Diabetics are no longer limited to a high-carbohydrate/low-fat diet, according to the latest guidelines issued by the American Diabetes Association (ADA). While that is still considered a healthy diet, they may now choose a high-monounsaturated fat diet instead. However, the total fat intake should be limited to no more than 30 grams a day.
The revision in US guidelines brings them into line with 1999 guidelines developed in Europe, which now form the core of dietary advice to people with diabetes, and people with elevated glucose levels, in the UK. Diabetes and elevated glucose levels are being seen with increasing frequeny among people taking Highly Active Antiretroviral Therapy. People with elevated glucose tolerance may not know that they are risk of developing diabetes, a major risk for heart disease. British HIV Association treatment guidelines recommend that people with HIV taking HAART should receiving regular monitoring for elevated glucose tolerance and dietary counselling if glucose tolerance rises above normal levels.
Dr. Abhimanyu Garg, professor of internal medicine and chief of nutrition and metabolic diseases at UT Southwestern Medical Center at Dallas, served on the expert panel of 12 convened by the ADA that formulated the new evidence-based guidelines, which emphasize individualized diets and a variety of food choices. Garg’s research showing the benefits of a high-monounsaturated fat diet was instrumental in leading to the change in guidelines.
“In the past a diet rich in carbohydrates and low in fats was recommended to all patients with diabetes,” Garg said. “We found that a diet rich in monounsaturated fatty acids led to improvement in HDL (high-density lipoprotein) cholesterol, triglycerides and most importantly, diabetes control.”
“Now diabetics can choose a diet rich in carbohydrates or a diet rich in monounsaturated fats. We can now offer them a choice, which they are more likely to stick to and are more compliant with,” Garg said.
Foods rich in monounsaturated fats include olive oil, rapeseed (canola) and peanut oils, as well as avocados and some nuts.
New dietary recommendations
The guidelines include several new recommendations for treating diabetes. The recommendations indicate that:
- Foods containing carbohydrates from whole grains, fruits, vegetables and low-fat milk should be included in a healthy diet.
- The total amount of carbohydrates in meals or snacks is more important than the source or type.
- Sucrose (table sugar) and sucrose-containing foods do not need to be restricted.
- Non-nutritive sweeteners are safe when consumed within the acceptable daily intake levels established by the Food and Drug Administration.
Sugar not forbidden, but best avoided
Based on research from several clinical trials, the panel found that sucrose did not negatively affect glucose control to a greater extent than starch and other carbohydrate-containing foods. But instead of diabetics consuming sugar-laden foods, the panel recommends that sucrose-containing foods be replaced with carbohydrate sources such as fruits and vegetables.
European guidelines do not encourage unrestricted use of sucrose
“As far as the carbohydrate-containing foods are concerned,” Garg said, “it’s best to use unrefined carbohydrates instead of sucrose. If you get your carbohydrates from fruits, vegetables and grains, then there are other beneficial substances that are not included in a package of sugar. If you compare the nutritional value of an apple to an equal amount of sugar, an apple would be more beneficial.”
Fibre recommended as important aid to sugar control
Another new component, which was implemented as a result of research conducted by Garg and his colleagues in the Center for Human Nutrition at UT Southwestern, is the inclusion of increased amounts of fibre in a diabetic’s diet. Last year Garg reported that a high intake of dietary fibre, mostly from fruits and vegetables, lowered blood glucose levels by 10 percent in study participants who consumed 50 grams of fiber in their daily diet. The high-fiber diet also decreased insulin in the blood and lowered blood lipid concentrations. The panel recommends that diabetics choose a variety of fiber-containing foods, such as grains, fruits and vegetables. These foods provide vitamins, minerals and other substances essential for good health as well.
Specifically, the new guidelines recommend that carbohydrate and monounsaturated-fat intake should account for 60 to 70 percent of calorie intake, and 15 to 20 percent of caloric intake should come from protein. Carbohydrate food sources recommended by the panel include whole grains, fruits, vegetables and low-fat milk. According to the new guidelines, less than 10 percent of caloric intake should come from saturated fats. Foods rich in saturated fats include butter, full fat milk, animal fat and lard.
Fat intake
A dietary cholesterol intake of less than 30 grams a day is recommended, and trans-unsaturated fatty acids should be minimized, according to the panel. Trans-unsaturated fatty acids - which are found in some margarines - are formed when liquid, unsaturated oils are converted into a soft, semisolid fat by hydrogenation. Trans-fatty acids are often included in margarines made from vegetable oils, and can detected by the words "Hydrogenated fat" in the labelling. Trans fatty acids are also found in many ready prepared foods, biscuits, cakes and pizzas where vegeatble oil is used.
Polyunsaturated fats should account for 10 percent of caloric intake. Corn, sunflower, safflower and soybean oils are rich in polyunsaturated fats.
In a multicentre study in 1994, dr. garg found that a diet rich in monounsaturated fats improved the heart health of patients with non-insulin dependent (type 2) diabetes, when compared to a diet high in carbohydrates. garg’s research led to a major revision in the ada’s dietary guidelines that same year.
The new guidelines are included as a supplement to the January issue of Diabetes Care and full text was freely available on the publication date of this story.