Lychee: the trials were run on the extract, not the fruit

Almost every trial run under the name lychee used a standardized extract, but the most serious finding on this page is about the fruit itself, in children. In Muzaffarpur, India, between May and July 2014, 390 children aged 15 or younger were admitted with acute brain illness, and 122 of them died. In a matched case-control study, eating litchis in the 24 hours before illness carried an odds ratio of 9.6 (95% CI 3.6 to 24), and the link was stronger in children who had missed the evening meal. Tests for infections and pesticides were negative. Metabolites of two natural fruit toxins that cause low blood sugar, hypoglycin A and MCPG, were found in the urine of 48 of 73 sick children and none of 15 controls. Thirty-six litchis from the area carried 12.4 to 152.0 mcg/g of hypoglycin A and 44.9 to 220.0 mcg/g of MCPG. These are odds ratios from an observational design, in children in a poor rural area, and no agency sets a safe intake for these toxins. The authors recommended minimizing litchi consumption and making sure children eat an evening meal. Lychee also stands out for allergy. At one Dutch allergy clinic, 66.7% of the adults who reported symptoms to lychee had lower airway or cardiovascular symptoms, the highest share among fruits, though fewer than 15 people reported lychee at all. The extract trials are a separate matter. In 66 overweight Japanese adults with a BMI of 25 or more and under 30, 63 of them analyzed, 200 mg a day of a lychee and tea flavanol extract for 12 weeks lowered abdominal visceral fat area against placebo. The abstract gives no size for that difference, and the product carries 40 mg of flavanol monomers and dimers rather than being fruit. The same trial found no clinically relevant adverse events, and 12 weeks is the longest human use tested. Rats tolerated far higher doses, but no agency sets an upper limit for the extract, and we have no study of it in pregnancy, breastfeeding or children, or with medicines.

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

How much is actually in it

• Lab analysis of 36 litchi arils from Muzaffarpur found hypoglycin A at 12.4 to 152.0 mcg/g and MCPG at 44.9 to 220.0 mcg/g, two natural fruit toxins that can cause low blood sugar. — litchis from Muzaffarpur, India, 2014 (n = 36 litchi arils) Evidence D source
  Hypoglycin A 12.4 to 152.0 mcg/g; MCPG 44.9 to 220.0 mcg/g in the edible aril

What it does to your health

• In 63 overweight Japanese adults, 200 mg a day of a lychee polyphenol extract for 12 weeks lowered abdominal visceral fat area against placebo. — 66 overweight adult men and women with BMI of 25 or more and less than 30, 63 analyzed, 12 weeks (n = 66 randomized, 63 analyzed) Evidence B source
  Visceral fat area on computed tomography reduced versus placebo, with no effect size given in the abstract
• Among 20 young male runners across a 2-month training block, a lychee flavanol extract held down the rise in interleukin-6 compared with placebo. — Twenty healthy male long-distance runners at a university, measured before, during and after a 2-month training period (n = 20) Evidence B source
  Smaller change in serum interleukin-6 between pre-training and mid-training, larger change in transforming growth factor beta between pre-training and post-training
• In 25 adults taking a lychee polyphenol extract for 14 days, finger skin temperature and blood flow after a cold water dip were higher on day 14 than on day 1. — 25 participants aged 45.0 on average, 3 males and 22 females, 14 days of capsules, finger immersed in water at 10 degrees (n = 25) Evidence B source
  Skin temperature and peripheral blood flow higher on day 14 than day 1 in both extract groups, with cold sensitivity on a visual analog scale improved over the same interval
• A lychee polyphenol drink held body temperature 0.17 degrees lower after a hot bath in 17 young men, against a placebo drink. — 17 healthy human male volunteers aged 21.6 on average, half-body immersion in water at 42 degrees for 30 min (n = 17) Evidence C source
  Tympanic temperature difference 0.17 degrees at post and at 60 min, mean body temperature difference 0.18 and 0.15 degrees, serum PGE2 up 13.3% against 29.6%, COX-2 up 15.6% against 21.8%

