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Head to head · Vitamins & Minerals

Sports Research Vitamin D3 + K2 (5000 IU) vs Thorne Iron Bisglycinate

Thorne scores higher overall (8.6 vs 7.8 out of 10), mainly on efficacy, quality & purity and transparency.

Updated September 2026 from our full reviews · How we score

Front of Sports Research D3 + K2 60 veggie softgel bottle
Sports ResearchVitamin D3 + K2 (5000 IU)
7.8
Good

Amazon's top D3+K2 pick: vegan lichen D3 plus MK-7 K2 in coconut MCT oil; the 5,000 IU dose exceeds the adult upper limit for daily use.

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Higher score
Front of Thorne Iron Bisglycinate 60-capsule bottle
ThorneIron Bisglycinate
8.6
Excellent

25 mg of chelated iron (Ferrochel bisglycinate) in a small, NSF Certified for Sport capsule; gentler than iron salts for most, but only for people who need iron.

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The short answer

Choose Sports Research if…

  • Vegans who want lichen-derived D3
  • People with a documented deficiency under medical guidance
  • Anyone who wants D3 and K2 in one small softgel

Choose Thorne if…

  • People with low ferritin who get stomach upset from ferrous sulfate
  • Menstruating women and athletes who need iron under medical guidance
  • Vegetarians with confirmed low iron
  • You care most about efficacy, quality & purity, transparency

Side by side

Vitamin D3 + K2 (5000 IU)Iron Bisglycinate
Our score7.8 / 108.6 / 10
Efficacy (30%)7.48.5
Quality & Purity (25%)7.49.3
Value (20%)7.87.6
Experience (15%)8.88.6
Transparency (10%)8.39.0
FormSoftgelCapsule
Serving1 veggie softgel60 servings per container1 capsule60 servings per container
Testing & certifications
Non-GMO Project VerifiedCertified VeganThird-party testedcGMP facility
NSF Certified for Sport
DietaryVegan, Gluten-free, Soy-free, Non-GMOGluten-free, Dairy-free, Soy-free
Key ingredients
  • Vitamin D3 (cholecalciferol from lichen, VegaDELight)125 mcg (5,000 IU)
  • Vitamin K2 (as menaquinone-7, from chickpea)100 mcg
  • Coconut MCT oil
  • Iron (as Ferrochel ferrous bisglycinate chelate)25 mg
Flavors——
Creator video reviews55

Pros and cons

Vitamin D3 + K2 (5000 IU)

  • Certified Vegan and Non-GMO Project Verified, with no soy, gelatin or carrageenan
  • D3 from lichen plus K2 as long-acting MK-7
  • Tiny, easy-to-swallow softgel in an MCT oil base
  • Official TikTok Shop listing rated 4.8 stars
  • 5,000 IU exceeds the 4,000 IU adult upper limit for daily use
  • No USP or NSF certification; testing claims are the brand's own
  • Evidence for K2's bone and arterial benefits is still limited
  • About $0.40 per day, more than plain D3

Iron Bisglycinate

  • Iron amino-acid chelate, a form NIH says may cause fewer GI side effects
  • NSF Certified for Sport
  • 25 mg dose sits below the 45 mg upper limit
  • Small 18 mm capsule with a short ingredient list
  • About $0.27 per day, more than generic ferrous sulfate
  • Some users still report nausea on an empty stomach
  • No vitamin C or other cofactors included
  • Not appropriate without a confirmed need for iron

Our verdicts

Vitamin D3 + K2 (5000 IU)

This is a well-made, vegan D3 and K2 combination that people clearly enjoy taking, which explains its bestseller status. The 5,000 IU dose is higher than most adults need day after day and exceeds the upper limit, so it fits best under a clinician's guidance or on a less-than-daily schedule; everyone else should consider the 2,500 IU version.

Full review

Iron Bisglycinate

If you have documented low iron and struggle with conventional iron pills, this is one of the best-tolerated and best-verified options available, at a fair premium. It is not something to take without a reason: check ferritin first, and space it from calcium, thyroid medication and zinc.

Full review

What creators say

Questions people ask

Is Sports Research better than Thorne?
In our scoring, Thorne Iron Bisglycinate rates higher overall (8.6 vs 7.8 out of 10). Thorne leads on efficacy, quality & purity and transparency. Scores weigh efficacy, quality, value, experience and transparency.
Are Sports Research and Thorne third-party tested?
Sports Research has no independent certification we could verify; Thorne carries NSF Certified for Sport. Sport-level certifications screen for banned substances, which matters for drug-tested athletes.
Who should choose Sports Research over Thorne?
Our reviews suggest Sports Research is best for vegans who want lichen-derived D3, people with a documented deficiency under medical guidance and anyone who wants D3 and K2 in one small softgel, while Thorne is best for people with low ferritin who get stomach upset from ferrous sulfate, menstruating women and athletes who need iron under medical guidance and vegetarians with confirmed low iron.

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