Rosmarinic acid is a compound concentrated in certain plants, including herbs and spices like rosemary and oregano (1).

People have used plants that are high in rosmarinic acid for thousands of years for culinary and medicinal purposes.

Studies show that rosmarinic acid has powerful antioxidant and anti-inflammatory properties. Some evidence suggests that it may help treat certain health conditions if you take it in concentrated doses (2).

This article explains everything you need to know about rosmarinic acid.

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Rosmarinic acid is a type of phenolic compound found in a variety of plants.

It’s concentrated in certain plant species, such as (3, 4, 5):

  • mint, salvia, lemon balm, marjoram, oregano, rosemary, and other species in the Labiatae or Lamiaceae family of plants
  • species in the Boraginaceae family of plants
  • ferns and hornworts

Also, certain dietary supplements, including Melissa officinalis (lemon balm), perilla extract, and rosemary extract, are concentrated sources of rosmarinic acid.

Rosmarinic acid was first isolated from rosemary in 1958 by two Italian chemists, who named the compound after the plant from which they isolated it — Rosmarinus officinalis or rosemary (5).

In plants, rosmarinic acid acts as a defense compound, protecting against pests and infections (6).

However, rosmarinic acid has different effects in humans. This compound is mainly known for its powerful antioxidant and anti-inflammatory properties. Research has shown it may have antiviral, antibacterial, pain-relieving, and potential anticancer effects (1, 7, 8).

People have used plants that are high in rosmarinic acid, like rosemary, throughout history in traditional medicine systems for relieving various ailments, including:

  • pain
  • spasms
  • headaches

Researchers have suggested that rosmarinic acid, along with other beneficial compounds found in these plants, is responsible for their therapeutic properties (9, 10, 11).

Summary

Rosmarinic acid is naturally present in certain plants, such as rosemary and oregano. You can also find it in supplement form.

Rosmarinic acid has been linked to several health benefits.

However, it’s important to note that most studies investigating the health effects of rosmarinic acid have been conducted in animals and test tubes — not people. More research on its potential effects in humans is needed.

Anti-inflammatory effects

Rosmarinic acid has powerful anti-inflammatory properties, and research suggests that it may help treat inflammatory conditions like arthritis, asthma, and atopic dermatitis (1).

A 2018, 1-month study including 44 people with asthma demonstrated that those who received a daily dose of a rosmarinic-acid-rich rosemary extract had significant improvements in asthmatic activity, including wheezing, cough, and sputum production (12).

However, rosemary extract contains a number of therapeutic compounds — not just rosmarinic acid, so we can’t be certain what caused these improvements in asthmatic symptoms.

A 2014, 16-week study showed that people with knee osteoarthritis had significantly decreased pain after drinking 2 cups (473 mL) of spearmint tea, which was high in rosmarinic acid, per day. Drinking the tea also led to improvements in walking ability.

Participants who drank a control tea, which was a regular strength mint tea, experienced significant improvements in stiffness and physical disability, but they did not experience decreased pain.

The high rosmarinic acid tea contained about 130–150 mg of rosmarinic acid per 1 cup (237 mL), while the control tea contained around 13 mg per cup (13).

Additionally, a 2008 study looked at the effects of topical rosmarinic acid on atopic dermatitis, an inflammatory skin disease.

The study found that when participants applied a rosmarinic acid emulsion to their skin, it helped improve dryness, itchy skin, and their general skin condition (14).

Findings from a number of animal studies also suggest that rosmarinic acid has powerful anti-inflammatory properties and may reduce both local and system-wide inflammation (1, 15).

However, research in humans is limited at this time, and more studies are needed to investigate the potential anti-inflammatory benefits of rosmarinic acid, especially for treating inflammatory conditions.

Acts as an antioxidant

Rosmarinic acid may have antioxidant effects, which might provide many benefits.

Antioxidants reduce or inhibit cellular damage. They do this by neutralizing harmful molecules called free radicals and protecting against a process called oxidative stress, which can lead to decreased antioxidant defenses and increased free radical production (16).

Studies have found that oxidative stress is linked to a number of chronic health conditions, including certain cancers, heart disease, and diabetes (17).

Rosmarinic acid has demonstrated potent antioxidant effects in animal and test-tube studies. It reduced markers of oxidative stress while increasing levels of antioxidant enzymes (18, 19, 20, 21, 22, 23, 24, 25).

A 2015 study gave aging mice high doses of rosmarinic acid for 30 days.

Compared with a control group, mice that received the treatment had significantly higher levels of certain antioxidant enzymes in their liver and kidneys, as well as significantly lower levels of the oxidative stress marker malondialdehyde (MDA) (18).

Interestingly, manufacturers use rosmarinic acid in food products because it helps reduce spoilage and increase shelf life (26).

