High-fiber diet reduces blood glucose
July 1, 2000
High-fiber diet reduces blood glucose
Fruits, veggies, whole grains key to better control
A diet loaded with bran, granola, whole wheat bread, and even more fruits and vegetables may be undesirable for people with Type 2 diabetes, but it may add up to significant lowering of blood glucose levels.
The diet high in soluble fiber leads to improved glycemic control, reduced insulin concentrations, and lower cholesterol and triglyceride concentrations in patients with Type 2 diabetes, according to a study from the University of Texas.1 (See High-Fiber Diet, p. 8.)
| High-Fiber Diet | |
| Food | Weight in grams |
| Breakfast | |
| orange sections | 300 |
| oatmeal | 50 |
| scrambled egg | 37 |
| olive oil | 10 |
| decaffeinated coffee | 2 |
| Lunch | |
| ham (5% fat) | 52 |
| mayonnaise | 12 |
| iceberg lettuce | 10 |
| fresh tomato | 15 |
| whole wheat bread | 60 |
| corn (canned) | 40 |
| dehydrated onion | 2 |
| olive oil | 10 |
| fresh green pepper | 10 |
| fresh celery | 15 |
| fresh papaya | 250 |
| instant tea | 2 |
| Dinner | |
| chicken breast (skinned) | 90 |
| bran flakes | 10 |
| oat bran | 5 |
| parmesan cheese | 1 |
| egg substitute | 10 |
| tomato (canned) | 105 |
| low-fat cheese | 19 |
| spaghetti | 19 |
| zucchini | 195 |
| olive oil | 19 |
| whole wheat bread | 30 |
| fresh peaches | 300 |
| instant tea | 2 |
| Bedtime snack | |
| fruit cocktail (canned) | 200 |
| cherries (canned) | 100 |
| granola | 15 |
| Source: University of Texas Southwestern Medical Center, Dallas. | |
| ADA Diet (from sample menus) | |
| Food | Weight in grams |
| Breakfast | |
| orange juice | 220 |
| white grits | 50 |
| egg substitute | 40 |
| olive oil | 10 |
| decaffeinated coffee | 2 |
| Lunch | |
| ham (5% fat) | 50 |
| mayonnaise | 6 |
| iceberg lettuce | 15 |
| fresh tomato | 30 |
| low-sodium bread | 60 |
| corn (canned) | 40 |
| cider vinegar | 5 |
| dehydrated onion | 2 |
| olive oil | 10 |
| fresh green pepper | 10 |
| fresh celery | 15 |
| instant tea | 2 |
| oatmeal raisin cookie | 20 |
| Dinner | |
| chicken breast (skinned) | 100 |
| bran flakes | 10 |
| low-sodium bread | 20 |
| parmesan cheese | 1 |
| whole egg | 1 |
| spaghetti | 45 |
| green beans | 75 |
| olive oil | 17 |
| whole wheat bread | 21 |
| graham crackers | 21 |
| instant tea | 2 |
| Bedtime snack | |
| mozzarella cheese | 30 |
| low-sodium bread | 30 |
| pineapple juice | 190 |
| Source: American Diabetes Association, Alexandria, VA. | |
While the cholesterol-lowering effects of soluble fiber are well-known, the effect of fiber on glycemic control has been controversial, explains Abhimanyu Garg, MD, professor of internal medicine and associate project director of the general clinical research center at the University of Texas Southwestern Medical Center in Dallas.
While the study was small, its powerful results could influence the current revision of guidelines for dietary consumption for patients with diabetes, according to a spokeswoman for the American Diabetes Association (ADA) in Alexandria, VA.
Thirteen patients participating in the study, all with Type 2 diabetes, were admitted for a five-day baseline period and given a daily diet containing 50 g of fiber, about twice the amount recommended by the ADA and nearly three times the consumption of the average American. Participants remained on the diet for six weeks and then crossed over to the ADA diet for six weeks. Patients were hospitalized for evaluation for the last week of each dietary period.
The experimental diet reduced blood glucose levels by about 10% in six weeks, a figure Garg calls significant. He suggests there will be further blood glucose reductions over time if the diet is sustained.
Garg explains that he was careful to design the study so none of the recommendations for the ADA diet were changed except the element of adding fiber. Fiber was increased to seven to eight servings of fruits and vegetables a day and three servings of whole grains. Carbohydrates, protein, and fat intakes were untouched. Both diets contained a daily caloric intake of 2,308 calories.
"When we started, we knew we would get beneficial effects from lowering cholesterol, which we did by 6.7%, but we didn’t predict what would happen to diabetic control," Garg says.
"Diet is the mainstay of diabetes treatment but is often neglected. This study supports the view that diet can improve glucose and lipid levels and thus reduce the risk of long-term diabetic complications," Garg adds.
"This is a very interesting study, and it’s good news to see that nutrition makes a difference," says Anne Daly, RD, CDE, the ADA’s vice president for health care and education and a clinician at the Springfield (IL) Diabetes and Endocrinology Center.
Daly says nutrition is "underutilized and overlooked with the many medications and treatments we have." There are dozens ranging from oral agents such as gluciophagfe, metformin, and sulfonylureas to thiazolidendiones to insulin.
"We should certainly consider this information and let our patients know," Daly says, adding that she has some concerns about whether patients will incorporate the diet into their routines, however. "Realistically, I wonder how many will really eat oat bran for dinner?"
The ADA’s dietary guidelines panel is revising nutrition recommendations, including the daily 25 g fiber recommendation, and expects to have new guidelines ready by the end of the year, says Daly. "They’ve seen the study, and we’ll have to wait and see what they do."
Reference
1. Manisha C, Abhimanyu G, Dieter G, et al. Beneficial effects of high dietary fiber intake in patients with type 2 diabetes mellitus. N Engl J Med 2000; 19:1,392-1,398.