Calcium gets all the attention, but vitamin K2 is what tells calcium where to go. Without enough K2, calcium can end up in your arteries instead of your bones — a problem worth understanding before you load up on supplements.
Vitamin K2 is one of the more underappreciated nutrients in bone health. Most people have heard of calcium and vitamin D, but K2 often gets left out of the conversation — which is a shame, because it plays a genuinely important role in how your body handles calcium once it's absorbed.
The simplified version: vitamin K2 activates proteins that bind calcium and direct it into bone tissue. Without adequate K2, those proteins stay inactive, and calcium can deposit in soft tissues — including arterial walls — rather than where it belongs. This is part of why the combination of calcium, vitamin D, and vitamin K2 is increasingly discussed together rather than in isolation.
Most people know vitamin K primarily from its role in blood clotting — that's mostly vitamin K1 (phylloquinone), found in leafy greens. Vitamin K2 (menaquinone) is a family of related compounds with different molecular chain lengths, designated as MK-4, MK-7, MK-8, and so on. For bone and cardiovascular health, MK-4 and MK-7 are the two forms you'll encounter most often in research and in supplements.
The key proteins activated by K2 include osteocalcin (which helps bind calcium into bone matrix) and matrix Gla protein (MGP), which inhibits calcium from depositing in arteries. Both require adequate K2 to function properly.
This is the question that comes up most often when people start looking at K2 supplements. The two forms are similar in function but differ in important ways:
| Feature | MK-4 | MK-7 |
|---|---|---|
| Natural sources | Meat, eggs, some cheeses | Natto, some fermented foods |
| Half-life in the body | ~1–2 hours | ~3 days |
| Typical supplement dose | 1,500 mcg (1.5 mg) | 90–200 mcg |
| Research base | Larger (mostly Japanese trials) | Growing, good quality |
| Cost per dose | Higher (needs large dose) | Lower (small dose effective) |
MK-7's much longer half-life means a single small daily dose can maintain consistent blood levels, which is why most modern supplements use MK-7. The pharmaceutical-dose MK-4 studies (using 45 mg/day) from Japan showed significant reduction in fracture rates in osteoporotic patients, but those doses are rarely used outside Japan. At the supplement doses of MK-4 available in Canada (often 100–500 mcg), the evidence is less compelling.
For most Canadians using a supplement, MK-7 at 100–200 mcg/day is the better-supported and more practical choice.
The richest dietary source of MK-7 by a wide margin is natto — fermented soybeans popular in Japan. A single 100g serving contains around 1,000 mcg of MK-7. The problem is that natto has a strong, polarizing flavour and smell, and it's not a regular part of most Canadian diets. You can find it at Japanese grocery stores in cities like Toronto, Vancouver, and Calgary, but it's not something most people are going to eat daily.
For the rest of us, other dietary sources tend to be modest:
That said, dietary K2 from non-natto sources is unlikely to reach the levels associated with the strongest bone benefits in clinical research. This is one area where supplementation genuinely may offer something that's hard to get from food alone (for most Canadians).
The evidence is strongest for MK-4 at high pharmaceutical doses in post-menopausal women — multiple Japanese randomized controlled trials found significant reduction in vertebral fracture risk. That said, these used 45 mg/day, far above what's available over-the-counter.
For MK-7 at supplement doses (90–200 mcg/day), a well-cited 2013 Dutch trial (Knapen et al.) found that MK-7 supplementation improved bone strength and reduced bone loss in post-menopausal women compared to placebo over three years. Other studies have shown improvements in osteocalcin carboxylation — a marker of K2 activity — with even modest MK-7 supplementation.
K2 is not a standalone treatment for osteoporosis and should not replace medication if that's been recommended by your physician. But as part of a broader supplement strategy — alongside calcium, vitamin D, and magnesium — there's reasonable evidence for including it, particularly for women after menopause.
Health Canada classifies vitamin K2 supplements as Natural Health Products (NHPs), so they require a product licence before being sold. You'll find K2 at most pharmacies and health food stores across the country:
One of Canada's most recognized supplement brands. Their MK-7 formulation is available at Shoppers Drug Mart, Rexall, and most major grocery chains. Typically offered at 120 mcg, which falls within the evidence-supported range.
BC-based company with an NPN-licensed MK-7 product. Available at health food stores like Whole Foods and IDA Pharmacy locations. Natural Factors is transparent about sourcing and often the preferred choice in independent health food stores.
Another Canadian brand with broad pharmacy distribution. Their K2+D3 combination product is popular and convenient for people who want to cover both nutrients in a single supplement.
American brand available in Canada, with competitive pricing. Uses MenaquinGold, a well-studied MK-7 form. A reasonable option if you order supplements online.
Compare MK-7 formulations from Canadian and international brands, with pricing and customer reviews. Many ship free with Prime.
Browse K2 Supplements →For general bone health support, most research on MK-7 uses 90–200 mcg/day. Health Canada does not have a formal Dietary Reference Intake for K2 specifically (it's lumped in with vitamin K generally), but 100–200 mcg of MK-7 is the standard range used in research and reflected in most Canadian supplements.
Vitamin K2 at these doses has an excellent safety profile. The main interaction to be aware of:
For people not on anticoagulants, K2 at supplement doses has no established toxicity and is generally considered safe for long-term use.
Vitamin K2 is not a miracle nutrient, and it won't reverse osteoporosis on its own. But it's a genuinely useful addition to a bone health supplement routine, particularly for post-menopausal women or anyone taking supplemental calcium and vitamin D.
The practical approach for most Canadians: eat aged cheese and eggs regularly, consider adding natto if you can tolerate it, and if you're supplementing calcium and D already, adding 100–200 mcg of MK-7 is a low-risk, evidence-supported step. Look for the Jamieson, Natural Factors, or Webber K2+D3 combinations at your local pharmacy — no prescription needed.