Eriodictyol

Eriodictyol is a flavanone, a compound in the flavonoid family, like hesperetin and naringenin. In the USDA data, one lemon (58 g) holds 12.4 mg of it. Of the foods ranked, peppermint has the most per 100 g, 30.9 mg.

Lemons and peppermint carry it as eriocitrin, its sugar-bound form. It also occurs in yerba santa, a plant native to the southwestern United States and northern Mexico. Its leaves were once used to mask the bitter taste of medicines.

Here is the part most readers do not know. In taste tests by flavor chemists, eriodictyol and three related flavanones from yerba santa lowered the bitterness of caffeine. They did so without a strong taste of their own.

And eriodictyol hardly shows up on its own in the blood. In people who ate lemon flavanones, it was found only as glucuronide and sulfate conjugates, forms with a chemical group attached.

The evidence is thin, and we say so throughout. We found no human trial of pure eriodictyol. The human studies on this page tested a lemon extract called Eriomin, or tracked what people absorb. Eriomin is described as 70% eriocitrin with some hesperidin and naringin.

The four Eriomin trials come from one Brazilian research group. Most of the rest is lab and animal work.

Health benefits of eriodictyol

• ★Lemon extract lowered blood glucose in prediabetesEriomin, a lemon extract rich in eriocitrin, lowered blood glucose about 5% over 12 weeks in 103 adults with prediabetes. It is a commercial extract, so the result is not eriodictyol alone.
• ★Lower 2-hour glucose when added to metforminIn people with prediabetes on metformin, a supplement (250 mg a day) cut 2-hour glucose by 5% and TNF-alpha, an inflammation marker, by 12%. The trial ran 12 weeks.
• ★Blood eriodictyol appeared only in changed formsAfter people took lemon peel flavanones, eriodictyol showed up in blood only attached to glucuronide or sulfate, found after lab enzymes removed them. The sugar-free form of the flavanones peaked at 1 hour.
• Population studyLinked to less overweight in US youthIn 5,970 US children and teens, high eriodictyol intake went with 0.69 times the odds of overweight or obesity. Citrus flavanones are eaten together, so eriodictyol cannot be separated from them.
• Population studyFlavonoid mix with eriodictyol linked to less asthmaIn 11,743 US adults, a mix of 29 flavonoids, with eriodictyol weighing most, went with lower odds of asthma (0.97 times).

Foods high in eriodictyol

Lemons and peppermint lead the USDA data. One lemon (58 g) gives 12.4 mg of eriodictyol, or 21.4 mg per 100 g. Peppermint has more per 100 g, 30.9 mg, but a 2 tbsp serving (3.2 g) gives only 0.99 mg. Almonds hold 0.25 mg per 100 g.

USDA reports eriodictyol itself, the sugar-free part. Lemons and peppermint carry it as eriocitrin. Eriocitrin is a major flavonoid in lemons and the main polyphenol in a peppermint leaf extract.

A 2017 analysis of five lemon cultivars found more phenolic compounds in peels and whole fruit than in other fruit parts. That study counted phenolics in general and found hesperidin to be the main flavanone.

Trial doses are far above a normal serving. An Eriomin dose of 200 mg that is 70% eriocitrin holds about 140 mg of eriocitrin. Eriocitrin weighs about 2.07 times as much as eriodictyol (molar masses 596.5 and 288.3). So that is about 68 mg of eriodictyol, roughly 5 or 6 lemons by the USDA figure.

This is a rough guide, since fruit and extracts vary. The ranking below is from USDA data.

How eriodictyol works

Most of what we know about how eriodictyol works comes from test tubes, cells and animals, and from a few absorption studies in people. Three ideas keep coming up.

It switches on the cell’s own defenses, and it blocks a pain-sensing channel. The body also changes it before it acts. Here is each one, and what has been seen in people.

It switches on the cell’s own defenses

Nrf2 is a control protein that tells cells to make their own protective enzymes. In human skin cells exposed to hydrogen peroxide, eriodictyol kept glutathione up. By switching on Nrf2, it raised the enzymes catalase and glutathione peroxidase 1, and the authors also describe a direct clean-up of reactive oxygen.

