Raw onions mainly provide vitamin C, with smaller amounts of B vitamins and folate that support everyday health.
When someone types “what vitamin is found in onion?” into a search bar, the real goal is simple: to know whether those sharp, tear-triggering bulbs add more than flavor to a plate. The short answer is yes. Onions bring vitamin C to your meals, along with a cluster of B vitamins and folate that quietly help many body processes run on track.
This article walks through the main vitamin in onion, how much you actually get per serving, how heat changes the numbers, and how to use onions in meals so their nutrients still make it to your fork. The focus stays on practical details you can use in everyday cooking, not just lab values on a chart.
What Vitamin Is Found In Onion? Main Answer
Across different types of onions, vitamin C stands out as the primary vitamin. Lab data on raw onions show that a 1-cup serving of chopped onion (about 160 grams) contains around 11.8 milligrams of vitamin C, which covers a little over one tenth of the usual daily target for adults.1
Onions also carry vitamin B6, folate (a form of vitamin B9), and small amounts of other B vitamins. These amounts are smaller than what you would get from foods like citrus or leafy greens, yet they still add up across the day, especially if you cook with onions often.
Vitamin Profile Of Onion At A Glance
To see where onions fit in your overall nutrient plan, it helps to view their vitamin profile side by side. The values below use raw onion data per 100 grams from large nutrition datasets that draw on USDA FoodData Central figures and related sources.1,2
| Vitamin | Approx. Amount Per 100 g Raw Onion | Role In The Body |
|---|---|---|
| Vitamin C (ascorbic acid) | 7–8 mg | Helps collagen formation, wound healing, and iron absorption |
| Vitamin B6 (pyridoxine) | 0.12–0.19 mg | Helps enzymes use protein and keep nerve signaling steady |
| Folate (vitamin B9) | 20–30 mcg | Helps build DNA and red blood cells |
| Thiamin (vitamin B1) | 0.05–0.07 mg | Helps cells turn carbohydrates into energy |
| Riboflavin (vitamin B2) | 0.02–0.04 mg | Helps energy production and normal vision |
| Niacin (vitamin B3) | 0.1–0.2 mg | Helps hundreds of metabolic reactions |
| Vitamin K | 0.5–1 mcg | Helps blood clotting and bone health |
These numbers show that onions are not just a garnish. Vitamin C, vitamin B6, and folate stand out in particular. While the levels are modest compared with dedicated vitamin-rich foods, onions join the long list of vegetables that layer small doses of many nutrients across the day.
How Much Vitamin C Do You Get From Onion?
On paper, 7–8 milligrams of vitamin C per 100 grams may not sound impressive next to oranges or bell peppers. The picture changes when you think about how often onions turn up in cooking. Many recipes use at least half an onion, sometimes more, and people snack on onion-based salads, salsas, and relishes as well.
Everyday Portions And Vitamin C Contribution
Using one cup of chopped raw onion as a reference point, you get about 11.8 milligrams of vitamin C in that serving.1 A typical medium onion (around 110 grams) lands a bit lower than that, while a large onion can edge higher. Over a full day of meals, onions can easily add 10–20 milligrams of vitamin C, especially when mixed into sauces, soups, and stir-fries.
An onion nutrition facts sheet from an agricultural education program lists a medium onion as a “good source” of vitamin C, vitamin B6, potassium, folate, and manganese, which lines up with the lab data above.3 In other words, onions are not a megadose source, yet they help lift your totals in a steady, quiet way.
Vitamins In Onion And Daily Needs
The main question, “what vitamin is found in onion?”, points straight to vitamin C, yet this vegetable also nudges your intake of several B vitamins toward daily targets. Adults usually need in the range of 75–90 milligrams of vitamin C per day, depending on sex and life stage, and onions can cover part of that number when they show up in multiple meals.4
Daily requirements for B vitamins sit in the microgram or low-milligram range. A bowl of onion-heavy vegetable soup or a serving of grilled onions on a sandwich helps fill those needs alongside other foods like grains, beans, and animal products.
Other Vitamins In Onion And What They Do
Vitamin C may get most of the spotlight, but the smaller vitamin amounts in onion still matter over time. These are the main ones to know about.
Vitamin B6: Steady Energy And Nerve Function
Onions provide roughly 0.19 milligrams of vitamin B6 per cup of chopped raw onion.1 This vitamin helps enzymes break down protein, carbohydrates, and fat, and it plays a role in making neurotransmitters that carry signals in the brain. Low intake can lead to fatigue, irritation, and a lower red blood cell count.
Folate And Other B Vitamins
Folate (vitamin B9) in onion supports DNA formation and normal growth. A cup of raw onion contains about 30 micrograms of folate, which adds to folate from legumes, leafy greens, and fortified grains.1 Thiamin and riboflavin in onions pitch in for energy production, while niacin assists with many metabolic steps that keep cells working well.
Onions also contain tiny amounts of fat-soluble vitamins like vitamin A (through carotenoids) and vitamin K. The levels are low on their own, yet they still contribute to the whole pattern of nutrients in a varied diet.
