November 2013 Issue
Set the Record Straight — Experts Dispel the Top Five Myths About the Diabetes Diet
By Jill Weisenberger, MS, RDN, CDE
Vol. 15 No. 11 P. 16
It’s common knowledge that diabetes is an epidemic in this country, affecting 8.5% of US adults aged 20 and older, and it shows no signs of slowing down.1 And while there’s a wealth of credible scientific information available about the disease and proven strategies to treat and manage it, there are also many misconceptions and even myths circulating among nutrition professionals about the types of foods clients and patients should eat and what they should avoid.
This article discusses the top five myths about diabetes and diet and also provides the facts based on the latest research and interviews with experts in the dietetics field.
1. White foods are bad. The belief that clients and patients should avoid white foods, including fruits such as apples and bananas and vegetables such as potatoes, is false. “The notion of avoiding anything white became popular with the low-carb craze,” says Constance Brown-Riggs, MSEd, RD, CDE, CDN, a national spokesperson for the Academy of Nutrition and Dietetics and the author of The African American Guide to Living Well With Diabetes.
“Of course, the phrase is an oversimplification and source of confusion,” she adds. The directive “don’t eat white foods” was meant to instruct people to avoid refined grains, but some individuals have taken this too literally and avoid items such as milk, yogurt, cottage cheese, potatoes, and bananas.
Moreover, the idea that white foods and processed grains are devoid of nutrients is false. “The Dietary Guidelines suggest that half the grains should be whole,” says Julie Miller Jones, PhD, professor emerita from St Catherine University in Minnesota. “That still leaves room for refined grains, which offer folate fortification and the benefit of reducing the number of pregnancies affected by neural tube defects.2 Supermarkets carry an array of both 100% whole grain products and those that combine whole and refined grains. This improves acceptability and the overall whole grain intake. It also means that the gains with folate fortification will not be lost.”
On average, Americans consume only 59% and 42% of the recommended amount of vegetables and fruits, respectively; therefore avoiding produce based on color is counterproductive.3 “Color doesn’t predict content of nutrients or phytochemicals,” says Joanne Slavin, PhD, RD, a professor in the department of food science and nutrition at the University of Minnesota. “Potatoes, for example, are high in potassium and vitamin C, and are a good source of fiber. Since fiber and potassium are shortfall nutrients in US diets, excluding potatoes only makes nutrient deficiencies worse.”
Nearly 25% of vegetable phenolic compounds in the American diet come from the potato.4 Bananas also provide an ample amount of potassium, fiber, and vitamin C, and they’re a good source of vitamin B6. Cauliflower and cabbage are cruciferous vegetables that contain phytochemicals often studied for their potential role in cancer prevention, as are broccoli, Brussels sprouts, collard greens, and kale, among others.5
Besides providing vitamin C and dietary fiber, apples contain the phytochemical quercetin, which is believed to have anti-inflammatory and antioxidant properties. One study found that a high consumption of white fruits and vegetables, namely apples and pears, may protect against stroke.6
2. Weight loss cures type 2 diabetes. This is a widely held misconception because the impact that weight loss has on diabetes depends on how long an individual has had the disease and at what point he or she loses the weight during its progression. “Timing is everything,” says Hope Warshaw, MMSc, RD, CDE, author of Diabetes Meal Planning Made Easy. Often, people have insulin resistance for years before crossing the line to full-blown type 2 diabetes, and more than likely they’ve lost a significant amount of insulin-producing function by that point.
Natalie Nicolas, RD, LDN, an outpatient dietitian at Holy Cross Hospital in Silver Spring, Maryland, explains to patients that blood glucose can be elevated for reasons other than being overweight. Whether individuals will regain normal glucose levels and for how long depends on many factors, including how early they are in the course of the disease, how much weight they have to lose, and what their diet and exercise habits are, Warshaw says. “However, getting to and staying at a healthful weight always is beneficial and may well translate to needing fewer medications,” she adds.
Patients need to know that diabetes may not go away, but it’s easier to manage blood glucose, lipids, and blood pressure at a healthful weight.
3. Foods with a high glycemic index (GI) score should be avoided. The GI ranks carbohydrate-containing foods from 0 to 100, indicating how a single food portion containing 50 g of digestible carbohydrate will affect blood glucose. The lower the number, the less blood glucose is affected.
While both the quantity and source of carbohydrate influence postprandial glucose levels, the total amount of carbohydrate consumed at a meal or snack is a stronger predictor of glycemic response.7 However, when combined with other methods of diabetes meal planning, such as carbohydrate counting, the GI, on average, can contribute to dropping hemoglobin A1c an additional 0.5 percentage points, such as 7.5% to 7%, a small but meaningful amount.8 Clients and patients who are already skilled in carbohydrate counting may find that fine-tuning their carbohydrate choices with the GI is advantageous.
Patients with diabetes benefit the most when they use the GI to make choices within the same food category, Jones explains. For example, sourdough bread has a lower GI than regular white bread, and al dente pasta has a lower GI than overcooked pasta. Patients can run into nutritional trouble if they choose ice cream over grapes because of their GI scores or if they avoid foods such as carrots and watermelon, which require someone to eat large portions to consume 50 g of digestible carbohydrate. Someone would have to eat 1 1/2 lbs of carrots to get 50 g of digestible carbohydrate, Jones says.
