NutriDex

The Supplement Research Compendium
🤎

Longan

Dimocarpus longan

Vitamin C-rich "dragon's eye" with polyphenol-packed pulp

Preliminary evidence 🍎Fruits

✚ Updated · How we grade evidence

Evidence tier
Preliminary
Research weight
Citations
8 verified / 8
Classification
Fruits
❝
What the evidence says. Early or small human trials; promising but not yet conclusive.

Nutrition per serving 1 cup, pitted (96 g)

96gSERVING
  • Water 79.5 g83%
  • Sugars 13.1 g14%
  • Fibre 1.1 g1%
  • Other carbs 0.2 g0%
  • Protein 1.3 g1%
  • Fat 0.1 g0%
What's in one serving, by weight — average composition (USDA).
Vitamin C90%Copper18%Potassium5%Riboflavin (B2)10%Magnesium2%Fiber4%
One serving as % of the adult daily requirement (FDA Daily Values). The bold outer ring = 100% of a day's needs.
57 kcal1.3 g protein1.1 g fiber0.1 g fat
NutrientPer serving% daily value
Vitamin C81 mg90%
Copper0.16 mg18%
Potassium255 mg5%
Riboflavin (B2)0.13 mg10%
Magnesium9.6 mg2%
Fiber1.1 g4%
Phosphorus20 mg2%
Manganese0.05 mg2%

Composition data: USDA FoodData Central ↗

What is Longan?

Longan (Dimocarpus longan) is a fruit used for exceptionally high vitamin c density for an antioxidant/immune-support contribution. NutriDex grades the human evidence as Preliminary. Longan ("dragon's eye") is a lychee relative whose fresh pulp is unusually rich in vitamin C and contains hydrolysable tannins (corilagin, gallic and ellagic acid) and bioactive polysaccharides. The great majority of the evidence is preclinical: cell and rodent studies show antioxidant, anti-inflammatory, anti-hyperglycemic (alpha-amylase/alpha-glucosidase inhibition), immunomodulatory and antitumor activity, mostly from concentrated pericarp, seed or polysaccharide extracts rather than the amount of pulp a person would eat. Human data are very sparse: a single 12-week randomized, double-blind, placebo-controlled trial (n=50, ages 55-75) of a longan pulp-and-seed extract beverage found a significant reduction in the bone-turnover marker alkaline phosphatase versus placebo, with no significant change in lipid or glycemic markers and a good safety profile. No large prospective cohorts or meta-analyses isolate whole longan intake from overall fruit consumption. Reported antioxidant/anti-diabetic effects also depend heavily on extract type and processing (e.g., thermal "aging" raises phenolic content), limiting translation to the raw fruit. Overall the human evidence is preliminary, and longan is best regarded as a nutritious vitamin-C-dense fruit rather than a proven therapeutic.

Purported Benefits

✓Exceptionally high vitamin C density for an antioxidant/immune-support contribution
✓Polyphenols (gallic acid, corilagin, ellagic acid) with in-vitro antioxidant and free-radical-scavenging activity
✓Preclinical anti-hyperglycemic effects via alpha-amylase / alpha-glucosidase inhibition (extract studies)
✓Longan-pulp polysaccharides show immunomodulatory and antitumor activity in animal/cell models
✓Possible favorable shift in a bone-turnover marker (single small human RCT of a pulp/seed extract)
✓Low fat, source of potassium and copper

Dosing & Compounds

Typical Dose
About 1 cup of fresh pitted pulp (~96 g, roughly 20-30 fruits); dried longan is far more energy- and sugar-dense per gram.
Active Compounds
Vitamin C (L-ascorbic acid)Hydrolysable tannins (corilagin, gallic acid, ethyl gallate)Ellagic acid and ellagitanninsFlavonoids (epicatechin, quercetin glycosides)Bioactive polysaccharides / polysaccharide-protein complexesPotassium and copperB-vitamins (riboflavin)

Safety & Cautions

Generally safe as a food. Dried longan is concentrated in sugar and calories and can spike blood glucose, so people with diabetes should account for it. Possible cross-reactive allergy in those sensitive to lychee or other Sapindaceae fruits. As with unripe lychee, eating large amounts on an empty/undernourished stomach has been linked theoretically to hypoglycin-type effects—keep portions moderate, especially in children. Bioactive-extract supplements are not interchangeable with the fruit and lack long-term human safety data; potential additive effects with glucose-lowering or immune-modulating drugs are unstudied. Educational only — always check with your doctor or pharmacist before combining Longan with any medicine.

