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Asparagus benefits center on two vitamins: half a cup of boiled asparagus supplies about a third of the Daily Value for folate and 38% for vitamin K, for only about 20 calories, according to USDA data. It also adds fiber, a little plant protein, copper and B vitamins, plus a type of fermentable fiber that feeds gut bacteria. Below are the USDA asparagus nutrition facts, what those nutrients do, how fresh, frozen and canned spears compare, who should be careful, and the science behind the famous asparagus pee smell.
Peptide Labs does not sell asparagus or asparagus products. This article is general nutrition information, not medical advice.
Key Takeaways
- Half a cup of boiled asparagus has about 20 calories, 34% of the Daily Value for folate and 38% for vitamin K in USDA data.
- Asparagus contains inulin, a fermentable fiber that can cause gas in sensitive people.
- Frozen asparagus holds up well; canned spears carry much more sodium.
- People on warfarin should keep vitamin K intake consistent rather than avoid green vegetables.
- The urine smell is real, and a genetic study found most people in its sample could not detect it.
Asparagus nutrition per half cup and per cup
The table uses two USDA FoodData Central SR Legacy entries: boiled, drained asparagus (FDC 168390), shown for half a cup of 90 grams, and raw asparagus (FDC 168389), shown for one cup of 134 grams. The percent Daily Value (%DV) uses the FDA Daily Values on Nutrition Facts labels.
| Nutrient | Boiled, 1/2 cup (90 g) | %DV | Raw, 1 cup (134 g) | %DV |
|---|---|---|---|---|
| Calories | 20 | Not applicable | 27 | Not applicable |
| Protein | 2.2 g | 4% | 3.0 g | 6% |
| Carbohydrate | 3.7 g | 1% | 5.2 g | 2% |
| Fiber | 1.8 g | 6% | 2.8 g | 10% |
| Folate (DFE) | 134 micrograms | 34% | 70 micrograms | 17% |
| Vitamin K | 45.5 micrograms | 38% | 55.7 micrograms | 46% |
| Copper | 0.15 milligrams | 16% | 0.25 milligrams | 28% |
| Thiamin (vitamin B1) | 0.15 milligrams | 12% | 0.19 milligrams | 16% |
| Riboflavin (vitamin B2) | 0.13 milligrams | 10% | 0.19 milligrams | 15% |
| Selenium | 5.5 micrograms | 10% | 3.1 micrograms | 6% |
| Vitamin E | 1.4 milligrams | 9% | 1.5 milligrams | 10% |
| Vitamin C | 6.9 milligrams | 8% | 7.5 milligrams | 8% |
| Iron | 0.8 milligrams | 5% | 2.9 milligrams | 16% |
| Vitamin A (RAE) | 45 micrograms | 5% | 51 micrograms | 6% |
| Potassium | 202 milligrams | 4% | 271 milligrams | 6% |
| Sodium | 13 milligrams | 1% | 3 milligrams | Under 1% |
One quirk is worth knowing: the USDA boiled entry lists about three times more folate per gram than the raw entry, and the raw entry lists more iron. The two entries come from separate analyses of different samples, so read both as approximate rather than proof that cooking adds folate. Either way, asparagus is mostly water, about 93% by weight, which keeps asparagus calories very low.
Asparagus benefits: folate, vitamin K and fiber
Folate. The ODS folate fact sheet lists asparagus among the richest food sources, alongside spinach, liver and Brussels sprouts. Folate is a B vitamin the body needs to make DNA and to divide cells, which is why it matters so much before and during pregnancy. Food folate is not the same as folic acid, the form used in supplements and fortified grains; our methylfolate guide explains the forms. Anyone who could become pregnant should talk to a clinician about folic acid rather than relying on vegetables alone.
Vitamin K. According to the ODS vitamin K fact sheet, vitamin K helps activate proteins involved in blood clotting and bone metabolism. Asparagus is a solid source, though dark leafy greens supply several times more; see our vitamin K food list for the full chart.
Fiber, including inulin. Asparagus is one of the vegetables that naturally contains inulin, a fermentable fiber described in a 2018 review in Current Developments in Nutrition and in Cleveland Clinic guidance. Gut bacteria ferment it, which is why asparagus shows up in our guide to prebiotic foods. It also adds lutein and zeaxanthin, the yellow pigments covered in our lutein guide, and smaller amounts of vitamins C and E (see antioxidant foods).
