Alfalfa sprouts: the trial placebo with an outbreak record

Two randomized trials used raw alfalfa sprouts as the placebo. In 48 people infected with H. pylori, 70 g a day for 8 weeks did not lower the markers of infection, while broccoli sprouts did. In a second trial, 16 healthy adults drank alfalfa sprout shakes for 4 days as the control arm against broccoli sprouts. Neither trial set out to test alfalfa itself, and we found no trial that did. What the record holds instead is outbreaks. In Norway in 2024 a Salmonella outbreak traced to alfalfa sprouts made 230 people ill and put 33 percent of them in hospital, and people who ate sprouts had 3.13 times the odds of illness. In Sweden the same year, among 100 cases, alfalfa sprout eaters had 8.94 times the odds (95% CI 2.96 to 27.1), though Salmonella was not found in the sprouted seed tested. Children aged 10 or younger made up 17 percent of those Swedish cases.

As people eat it, per 3.5 oz (100 g)

How much is actually in it

• Raw alfalfa sprouts in UK data carry 24 calories, 4.0 g protein, 1.7 g fiber and 1.0 mg iron per 3.5 oz (100 g). — CoFID 2021 Alfalfa sprouts, raw (13-148) (n = 1 record) Evidence E source
  24 calories, protein 4.0 g, NSP fiber 1.7 g, fat 0.7 g, calcium 32 mg, iron 1.00 mg, potassium 79 mg, water 93.4 g per 3.5 oz (100 g)

What a real portion looks like

• A cup of raw alfalfa sprouts weighs 1.2 oz (33 g) in USDA survey data and gives about 8 calories, 1.3 g protein and 10 ug vitamin K. — USDA FNDDS Alfalfa sprouts, raw (75100500) (n = 2 measures) Evidence E source
  Per 100 g: 23 calories, protein 3.99 g, vitamin K 30.5 ug, folate 36 ug DFE; 1 cup 33 g; unspecified quantity 17 g

What cooking and storage change

• In a 1999 Colorado outbreak of 112 Salmonella infections, the grower who presoaked seeds in 20,000 ppm calcium hypochlorite had 0.29 infections per seed bag against 1.13 for the one who did not. — 20 cases and 58 matched controls; 112 culture-confirmed illnesses (n = 112) Evidence C source
  0.29 vs 1.13 culture-confirmed infections per 50-pound bag of seed
• A 2001 outbreak of 31 Salmonella Kottbus cases followed alfalfa seeds soaked in 2,000 ppm sodium hypochlorite instead of the FDA-recommended 20,000 ppm calcium hypochlorite. — 31 cases in three western US states; 10 cases and 20 matched controls (n = 31) Evidence C source
  Illness statistically associated with alfalfa sprouts; seeds disinfected below FDA-recommended strength
• FDA advises children, older adults, pregnant women and people with weakened immunity to avoid raw or lightly cooked sprouts of any kind, including alfalfa, and notes thorough cooking kills harmful bacteria. — people more vulnerable to foodborne illness Evidence E source
  Avoid raw or lightly cooked sprouts; thorough cooking kills harmful bacteria

What it does to your health

• In an RCT of 48 H. pylori-infected patients, 70 g a day of alfalfa sprouts for 8 weeks served as placebo and did not lower colonization markers, while broccoli sprouts did. — Helicobacter pylori-infected patients (n = 48) Evidence B source
  Alfalfa sprouts 70 g/d: no decrease in urea breath test, stool antigen or pepsinogens; broccoli sprouts decreased them
• In a double-blind RCT, 16 adults drank alfalfa sprout shakes for 4 days as the control arm, and broccoli sprout shakes in 13 adults raised NK-cell granzyme B after a flu vaccine more than alfalfa did. — healthy non-smoking volunteers given live attenuated influenza vaccine (n = 29) Evidence B source
  Broccoli vs alfalfa: higher virus-induced granzyme B in NK cells on day 2
• Across 3 US cohorts, alfalfa sprouts ranked among the top 5 of 52 fruits and vegetables for favorable cardiometabolic biomarkers, and a higher share of such items was linked to 11% to 16% lower chronic disease risk. — 41,714 participants for biomarkers; 207,241 followed 32 years (HPFS, NHS, NHSII) (n = 207241) Evidence C source
  Highest vs lowest quality proportion: HR 0.85 (0.81-0.90) to 0.89 (0.84-0.94) across quantity strata

What people believe that the data does not support

• Macaques fed alfalfa sprouts developed a lupus-like syndrome, and L-canavanine, a constituent of the sprouts, reactivated it when added to their diet. — cynomolgus macaques Evidence D source
  Hematologic and serologic abnormalities similar to SLE; reactivated by dietary L-canavanine sulfate

