Asparagus: Nutrients, What Research Shows and Safety

Asparagus (Asparagus officinalis) is the young shoot, or "spear," of a perennial plant in the asparagus family. Green spears are the most common; white spears are grown without light. People eat asparagus for its taste and as a source of folate and vitamin K. This page keeps the food apart from supplements and extracts, and says plainly where evidence is thin.

Read this first

• Warfarin (Coumadin): asparagus contains vitamin K, and MedlinePlus says sudden changes in vitamin K intake can change how this medicine works. Eat a steady amount and tell the person who manages your warfarin before you change it. [1][2]
• Pregnancy: asparagus is a natural folate source, but MedlinePlus says it can be hard to get enough folate from food, so people planning a pregnancy are advised to ask about folic acid. [3]
• Urine smell: a strong sulfur smell in urine after eating asparagus is a known, harmless effect. Not everyone makes it, and not everyone can smell it. [4][5][6]
• Allergy: true asparagus allergy is uncommon but reported, including from handling raw spears. For trouble breathing or swelling of the face or throat, call 911. [7][8]
• Evidence in one line: asparagus is a useful folate and vitamin K food; we found no trials showing that eating it prevents or treats any disease.

What is in it (USDA values)

USDA FoodData Central, "Asparagus, raw" (SR Legacy). [9] % Daily Value uses the FDA 2016 Daily Values; values vary with variety, ripeness and storage.

USDA also lists lutein plus zeaxanthin (710 mcg per 100 g) and beta-carotene (449 mcg per 100 g) in raw asparagus. [9] These are carotenoids (yellow-orange plant pigments). We did not find a human trial that tests these amounts in asparagus for a health outcome. A review of green and white asparagus describes a rich mix of plant chemicals and notes that more research is needed. [10]

What research says

Eaten as food vs taken as a supplement or extract. The cancer, burning mouth and exercise studies above used manufactured granules, capsules, liquids or root extracts. They tell us little about a plate of spears. Our search found no trial of eating asparagus as a food for a disease outcome: Proper evidence not found in the sources we read.

How much is a normal serving

• USDA household portion: 1 cup of raw asparagus is 134 g; a medium spear is 16 g, a large spear 20 g. [9] Five medium spears is about 80 g by simple arithmetic.
• NHS (reviewed 9 June 2026): 80 g of fresh, canned or frozen vegetables counts as one portion of 5 A DAY. [19]
• WHO (26 January 2026): at least 400 g of fruits and vegetables a day for people older than 10. [20]
• These are official figures for information, not a prescription. We did not find a source we could read on how cooking changes the folate or vitamin K in asparagus, so we make no claim. Fresh, frozen and canned vegetables are compared on our page about fresh, frozen and canned produce.

Safety, allergy and medicines

• Warfarin and other vitamin K medicines: MedlinePlus advises keeping vitamin K intake about the same each day because sudden changes can change the medicine's effect. [2] Asparagus is listed among foods with vitamin K. [1] Ask your prescriber or pharmacist. See foods and medicine interactions: vitamin K, grapefruit and others.
• Urine odor: about 43% of 800 volunteers in one study made odorous urine after eating asparagus, and the trait looked inherited. [5] A later study found that making the odor and being able to smell it are separate traits, and that the inability to smell it is linked to a gene variant in a cluster of smell receptors. [4] Asparagusic acid, a sulfur compound in asparagus, is thought to be the source, and is described as apparently harmless in toxicology terms. [6] In one crowdsourced study the effect had a half-life of about 4.7 hours. [21] Persistent smelly urine, pain or fever are not explained by asparagus; see a clinician.
• Allergy: a series of 27 people with asparagus allergy described contact dermatitis, hives on handling, asthma and food allergy, and named lipid transfer proteins as allergens. [7] Two people reacted to fresh asparagus fumes while preparing it but not to cooked asparagus. [8] Allergic contact dermatitis in a farm worker has also been reported. [22] NC State Extension adds that young raw shoots can cause contact dermatitis. [23] For breathing trouble or swelling of the face or throat, call 911. See food allergy basics and emergency signs.
• Purines and gout: purines are natural compounds the body turns into uric acid. A review links high purine intake, mainly from meat, plus alcohol and high fructose corn syrup, to higher uric acid. [13] We did not find a source we could read that gives asparagus-specific purine data or a gout trial, so we make no claim about asparagus. The NHS gout page gives general diet advice only and does not name foods to avoid. [24]
• Garden asparagus berries: the red berries on mature plants are not food. NC State Extension lists the fruits and stems as having low toxicity and says eating the berries can cause stomach problems. [23] Keep them away from children. We did not read a human source on the ornamental asparagus fern, so we make no claim about it.
• Pregnancy: MedlinePlus advises folic acid before and during pregnancy to help prevent neural tube defects. [3] Wash produce under running water. [25] See foods in pregnancy: what official bodies advise.
• Supplements and extracts: reviews of asparagus products in cancer care and burning mouth syndrome report low-certainty evidence and note small samples. [15][16] Products vary and are not covered by the vegetable's safety record. Tell your care team if you take them, especially with chemotherapy.
• Gas and bloating: asparagus plants make fructans, a fiber type that gut bacteria ferment. [14] We did not read a source giving an asparagus FODMAP rating, so we make no claim for people with irritable bowel syndrome.

Choosing, storing and food safety

• Choose spears that are not bruised or damaged, and keep perishable produce in a refrigerator at 40 F or below. [25]
• Rinse under running water, including homegrown spears. Do not use soap, detergent or produce wash. Washing reduces bacteria but does not eliminate them. [25]
• Wash cutting boards and utensils with soap and hot water after raw meat, poultry or seafood. [25]

Related pages

• Foods and medicine interactions: vitamin K, grapefruit and others
• Foods in pregnancy: what official bodies advise
• Fresh, frozen and canned produce
• Prebiotic foods: inulin, onions, garlic and more
• Food allergy basics and emergency signs
• Food and drink interactions with medicines