Safety, limits and interactions

• In an RCT on 66 overweight Japanese adults, 200 mg a day of the lychee extract Oligonol for 12 weeks caused no clinically relevant adverse events. Twelve weeks is the longest human use tested. — overweight Japanese adults, BMI 25 to under 30 (n = 66 randomized, 63 analyzed) Evidence B source
  200 mg Oligonol a day for 12 weeks: no clinically relevant adverse events related to intake
• Lab data suggest a wide margin: in rats a single 2000 mg/kg dose of Oligonol caused no adverse effects, and 90 days at up to 1000 mg/kg a day showed no significant changes in blood tests or organ pathology. — male and female rats and mice Evidence D source
  LD50 above 2000 mg/kg; no significant adverse effects at up to 1000 mg/kg bw a day for 90 days in rats
• Lab data suggest the green tea part of Oligonol does not cause the nasal damage seen with some tea catechin extracts: rats given up to 1000 mg/kg a day for 13 weeks had no treatment-related nasal lesions. — rats given 100, 300 and 1000 mg/kg a day Evidence D source
  No treatment-related nasal lesions; clinical signs and mortality unaffected
• Among adults at a Dutch allergy clinic, lychee was the fruit most often linked to severe reactions: 66.7% of those reporting lychee symptoms had lower airway or cardiovascular symptoms, though fewer than 15 patients reported lychee. — adults seen at the allergology clinic of University Medical Centre Utrecht, the Netherlands, July 2018 to September 2023 (n = 1085 (lychee reporters fewer than 15)) Evidence C source
  Severe reaction (lower airway or cardiovascular symptoms) in 66.7% of patients who reported symptoms to lychee, the highest share among fruits
• Lychee carries profilin, the pan-allergen of plants, which is why people sensitized to pollen can react to it. — One atopic adult with pollen sensitization, plus immunoblot and inhibition assays on lychee extract (n = 1) Evidence D source
  Broad cross-reactivity between lychee and other plants, with profilin identified as the responsible protein
• A 26-year-old man swelled up within 15 minutes of eating lychee, and the workup pointed at mugwort rather than latex as the cross-reacting allergen. — A 26-year-old man with oral food allergy syndrome to parsley and sensitization to mugwort (n = 1) Evidence C source
  Pruritus, generalized urticaria and severe angioedema of lips and tongue with dyspnea within 15 minutes, with positive basophil activation and prick-to-prick tests and no lychee-specific IgE

Who this works differently for

• Observational data link eating litchis with an outbreak of acute brain illness in children in Muzaffarpur, India, in 2014, when 122 of 390 children died. Eating litchis in the previous 24 hours carried a matched odds ratio of 9.6. The link was stronger in children who skipped the evening meal. — children aged 15 years or younger admitted to two hospitals in Muzaffarpur, India, May to July 2014 (n = 104 cases, 104 controls (390 patients under surveillance)) Evidence C source
  390 cases, 122 died; litchi eaten in prior 24 h mOR 9.6 (95% CI 3.6 to 24); no evening meal mOR 2.2 (1.2 to 4.3); toxin metabolites in 48 of 73 case urines, 0 of 15 controls
• A 12-year-old girl reacted to half a lychee under supervised provocation, with hives and stridor 50 minutes later. — A 12-year-old girl with seasonal allergic rhinoconjunctivitis, tested by oral provocation (n = 1) Evidence C source
  Restlessness, flush, generalized urticaria and inspiratory stridor 50 min after half a lychee, with a positive skin prick test to raw lychee and IgE to latex
• In the 2012 Bangladeshi outbreak of sudden death among children, eating lychees carried no association with illness, while visiting a sprayed orchard did. — 14 case-patients aged 1 to 12 years in northern Bangladesh in 2012, compared with village and neighborhood controls (n = 14 cases) Evidence C source
  Visiting a lychee orchard within 24 hours before onset age-adjusted odds ratio 11.6 (1.02 to 109.8), family members working in an orchard 7.2 (1.7 to 29.4), eating lychees not associated

