Lemon peel: a decent label, and trials that tested extracts

Most of what is said about lemon peel rests on citrus flavonoid supplements, and none of the pooled trials here fed people the peel itself. A meta-analysis of 8 randomized trials with 596 adults found citrus flavonoid supplements raised flow-mediated dilation, a test of blood vessel function, by 2.75 percentage points against placebo (95% CI 1.29 to 4.20), with results that varied widely between trials. For hesperidin, the flavanone sold as a component of citrus peel extract, two earlier meta-analyses found nothing. Across 6 trials with 318 adults it did not change fasting glucose, insulin or HbA1c, and across 10 trials with 577 people it did not change total or LDL cholesterol or blood pressure. A 2025 meta-analysis did report lower fasting glucose, total and LDL cholesterol, with the falls showing in subgroups taking more than 500 mg a day and in trials longer than 12 weeks. The hesperidin answer stays open for a plain reason: the older and newer pooled analyses disagree, and the newer abstract gives the direction of the effect without its size. As a food, raw lemon peel carries 129 mg vitamin C and 10.6 g fiber per 3.5 oz (100 g) in USDA data, within 3 percent of the UK figures, each from a single record.

The numbers, per 3.5 oz (100 g)

How much is actually in it

• Lemon peel in UK data carries 10.6 g fiber, 130 mg vitamin C and 130 mg calcium per 3.5 oz (100 g). — CoFID 2021 Lemon peel (14-337) (n = 1 record) Evidence E source
  Per 100 g: AOAC fiber 10.6 g, vitamin C 130 mg, calcium 130 mg, potassium 160 mg, protein 1.5 g, fat 0.3 g, water 81.6 g
• Raw lemon peel in USDA data gives 129 mg vitamin C, 10.6 g fiber and 134 mg calcium per 3.5 oz (100 g), within 3% of the UK figures. — USDA SR Legacy Lemon peel, raw (FDC 167749) (n = 1 record) Evidence E source
  Per 100 g: vitamin C 129 mg, fiber 10.6 g, calcium 134 mg; CoFID 130 mg, 10.6 g, 130 mg

What your body absorbs

• In a crossover RCT of 12 adults, fresh oranges gave 2.4 times more flavanones than juice but urinary hesperetin did not differ significantly, possibly because absorption saturates or the fiber-rich matrix traps them. — healthy adults, single test meal (n = 12) Evidence B source
  Urinary hesperetin 21.6 vs 18.3 umol, p = 0.5209
• US survey data link recent eating of citrus-rich foods with 82% higher serum limonene per kg eaten. — NHANES 2013-2014 participants aged 6 to 80 years (n = 2213) Evidence C source
  Serum limonene +82.1% per 1 kg citrus-rich food (p = 0.0002)

What it does to your health

• In a crossover RCT of 30 adults with high blood sugar, 200 mg a day of eriocitrin supplement (Eriomin) for 12 weeks lowered blood glucose by 5% and HOMA-IR by 11%. — adults with fasting glucose above 110 mg/dL, 12 weeks per arm (n = 30) Evidence B source
  Glucose -5%, HOMA-IR -11%, glucagon -13%, IL-6 -14%, TNF-alpha -20%, GLP-1 +17% (P <= .05)
• A meta-analysis of 8 RCTs with 596 people found citrus flavonoid supplements raised flow-mediated dilation by 2.75 percentage points versus placebo. — adults in 8 randomized trials of citrus flavonoid supplements (n = 596) Evidence A source
  FMD +2.75% (95% CI 1.29 to 4.20), I2 87.3%; +1.09% per 200 mg/d
• A 2025 meta-analysis of RCTs found hesperidin lowered fasting glucose, total and LDL cholesterol, and in subgroups these falls were significant above 500 mg a day and in trials longer than 12 weeks. — adults in randomized trials of hesperidin, search to August 2023 Evidence A source
  Reductions in FBS, TG, TC, LDL-C, SBP, TNF-alpha; no effect on insulin, HOMA-IR, HDL-C, DBP, hs-CRP
• In an RCT of 80 older adults with memory complaints, 400 mg a day of citrus peel extract for 36 weeks gave no cognitive benefit over placebo. — adults with subjective cognitive decline, 36 weeks (n = 80) Evidence B source
  RBANS improved in both arms, time x treatment p = .910