Who this works differently for

• A 2024 Norwegian Salmonella outbreak traced to alfalfa sprouts sickened 230 people and hospitalized 33%, with sprout eaters at 3.13 times the odds of illness. — 230 cases, median age 48 years, Norway, October to December 2024 (n = 230) Evidence C source
  Hospitalization 33%; penalized adjusted OR 3.13 for sprout consumption
• In a 2024 Swedish outbreak of 100 Salmonella cases, 17% were children up to 10 years, and eating alfalfa sprouts carried 8.94 times the odds of illness. — 100 confirmed cases, Sweden, August to November 2024 (n = 100) Evidence C source
  Adjusted OR 8.94 (95% CI 2.96-27.1); 17% of cases aged 0-10 years
• Two 2003 E. coli O157 outbreaks in Minnesota and Colorado were traced to alfalfa sprouts from one seed source, even where the sprouter followed FDA guidance. — 7 persons in Minnesota and 13 in Colorado (n = 20) Evidence C source
  Infections linked to eating alfalfa sprouts in independent case-control studies

The bottom line

As food the sprouts are light. UK tables give 24 calories, 4.0 g of protein, 1.7 g of fiber and 1.0 mg of iron per 3.5 oz (100 g), from a single record. A cup weighs 1.2 oz (33 g) in US survey data, which comes to about 8 calories, 1.3 g of protein and 10 micrograms of vitamin K. In three large US cohorts followed for up to 32 years, alfalfa sprouts ranked in the top 5 of 52 fruits and vegetables for favorable cardiometabolic blood markers. People whose produce leaned toward those high-quality items had lower chronic disease risk, with hazard ratios between 0.84 and 0.89. That is an association for the whole group of such vegetables and says nothing about alfalfa on its own. Disinfecting the seed lowers the risk and does not remove it. In a 1999 Colorado outbreak of 112 Salmonella infections, the one grower who presoaked seed in 20,000 ppm calcium hypochlorite accounted for 0.29 infections per 50-pound bag against 1.13 for the grower who did not, and the sprouts in that outbreak were clover. A 2001 outbreak of 31 cases across three western US states followed alfalfa seed soaked in 2,000 ppm sodium hypochlorite instead of the recommended calcium hypochlorite at 20,000 ppm. Two 2003 E. coli O157 outbreaks, 7 people in Minnesota and 13 in Colorado, came from one seed source, and the Colorado sprouter had reportedly followed FDA guidance. The FDA notes that thorough cooking kills harmful bacteria. Who should be careful. The FDA advises children, older adults, pregnant women and people with weakened immunity to avoid raw or lightly cooked sprouts of any kind, alfalfa included. The lupus story comes from monkeys. In a 1982 study, cynomolgus macaques fed large amounts of alfalfa sprouts developed blood abnormalities resembling lupus, and L-canavanine, a compound in the sprouts, reactivated the syndrome when added to their diet. We found no human data on eating sprouts and lupus, so this remains an animal finding.