Key Studies

RCT Journal of Functional Foods 2025 (n=50) ✓ Full text
12-week randomized, double-blind, placebo-controlled trial in adults 55-75 y: a longan pulp-and-seed extract beverage significantly reduced alkaline phosphatase (a bone-turnover marker; mean difference -7.06 U/L, p=0.023) vs placebo, with no significant change in lipid or glycemic markers and no safety concerns.
In vitro/animal study Tan 2023 (Molecules) ✓ Full text
Longan-byproduct polyphenol extract showed strong in-vitro antioxidant capacity and, in obese mice, reduced body-weight gain (~11.8%) and serum/liver lipids while ameliorating hepatic steatosis via PPARalpha/LXRalpha pathways.
Experimental study Hong-in 2021 (Scientific Reports) ✓ Full text
Thermal/aging processing of longan markedly increased total phenolic content (gallic and ellagic acid up ~10-fold, corilagin doubled) and antioxidant and biological activities, showing that processing strongly modulates longan's bioactive profile.
In vitro study Wang 2019 ✓ Full text
Across longan varieties, methanolic extracts inhibited alpha-amylase (up to ~97.6%) and alpha-glucosidase (up to ~88.6%) and showed strong DPPH/ABTS radical scavenging, supporting in-vitro anti-hyperglycemic potential.
In vitro study Tang 2019 ✓ Full text
Longan pericarp and seed byproducts are rich in corilagin (major polyphenol) and exhibit antioxidant, nitrite-scavenging and in-vitro anti-hyperglycemic activities, positioning seed flavonoids and pericarp alkaloids as candidate anti-diabetic agents.
Animal study Yi 2011 (Molecules) ✓ PubMed
A polysaccharide-protein complex (LP3) from longan pulp given orally to immunosuppressed mice (100 mg/kg/day) increased antibody production, ConA-induced splenocyte proliferation, macrophage phagocytosis, NK-cell cytotoxicity and serum IFN-gamma/IL-2.
In vitro/animal study Meng 2014 (IJMS) ✓ Full text
A water-soluble longan-pulp polysaccharide (LP1) showed antitumor activity in vitro (~40-50% inhibition of SKOV3/HO8910 cells) and immunostimulatory effects, including increased IFN-gamma and B/T-lymphocyte proliferation.
Preclinical study Zhong 2015 ✓ Full text
Polyphenol-enriched longan pericarp extracts inhibited carbohydrate-digesting enzymes and reduced postprandial hyperglycemia, attributed to 4-O-methylgallic acid, corilagin and ellagic acid.
8 sources cited · 8 verified Search all studies on PubMed ↗

Common questions about Longan

What is Longan used for?

Longan is most often taken for Exceptionally high vitamin C density for an antioxidant/immune-support contribution, Polyphenols (gallic acid, corilagin, ellagic acid) with in-vitro antioxidant and free-radical-scavenging activity, Preclinical anti-hyperglycemic effects via alpha-amylase / alpha-glucosidase inhibition (extract studies), Longan-pulp polysaccharides show immunomodulatory and antitumor activity in animal/cell models. Vitamin C-rich "dragon's eye" with polyphenol-packed pulp

Does Longan work — what does the evidence say?

Preliminary evidence. Early or small human trials; promising but not yet conclusive. Longan ("dragon's eye") is a lychee relative whose fresh pulp is unusually rich in vitamin C and contains hydrolysable tannins (corilagin, gallic and ellagic acid) and bioactive polysaccharides. The great majority of the evidence is preclinical: cell and rodent studies show antioxidant, anti-inflammatory, anti-hyperglycemic (alpha-amylase/alpha-glucosidase inhibition), immunomodulatory and antitumor activity, mostly from concentrated pericarp, seed or polysaccharide extracts rather than the amount of pulp a person would eat. Human data are very sparse: a single 12-week randomized, double-blind, placebo-controlled trial (n=50, ages 55-75) of a longan pulp-and-seed extract beverage found a significant reduction in the bone-turnover marker alkaline phosphatase versus placebo, with no significant change in lipid or glycemic markers and a good safety profile. No large prospective cohorts or meta-analyses isolate whole longan intake from overall fruit consumption. Reported antioxidant/anti-diabetic effects also depend heavily on extract type and processing (e.g., thermal "aging" raises phenolic content), limiting translation to the raw fruit. Overall the human evidence is preliminary, and longan is best regarded as a nutritious vitamin-C-dense fruit rather than a proven therapeutic.

What is the typical dose of Longan?

About 1 cup of fresh pitted pulp (~96 g, roughly 20-30 fruits); dried longan is far more energy- and sugar-dense per gram.

Is Longan safe? Any cautions or side effects?

Generally safe as a food. Dried longan is concentrated in sugar and calories and can spike blood glucose, so people with diabetes should account for it. Possible cross-reactive allergy in those sensitive to lychee or other Sapindaceae fruits. As with unripe lychee, eating large amounts on an empty/undernourished stomach has been linked theoretically to hypoglycin-type effects—keep portions moderate, especially in children. Bioactive-extract supplements are not interchangeable with the fruit and lack long-term human safety data; potential additive effects with glucose-lowering or immune-modulating drugs are unstudied.

How many studies support Longan?

NutriDex cites 8 sources for Longan, graded "Preliminary".

Cite this page
APA

Peh, D. (2026). Longan (Dimocarpus longan): Benefits, Dosage, Side Effects & Evidence. NutriDex — The Supplement Research Compendium. Retrieved 26 Jun 2026, from https://nutridex.info/s/longan

BibTeX
@misc{nutridex_longan,
  author       = {Peh, Daryl},
  title        = {Longan (Dimocarpus longan): Benefits, Dosage, Side Effects \& Evidence},
  year         = {2026},
  howpublished = {NutriDex --- The Supplement Research Compendium},
  url          = {https://nutridex.info/s/longan},
  note         = {Reviewed by Dr Daryl Peh, MBBS Singapore, MMed FM. Accessed 2026-06-26}
}

For medical claims, citing the underlying primary studies linked above is preferred. NutriDex is an educational reference, not medical advice.

← Back to the full dex · All substances