The bottom line

Two further randomized trials used the same class of extract. Among 20 male university distance runners across a 2-month training block, the extract held down the rise in interleukin-6 between the start and the middle of training compared with placebo, which is a blood marker rather than an illness or a finishing time. In 25 people averaging 45 years, 22 of them women, finger skin temperature and blood flow after a dip in 10 degree water were higher on day 14 of capsules than on day 1. That comparison runs inside each group over time rather than against the placebo group. One more extract study is worth the size of its effect. Seventeen young men averaging 21.6 years drank a lychee polyphenol beverage before a 30 minute half-body soak at 42 degrees, and their tympanic temperature afterward sat 0.17 degrees lower than on placebo, in a controlled trial that does not state randomization. A sixth of a degree in a laboratory heat challenge is the whole finding. An earlier outbreak gives a different picture. In the 2012 outbreak of sudden death among children in northern Bangladesh, 14 cases aged 1 to 12 were compared with village and neighborhood controls, and eating lychees carried no association with illness. What did was visiting a lychee orchard within 24 hours before onset, at an age-adjusted odds ratio of 11.6 with an interval of 1.02 to 109.8, and having family who worked in an orchard, at 7.2 (1.7 to 29.4). Those are odds ratios on 14 children, and the authors name the absence of acute specimens as a major limitation. Two outbreaks reached two different conclusions, and the larger one, with toxin metabolites measured in the children, linked illness to eating the fruit. Nothing on this page is a clearance for this fruit in children. Beyond the clinic series above, the allergy evidence is built out of single patients. A 26-year-old man had itching, hives and severe swelling of lips and tongue with breathlessness within 15 minutes of eating lychee, with no lychee-specific IgE found, so the case rested on prick-to-prick and basophil activation tests. Laboratory work around one atopic adult found a significant amount of profilin in lychee, the pan-allergen of plants, which describes a route rather than counting how many people take it. Under supervised provocation a 12-year-old girl with seasonal hay fever developed restlessness, flush, generalized hives and inspiratory stridor 50 minutes after half a lychee, and her specific IgE was to latex rather than to lychee. Three patients is three patients. It supports meeting this fruit carefully if you are sensitized to pollen, mugwort or latex, and neither the cases nor the clinic series give a rate for the population. Nothing on this page covers absorption, cooking or what a bowl of the fresh fruit does to anyone, because we found no trial that asked.