Sources

1. alfs-daily-r4-01 · food composition dataset
   Alfalfa sprouts, raw (13-148): Energy 24 kcal | Protein 4.0 g | NSP 1.7 g | Fat 0.7 g | Calcium 32 mg | Iron 1.00 mg | Potassium 79 mg | Water 93.4 g
   CoFID 2021 (Public Health England, OGL v3.0), code 13-148 Alfalfa sprouts, raw · checked 2026-09-29
2. alfs-daily-r4-02 · reference dataset
   Alfalfa sprouts, raw, FNDDS 75100500, fdc_id 2709765: 1 cup 33 g | Quantity not specified 17 g || Energy 23 kcal | Protein 3.99 g | Vitamin K (phylloquinone) 30.5 ug | Folate, DFE 36 ug per 100 g
   USDA FNDDS (FoodData Central survey 2024-10-31), Alfalfa sprouts, raw, food code 75100500, fdc_id 2709765 · checked 2026-09-29
3. alfs-daily-r4-08 · case-control
   Only one of the sprouters presoaked seeds as recommended, and fewer infections were attributable to this sprouter (0.29 vs. 1.13 culture-confirmed infections/50-pound (110.1-kg) bag of seed). ... Presoaking contaminated seeds in a 20,000 mg/liter calcium hypochlorite solution reduces, but does not eliminate, the risk of infection.
   Am J Epidemiol, 2001 · checked 2026-09-29
4. alfs-daily-r4-09 · case-control
   Overall, we identified 31 cases from three western states. ... Our case-control study found illness to be statistically associated with alfalfa sprout consumption. ... Most implicated sprouts were from seeds that underwent heat treatment and soaking with a 2,000-ppm sodium hypochlorite solution rather than the Food and Drug Administration (FDA)-recommended 20,000-ppm calcium hypochlorite soak.
   J Food Prot, 2003 · checked 2026-09-29
5. alfs-daily-r4-10 · agency guidance
   People who are more vulnerable to foodborne illness (as identified above) should avoid eating raw or lightly cooked sprouts of any kind (including onion, alfalfa, clover, radish, and mung bean sprouts). ... Cooking produce thoroughly kills harmful bacteria and reduces the risk of illness.
   FDA, Selecting and Serving Produce Safely, consumer guidance, updated 2024 · checked 2026-09-29
6. alfs-daily-r4-03 · randomized controlled trial
   Forty-eight H. pylori-infected patients were randomly assigned to feeding of broccoli sprouts (70 g/d; containing 420 micromol of SF precursor) for 8 weeks or to consumption of an equal weight of alfalfa sprouts (not containing SF) as placebo. Intervention with broccoli sprouts, but not with placebo, decreased the levels of urease measured by the urea breath test and H. pylori stool antigen (both biomarkers of H. pylori colonization) and serum pepsinogens I and II (biomarkers of gastric inflammation).
   Cancer Prev Res (Phila), 2009 · checked 2026-09-29
7. alfs-daily-r4-04 · randomized controlled trial
   We carried out a randomized, double-blinded, placebo-controlled study measuring the effects of BSH (N = 13) or placebo (alfalfa sprout homogenate, ASH; N = 16) on peripheral blood mononuclear cell responses to a standard nasal vaccine dose of LAIV in healthy volunteers. ... BSH supplementation further increased LAIV-induced granzyme B production (day2) in NK cells compared to ASH
   PLoS One, 2016 · checked 2026-09-29
8. alfs-daily-r4-05 · prospective cohort
   Of 52 FV items, 19 were identified as high-metabolic quality (top 5: apples/pears, iceberg/head lettuce, raw spinach, alfalfa sprouts, and eggplant/summer squash). ... In each quantity level stratum (quartiles Q1-Q4), comparing the highest to the lowest quality proportion quartiles, the hazard ratio (HR) (95% confidence interval [CI]) were 0.85 (0.81-0.90), 0.86 (0.82-0.90), 0.84 (0.80-0.89), and 0.89 (0.84-0.94), all P-trend < 0.001.
   Am J Clin Nutr, 2024 · checked 2026-09-29
9. alfs-daily-r4-12 · animal study
   Hematologic and serologic abnormalities similar to those observed in human systemic lupus erythematosus (SLE) developed in cynomolgus macaques fed alfalfa sprouts. L-Canavanine sulfate, a constituent of alfalfa sprouts, was incorporated into the diet and reactivated the syndrome in monkeys in which an SLE-like syndrome had previously been induced by the ingestion of alfalfa seeds or sprouts.
   Malinow MR et al. Systemic lupus erythematosus-like syndrome in monkeys fed alfalfa sprouts: role of a nonprotein amino acid. Science, 1982 · checked 2026-09-29
10. alfs-daily-r4-06 · case-control
    A total of 230 cases (69% female, median age: 48 years) were identified, with 33% requiring hospitalization. ... A matched case-control study found cases to be associated with consumption of sprouts (penalized adjusted odds ratio of 3.13). WGS established genetic links between clinical, food, and environmental isolates, identifying alfalfa sprouts as the outbreak source.
    Infection, 2025 · checked 2026-09-29
11. alfs-daily-r4-07 · case-control
    The highest proportions of cases were observed among individuals aged 0-10 years (17%) and 41-50 years (20%), with females representing 65% of the total cases. ... A matched case-control study found cases to be associated with the consumption of alfalfa sprouts (adjusted odds ratio = 8.94, 95% CI: 2.96-27.1).
    Epidemiol Infect, 2025 · checked 2026-09-29
12. alfs-daily-r4-11 · case-control
    Escherichia coli O157 outbreaks were identified in Minnesota in February 2003 involving seven persons and in Colorado in July 2003 involving 13 persons. ... The Colorado sprouter reportedly complied with the Food and Drug Administration (FDA) sprout guidance, whereas the Minnesota sprouter did not. ... This reaffirms the FDA recommendation that raw alfalfa sprouts should be considered potentially contaminated and avoided by persons at high-risk such as the elderly, young children, and immunocompromised persons.
    Epidemiol Infect, 2005 · checked 2026-09-29