Astaxanthin

With astaxanthin, the dose on the label matters as much as the ingredient. These are the questions our naturopaths ask in store before you pick a strength.

A good fit if

• Dry skin that's lost some of its spring is the reason you're looking, which is where the best evidence is
• You're happy with a low dose. The skin trials used 2 to 6 mg a day, so a 4 mg capsule fits them well
• You spend long hours on screens and your eyes feel it. The best trial was in children, so the adult evidence is thinner
• You want the natural algae form, which is the only one allowed as the active ingredient here

Check with us first if

• You take aspirin or another antiplatelet medicine. The published bleeding case also involved aspirin, and no trial has tested the two together.
• You're pregnant or breastfeeding. No trial has included pregnant or breastfeeding women, so no one can say whether it's safe.
• It's for a child. One trial used 4 mg a day in children aged 10 to 14 with no safety concerns, and nothing supports the 12 mg products for children.
• You're buying it for training and recovery. The strongest exercise results came from doses higher than can be sold here, in very small studies.
• You're comparing it with krill oil. Krill products contain small, usually unstated amounts of astaxanthin, and krill is a shellfish.
• You take any prescription medicine. Check with your doctor, pharmacist or our naturopaths before starting.

• Astaxanthin esters from Haematococcus pluvialis (algal softgel). Best known for: The only form allowed as the active ingredient in an Australian listed medicine, and the form behind almost all the human trials. Absorption: We found no human absorption study. The only data is an animal finding that algal biomass raised uptake. Typical use: 4 mg or 12 mg once a day. The label gives milligrams of astaxanthin, not of the extract, because the cap applies to the astaxanthin.
• Branded algal material (for example AstaReal). Best known for: The same allowed form, from one manufacturer with its own trials. The children's eye-strain trial used it. Absorption: Same as algal esters. Typical use: A result for a branded material belongs to that material. It doesn't automatically carry over to every astaxanthin capsule.
• Synthetic astaxanthin. Best known for: Chemically different from the natural form, and made mainly for fish-farm feed. Absorption: Not assessed in the evidence we hold. Typical use: Not allowed as the active in an Australian listed medicine, and few human or animal safety studies exist for it.
• Krill oil containing astaxanthin. Best known for: Omega-3 fats with a small amount of astaxanthin, usually not stated on the label. Absorption: Not assessed for the astaxanthin part. Typical use: Buy it for the omega-3. A krill trial result isn't an astaxanthin result, because the product has several actives.
• Topical creams and serums. Best known for: Astaxanthin applied to the skin rather than swallowed. Absorption: Not applicable. Typical use: Regulated as a cosmetic here, because the allowed form is for oral medicines only. The only studies were open-label, with no placebo.
• Salmon, trout, prawns and krill. Best known for: Where you get astaxanthin in food. Absorption: Not assessed. Typical use: Wild sockeye has about four to five times as much as farmed Atlantic salmon.

Reference values. There isn't one. Astaxanthin isn't a nutrient, so the NHMRC doesn't set a recommended intake, and there's no amount you're meant to get each day.

Typical supplemental range. Australian products come as a 4 mg or 12 mg softgel, taken once a day. Trial doses ranged from 2 mg to 28 mg, and the dose that worked depended on what was measured. The skin trials used 2 to 6 mg a day for 9 to 12 weeks. The children's eye strain trial used 4 mg for 84 days. The exercise and CRP (an inflammation marker) findings needed more than 12 mg a day, which can't be sold here, and at 12 mg the exercise evidence covers blood markers only.

Upper level. An Australian listed medicine can't contain more than 12 mg of astaxanthin in its maximum daily dose. Overseas, approved doses range from 2 to 24 mg. A review of 87 human studies found no safety concerns with natural astaxanthin, 35 of them at 12 mg a day or more, though most trials ran for 24 weeks or less.

Worth knowing. Because it dissolves in fat, it comes in an oil capsule. You'll often see advice to take it with a fatty meal, but we couldn't find a human study behind that, so we don't present it as proven. For skin, a 4 mg product is closer to the trial doses than a 12 mg one. What you need depends on your age, diet and health, so talk to one of our naturopaths.

Food first, where the diet allows it.

• Wild sockeye salmon, 150 g fillet: roughly 3.9 to 5.7 mg, worked out from 26 to 38 mg per kg of flesh
• Farmed Atlantic salmon, 150 g fillet: roughly 0.9 to 1.2 mg, from 6 to 8 mg per kg
• Japanese large trout, 150 g: roughly 3.8 mg, from 25 mg per kg
• European large trout, 150 g: roughly 0.9 mg, from 6 mg per kg
• Krill: 0.12% of dry weight; no per-serve figure is available, so none is stated

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

• You take warfarin or another vitamin K antagonist. In a published case, INR rose from 1.4 to 10.38 with bruising, so check with your prescriber.
• You take antiplatelet medicines such as aspirin. The person in that case also took aspirin; there's no trial evidence either way.
• You're pregnant. There's no data, so talk to a health professional; we can't say whether it's safe or unsafe.
• You're breastfeeding. There's no data, so the same applies as for pregnancy.
• Children. Only 4 mg a day in ages 10 to 14 has been studied; there's no evidence for 12 mg products in children.
• You plan to take it long term. Most trials ran for 24 weeks or less.
• You're allergic to shellfish and looking at krill-based products. They're made from shellfish.
• If you take prescription medicines, check with your doctor, pharmacist or our naturopaths before you start.