Sources

1. hf2-lych-5 · laboratory analysis
   presence of hypoglycin A or methylenecyclopropylglycine (MCPG), naturally-occurring fruit-based toxins that cause hypoglycaemia and metabolic derangement. ... In 36 litchi arils tested from Muzaffarpur, hypoglycin A concentrations ranged from 12·4 μg/g to 152·0 μg/g and MCPG ranged from 44·9 μg/g to 220·0 μg/g.
   The Lancet Global Health, 2017: Association of acute toxic encephalopathy with litchi consumption in an outbreak in Muzaffarpur, India, 2014 · checked 2026-10-08
2. lych-daily-r3-01 · randomized controlled trial
   Intake of 200 mg Oligonol significantly reduced abdominal VFA compared with the placebo group.
   J Nutr Sci Vitaminol (Tokyo), 2025 · checked 2026-09-24
3. lych-daily-r3-02 · randomized controlled trial
   Compared with the placebo group, the change in the serum interleukin-6 level between pre- and mid-training were significantly lower in the FRLFE group, while the change in the transforming growth factor-β level between pre- and post-training was significantly greater in the FRLFE group.
   Phytother Res, 2011 · checked 2026-09-24
4. lych-daily-r3-03 · randomized controlled trial
   Skin temperature and blood flow in peripheral tissue increased in the OPLFE and mixed plant extract with OPLFE groups on day 14 compared with those on day 1.
   J Nutr Sci Vitaminol (Tokyo), 2020 · checked 2026-09-24
5. lych-daily-r3-04 · controlled clinical trial
   Oligonol intake significantly prevented elevation of tympanic (temperature difference: 0.17°C at Post, P<.05; 0.17°C at Re-60, P<.05) and mean body temperatures (temperature difference: 0.18°C at Post, P<.05; 0.15°C at Re-60, P<.05), and lowered concentrations of serum PGE2 (increased by 13.3% vs. 29.6% at Post, P<.05) and COX-2 (increased by 15.6% vs. 21.8% at Post, P<.05), compared to placebo beverage.
   J Med Food, 2013 · checked 2026-09-24
6. hf2-lych-1 · randomized controlled trial
   This randomized, double-blind, placebo-controlled trial was performed including 66 overweight adult men and women (body mass index [BMI] of 25 or more and less than 30 kg/m2) who were assigned to receive a daily dose of placebo or 200 mg Oligonol (40 mg as monomers and dimers of flavanols from lychee and tea) for 12 wk. ... No clinically relevant adverse events related to the intake of Oligonol were observed.
   J Nutr Sci Vitaminol (Tokyo), 2025 · checked 2026-10-08
7. hf2-lych-2 · animal toxicology
   Oligonol caused no adverse effects and body weight gain and food consumption were within normal range, thus the LD(50) of Oligonol was determined to be greater than 2000mg/kg. A 90 day subchronic study (100, 300 and 1000mg/kgbw/day, oral gavage) in male and female rats reported no significant adverse effects in food consumption, body weight, mortality, clinical chemistry, haematology, gross pathology and histopathology.
   Food and Chemical Toxicology, 2008: Acute, subchronic and genotoxicity studies conducted with Oligonol · checked 2026-10-08
8. hf2-lych-3 · animal toxicology
   To assess the potential for Oligonol to induce nasal toxicity a 13-week repeated oral dose toxicity study was conducted in rats using doses of 100, 300, and 1000 mg/kg/d. Clinical signs and mortality were not affected by Oligonol treatment. ... Histopathological evaluation of the nasal cavity tissues revealed no treatment-related lesions.
   Regulatory Toxicology and Pharmacology, 2014: Thirteen-week oral dose toxicity study of Oligonol · checked 2026-10-08
9. hf2-lych-6 · retrospective clinic series
   The fruits to which patients most frequently reported severe reactions were mostly tropical, with a severe reaction to lychee in 66.7%, papaya in 50.0%, jackfruit in 45.5%, both persimmon and pomegranate in 33.3%, fig in 31.8%, and mango in 20.3%. Except for mango and fig, these were fruits for which patients were less likely to report symptoms to (n < 15).
   J Allergy Clin Immunol Global, 2026: Frequency and severity of 192 foods causing food allergy in adults · checked 2026-10-08
10. lych-daily-r3-06 · case report with laboratory assays
    Lychee fruit contains a significant amount of profilin. Consumption of this exotic fruit can cause severe anaphylactic reactions in patients being sensitized against the plant pan-allergen profilin.
    Clin Exp Allergy, 1995 · checked 2026-09-24
11. lych-daily-r3-07 · case report with laboratory assays
    We describe the case of a 26-year-old man who developed pruritus, generalized urticaria, and severe angioedema of his lips and tongue with dyspnea within 15 minutes after lychee fruit intake.
    J Investig Allergol Clin Immunol, 2007 · checked 2026-09-24
12. hf2-lych-4 · case-control study
    Between May 26, and July 17, 2014, 390 patients meeting the case definition were admitted to the two referral hospitals in Muzaffarpur, of whom 122 (31%) died. ... Litchi consumption (matched odds ratio [mOR] 9·6 [95% CI 3·6 - 24]) and absence of an evening meal (2·2 [1·2-4·3]) in the 24 h preceding illness onset were associated with illness. The absence of an evening meal significantly modified the effect of eating litchis on illness (odds ratio [OR] 7·8 [95% CI 3·3-18·8], without evening meal; OR 3·6 [1·1-11·1] with an evening meal). Tests for infectious agents and pesticides were negative. Metabolites of hypoglycin A, MCPG, or both were detected in 48 [66%] of 73 urine specimens from case-patients and none from 15 controls
    The Lancet Global Health, 2017: Association of acute toxic encephalopathy with litchi consumption in an outbreak in Muzaffarpur, India, 2014 · checked 2026-10-08
13. lych-daily-r3-05 · case report
    Upon oral provocation, she developed restlessness, flush, generalized urticaria and inspiratory stridor 50 min after eating half a lychee.
    Pediatr Allergy Immunol, 2002 · checked 2026-09-24
14. lych-daily-r3-08 · case-control study
    Eating lychees was not associated with illness in the case-control study. The outbreak was linked to lychee orchard exposures where agrochemicals were routinely used, but not to consumption of lychees.
    Am J Trop Med Hyg, 2017 · checked 2026-09-24