Onion tops, also known as onion greens, are the green stalks and leaves that extend from the onion bulb. They are often trimmed off and discarded before the onion is used. However, onion tops are edible and provide some health benefits.
Nutritional value
Onion tops are highly nutritious, sometimes even more so than the onion bulb itself. Here is how 3.5 ounces (100 grams) of raw onion tops compare nutritionally to the same amount of raw onion bulb (1):
| Nutrient | Onion tops | Onion bulb |
|---|---|---|
| Calories | 28 | 40 |
| Protein | 1.5 g | 1.1 g |
| Carbs | 5.4 g | 9.3 g |
| Sugar | 2.5 g | 4.2 g |
| Fiber | 1.7 g | 1.7 g |
| Vitamin C | 11% DV | 8% DV |
| Vitamin B6 | 14% DV | 12% DV |
| Folate | 6% DV | 3% DV |
| Calcium | 5% DV | 3% DV |
| Iron | 11% DV | 3% DV |
| Magnesium | 7% DV | 4% DV |
| Potassium | 8% DV | 5% DV |
As you can see, onion tops contain more protein, vitamin C, vitamin B6, folate, calcium, iron, magnesium and potassium than the bulb. The greens have fewer calories and carbohydrates as well.
Antioxidants and quercetin
Onion tops are an excellent source of antioxidants, including the flavonoid quercetin. Quercetin is concentrated mostly in the outer layers of onion, so the leaves and stalks are very high in this compound (2).
Quercetin has been shown to reduce inflammation, lower blood pressure, improve heart health and have antioxidant effects that help fight cancer. It may also help reduce symptoms of prostatitis and boost athletic performance (2, 3, 4).
One study found that shallot skins, which have a similar nutrient profile to onion skins and tops, have nearly six times the antioxidant activity of the shallot flesh (5).
Quercetin and other antioxidants are concentrated in the outermost layers of onions, so make sure to use the tops and even the skins of onions whenever possible.
Other plant compounds
In addition to quercetin, onion tops contain other beneficial plant compounds, such as (6):
- Anthocyanins: These give red onion tops their color and act as antioxidants in your body.
- Kaempferol: An antioxidant that may protect against cancer and heart disease.
- Myricetin: Also an antioxidant that may lower the risk of certain cancers.
- Glycosides: Compounds that may lower blood pressure.
These and other plant compounds found in the leaves and stalks of onions provide additional health benefits.
Uses in cooking
Onion tops can be used raw or cooked. They have a taste that is more mild than regular onion bulbs.
Here are some ways you can use onion tops in recipes:
- Chop up raw tops and add to salads, soups, tacos, burritos, salsa and guacamole.
- Saute onion greens in olive oil and add seasonings to make a side dish.
- Add onion tops to any dish you would normally add onion bulbs to, like casseroles, pasta, pizza, etc.
- Use chopped onion leaves as a garnish over finished dishes.
- Puree into sauces, dips and dressings.
- Juice along with other veggies and fruits.
- Pickle onion greens as a snack or condiment.
- Wrap food in onion tops in place of tortillas.
Onion skins can also be used to add color and flavor to dishes. Add skins to stocks and broths while cooking, then remove before serving.
Potential concerns
Onion tops are very low in calories and carbs and can be enjoyed as part of a healthy diet.
However, they do contain fructans, which are FODMAPs that can cause issues for some people with irritable bowel syndrome (IBS) or small intestinal bacterial overgrowth (SIBO) (7).
Start by eating just a little bit of onion greens at a time if you have IBS or SIBO and monitor for any discomfort. Cooking the tops may help reduce the FODMAP content.
Additionally, onion tops have been shown to be goitrogenic in animals, meaning they can interfere with proper thyroid function if consumed in very high amounts for a long period of time (8).
This is likely only a concern for people eating huge amounts of onion tops every day for years, so moderate intake should not be an issue.
Conclusion
Onion tops are highly nutritious, providing a concentrated dose of flavonoids, anthocyanins, vitamin C and other antioxidants.
Adding onion leaves and stalks to your diet is an easy way to get more nutrients and take advantage of these healthy vegetable scraps.
Use onion tops raw or cooked in a variety of recipes to boost the nutritional value of your meals.
