Quick Answer: Five spears of raw asparagus (about 75 g) provide roughly 15 calories, 1.6 g of fibre, 1.7 g of protein and almost no fat.
Its two standout nutrients are vitamin K, at around a quarter of the Daily Value in that small serving, and folate, at around a tenth. Everything else it contains is present in modest amounts. Asparagus is a genuinely nutritious vegetable with a very low energy cost, which is a good enough reason to eat it. It is not a superfood, and the more dramatic claims made for it do not hold up.
What Is Asparagus?
Asparagus is a perennial flowering plant grown for its edible young shoots, native to Europe, northern Africa and western Asia. Botanically and culinarily it is a vegetable, and it has been eaten for well over two thousand years. Green, white and purple varieties are the same plant grown differently: white asparagus is blanched by mounding soil over the shoots to keep light out, which is why it is paler and milder.
Asparagus Nutrition Facts
Values calculated from USDA FoodData Central and rounded.
| Nutrient | 5 spears raw (75 g) | %DV | Per 100 g raw | Per 100 g boiled |
|---|---|---|---|---|
| Calories | 15 | – | 20 | 22 |
| Protein | 1.7 g | 3% | 2.2 g | 2.4 g |
| Total fat | 0.1 g | 0% | 0.1 g | 0.2 g |
| Total carbohydrate | 2.9 g | 1% | 3.9 g | 4.1 g |
| Dietary fibre | 1.6 g | 6% | 2.1 g | 2.0 g |
| Sugars | 1.4 g | – | 1.9 g | 1.3 g |
| Sodium | 2 mg | 0% | 2 mg | 14 mg |
| Vitamin K | 31 mcg | 26% | 41.6 mcg | 51 mcg |
| Folate | 39 mcg | 10% | 52 mcg | 149 mcg |
| Iron | 1.6 mg | 9% | 2.1 mg | 0.9 mg |
| Vitamin C | 4.2 mg | 5% | 5.6 mg | 7.7 mg |
| Potassium | 152 mg | 3% | 202 mg | 224 mg |
| Vitamin A | 29 mcg RAE | 3% | 38 mcg RAE | 50 mcg RAE |
| Calcium | 18 mg | 1% | 24 mg | 23 mg |
Two notes on that table. Vitamin K is the headline, and it is genuinely high: five spears cover about a quarter of a day’s reference intake, which places asparagus among the better vegetable sources. The folate figures are worth reading carefully – USDA lists boiled asparagus at nearly three times the folate of raw, per 100 g. Some of that is water loss concentrating the remainder by weight, but the gap is larger than that alone explains and the two entries come from different analyses. Treat both as approximate rather than assuming cooking triples the folate.
What Asparagus Actually Does
- Very low energy cost for real volume. A generous portion costs almost nothing in calories while adding fibre and bulk, which is useful for fullness.
- A meaningful vitamin K source. Vitamin K is required for blood clotting and is involved in bone metabolism. Asparagus delivers a real share of it in a small serving.
- A good folate source. Folate is needed for cell division and DNA synthesis, and it matters particularly before and during early pregnancy.
- Contains antioxidants including flavonoids such as quercetin, plus glutathione. Antioxidant content in a food is a reasonable thing to want. It is not a treatment for anything.
- Mildly diuretic. Well known, and why it can slightly increase urine output. That is a comfort effect rather than a weight-loss mechanism, since water weight is not fat.
Asparagus, Folate and Pregnancy
This deserves its own section because the advice circulating online is often exactly backwards.
Asparagus is a good source of folate, and folate is specifically recommended before conception and in early pregnancy to reduce the risk of neural tube defects. There is no reason for most pregnant women to avoid asparagus, and pages telling them to do so have it the wrong way round.
Two things to keep in proportion. Dietary folate from vegetables is a useful contribution but is not a substitute for a folic acid supplement, which health authorities recommend separately because diet alone rarely reaches the intake shown to reduce risk. And asparagus should be washed and cooked as you would any vegetable. Follow your midwife or doctor on supplements and on anything else about your diet in pregnancy.
Who Should Take Care
- People taking warfarin. This is the one that matters most. Asparagus is high in vitamin K, which directly opposes the action of warfarin and similar anticoagulants. You do not need to avoid it – the goal is consistency. Keep your intake of vitamin K-rich vegetables roughly steady week to week rather than swinging between none and a lot, and tell your anticoagulation clinic about any significant dietary change. Newer anticoagulants such as apixaban and rivaroxaban are not affected in the same way.
- People with kidney disease. Asparagus contains potassium and purines. If you have been given dietary limits, follow them.
- Gout. Asparagus is moderately high in purines. Whether vegetable purines matter in practice is genuinely debated, and the evidence is weaker than for meat and seafood, but it is worth raising with your doctor if you get frequent flares.