Safety, limits and interactions

• A baking-ingredient worker who handled grated lemon peel and lemon oil for years developed allergic contact dermatitis traced to geraniol in the peel. — one 32-year-old woman, occupational exposure (n = 1) Evidence D source
  Allergic contact dermatitis of fingers; geraniol the only source
• In a man with anaphylactoid reactions to lemon, serum IgE bound a protein of about 25 kDa from lemon peel, and the lemon surface can carry Candida and other fungi. — one adult man with heroin use and lemon allergy (n = 1) Evidence D source
  Specific IgE to lemon 0.49 kU/L; recognition of 25 kDa lemon peel protein
• A 36-year-old woman had acute cholestatic liver injury after an over-the-counter liver tea made of six herbs, one of them lemon peel. — one 36-year-old woman (n = 1) Evidence D source
  Clinically significant acute cholestatic liver injury
• US FDA lists lemon peel among essential oils and natural extracts generally recognized as safe for their intended use in food. — US food regulation Evidence E source
  Lemon peel (Citrus limon) on the GRAS list of 21 CFR 182.20

What people believe that the data does not support

• A meta-analysis of 6 RCTs with 318 adults found hesperidin supplements did not change fasting glucose, insulin or HbA1c. — adults in 6 randomized trials of hesperidin (n = 318) Evidence A source
  Fasting glucose WMD -1.10 mg/dL (95% CI -3.79 to 1.57), HbA1c WMD -0.04% (95% CI -0.14 to 0.04)
• A meta-analysis of 10 RCTs with 577 people found hesperidin supplements did not change total or LDL cholesterol or blood pressure. — adults in 10 randomized trials of hesperidin (n = 577) Evidence A source
  Total cholesterol WMD -1.04 mg/dl (95% CI -5.65 to 3.57), LDL WMD -1.96 mg/dl (95% CI -7.56 to 3.64)
• The EU did not authorize a claim that hesperidin from citrus peel extract helps maintain normal blood cholesterol. — EU health claims register Evidence E source
  Status Non-authorized
• The EU did not authorize a claim that citrus bioflavonoids help maintain healthy venous circulation. — EU health claims register Evidence E source
  Status Non-authorized

Who this works differently for

• In a randomized crossover study, citrus flavanones were absorbed equally from whole orange and juice, urinary yield ranged 0 to 59% between people, and hesperetin excretion fell with age. — 20 adults in crossover plus 109 adults aged 18 to 80 years, single portion (n = 129) Evidence B source
  No fruit vs juice difference; urinary yield 0-59%; small decline in hesperetin excretion with age (P < 0.05)

The bottom line

Two trials used specific products. In a crossover trial of 30 adults with fasting glucose above 110 mg/dL, 200 mg a day of the eriocitrin supplement Eriomin for 12 weeks lowered blood glucose by 5 percent and HOMA-IR, a measure of insulin resistance, by 11 percent. That is a small sample, and the abstract does not name lemon as the source. In 80 older adults with memory complaints, 400 mg a day of a citrus peel extract for 36 weeks gave no cognitive benefit over placebo, with both groups improving. How much of the peel flavanones you absorb varies a lot between people. We found no lemon study, so these numbers come from oranges. Across 129 adults, urinary yield of flavanones ranged from 0 to 59 percent, was the same from whole fruit and juice, and for hesperetin fell slightly with age. In 12 adults, fresh oranges delivered 2.4 times the dose of juice, yet urinary hesperetin did not differ significantly, 21.6 against 18.3 micromol. US survey data on 2213 people aged 6 to 80 link each kilogram of recent citrus-rich food with 82 percent higher serum limonene, the main peel oil compound. That is an association, and smoke and cleaning products also supply limonene. The cautions come from single cases. A 32-year-old woman who handled grated lemon peel and lemon oil at a baking-ingredient company for years developed allergic contact dermatitis on her fingers, traced to geraniol, from contact at work rather than from eating. In one man who used heroin and had anaphylactoid reactions to lemon, his IgE bound a lemon peel protein of about 25 kDa, and the authors note the lemon surface can carry Candida and other fungi. A 36-year-old woman had acute cholestatic liver injury after a six-herb liver tea sold over the counter that included lemon peel, and which herb caused it was never established. We found no data on pregnancy, children, kidney disease or drug interactions for lemon peel. The US FDA lists lemon peel among essential oils and natural extracts generally recognized as safe for their intended use in food, which covers flavoring amounts and says nothing about supplement doses. The EU did not authorize claims that hesperidin from citrus peel extract keeps blood cholesterol normal or that citrus bioflavonoids support venous circulation.