A screen of dietary flavonoids on human retinal cells found eriodictyol among those that protected the cells from oxidative death. Many of the effective flavonoids switched on Nrf2. In diabetic rats, eriodictyol raised Nrf2 in the kidneys.

Not every test points to eriodictyol. In extracts of 14 yerba santa types, the protection of nerve cells tracked another flavanone, sterubin, and not eriodictyol. And these dish and rat studies do not show that the amounts in food do the same in people.

It blocks a pain-sensing channel

TRPV1 is a channel on pain-sensing nerves that capsaicin, the hot compound in chili peppers, switches on. In lab tests, eriodictyol behaved as a TRPV1 blocker. It displaced a radioactive TRPV1 ligand at 47 nM and cut capsaicin-driven calcium inflow at 44 nM.

In animals it eased pain behavior without changing body temperature, a problem with some TRPV1-blocking drugs. We found no human study of eriodictyol and pain.

Gut bacteria and the body change it first

In lemons, eriodictyol comes as eriocitrin, eriodictyol with a sugar attached, and gut bacteria handle it first. In mice fed eriocitrin, colon contents held eriocitrin and six metabolites, including eriodictyol, homoeriodictyol and hesperetin.

In people who took lemon flavanones, free eriodictyol was not found in blood up to 4 hours after the dose. It appeared only after enzymes removed attached glucuronide and sulfate groups.

This slow route has a cost. In 16 people, total flavanone metabolites peaked at 6.0 h after an eriocitrin-rich lemon extract and 8.0 h after an orange extract. The same study reports that hesperetin and eriodictyol can convert into each other in people.

Because eriodictyol turns into other forms on the way, results from a related flavanone such as hesperetin or naringenin cannot be read across.

What has been seen in people

The human trials measure blood sugar and inflammation markers, not these mechanisms. In the four Eriomin trials, blood glucose fell about 5% to 6%. GLP-1 rose 15% to 22% in three of them, and TNF-alpha fell 11% to 20% in three of them.

That fits the gut and inflammation story, but none of the trials tested Nrf2 or pain receptors in people. The effects are small, the product is a mixture, and the trials come from one research group. All of these trials are among the study cards above.

Is eriodictyol safe? Supplements, dose and interactions

Eating lemons and other foods that contain eriodictyol is not known to cause problems. None of the sources below sets a daily need or an upper level for it.

JECFA, the expert committee on food additives of the FAO and WHO, evaluated eriodictyol as a flavoring agent in 2012. It found no safety concern at current levels of intake. In the US, yerba santa (Eriodictyon californicum) is on the FDA’s list of natural flavoring substances (21 CFR 172.510). FEMA lists its fluid extract as GRAS (generally recognized as safe) reference 3118, and these cover flavoring amounts, not supplement doses.

• Trial doses. The Eriomin trials gave 200 to 800 mg a day for 12 weeks, and one gave 250 mg a day of the same supplement. None was designed mainly to test safety, and we found no report of use beyond 12 weeks.
• Diabetes medicines. The trials lowered blood glucose by about 5%, and one was in people taking metformin. We found no interaction study or case report. The concern is theoretical, but people on glucose-lowering drugs should ask their clinic before adding an extract.
• Pregnancy, breastfeeding and children. We found no safety studies of eriodictyol or eriocitrin supplements in these groups, so ask your doctor.

How to get more eriodictyol

• Best food. Lemons, at 21.4 mg per 100 g, or 12.4 mg in one fruit. Using the peel as well as the juice may add more phenolics, according to one analysis of lemon parts. But it did not measure eriodictyol.
• Peppermint is strong per 100 g but weak per serving. It tops the USDA list at 30.9 mg per 100 g, but 2 tbsp (3.2 g) gives 0.99 mg.
• Expect a slow route. After a lemon extract, flavanone metabolites peaked at 6.0 h on average. When people took lemon flavanones without the sugar, the peak came at 1 hour, and total exposure was higher than with the sugar-bound form.