The GI of a particular food also depends on the cooking method and food combinations. “The GI of white bread goes way down when buttered, showing that the measure may not be really valuable for planning,” Jones says. In one study, when researchers used the GI to calculate the amount of carbohydrate individual foods contributed to a meal, they found they overestimated the GI for that meal. For example, the GI of a meal comprised of potatoes, carrots, peas, and chicken was 22% lower than the predicted GI, suggesting that the effects of fat and protein aren’t adequately considered.9
According to Brown-Riggs, “There’s great potential for someone to miss out on healthful, nutrient-dense foods when they select foods based solely on the GI.” For example, potatoes, bananas, and whole wheat bread have GI scores that many people consider too high. So it’s imperative for nutrition professionals to teach patients that the GI score alone doesn’t suggest the suitability of a food in a diet for diabetes management. Foods must be evaluated in a broader context of balanced eating.
4. Patients can discontinue medications when A1c drops to normal levels. Because type 2 diabetes is a progressive disease, typically the need for medications increases over time. In fact, insulin therapy eventually is indicated for many patients with type 2 diabetes.10 However, people often fear diabetes medications and even think that medications are responsible for diabetes complications, Brown-Riggs says.
To discontinue medications, patients may resort to very restricted eating, which is both unhealthful and unsustainable. Once medications are discontinued, blood glucose levels and A1c frequently increase. “I explain to them the health benefits of having a better blood glucose with meds vs. the long-term complications they may experience down the road without [them],” says Lisa Stollman, MA, RDN, CDE, CDN, author of The Teen Eating Manifesto.
Mindy Komosinsky, RD, CDE, a nutritionist and diabetes educator at Capital Health Medical Center in Hopewell, New Jersey, teaches patients how their medications work and explains that research suggests starting medications early protects them in the long run. Also, Kim Slominsky, RD, LDN, CDE, a clinical health consultant for Health Diagnostic Laboratory in Richmond, Virginia, explains to patients that it isn’t a defeat to be on diabetes medications.
5. Blood glucose is the most important measure of diabetes control. Whether a patient has type 1 or type 2 diabetes, it’s critical to pay attention to what’s called the ABCs—A1c, blood pressure, and cholesterol—Warshaw says. Overall, coronary vascular disease accounts for about 25% of deaths among patients who develop diabetes before the age of 20.11 Moreover, type 2 diabetes is an independent risk factor for macrovascular disease, and people with diabetes in the United States are 200% to 400% more likely to die from coronary artery disease than age-matched individuals without diabetes.12
Insulin resistance is a hallmark of prediabetes and type 2 diabetes. To help patients see the bigger picture, Brown-Riggs teaches them the ways in which insulin resistance manifests itself. “I refer to the cell as being hard of hearing and not hearing insulin knocking at the cell door,” she says. This leads to a discussion about the effects of insulin resistance: fatty liver, hypertension, dyslipidemia, metabolic syndrome, cardiovascular disease, and more. Brown-Riggs tells patients that the “goal of management is more than simply reducing blood glucose levels.”
Because of the misinformation in the media and on the Internet, patients with diabetes will continue to fear eating certain foods and taking medications and have unrealistic expectations. Dietetics professionals can allay unnecessary concerns and help clients and patients make valuable lifestyle changes by first identifying and then addressing their many misconceptions.
— Jill Weisenberger, MS, RDN, CDE, is a freelance writer and a nutrition and diabetes consultant to the food industry, including Daisy Brand Cottage Cheese and the Alliance for Potato Research and Education. She has a private practice in Newport News, Virginia, and is the author of Diabetes Weight Loss — Week by Week.
1. FASTSTATS Diabetes. Centers for Disease Control and Prevention website. http://www.cdc.gov/nchs/fastats/diabetes.htm. Updated May 30, 2013. Accessed August 6, 2013.
2. Crider KS, Bailey LB, Berry RJ. Folic acid food fortification — its history, effects, concerns, and future directions. Nutrients. 2011;3(3):370-384.
3. US Department of Agriculture, US Department of Health and Human Services. Dietary Guidelines for Americans, 2010. 7th ed. Washington, DC: US Government Printing Office; 2010:46.
4. Weaver C, Marr ET. White vegetables: a forgotten source of nutrients: Purdue Roundtable Executive Summary. Adv Nutr. 2013;4(3):318S-326S.
5. Foods that fight cancer: broccoli and cruciferous vegetables. American Institute for Cancer Research website. http://www.aicr.org/foods-that-fight-cancer/broccoli-cruciferous.html. Updated May 17, 2013. Accessed May 25, 2013.
6. Oude Griep CM, Verschunen WM, Kromhout D, Ocké MC, Geleijnse JM. Colors of fruit and vegeatables and 10-year incidence of stroke. Stroke. 2011;42(11):3190-3195.
7. Sheard NF, Clark NG, Brand-Miller JC, et al. Dietary carbohydrate (amount and type) in the prevention and management of diabetes: a statement by the American Diabetes Association. Diabetes Care. 2004;27(9):2266-2271.
8. Thomas D, Elliott EJ. Low glycaemic index, or low glycaemic load, diets for diabetes mellitus. Cochrane Database Sys Rev. 2009;1:CD006296.
9. Dodd H, Williams S, Brown R, Venn B. Calculating meal glycemic index by using measured and published food values compared with directly measured meal glycemic index. Am J Clin Nutr. 2011;94(4):992-926.
10. American Diabetes Association. Standards of medical care in diabetes—2013. Diabetes Care. 2013;36 Suppl 1: S11-S66.
11. Kaufman FR, ed. Medical Management of Type 1 Diabetes. 6th ed. Alexandria, VA: American Diabetes Association; 2012:242.
12. Burant CF, Young LA, eds. Medical Management of Type 2 Diabetes. 7th ed. Alexandria, VA: American Diabetes Association; 2012:118.