L-Ergothioneine

Ergothioneine is an unusual one, because the Australian rules are narrow and the research is young. These are the questions our naturopaths ask in store.

A good fit if

• You're an adult who wants to understand where ergothioneine comes from before deciding anything
• You'd like to eat more of it and want to know which foods contain it
• You're looking at a skin product that lists it and want to know what the Australian rules allow
• You're comfortable that the human evidence is early and small, and you're not pregnant or breastfeeding

Check with us first if

• You take any prescription medicine. Ergothioneine's interactions with medicines haven't been studied, and it shares a cell transporter with other compounds, so nobody can tell you there are none.
• You're on haemodialysis or peritoneal dialysis. Dialysis strips ergothioneine from your blood, but whether topping it up helps hasn't been tested, so talk to your kidney team first.
• You're buying an ergothioneine capsule. It can't be an AUST L listed medicine in Australia, so whether it can legally be sold here has to be checked product by product.
• You plan to take more than 25 mg a day. Human safety data doesn't go above that.

• Topical ergothioneine, applied to the skin. Best known for: The only form allowed in an Australian listed medicine. Absorption: There's no human study of absorption through the skin. Typical use: Creams and serums at no more than 0.0005%, never in eye products.
• Isolated L-ergothioneine capsule. Best known for: The form sold overseas as a supplement you swallow. Absorption: Not measured directly in the studies we hold. Typical use: Trials used 25 mg three times a week. It can't be sold as an AUST L listed medicine here.
• Whole mushrooms, eaten as food. Best known for: Where most of the human evidence comes from. Absorption: Shown directly: red blood cell levels rose after a mushroom meal. Typical use: Everyday cooking. Button, portobello and oyster mushrooms have been studied.
• Mushroom powder in capsules. Best known for: A food-based way to raise ergothioneine in your blood. Absorption: Shown: 5 g a day of button mushroom powder raised blood levels. Typical use: A food concentrate, not a listed medicine.
• Listed mushroom medicines (shiitake, reishi, turkey tail). Best known for: Mushroom species that Australian listed medicines can use. Absorption: The sources we hold didn't measure their ergothioneine content. Typical use: AUST L capsules and powders, with claims set by each product's own listing.

Reference values. There's no Australian recommended intake for ergothioneine. It isn't treated as an essential nutrient in the Australian and New Zealand nutrient reference values.

Typical supplemental range. There's no Australian listed medicine dose to quote, because ergothioneine can't be a listed medicine taken by mouth here. For context, the one trial of ergothioneine on its own that we've reviewed used 25 mg capsules three times a week for a year.

Upper level. No upper limit is set. The human studies reviewed so far reported no safety concerns at up to 25 mg a day, and there's no human data on higher amounts. For skin products, the Australian legal maximum is 0.0005% of the product.

Worth knowing. Mushrooms are the practical everyday source, and how much you get depends on the type of mushroom, how it's cooked and for how long. What you need depends on your age, diet and health, so talk to one of our naturopaths.

Food first, where the diet allows it.

• Mushrooms, as a group: about 0.4 to 2.0 mg per gram, dry weight
• Button or portobello mushroom (Agaricus bisporus), as powder: 8 g and 16 g in a meal raised red blood cell levels
• Button mushroom powder, taken daily: 5 g a day for 8 weeks raised blood levels significantly
• Oyster mushroom (Pleurotus ostreatus): described as rich in ergothioneine; the amount per serve wasn't reported
• Cooked mushrooms generally: content varies with the species, the cooking method and the cooking time

If any of these sound like you, talk to one of our naturopaths or your doctor before you start.

• Pregnancy and breastfeeding. Safety isn't established, so we advise against it; talk to your doctor or midwife.
• Babies and children. Safety isn't established, so it's not for children.
• Use in the eye. The Schedule 1 condition for ERGOTHIONEINE rules this out.
• Prescription medicines. Interactions haven't been studied; competition for the OCTN1 transporter is theoretical and untested.
• Haemodialysis or peritoneal dialysis. Blood levels are lowered, but whether topping them up helps is untested; check with your kidney team.
• Oral capsules. Not allowed as an oral listed medicine in Australia; the legal basis needs checking for each product.
• Doses above 25 mg a day. These are beyond the human safety data reviewed.
• If you take prescription medicines, check with your doctor, pharmacist or one of our naturopaths before you start.