Vitamin K2 180 Max

These are the questions our naturopaths ask in store, to make sure MK-7 is the right fit for why you're buying it.

A good fit if

• You're past menopause and want to look after your bones, which is where nearly all the MK-7 research has been done
• You want 90 to 180 micrograms a day, the range that has both research behind it and is legal in Australia
• You already take vitamin D and want the partner it's most often studied with
• You eat almost no fermented food, so you're not getting any from natto or fermented cheese

Check with us first if

• You have a condition that affects how you absorb fat, such as Crohn's disease, cystic fibrosis or cholestasis. Vitamin K needs fat from your food to be carried
• You're on dialysis or have advanced chronic kidney disease. Low vitamin K is common there, and it's a conversation for your kidney specialist team
• You're pregnant or breastfeeding. The Adequate Intake doesn't change, but no trial has tested supplement doses in pregnancy or breastfeeding, so we can't reassure you about a dose
• It's for a child. The legal limit is 90 micrograms a day for ages 10 to 18 and 45 micrograms for under-10s
• You're a man buying it for your bones. The one trial that tested both men and women found the benefit in women past menopause and no effect in men
• If you take prescription medicines, check with your doctor, pharmacist or our naturopaths before starting

• Vitamin K2 as MK-7 (menaquinone-7). Best known for: The long-chain menaquinone from natto, and the form almost every Australian K2 product is built on. Absorption: Tested head to head against MK-4 and clearly ahead: a single 420 µg dose peaked in the blood at six hours and could still be detected 48 hours later. Typical use: Bone maintenance in postmenopausal women, where the long trials are genuinely split rather than all positive. Schedule 1 item 3252, allowed with conditions, limited to 180 µg a day for adults.
• Vitamin K2 as MK-4 (menatetrenone). Best known for: The short-chain menaquinone behind the Japanese bone research, used there as a 45 mg a day prescription drug rather than a supplement. Absorption: The finding against it: at a single 420 µg dose, MK-4 couldn't be detected in anyone's blood at any time point. Typical use: Not on Schedule 1, so it can't be an active ingredient in an Australian listed medicine.
• "Vitamin K2" with no menaquinone named. Best known for: A label that tells you the family and nothing more. Absorption: Varies hugely by form, which is exactly why the name alone isn't enough to choose on. Typical use: Not a Schedule 1 name on its own. A compliant Australian product names the menaquinone, and in practice that's this one, MK-7.

Reference values. There's no reference value for MK-7 on its own. The NHMRC and NZ Ministry of Health set an Adequate Intake for vitamin K as a whole rather than an RDI: 60 µg a day for women 19 and over, 70 µg for men, and 60 µg through pregnancy and breastfeeding.

Typical supplemental range. Australian MK-7 products usually give you 60 to 180 micrograms a day, and 180 is the legal limit, not a recommendation. The research within that range is limited but real: 90 micrograms a day slowed bone loss at the hip (the femoral neck) in women past menopause over a year, and 180 micrograms a day was the dose in the longest positive MK-7 trial. Much of the wider research used 200, 360 or 375 micrograms, more than can legally be sold here, so treat those numbers as research findings rather than a dose to take.

Upper level. No upper level has been set for any form of vitamin K. In the NHMRC's own words: "No adverse effects have been associated with vitamin K consumption as food or supplements in humans or animals, so it is not possible to set a UL." That's separate from the legal question. The 180 microgram Australian cap on MK-7 comes from the Permissible Ingredients Determination, not from a safety limit.

Worth knowing. Take it with a meal that has some fat in it. Vitamin K is fat-soluble and travels on the fat-carrying particles in your blood. What you need depends on your age, diet and health, so talk to one of our naturopaths.

Food first, where the diet allows it.

• Natto (fermented soybeans), 85 g: 850 µg of vitamin K, mostly as MK-7: realistically the only common food that's a serious source
• Fermented cheeses, Jarlsberg among them: no figure in the reference tables we use, but MK-7 status improved in one study on Jarlsberg
• Green leafy vegetables: spinach, kale, broccoli: 110 to 145 µg a serve, but that's K1, not MK-7

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

• Warfarin or another vitamin K blocker (antagonist). It interacts directly and significantly; this is for your prescriber to manage, never something we'd advise on in store.
• Eating natto while on warfarin. Published advice is that normal natto must be avoided.
• Any blood thinner taken by mouth. This food interaction is treated as significant for the whole class.
• Pregnancy. The Adequate Intake stays at 60 µg a day, but there's no trial of supplement doses, so we'll refer you rather than reassure you.
• Breastfeeding. Same as pregnancy; we found no evidence on supplement doses.
• Children. The legal limit is 90 µg a day for ages 10-18 and 45 µg for under-10s.
• Conditions that affect fat absorption (Crohn's, cystic fibrosis, cholestasis). Low levels are common, so get assessed.
• Dialysis and advanced chronic kidney disease. Low levels are common and results are inconsistent; this needs a practitioner.
• Men taking it for bone health. The only trial that tested both sexes found no effect in men.
• If you take prescription medicines, check with your doctor, pharmacist or our naturopaths before you start.