Sources

1. lmpl-r5-01 · food composition dataset
   Lemon peel (14-337): AOAC fibre 10.6 g | Vitamin C 130 mg | Calcium 130 mg | Potassium 160 mg | Protein 1.5 g | Fat 0.3 g | Water 81.6 g
   CoFID 2021 (Public Health England, OGL v3.0), code 14-337 Lemon peel · checked 2026-09-30
2. lmpl-r5-02 · food composition dataset
   Lemon peel, raw, SR Legacy fdc_id 167749: Vitamin C 129 mg | Fiber 10.6 g | Calcium 134 mg per 100 g
   USDA FoodData Central SR Legacy (2018), Lemon peel, raw, fdc_id 167749 · checked 2026-09-30
3. lmpl-r5-10 · randomized crossover trial
   Differences in urinary hesperetin excretion were found to be nonsignificant (p = 0.5209) both after consumption of orange fruit (21.6 ± 8.0 μmol) and juice (18.3 ± 7.2 μmol). ... CONCLUSION: Despite 2.4-fold higher doses, excretion of flavanones from ingested fresh orange fruit did not differ from that following orange juice consumption, possibly due to a saturation of absorption or their entrapment in the fiber-rich matrix of the fruit.
   Mol Nutr Food Res, 2016 · checked 2026-09-30
4. lmpl-r5-11 · cross-sectional study
   In addition, we found that recent consumption of citrus-rich foods (rates per 1 kg consumed) was associated with significantly higher serum α-pinene (32.8 %, p = 0.0042) and limonene (82.1 % p = 0.0002).
   J Chromatogr B Analyt Technol Biomed Life Sci, 2026 · checked 2026-09-30
5. lmpl-r5-03 · randomized controlled trial
   Subjects (n = 30), divided into two groups (Eriomin or Placebo), who received a dose of 200 mg/d of the designated supplement for 12 weeks and, after a washout period of 2 weeks, switched to the other supplement in the following 12 weeks. ... Treatment with 200 mg/d of Eriomin significantly decreased blood glucose (-5%), homeostasis model assessment of insulin resistance (-11%), glucagon (-13%), interleukin-6 (-14%), tumor necrosis factor alpha (-20%), and alkaline phosphatase (-13%); but increased glucagon-like peptide 1 (GLP-1) by (17%) (P ≤ .05).
   J Med Food, 2022 · checked 2026-09-30
6. lmpl-r5-04 · meta-analysis of RCTs
   A total of eight eligible RCTs, comprising 596 participants, were included in the analysis. The pooled data demonstrated a statistically significant augmentation in flow-mediated vasodilation (FMD) (2.75%; 95% CI: 1.29, 4.20; I2 = 87.3%; p < 0.001) associated with CFS compared to the placebo group.
   Phytother Res, 2024 · checked 2026-09-30
7. lmpl-r5-07 · meta-analysis of RCTs
   The results of this study demonstrate that hesperidin supplementation had a significant impact on reducing FBS, TG, TC, LDL-C, SBP, and TNF-α. However, there was no significant effect observed on insulin, HOMA-IR, QUICKI, HDL-C, DBP, and hs-CRP. The study's subgroup analyses also revealed that interventions lasting more than 12 weeks were effective in reducing FBS, TG, TC, and LDL-C. Moreover, hesperidin dosage exceeding 500 mg/day showed significance in reducing FBS, TC, and LDL-C levels.
   Nutr Rev, 2025 · checked 2026-09-30
8. lmpl-r5-08 · randomized controlled trial
   Eighty participants were randomly assigned to active treatment (400 mg of Citrus peel extract containing 3.0 mg of naringenin and 0.1 mg of auraptene) or placebo at 1:1 ratio for 36 weeks. ... CONCLUSIONS: In this randomized clinical trial, long-term Citrus peel extract supplementation did not show cognitive benefits over placebo in participants with SCD, possibly due to high placebo response.
   Nutr J, 2024 · checked 2026-09-30
9. lmpl-r5-12 · case series
