the average person), which leaves room for some servings (i.e., 1 slice bread, ½ cup rice or pasta, 1 cup breakfast cereal flakes, 1 small tortilla or pancake) of refined grains.