- Digestive upset. Some people get bloating or gas from asparagus, which contains fructans. That is a tolerance issue rather than a danger, and it is why asparagus is restricted on a low-FODMAP elimination diet.
And the harmless one everyone asks about: asparagus can make urine smell distinctive within about half an hour. This is normal, caused by sulphur compounds, and not a sign of anything wrong. Some people cannot smell it at all.
How to Cook It
- Heat the oven to 400°F (200°C) and wash the spears.
- Snap or trim off the woody ends.
- Toss with a little olive oil, season, and spread on a baking tray in a single layer.
- Roast 10 to 15 minutes until just tender and lightly browned.
Steaming or a quick sauté work equally well. If you are eating asparagus partly for its folate and vitamin C, both are water-soluble, so steaming or roasting preserves more than boiling does – boiling leaches them into water you then pour away. Vitamin K is fat-soluble and largely unaffected by cooking method, and a little oil may help you absorb it.
Finishing with lemon or balsamic vinegar is optional. Butter and olive oil are not unhealthy in normal amounts – they simply add calories, which is worth knowing rather than worrying about.
Asparagus Nutrition, Top 5 Health Advantages
Frequently Asked Questions
About 15 calories in five raw spears, roughly 75 g, and about 20 calories per 100 g raw or 22 per 100 g boiled. That serving also carries around 1.6 g of fibre and 1.7 g of protein with almost no fat, which is why asparagus adds real volume to a plate at a very low energy cost.
Vitamin K and folate are the two that matter. Five spears supply roughly 31 mcg of vitamin K, about 26 percent of the Daily Value, and around 39 mcg of folate, about 10 percent. Iron comes in at roughly 9 percent. Everything else, including vitamin A, vitamin C, potassium and calcium, is present in modest amounts of 5 percent or less per serving. Asparagus also contains flavonoids such as quercetin.
Yes, for most people, and the advice to avoid it is backwards. Asparagus is a good source of folate, which is specifically recommended before conception and during early pregnancy to reduce the risk of neural tube defects. Wash and cook it as you would any vegetable. Dietary folate is a useful contribution but does not replace a folic acid supplement, which health authorities recommend separately. Follow your midwife or doctor on supplements and diet.
Yes, through its vitamin K content, which opposes the action of warfarin and similar anticoagulants. The advice is not to avoid asparagus but to keep intake of vitamin K-rich vegetables reasonably consistent rather than swinging from none to a lot, and to tell your anticoagulation clinic about significant dietary changes. Newer anticoagulants such as apixaban and rivaroxaban are not affected in the same way.
There is no good human evidence for either. Folate and vitamin C are required for normal physiology, but supplying a nutrient to someone who is not deficient does not raise testosterone, and no vegetable makes conception easier. Fertility difficulties deserve proper medical assessment rather than dietary folklore.
No. Diets rich in vegetables are associated with lower risk of some cancers, but no single vegetable protects against cancer or fights cancer cells in the body, and activity observed in a laboratory dish is not a clinical effect. As for detox, your liver and kidneys perform that continuously and no food improves on it. Detox is a marketing idea rather than a physiological one.
No. A cup of asparagus supplies roughly 3 g of protein, against about 6 g in a large egg, and the egg provides a complete protein while asparagus does not. Asparagus is a vegetable, not a protein food, and claims that it matches an egg for protein are simply wrong.
Superfood is a marketing term with no scientific or regulatory definition. Asparagus is a nutritious vegetable worth eating for its vitamin K, folate and fibre at a very low calorie cost. It does not have special powers, and no single food does.
Sulphur compounds in asparagus are broken down into volatile substances that appear in urine within about 30 minutes. It is entirely harmless and not a sign of anything wrong. Some people are genetically unable to smell it at all, which is why not everyone notices.
Related Reading
- How to read nutrition labels to make smarter food choices
- Balsamic vinegar nutrition facts and what the evidence says
- Exploring the Mediterranean diet
- How to spot a fad diet: red flags and the real evidence
Sources
- USDA FoodData Central, for raw and boiled asparagus nutrient data.
- US FDA, Daily Value on the Nutrition and Supplement Facts Labels, for the reference values used in the %DV column.
- Harvard T.H. Chan School of Public Health, Asparagus.
- CDC, About Folic Acid, on folate before and during pregnancy.
Last reviewed and rewritten September 2026. Nutrition figures are calculated from USDA FoodData Central and are approximate; they vary with variety, growing conditions, freshness and preparation. This article is general information, not medical or dietetic advice. If you take warfarin or another vitamin K-sensitive anticoagulant, have kidney disease or gout, or are pregnant, discuss dietary changes with your doctor, pharmacist or midwife. How we research and check this content is described in our editorial process and sources cited policy.