   A 32-year-old female patient working in a company for baking ingredients, who had been handling grated lemon peel and lemon oil (oleum citri) for several years, developed allergic contact dermatitis of the fingers of both her hands. By means of thin-layer chromatography, we identified geraniol in both lemon peel and lemon oil and proved it to be the only source of the allergic reaction.
   Z Hautkr, 1990 · checked 2026-09-30
10. lmpl-r5-13 · case series
    The immunodetection showed that the patient's serum recognised a protein of approximately 25kDa of lemon peel, one of approximately 12-13kDa of Penicillium, and perfectly recognised Alt a 1. CONCLUSIONS: Lemon surface can be contaminated by Candida and other fungi.
    Allergol Immunopathol (Madr), 2016 · checked 2026-09-30
11. lmpl-r5-14 · case series
    We describe the case of a 36-year-old female who developed a clinically significant acute liver injury with a cholestatic pattern due to an over-the-counter herbal liver detox tea. This is the first case reported of a hepatotoxic effect from any of these compounds or ingredients in the detox tea: burdock root, stinging nettle leaf, cleavers herb, dandelion root, lemon peel, and lemon myrtle leaf (Backhousia citriodora).
    Case Rep Gastroenterol, 2022 · checked 2026-09-30
12. lmpl-r5-15 · regulatory list
    Essential oils, oleoresins (solvent-free), and natural extractives (including distillates) that are generally recognized as safe for their intended use, within the meaning of section 409 of the Act, are as follows: ... Lemon peel Citrus limon (L.) Burm. f.
    21 CFR 182.20, Essential oils, oleoresins, and natural extractives (FDA) · checked 2026-09-30
13. lmpl-r5-05 · meta-analysis of RCTs
    Six trials with 318 participants were reviewed in the present systematic review. The results showed that hesperidin had no significant effect on serum fasting blood glucose (weighted mean difference [WMD] = -1.10 mg/dL, 95% CI: -3.79, 1.57), plasma insulin (WMD = -0.01 μU/mL, 95% CI: -1.20, 1.19), glycated haemoglobin A1c (WMD = -0.04%, 95% CI: -0.14, 0.04)
    Br J Clin Pharmacol, 2020 · checked 2026-09-30
14. lmpl-r5-06 · meta-analysis of RCTs
    Ten RCTs (577 participants) were eligible to be included in the systematic review. The meta-analysis revealed that hesperidin supplementation had no effect on serum total cholesterol (weighted mean difference [WMD] = -1.04 mg/dl; 95% confidence interval [CI]: -5.65, 3.57), low-density lipoprotein cholesterol (WMD = -1.96 mg/dl; 95% CI [-7.56, 3.64])
    Phytother Res, 2019 · checked 2026-09-30
15. lmpl-r5-16 · regulatory register
    POL-HC-7258 Hesperidin (a component of citrus peel extract and precursor of hesperitin) (ingredient not found in the spanish food laws) Helps maintain normal blood cholesterol levels/Supports heart health (to be evaluated by EFSA). Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-7258, snapshot 2026-09-21 · checked 2026-09-30
16. lmpl-r5-17 · regulatory register
    POL-HC-6772 Bioflavonoids from citrus Helps to maintain healthy venous circulation. Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-6772, snapshot 2026-09-21 · checked 2026-09-30
17. lmpl-r5-09 · randomized crossover trial
    Analysis of the plasma pharmacokinetic and urinary excretion data on a dose-adjusted basis indicated no difference in absorption or excretion of either flavanone between the fruit and juice matrices. In the extended urinary excretion dataset the individual variation was very large (range 0-59 % urinary yield). There was a small but significant (P < 0.05) decrease in the excretion of hesperetin (but not naringenin) with increasing age (P < 0.05)
    Br J Nutr, 2009 · checked 2026-09-30