Benefits
Fasting glucose and triglycerides with dried spear powder
In a 12-week placebo-controlled trial in 44 overweight or obese adults, capsules of dried green asparagus spear powder (about 2.5 to 3.5 g a day) kept fasting glucose and triglycerides lower than maltodextrin placebo. Much of the gap came from rises in the placebo group, which also started higher; insulin and LDL cholesterol did not differ between groups, and this was a single small trial.
A source of folate, vitamin K and fiber
Per 100 g raw, USDA lists about 52 micrograms of folate, 41.6 micrograms of vitamin K, 2.1 g of fiber, 202 mg of potassium and 20 kcal. USDA's boiled asparagus entry lists 149 micrograms of folate per 100 g; the two entries come from different samples, so folate varies.
Rutin, saponins and inulin-type fructans in the spear
Laboratory analyses found green spears, especially the tips, rich in the flavonoid rutin (about 1.5 to 7.3 mg per g dry weight), and white spears rich in the saponin protodioscin. Spears and by-products also contain inulin-type fructans, fermentable fibers like those in chicory inulin. These are composition data, not measured effects in people.
Night waking with an enzyme-treated stem extract (ETAS)
ETAS is a branded, enzyme-treated asparagus stem extract, not the vegetable. In a 14-day placebo-controlled crossover in 38 adults unhappy with their sleep, 300 mg a day did not change deep sleep, the main outcome, but cut time awake after falling asleep by about 9 minutes. The extract's maker funded and ran the study.
Blood pressure and cholesterol with asparagus by-product powders
In a 10-week open study in 28 Japanese volunteers, 6 g a day of powder from the woody stem bottoms or the fern-like cladophylls was followed by lower blood pressure, fasting glucose and total cholesterol within each group. There was no placebo or untreated group, and a powder supplier co-authored the study.
Asparagus root extract alongside interval training
In a 12-week unblinded trial in 72 young overweight adults, interval training improved blood fats and glucose, while a root extract rich in 20-hydroxyecdysone taken without exercise did not; LDL cholesterol and a marker of oxidative damage rose within the extract-only group. Root extract is a different material from the spear.
Mechanism of action
Fermentable fructans feed gut bacteria
Asparagus spears and by-products contain inulin-type fructans and other non-digestible carbohydrates. In laboratory cultures, spear by-product material selectively supported the growth of lactobacilli and bifidobacteria strains. These culture results have not been confirmed in people eating asparagus.
Asparagusic acid and the urine odor
Asparagusic acid, a small sulfur-containing compound that appears unique to asparagus, is considered the most likely precursor of the odor. Within a few hours of eating asparagus, urine can contain methanethiol, dimethyl sulfide, dimethyl disulfide and related sulfur compounds. The odor appears to be harmless.
Alcohol-processing enzymes in liver cell studies
In human liver cancer cells (HepG2), extracts of asparagus leaves and shoots more than doubled the activity of alcohol dehydrogenase and aldehyde dehydrogenase and reduced damage from ethanol and hydrogen peroxide. This is cell work only; no human hangover trial was found.
Clinical trials
Randomized, double-blind, placebo-controlled exploratory trial (NCT06195813) of capsules of oven-dried green asparagus spear powder (40 mg/kg/day, about 2.5 to 3.5 g/day, not standardized) versus maltodextrin. The paper names fasting glucose as the primary endpoint, but the trial was registered only after it ended and the registry lists eight primary outcomes, including body fat, which did not differ. Funded by a Burapha University faculty grant; no conflicts declared. (Mongraykang et al. 2025, Life (Basel))
48 overweight or obese adults aged 18 to 59 in Chonburi, Thailand; 44 completed (23 asparagus, 21 placebo).
Fasting glucose fell from 94.5 to 92.3 mg/dL with asparagus and rose from 97.4 to 99.9 mg/dL with placebo (between-group p = 0.045). Triglycerides changed by -3 mg/dL with asparagus versus +43 mg/dL with placebo (p = 0.043); glucose area under the curve and the oxidation marker MDA were also lower. Insulin, HOMA-IR, LDL, HDL and total cholesterol did not differ between groups. Between-group tests compared end-of-study values adjusted for age, and the placebo group started higher for both glucose and triglycerides (138.8 versus 116.3 mg/dL), so much of the difference reflects the placebo group's starting point and worsening.
Open-label study in which volunteers were randomized to one of two asparagus by-product powders, 6 g/day, with no placebo or untreated group. The bottom-stem powder was blended 1:1:7 with trehalose and dextrin. Powders were supplied by Hokushin Foods, whose staff member is a co-author. (Nishimura et al. 2013, J Tradit Complement Med)
28 Japanese volunteers (14 per group); 27 completed.
Within the bottom-stem group, systolic pressure fell from 143.2 to 134.6 mmHg at 10 weeks; both groups showed lower fasting glucose (for example 104.1 to 100.9 mg/dL) and total cholesterol, and HbA1c did not change. Only before-and-after changes were tested, so the results cannot separate an asparagus effect from time, season or study participation.
Randomized, non-blinded, four-arm trial (TCTR20230608004, registered retrospectively): usual activity, root extract only (20-hydroxyecdysone about 1.71 mg/kg/day), interval training only, or both, for 12 weeks. Funded by the National Research Council of Thailand and Burapha University. (Prasertsri et al. 2025, Int J Mol Sci)
72 overweight or obese adults aged 18 to 30 in Thailand (18 per group).
Training alone improved total cholesterol, the cholesterol/HDL ratio, HDL and glucose versus control. The extract-only group showed higher superoxide dismutase activity but also rises in malondialdehyde (an oxidative damage marker) and LDL cholesterol (+14 mg/dL within the group). Neither extract nor training alone changed IL-6 or TNF-alpha; the combined group had lower IL-6 and protein carbonyls.
Randomized, placebo-controlled, double-blind crossover (UMIN000055685): ETAS50 300 mg/day or dextrin placebo for 14 days each, 14-day washout, sleep measured by home EEG. Funded by Amino Up, the maker of ETAS, and all authors were Amino Up employees. (Misu et al. 2026, Sleep Med X)
38 healthy Japanese adults dissatisfied with their sleep.
The primary outcome, the proportion of deep (N3) sleep, did not differ from placebo. Wake time after sleep onset fell by about 8.7 minutes (p = 0.029) and N1 time also fell, and Athens Insomnia Scale scores improved. Subgroup findings in poor sleepers came from post-hoc analyses.
Randomized, double-blind, placebo-controlled trial of 30 mg/day of 20-hydroxyecdysone derived from an asparagus extract, with supervised resistance training three times a week. Funding is not stated in the abstract. (Sripinyowanich et al. 2025, J Nutr Sci Vitaminol (Tokyo))
20 healthy resistance-trained young men (10 per group).
Arm fat fell more than with placebo, and fat oxidation was higher only at 40% of peak oxygen uptake. Fasting insulin, free fatty acids and an insulin sensitivity index improved within the 20-hydroxyecdysone group. This tests a single plant steroid, not asparagus as a food; see the ecdysterone page.
Controlled crossover in which each person ate 125 g of roasted asparagus and, on another day, a bread roll; urine samples were judged by forced-choice sniff tests, and an olfactory gene variant was typed. (Pelchat et al. 2011, Chem Senses)
38 adults aged 18 to 65 in Philadelphia, in two experiments.
Most people produced a detectable odor within 2 hours, but 3 of 37 who gave urine did not produce enough to be detected, and 2 of 31 who did the sniff tests could not smell it in others' urine despite a normal sense of smell. Inability to smell it was linked to a variant near an olfactory receptor gene cluster.