To obtain the maximum amount of the vitamin, avoid cutting yellow onions until right before use and eat them either lightly cooked or raw. Store yellow onions in a cool, dark place and try to use them within three or four days of purchase.
http://healthyeating.sfgate.com/nutrient-medium-yellow-onion-2603.html
What’s the Difference Red Onions vs White Onions. There are quite a few commonalities between both red and white onions. Both types of onions are considered low on the glycemic index, with a rating of 10. They both also provide about 10 percent of the daily value for vitamin C and the same amount of calcium per serving.
http://www.healthextremist.com/red-onions-vs-white-onions-which-ones-healthier/
Onion Nutrition Facts. In the rush to gather health information on the processed foods we eat, it can be easy to forget to check the nutritional facts of vegetables like the onion. Onions are high in vitamin C, a good source of fiber, and with only 45 calories per serving, add abundant flavor to a wide variety of food. Onions are sodium, fat, and cholesterol free, and provide a number of other key nutrients.
https://www.onions-usa.org/all-about-onions/nutritional-facts-vegetables
While 1/2 cup of yellow onions provides trace amounts of vitamin B-6, folate and vitamin A, it contains a high concentration of vitamin C. Each serving fulfills between 8 and 10 percent of the RDA of vitamin C. Regular vitamin C intake may prevent atherosclerosis, osteoarthritis, certain types of cancer, high blood pressure and age-related tissue ...
http://healthyeating.sfgate.com/nutrient-medium-yellow-onion-2603.html
Yellow onions contain significant amounts of vitamins, minerals, dietary fiber and antioxidant compounds. According to the National Onion Association, 87 percent of the United States onion crop consists of yellow onions, with 2- to 3 1/4-inch, medium-sized yellow onions the most common retail size available.
http://healthyeating.sfgate.com/nutrient-medium-yellow-onion-2603.html
Related to Diet & Weight Management. Onions: Full of Nutrients. These members of the allium genus deliver plenty of health benefits. Peel away the skin of this vegetable to find whole layers of health benefits. Worshiped by the Egyptians as far back as 3500 B.C., the onion symbolized eternity because of its concentric-circle construction.
http://www.webmd.com/diet/features/onions-full-of-nutrients
Onions: Full of Nutrients. These members of the allium genus deliver plenty of health benefits. From the WebMD Archives. Peel away the skin of this vegetable to find whole layers of health benefits. Worshiped by the Egyptians as far back as 3500 B.C., the onion symbolized eternity because of its concentric-circle construction.
http://www.webmd.com/diet/features/onions-full-of-nutrients
– Antioxidant Properties. Overall, red onions contain a higher amount of antioxidant compounds. They are higher in total flavonoids than white onions and yellow onions are considered to be in the middle. Red onions contain 415 to 1917 mg of flavonols compared to yellow ones, which only contain 270 to 1187 mg. One of the most beneficial compounds in red onions is quercetin, which is a polyphenol compound.
http://www.healthextremist.com/red-onions-vs-white-onions-which-ones-healthier/
This genus also contains several other species variously referred to as onions and cultivated for food, such as the Japanese bunching onion (Allium fistulosum), the tree onion (A. ×proliferum), and the Canada onion (Allium canadense). The name wild onion is applied to a number of Allium species, but A. cepa is exclusively known from cultivation. Its ancestral wild original form is not known, although escapes from cultivation have become established in some regions.
https://en.wikipedia.org/wiki/Onion
Onions contain low amounts of essential nutrients (right table), are low in fats, and have an energy value of 166 kJ (40 kcal) per 100 g (3.5 oz). They contribute their flavor to savory dishes without raising caloric content appreciably.
https://en.wikipedia.org/wiki/Onion
what vitamins do white onions have
White Onions has Vitamin C. The white onions have vitamin C. White onions have vitamin C.