Alfalfa and vitamin K2: what's actually the difference

Alfalfa is a plant source of vitamin K1 (phylloquinone), not vitamin K2 (menaquinone) — the two are related compounds but not interchangeable, and alfalfa doesn't contribute meaningful K2. The reason the two get searched together is that many retail vitamin K2 capsules list alfalfa leaf powder as an added "other ingredient" anyway, separate from the K2 itself.

K1 and K2 aren't the same nutrient

Vitamin K1 (phylloquinone) is the form found in green plants, including alfalfa, and it's the majority form in a typical diet. Vitamin K2 (menaquinone) is a different, related compound, made by bacteria and found in fermented foods and some animal products; supplement K2 is usually sold as a specific subtype, MK-4 or MK-7. NIH's LactMed monograph on alfalfa lists vitamin K among its documented compounds — that's K1, not K2, and alfalfa isn't a plant source of the menaquinone forms sold in a K2 capsule.

MK-4 and MK-7 aren't the same K2 either

Retail K2 supplements are most commonly sold as one of two menaquinone subtypes: MK-4, typically dosed at higher amounts (often around 100 mcg or more per capsule) and cleared from the body faster, or MK-7, typically dosed lower (often in the 45–180 mcg range) and longer-lasting in circulation. Neither subtype comes from alfalfa — MK-4 is usually made synthetically, and MK-7 is usually derived from a fermentation process (commonly associated with natto, a fermented soybean food). Checking which subtype and dose a specific product uses is a separate label question from whether it also contains alfalfa.

Why alfalfa shows up on K2 labels anyway

It's common for a retail vitamin K2 capsule to list alfalfa leaf powder — often in the tens to a few hundred milligrams — as a separate ingredient alongside the actual K2 compound, usually marketed as a "natural" plant addition rather than as the source of the K2 itself. That's a formulation choice, not a sign that alfalfa is contributing the vitamin K2 on the label; the K2 amount stated on the Supplement Facts panel comes from the menaquinone ingredient, not the alfalfa.

If you're specifically trying to avoid alfalfa

Some people look for a K2 product without alfalfa for reasons unrelated to the vitamin itself — commonly because of the caution around alfalfa and blood thinners, or the lupus/autoimmune signal covered in who should not take alfalfa. If either applies to you, check the "other ingredients" line on a K2 label specifically, since alfalfa can be present in a product built around a completely different vitamin without it being obvious from the front of the bottle.

Questions people ask

Does alfalfa contain vitamin K2?

No — alfalfa is a source of vitamin K1 (phylloquinone), a related but different compound from the menaquinone (K2) sold in a vitamin K2 supplement.

Why is alfalfa in my vitamin K2 supplement?

Many K2 capsules add alfalfa leaf powder as a separate ingredient, marketed as a natural plant addition — it isn't the source of the K2 itself, which comes from a menaquinone (MK-4 or MK-7) ingredient stated separately on the label.

Can I take vitamin K2 without alfalfa?

Yes — check the "other ingredients" line on the label, since not every K2 product includes it. K2 and alfalfa aren't the same thing and don't have to be sold together.

Related reading: what is alfalfa, alfalfa and medications: what to check, and who should not take alfalfa.