Unfortunately people with diabetes, as well as health professionals, frequently read, hear, and are given conflicting advice on the best nutrition therapy interventions for patients with diabetes.
Reporters, often looking for sensational headlines, question traditional advice. Medical professionals, including doctors, write and sell books promoting their theories. Talk show hosts and guests are delighted to share their supposed wisdom on what patients with diabetes should eat and do. The end result is often confusing advice based on theories and assumptions with little, if any, supporting scientific evidence.
Carbohydrates, what kind, how much, and when to eat, are popular topics of discussion and advice. Here are four myths surrounding carbohydrates and nutrition we’ll be evaluating:
- Myth 1: People with diabetes should eat a low-carbohydrate diet
- Myth 2: For weight loss and management, a low-carbohydrate diet is the best option
- Myth 3: Eating a high carbohydrate diet causes insulin resistance
- Myth 4: Patients with diabetes should not eat bread
First, it may be helpful to review some basic facts about carbohydrate and diabetes.
A major goal of nutrition therapy interventions for people with diabetes is to attain individualized glucose, blood pressure, and lipid goals.1 Because carbohydrates are the major determinant of postprandial blood glucose levels, low-carbohydrate diets might seem to be the logical approach for achieving this goal. However, the important factor is the balance between carbohydrate intake and available insulin.
When endogenous insulin released from the pancreas is sufficient to meet food intake needs, individuals remain euglycemic regardless of the amount of carbohydrate they consume. Also of importance is that foods containing carbohydrate are important sources of energy, fiber, vitamins, and minerals and are a key component of healthful eating.
Dietary reference intakes state that the recommended dietary allowance (RDA) for carbohydrate for adults and children is 130 g/day as an average minimum requirement.2 This minimum is based on the need for glucose as an energy source in the brain and central nervous system.
It also is of interest to note that the majority of patients with diabetes in the United States do not eat a low- or high-carbohydrate diet, but rather report a moderate intake of carbohydrates; studies indicate this is ~44% of total calories in individuals with type 2 diabetes3 and ~46% in individuals with type 1 diabetes.4 Furthermore, it appears difficult for patients to eat either a high- or low-carbohydrate diet.
In the United Kingdom Prospective Study, despite receiving individual education from dietitians on the recommended carbohydrate intake of 50% to 55%, patients reported intake from carbohydrate of 43%, which was similar to that in the general public.5
In longer term studies of low-carbohydrate diets, high drop-out rates are common in groups of persons who are trying to eat a low-carbohydrate diet.6
Monitoring carbohydrate intake continues to be, however, a key strategy in achieving glycemic control.1 Many aspects related to this strategy have been, and continue to be, controversial, often because they are based on theories or assumptions and not on scientific evidence.
Some of the resulting myths include:
- People with diabetes should eat a low-carbohydrate diet to improve and maintain glycemic control
- For weight loss and management, a low-carbohydrate diet is the best option for people with diabetes
- Eating carbohydrate causes insulin resistance in people with diabetes and prediabetes
- People with diabetes should not eat bread