Onions make a tasty addition to salads, burgers, soups and casseroles. Because you can buy them year-round, they fit in dishes for all seasons. High in fiber, protein and minerals, onions offer a great deal of nutritional value. When it comes to vitamins, onions contain low levels of vitamin K, but they make up for it with fair amounts of other vitamins.
Vitamin K is responsible for your blood's ability to clot properly. However, if you have a medical condition that requires you to be on blood thinners, vitamin K may interfere with your medication's ability to work properly. If you like onions, there is good news -- onions contain only a trace amount of vitamin K, so keeping them in your diet should not have adverse effects on your medication. A 1 cup serving of raw, chopped onion contains 0.6 mcg of vitamin K, which is 1 percent of the recommended daily intake. Spring onions, or scallions, contain 206 mcg of vitamin K in 1 cup, which could be significant if you are restricting vitamin K. If you are on blood thinners, ask your doctor about the safe amount of vitamin K foods you can consume.
Onions are also rich in vitamin C, with 11.8 mg in a 1 cup serving, which is 11 percent of the recommended daily intake. Vitamin C is an antioxidant vitamin that helps protect the body from chronic disease, including cancer and heart disease. Other roles of vitamin C in the body include the synthesis of collagen and production of connective tissues and mucous membranes, strengthening of the immune system and absorption of iron. Those with higher intakes of vitamin C have a lower risk of developing eye trouble, such as age-related macular degeneration, notes the Office of Dietary Supplements. Vitamin C is water-soluble, which means it is not stored in the body and needs to be replaced daily. Adding raw onion to your salads or sandwiches will help you reach 100 percent of your recommended vitamin C intake each day.
Onions contain all members of the B vitamin family, with the exception of B-12, which is found only in animal products. Vitamin B-6 and folate have the highest concentration, with a 1 cup serving delivering 0.2 mg of B-6, which is 10 percent of the RDI, and 30.4 mcg of folate, which is 8 percent of the RDI. A report from the Harvard School of Public Health explains that vitamin B-6 and folate work together to fight heart disease, cancer and birth defects. The report also states that vitamin B-12 works alongside B-6 and folate to maximize these benefits, so adding raw onion to a burger is a good way to get the three vitamins together. Other B vitamins in onion include thiamin, riboflavin, pantothenic acid and niacin. All B vitamins work to produce red blood cells and promote energy metabolism.
Onions contain only a trace amount of vitamin A -- 3.2 IU in a 1 cup serving which is not even 1 percent of your RDI. Though it may not seem substantial, every bit helps you reach your intake goal for the day. Vitamin A is an antioxidant vitamin that plays a major role in eye health.