What is American Mountain Ash?

American mountain ash is a small North American tree. Folk healers used its bark and its bright orange-red berries. Old names for it include round-wood, dogberry and American rowan.

The berries were cooked into jelly, syrup or a tart drink. The bark was dried and boiled into a bitter tea. Eclectic doctors of the 1800s called the bark a tonic and an astringent (a drying agent).

Here is the honest verdict. There are no good human trials on this plant for any health use. Traditional use is not proof that it works, and it is not proof that it is safe.

One point matters before anything else. Raw berries upset the stomach and can make you vomit. Cooking or hard frost changes that.

How does American Mountain Ash work?

No one has shown how, or whether, this plant helps people. What follows is proposed, not proven.

The bark holds a lot of tannins. In test tubes, tannins bind proteins and tighten tissue. That is the basis of the old claim that bark tea firms up loose bowels.

The berries hold vitamin C. Vitamin C does prevent and treat scurvy, and that is well established in people. It says nothing about the other folk uses.

Lab work on rowan-type species points to antioxidant and mild antibacterial activity. Those are cell and test-tube results. Whether anything useful happens inside your body is unknown.

Raw berries contain parasorbic acid. It irritates the gut lining, which is why raw fruit causes vomiting. Heat and freezing turn it into sorbic acid, which is far gentler.

What forms does American Mountain Ash come in?

You are far more likely to meet this tree as food than as a supplement.

Common forms:

- Cooked berry jelly, jam or syrup.

- Dried berries, steeped as tea.

- Dried bark, boiled into a decoction (a strong tea).

- Tincture (an alcohol extract) of bark or berry, from a few herb suppliers.

Cooking is not a flourish. Heat and frost break down the compound behind raw-berry stomach upset. That is why old recipes always cooked the fruit.

Capsules are rare. Strength varies widely between makers.

Where it comes from:

Eclectic and folk practitioners in 1800s North America used both the bark and the fruit.

King's American Dispensatory listed the bark as a tonic and astringent. It was given in fevers and in what writers then called ague (a malaria-type fever). Some used it for loose bowels and as a gargle.

The berries were made into tart jelly or a sour drink. Settlers valued sharp fruit like this against scurvy. Indigenous peoples of the northeast also used parts of the tree, including as food.

Medical use faded as modern drugs arrived. Today the tree is mostly a wild food and an ornamental.

What does American Mountain Ash help with?

• Loose stools (diarrhoea): This is the main old use of the bark. Tannins tighten tissue in test tubes, and that is the stated reason. No human trial has tested this plant for diarrhoea. Treat the claim as unproven.
• Sore throat, as a gargle: Folk practice used cooled bark tea as a gargle. Tannins give a puckering feel that some people find soothing. There is no trial evidence here. Any relief is likely brief and does not treat the cause.
• Scurvy prevention, from the vitamin C in the fruit: Vitamin C prevents and treats scurvy. That is settled fact, and the cooked berries are a fair source. This is a food effect, not a special power of this tree. Any vitamin C source does the same job.
• Poor appetite and weak digestion: Bitter plants were widely used to 'wake up' digestion. Mountain ash bark was one of them. No study has tested it for appetite in people. The claim rests on tradition alone.
• Fevers (historical use only): Eclectic texts used the bark in fevers, including ague (a malaria-type fever). It did not work for malaria, and quinine replaced it. Do not rely on this plant for any fever. A fever that lasts or climbs needs a doctor.

Which foods are rich in American Mountain Ash?

The cooked berries are themselves a food. They are used in jelly, jam and some country wines and liqueurs, often with apple added for pectin.

What are the side effects of American Mountain Ash?

• Nausea and vomiting, mainly from raw berries
• Stomach cramps
• Diarrhoea
• Kidney irritation after large amounts of raw fruit
• Constipation or stomach upset from tannin-rich bark tea
• Lower iron uptake from food, with repeated bark tea
• Allergic rash or swelling, rarely

Good to know:

Most trouble comes from eating the berries raw. Nausea, vomiting and cramps are common in that case, and can be strong in children.

Cooked fruit is far better tolerated and is eaten as a normal food in parts of North America and Europe.

Serious harm is not well reported, but the plant has never been studied properly for safety. Absence of reports is not the same as proof of safety.

How much American Mountain Ash should you take?

• Recommended daily: There is no accepted dose for this plant, and this page does not give one. No trial has set a safe or useful amount. Products are not standardised, so two tinctures can differ a lot in strength. Cooked berries eaten as jelly are a food. Bark preparations are a different matter and should be discussed with a doctor or a trained herbalist first. Raw berries should not be eaten at all.
• Best time of day: Timing has not been studied and probably does not matter. Berry jelly is eaten with meals like any other preserve.
• With or without food: Take anything bark-based with food. Tannins on an empty stomach often cause nausea. Berry preserves are already eaten as food.
• Time to effect: Honestly, it may do nothing at all. If a bark gargle or tea helps a symptom, people report it within minutes to hours. Nothing about that is proven. There is no evidence for a slow build-up of benefit over weeks.
• How long to take it: No safe length of use has been studied. Long-term use of tannin-rich bark tea is not advised, since tannins can upset the stomach and block iron uptake. If you are using it for a symptom that lasts more than a few days, see a doctor instead.