Even though these findings are promising, there’s currently a lack of human studies investigating the antioxidant effects of rosmarinic acid. That means that we don’t know enough about it to say with certainty how it affects people.

Other potential health benefits

Research has linked rosmarinic acid to several other potential health benefits.

  • May benefit brain health. Rodent studies suggest that rosmarinic acid may help protect against cognitive decline and depression and benefit learning and memory. However, human research is needed (27, 28, 29).
  • May protect against allergies. A 2004 study found that people with mild seasonal allergies who took a plant extract high in rosmarinic acid for 21 days had reduced symptoms, including itchy nose, watery eyes, and itchy eyes (1, 30).
  • May have anticancer effects. Findings from a number of test-tube and animal studies suggest that rosmarinic acid has anticancer effects. However, there’s no evidence that rosmarinic acid can fight cancer in humans (31, 32, 33, 34, 35).

Rosmarinic acid may have other health benefits, too. For example, some evidence suggests that it may have antiviral, antibacterial, and antidiabetic effects (36, 37, 38, 39, 40).

Human research is needed to investigate these and other potential benefits of rosmarinic acid.

Summary

Studies show that rosmarinic acid has powerful antioxidant and anti-inflammatory properties, and some suggest that it may help treat certain inflammatory conditions, allergies, and more. However, human research is currently lacking.

There’s not a lot of information about the potential side effects of isolated rosmarinic acid.

Studies that have investigated the effects of products high in rosmarinic acid have reported mild side effects. These products included rosemary extract, mint tea, and rosmarinic-acid-enriched Perilla frutescens.

For example, in a 2014 study, some people who consumed spearmint tea that contained 130–150 mg of rosmarinic acid per 1 cup (237 mL) reported side effects like headache, constipation, and diarrhea (13).

Another study reported that some participants who took rosemary extract experienced skin rashes and abdominal pain (12).

Many dietary supplements, including herbal extracts high in rosmarinic acid, may cause side effects and interact with medications.

As such, it’s important to check with a healthcare professional before starting a new supplement, especially if you’re taking medication or have a health condition.

Summary

Some supplements that contain rosmarinic acid could lead to side effects. Check with a healthcare professional before starting any supplement to ensure it’s a safe choice.

Even though rosmarinic acid is named after rosemary, you can also find it in concentrated amounts in several other plants.

Here are the richest sources of rosmarinic acid and the approximate concentrations they contain (2):

  • Selfheal (Prunella vulgaris L.): 61,000 ppm
  • Oregano: 55,000 ppm
  • Spearmint: 43,000 ppm
  • Rosemary: 38,957 ppm

Here are a few other good sources of rosmarinic acid (2):

  • sweet basil
  • mint
  • lemon balm
  • sage
  • Spanish sage
  • marjoram
  • thyme
  • lavender
  • perilla
  • beebalm
  • wild bergamot
  • creeping thyme
  • alehoof
  • summer savory

Dosages and forms

The available evidence from human research suggests that daily doses ranging from 200–300 mg of rosmarinic acid may help treat inflammation, allergies, and asthma symptoms (12, 13, 30).

However, there isn’t a lot of research investigating the effective dosages of rosmarinic acid. More research is needed to fully understand how high-dose rosmarinic acid supplements affect health and what dosages may be most effective for treating specific ailments.

If you search for rosmarinic acid supplements, you probably won’t find isolated rosmarinic acid. Instead, you’ll probably find it as an ingredient in supplements that contain plants and their extracts.

Rosmarinic acid is present in the following types of supplements:

  • rosemary extract
  • selfheal (Prunella vulgaris L.) supplements
  • lemon balm extract
  • oil of oregano supplements

Keep in mind that most of these supplements don’t list the amount of rosmarinic acid they contain.

If you’re interested in trying a supplement that contains rosmarinic acid, make sure you consult a healthcare professional first. They can help you determine whether supplements are necessary and appropriate for your specific needs.

Rather than taking supplements that contain rosmarinic acid, you could consider adding more rosmarinic-acid-rich herbs, such as oregano, rosemary, mint, marjoram, thyme, and lemon balm, to your diet.

Summary

Some plants contain rosmarinic acid, including mint, oregano, rosemary, and lavender. Also, certain supplements, such as selfheal and rosemary extract, contain rosmarinic acid, but most don’t list how much rosmarinic acid they contain.

Rosmarinic acid is a compound found in a number of common kitchen herbs and other plants, including rosemary.

Rosmarinic acid may have therapeutic properties, including antioxidant and anti-inflammatory effects, but human research investigating rosmarinic acid’s health effects is currently limited. That means we can’t say with certainty how it affects humans.

If you want to increase your consumption of rosmarinic acid, try increasing your intake of rosmarinic-acid-rich herbs, such as rosemary, oregano, spearmint, and thyme.

You could also try taking herbal supplements that contain rosmarinic acid, but they likely won’t tell you how much you’re getting per serving.