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 in an Australian listed medicine, and the form behind almost all the human trials. Absorption: No human absorption study was found. The only data is an animal finding that algal biomass raised uptake. Typical use: 4 mg or 12 mg once a day. The label states 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 permitted form, from one manufacturer with its own trial file. The children's eye-strain trial used it. Absorption: As for algal esters. Typical use: A result from 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 this evidence set. Typical use: Not permitted as the active in an Australian listed medicine. 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 unstated 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 holds several actives.
• Topical creams and serums. Best known for: Astaxanthin applied to skin rather than swallowed. Absorption: Not applicable. Typical use: Regulated as a cosmetic here, because the permitted 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 meet astaxanthin in food. Absorption: Not assessed. Typical use: Wild sockeye carries 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

This list is the part of the page we will not shorten. If any of it applies to you, talk to one of our naturopaths or your doctor before starting.

• Warfarin and other vitamin K antagonists. INR rose from 1.4 to 10.38 with bruising in a published case; refer to the prescriber.
• Antiplatelet medicines such as aspirin. The case patient also took aspirin; no trial evidence either way.
• Pregnancy. No data; refer to a health professional and don't state it's safe or unsafe.
• Breastfeeding. No data; same position as pregnancy.
• Children. Only 4 mg a day in ages 10 to 14 has been studied; 12 mg products aren't evidenced in children.
• Long-term use. Most trials ran 24 weeks or less.
• Krill-based products. Shellfish-derived.
• If you take prescription medicines, check with your doctor, pharmacist or our naturopaths before starting.