How Onion Vitamins Help Your Body
Vitamin C is central to many of the health stories tied to onions. The National Institutes of Health notes that vitamin C helps the body make collagen, a structural protein found in skin, cartilage, and blood vessels. It also improves iron absorption from plant foods and helps the immune system work against infections.4,5
Folate and vitamin B6 in onion play steady backstage roles. Folate helps form red blood cells and supports normal growth and development, while vitamin B6 helps the body process amino acids and maintain a healthy nervous system. When onions share the plate with beans, lentils, or meat, the combined mix of vitamins, minerals, and plant compounds gives your body many of the tools it needs to stay in balance.
For readers who want a deeper dive on vitamin C in general, the National Institutes of Health provides a detailed vitamin C fact sheet that covers functions, daily needs, and safety ranges.4
Does Cooking Onion Change Its Vitamin Content?
Vitamin C does not handle heat very well. It breaks down in long cooking times and can leak into cooking water. That means a long-simmered onion soup will keep far less vitamin C in the onion pieces compared with a raw salad or a quick sauté.
B vitamins are water-soluble too, so they can move from chopped onion into the surrounding liquid during boiling or stewing. In dishes where you eat the broth, like soups and stews, you still take in those vitamins. In cooking methods where the liquid goes down the drain, such as boiling onions and then discarding the water, more vitamin loss occurs.
Ways To Keep More Vitamin C In Your Onions
- Use raw onion in salads, salsas, or as a topping for tacos, burgers, and grain bowls.
- Cook onions just until soft for stir-fries or quick sauces instead of stewing them for long periods.
- Keep the cooking water when you simmer onions and turn it into part of a soup, sauce, or gravy.
- Add a handful of chopped raw onion at the end of cooking to freshen flavor and boost vitamin C in the finished dish.
These small cooking choices help you keep more of the vitamin C that drew you to onions in the first place.
Cooking Method And Vitamin C Retention
Estimating exact vitamin loss for each pot of soup or pan of stir-fried vegetables is tricky, since many factors play a role: cut size, cooking time, heat level, and whether the liquid stays in the dish. Still, research on vegetables in general points to some clear patterns for vitamin C retention.
| Onion Preparation | Estimated Vitamin C Retention | Best Use |
|---|---|---|
| Raw, finely chopped | Near 100% | Salads, salsas, sandwich toppings |
| Light sauté (5–7 minutes) | High | Stir-fries, quick sauces, omelets |
| Oven-roasted wedges | Medium | Side dishes, tray bakes, grain bowls |
| Long stew or soup, broth eaten | Medium | Hearty soups and stews |
| Boiled, water discarded | Low | Use only when texture is the main goal |
This table gives rough patterns rather than lab-measured values, but it lines up with what scientists see when they test vitamin C in many vegetables under different cooking conditions. Raw and lightly cooked onions keep more vitamin C, while intense heat and discarded cooking water cut those levels down.
Easy Ways To Eat More Onion For Vitamin C
Once you know that vitamin C is the main answer to “what vitamin is found in onion?”, the next step is simple: find pleasant ways to include onions in meals so you enjoy both flavor and nutrients. Here are some ideas that fit into busy routines.
Raw Uses
- Toss finely chopped red or white onion into tomato salads or cucumber salads.
- Sprinkle a spoonful of raw onion over lentil soup, chili, or bean bowls right before serving.
- Mix raw onion into homemade salsa or pico de gallo and serve with eggs, tacos, or grilled fish.
Lightly Cooked Options
- Sauté onion just until translucent as the base for pasta sauces, rice dishes, and skillet meals.
- Add sliced onion to quick stir-fries with peppers, broccoli, or snap peas.
- Cook onion wedges on a sheet pan with chicken, tofu, or chickpeas so the juices stay in the pan.
Onion Dishes And Approximate Vitamin C
The table below gives a rough sense of how onion-heavy dishes can contribute vitamin C. Values assume raw or lightly cooked onion portions based on typical recipes.
| Dish Or Portion | Onion Amount | Estimated Vitamin C |
|---|---|---|
| Heaped tablespoon raw onion on a taco | 10 g | About 1 mg |
| Side of cucumber and onion salad | 40 g | Around 3 mg |
| Stir-fry with half a large onion | 80 g | 6–7 mg (raw equivalent) |
| Vegetable soup with one medium onion | 110 g | 7–8 mg spread through the pot |
| Tray bake with two large onions | 300 g | 20+ mg shared among portions |
These numbers stay on the cautious side, since cooking and storage can trim vitamin C. Still, they show how onions, used in generous amounts across dishes, help you approach daily vitamin C targets, especially when paired with other fruits and vegetables.
For a closer look at onion nutrient data, an educational onion nutrition facts sheet based on USDA figures is available through an onion nutrition facts PDF that lists vitamin C, vitamin B6, folate, and more per medium onion.3
What Vitamin Is Found In Onion? Final Thoughts
By now the main takeaway is clear: vitamin C is the standout answer to “what vitamin is found in onion?”, with vitamin B6, folate, and other B vitamins playing smaller yet steady roles. Onions will not replace citrus fruit as your only vitamin C source, yet they fill in gaps across the day and bring helpful plant compounds alongside their vitamins.
When you chop an onion for a stew, toss a spoonful of raw onion on tacos, or roast onions with chicken, you add flavor and a quiet layer of nutrients at the same time. Used often, in a mix of raw and lightly cooked dishes, onions help you move closer to daily vitamin C and B-vitamin needs while keeping meals familiar, affordable, and easy to prepare.