Whether you use them as a main ingredient, condiment and garnish, onions add flavor to a variety of dishes. Onions are a low-calorie, healthful food to include in your diabetic diet, providing you with fiber, iron, potassium, vitamin C and other micronutrients. Some evidence suggests that certain chemicals in onions may help you maintain blood sugar control.
Low Carbohydrates And Calories
The American Diabetes Association recommends that you eat at least three to five servings of vegetables daily. Adding onions to your soups, stews, sandwiches, salads and casseroles boosts your vegetable intake without adding a large number or calories or carbohydrates to your diet. A half cup of chopped spring onions contains 26 calories and 5.9 g of carbohydrates. Storage onions, such as yellow, white or red onions, contain 16 calories and 3.7 g of carbohydrates per half cup.
Mild onion varieties, or "sweet" onions, are a seasonal favorite. Compared with storage onions, sweet onions have a higher percentage of water and a lower concentration of sulfur-containing chemicals that impart onions with their pungency. The sugar concentration in fresh sweet onions, however, is not significantly higher than that in storage onions. Therefore, you can include sweet onions in your diabetic diet without worrying about them causing a spike in your blood sugar level.
Like all vegetables, onions contain plant fiber. Spring onions contain slightly less fiber than storage onions, with 1.3 g and 2.1 g per half cup, respectively. Dietary fiber helps keep your bowels active, preventing constipation. If you are prone to constipation due to diabetes-related nerve problems, consuming the recommended 25 to 30 g of fiber daily proves especially important. In addition, a high-fiber diet may help control your blood cholesterol level, reducing your risk of heart disease.
Vitamins and Minerals
Onions contain a moderate amount of vitamin C, or ascorbic acid. A half cup of chopped spring onions provides you with 9.4 mg of vitamin C; a similar serving of storage onions contains 15 mg. Other vitamins found in significant amounts in onions include vitamins A and K, folate and niacin. Your body also gains an array of minerals from onions, including iron, zinc, magnesium, potassium and phosphorus.
Blood Sugar Effects
Onions contain high concentrations of micronutrients called flavonoids, a group of plant-derived chemicals that have many health-related effects on your body. Quercetin is one of the most abundant flavonoids in onions; others include include cysteine and allyl propyl disulphide. Biomedical scientists speculate that flavonoids in onions may affect blood glucose levels. In an October 2010 study published in the journal, "Environmental Health Insights," pharmacologist Imad Taj Eldin and colleagues report that consumption of fresh onions reduced blood glucose levels among type 1 and type 2 diabetics. Additional research is need to determine whether onions may be a useful addition to diabetes nutritional therapy.