History of eriodictyol

Eriodictyol’s story starts with yerba santa, Spanish for “sacred herb.” The plants of the genus Eriodictyon grow in the southwestern United States and northern Mexico. Indigenous peoples have used them for centuries, in particular for respiratory complaints. The genus name comes from Greek roots and refers to the woolly underside of the leaves.

The leaves were also used to mask the bitter taste of medicines. In 2005, chemists at the flavor maker Symrise reported on flavanones from the plant in sensory tests. Eriodictyol, homoeriodictyol, its sodium salt and sterubin lowered the bitterness of caffeine.

The sodium salt of homoeriodictyol became the lead compound, with 10% to 40% masking across bitter molecules. In 2012 JECFA evaluated eriodictyol as a flavoring agent.

The lemon side of the story is newer. Eriocitrin was tested in people as the main part of Eriomin, a lemon flavonoid extract, in a 2019 trial in prediabetes. In 2021 a Spanish team reported that a lemon extract gave more flavanone metabolites in blood than an orange extract.

Frequently asked questions about eriodictyol

What does eriodictyol do for the body?

The best-supported finding is small and comes from a lemon extract, not pure eriodictyol. In four trials of Eriomin, a lemon extract that is about 70% eriocitrin, blood glucose fell about 5% to 6% over 12 weeks. The trials were in people with prediabetes or raised blood sugar. The effects on pain, skin and kidneys come from cells and animals, and no finding on this page reaches moderate or strong evidence.

Which foods are high in eriodictyol?

Lemons and peppermint lead the USDA data. A lemon (58 g) gives 12.4 mg. Peppermint has 30.9 mg per 100 g, but a 2 tbsp serving (3.2 g) gives only 0.99 mg. Almonds have 0.25 mg per 100 g. In one analysis, lemon peels and whole fruit were richer in phenolic compounds than other parts, but it did not measure eriodictyol.

Is eriodictyol the same as eriocitrin?

No. Eriocitrin is eriodictyol with a sugar attached, and it is the form found in lemons and peppermint. Gut bacteria break it down first. In mice, eriodictyol was one of six metabolites found in the colon after eriocitrin. The human trials on this page used Eriomin, a lemon extract described as 70% eriocitrin, not pure eriodictyol.

How much eriodictyol should you take a day?

No dose is established. The Eriomin trials used 200 to 800 mg a day of the extract for 12 weeks. A 200 mg dose holds about 140 mg of eriocitrin, roughly 68 mg of eriodictyol, or 5 or 6 lemons by the USDA figures. We found no upper level set for eriodictyol, so talk to a clinician before using an extract, especially if you take diabetes medicine.

Does eriodictyol have side effects?

We found no report of harm from food amounts, and JECFA found no safety concern for eriodictyol as a flavoring agent in 2012. The supplement trials ran 12 weeks and were not designed mainly to test safety. Because they lowered blood glucose by about 5%, people on glucose-lowering drugs should ask their clinic first. We found no safety studies in pregnancy or breastfeeding.

Does eriodictyol or lemon extract lower blood sugar?

Slightly, in one research group’s trials. Blood glucose fell 5% to 6% on Eriomin, and insulin resistance fell 7% in one trial and 11% in another. In the trial with metformin, 2-hour glucose fell 5%. The extract is a mixture, the maker funded the two later trials, and we found no trial by another group.

What is the difference between eriodictyol, hesperetin and naringenin?

All three are citrus flavanones with separate entries in the USDA data. Each has its own page with its own studies: see hesperetin and naringenin. One human study reports that the body can convert hesperetin and eriodictyol into each other. But we do not carry results across from one to another.

Can eriodictyol block bitter taste?

In sensory tests it lowered the bitterness of caffeine without a strong flavor of its own. The best-studied of the yerba santa flavanones, the sodium salt of homoeriodictyol, masked 10% to 40% of the bitterness of several compounds. The abstract gives no figure for eriodictyol, and the authors work for Symrise, a flavor maker.