Why does asparagus make your pee smell?
The asparagus pee smell is real and well studied. Researchers at the Monell Chemical Senses Center described it in a 2011 study in Chemical Senses as a sulfurous odor similar to cooked cabbage, and found that people differ both in whether they produce the odor compounds in noticeable amounts and in whether they can smell them. The odor comes from sulfur compounds formed as the body breaks down substances in asparagus.
A 2016 Harvard genome-wide study in the BMJ looked at 6,909 men and women of European-American descent from two long-running health studies. Only people who strongly agreed that they noticed a strong odor counted as smellers; by that measure, 58% of the men and 61.5% of the women could not detect it. The inability was linked to genetic variants near a cluster of olfactory receptor genes on chromosome 1, and the authors said the finding needs replication. Neither study describes the smell as a health problem; it is a quirk of digestion and genetics.
Fresh, frozen and canned asparagus
Frozen asparagus is a good stand-in for fresh, while regular canned spears add a lot of salt. Here is how the USDA entries compare per serving:
| Form (USDA entry) | Serving | Calories | Folate %DV | Vitamin K %DV | Sodium |
|---|---|---|---|---|---|
| Boiled, fresh (168390) | 1/2 cup (90 g) | 20 | 34% | 38% | 13 milligrams |
| Raw (168389) | 1 cup (134 g) | 27 | 17% | 46% | 3 milligrams |
| Frozen, boiled, no salt (169209) | 1/2 cup (90 g) | 16 | 30% | 60% | 3 milligrams |
| Canned, drained (169207) | 1/2 cup (121 g) | 23 | 29% | 42% | 347 milligrams |
USDA SR Legacy does not list separate values for white or purple asparagus, so the table covers standard green spears. For canned asparagus, a no-salt-added label is the simplest way to keep sodium down.
Is asparagus good for you? Who should be careful
For most people, yes: asparagus is a nutrient-dense, low-calorie vegetable. A few groups should pay attention:
- People taking warfarin: ODS calls the warfarin and vitamin K interaction serious, and MedlinePlus advises eating consistent amounts of vitamin K foods from week to week and talking to your doctor before you change your diet. Asparagus is fine for many people on warfarin, but sudden large changes in how much you eat are what matter.
- Sensitive digestion: inulin-type fructans are FODMAPs, the fermentable carbohydrates Monash University researchers link to gut symptoms in some people. If asparagus leaves you gassy, our low-FODMAP guide and gas and bloating guide explain why.
- Herbal confusion: shatavari is an herbal supplement made from a different Asparagus species, not from the vegetable; see our shatavari guide.
Asparagus also pairs well with other vegetables on a plate; our sibling guide to carrots covers a vegetable that brings the vitamin A that asparagus lacks.
Frequently Asked Questions
What are the main asparagus benefits?
Asparagus is rich in folate and vitamin K, with fiber, copper and B vitamins, for very few calories in USDA data.
How many calories are in asparagus?
About 20 calories in half a cup of boiled asparagus and about 27 in a cup of raw asparagus, according to USDA.
Why does asparagus make urine smell?
The body breaks down asparagus into sulfur compounds that pass into urine. Many people either do not produce enough to notice or cannot smell it.
Is frozen asparagus as nutritious as fresh?
In USDA data, frozen boiled asparagus is close to fresh for folate and vitamin K. Canned spears carry much more sodium.
Can I eat asparagus if I take warfarin?
Usually yes, but keep your vitamin K intake consistent from week to week and ask your doctor before making changes.
Is asparagus good for gut health?
It contains inulin, a fermentable fiber that gut bacteria use. That same fiber can cause gas in sensitive people.
Questions about a label? Contact us or read our Buyer’s Guide. Food comes first; follow the label and ask a healthcare provider before starting a supplement, especially if you take medicines, are pregnant or have a food allergy. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Last reviewed October 2026.
Related guides: Carrots Benefits: USDA Carrot Nutrition, Vitamin A and Skin Color, Foods High in Vitamin K: USDA List, K1 vs K2 and Warfarin Notes, High Fiber Foods: USDA List of Fruits, Vegetables, Beans and Grains.