Should I take 5000 IU of vitamin D every day?

Only if a blood test (25-hydroxyvitamin D) shows you're low — 5000 IU is a generous, deficiency-correcting dose. In people already replete, VITAL found little added benefit, and high long-term intakes should be discussed with a clinician.

Why combine D3 with K2?

D3 raises calcium absorption; K2 (MK-7) activates proteins like matrix Gla protein that influence where calcium goes. The mechanistic/surrogate evidence for K2 is reasonable, but hard outcome proof (fewer fractures or cardiac events) is still limited.

Is this suitable for vegans?

Yes. The D3 is from lichen and the K2 (MK-7) from fermented chickpea, and it's Vegan Certified and Non-GMO Project Verified — unusual for D3, which is often from lanolin.

D3 + K2 or plain D3 — do I actually need the K2?

Plain D3 corrects a low vitamin D level; the K2 (MK-7) here is added to activate proteins like matrix Gla protein that influence where calcium ends up. If you specifically want that calcium-handling angle, the combo makes sense — a standalone D3 or a multivitamin (which typically has little or no K2, and only 400–1000 IU of D) won't give it to you. The mechanistic case for K2 is reasonable; hard outcome proof is still limited.

Is there proof this prevents fractures or heart problems?

Be realistic — this is where honesty matters. In VITAL, 2000 IU/day of D3 did not lower cancer or major cardiovascular events over ~5 years in mostly D-replete adults, so routine supplementation has limited benefit unless you're actually deficient. And a 3-year RCT found 375 µg/day of K2 (MK-7) did not improve bone density or microarchitecture versus placebo. K2's arterial-stiffness data are promising but surrogate. Test your D level first; don't take 5000 IU on spec. Not medical advice.

Sports Research Vitamin D3 + K2 Review

What does the research say about the Sports Research Vitamin D3 + K2?

Every claim below is tied to a source you can open, quoted verbatim — how we research picks.

“Supplementation with vitamin D did not result in a lower incidence of invasive cancer or cardiovascular events than placebo.”

In a large RCT of mostly D-replete adults, 2000 IU/day D3 did not lower invasive cancer or major cardiovascular events over ~5.3 years — evidence that routine supplementation has limited benefit when you are not deficient.
Manson JE et al., NEJM (VITAL) · 2019 ↗
“In conclusion, long-term use of MK-7 supplements improves arterial stiffness in healthy postmenopausal women, especially in women having a high arterial stiffness.”

Three years of 180 µg/day MK-7 improved arterial stiffness and increased carboxylation of vitamin K-dependent proteins in healthy postmenopausal women, supporting K2's role in calcium handling.
Knapen MHJ et al., Thrombosis and Haemostasis · 2015 ↗
“BMD decreased at all sites without differences between the MK-7 and placebo-treated women. Changes in bone turnover markers and microstructure were similar between the two groups.”

A 3-year double-blind RCT (142 postmenopausal women with osteopenia) found 375 µg/day MK-7 did NOT improve bone mineral density or microarchitecture versus placebo — a null result for bone outcomes.
Rønn SH et al., 3-year RCT (Osteoporosis Int.) · 2020 ↗

Educational summary of the research — not medical or veterinary advice. Evidence strength varies and individual results differ; talk to a qualified professional before changing your (or your pet's) health routine.

How does the Sports Research Vitamin D3 + K2 compare?

	D3 + K2	D3 alone	Multivitamin
Includes K2 (MK-7)	Yes, 100 mcg	No	Rarely / low
Vitamin D3 dose	5000 IU (high)	Varies, often high	Typically 400-1000 IU
Vegan D3 source	Yes (lichen)	Varies	Usually not
Focus	Bone + calcium handling	D-status correction	Broad, low doses

Buy it if

People whose bloodwork confirms low vitamin D
Vegans and vegetarians who can't use lanolin-derived D3
Those who specifically want K2 (MK-7) alongside D3
Anyone who prefers a third-party-tested single-softgel format

Skip it if

People who haven't tested and may already be D-replete
Anyone on warfarin / vitamin K-antagonist anticoagulants without clinician sign-off
Those wanting a lower maintenance dose (1000-2000 IU)

Is the Sports Research Vitamin D3 + K2 worth it?

A genuinely well-made vegan D3 + K2 (MK-7) softgel with credible third-party testing and the better-studied K2 form. Evidence supports D3 for bone health when you're actually deficient, and K2 has plausible mechanistic backing — but the 5000 IU dose is best matched to a confirmed low level, not taken on spec. Test first. Not medical treatment.

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Questions, answered

Should I take 5000 IU of vitamin D every day?: Only if a blood test (25-hydroxyvitamin D) shows you're low — 5000 IU is a generous, deficiency-correcting dose. In people already replete, VITAL found little added benefit, and high long-term intakes should be discussed with a clinician. Source Manson et al., NEJM (VITAL) ↗
Why combine D3 with K2?: D3 raises calcium absorption; K2 (MK-7) activates proteins like matrix Gla protein that influence where calcium goes. The mechanistic/surrogate evidence for K2 is reasonable, but hard outcome proof (fewer fractures or cardiac events) is still limited. Source Knapen et al., Thromb Haemost ↗
Is this suitable for vegans?: Yes. The D3 is from lichen and the K2 (MK-7) from fermented chickpea, and it's Vegan Certified and Non-GMO Project Verified — unusual for D3, which is often from lanolin. Source Sports Research, Vitamin D3 + K2 product page ↗
D3 + K2 or plain D3 — do I actually need the K2?: Plain D3 corrects a low vitamin D level; the K2 (MK-7) here is added to activate proteins like matrix Gla protein that influence where calcium ends up. If you specifically want that calcium-handling angle, the combo makes sense — a standalone D3 or a multivitamin (which typically has little or no K2, and only 400–1000 IU of D) won't give it to you. The mechanistic case for K2 is reasonable; hard outcome proof is still limited. Source Knapen et al., Thromb Haemost ↗
Is there proof this prevents fractures or heart problems?: Be realistic — this is where honesty matters. In VITAL, 2000 IU/day of D3 did not lower cancer or major cardiovascular events over ~5 years in mostly D-replete adults, so routine supplementation has limited benefit unless you're actually deficient. And a 3-year RCT found 375 µg/day of K2 (MK-7) did not improve bone density or microarchitecture versus placebo. K2's arterial-stiffness data are promising but surrogate. Test your D level first; don't take 5000 IU on spec. Not medical advice. Source Manson et al., NEJM (VITAL) ↗Rønn et al., 3-year RCT (Osteoporosis Int.) ↗Knapen et al., Thromb Haemost ↗