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Vitamin D-3, High Potency, 5,000 IU, 120 Softgels vs Nutravita Vitamin D3 4000 iu - 400 High Strength Easy to Swallow Premium Softgels - Over A Year's Supply - Max Strength Vitamin D3 Cholecalciferol Supplement - Manufactured in The UK

Side-by-side comparison of scores, ingredients, prices and real customer feedback for Vitamin D-3, High Potency, 5,000 IU, 120 Softgels and Nutravita Vitamin D3 4000 iu - 400 High Strength Easy to Swallow Premium Softgels - Over A Year's Supply - Max Strength Vitamin D3 Cholecalciferol Supplement - Manufactured in The UK.

Last verified: 07 Apr 2026 · Based on 67 reviews

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82.0
Quick Answer

Vitamin D-3, High Potency, 5,000 IU, 120 Softgels scores 82.0/100 vs Nutravita Vitamin D3 4000 iu - 400 High Strength Easy to Swallow Premium Softgels - Over A Year's Supply - Max Strength Vitamin D3 Cholecalciferol Supplement - Manufactured in The UK at 80.0/100. Vitamin D-3, High Potency, 5,000 IU, 120 Softgels wins on effectiveness, ingredient quality. Nutravita Vitamin D3 4000 iu - 400 High Strength Easy to Swallow Premium Softgels - Over A Year's Supply - Max Strength Vitamin D3 Cholecalciferol Supplement - Manufactured in The UK is stronger on side effects and certifications.

How Do the Scores Compare?

Vitamin D-3, High Potency, ...
Nutravita Vitamin D3 4000 i...
Vitamin D-3, High Potency, 5,000 IU, 120 Softgels
Vitamin D-3, High Potency, ...
NOW Foods
 Nutravita Vitamin D3 4000 iu - 400 High Strength Easy to Swallow Premium Softgels - Over A Year's Supply - Max Strength Vitamin D3 Cholecalciferol Supplement - Manufactured in The UK
Nutravita Vitamin D3 4000 i...
Nutravita
Overall Score 82.0 80.0
Effectiveness 86.0/100
Best
 80.0/100
Ingredient Quality 83.0/100
Best
 77.0/100
Value for Money 90.0/100
Best
 90.0/100
Best
Side Effects 87.0/100 88.0/100
Best
Certifications 58.0/100 62.0/100
Best
Best Price £6.74 iHerb →
Cheapest
 £8.99 Amazon UK →
Form None Softgel
Dose None 116 Grams
Third-Party Tested ✗ No ✗ No
Reviews Analysed 50 17

Vitamin D-3, High Potency, 5,000...

Pros

  • ✓D3 (cholecalciferol) in an olive oil and safflower oil base — the most bioavailable form, in the most appropriate delivery medium for a fat-soluble vitamin
  • ✓Multiple reviewers confirmed blood test levels returning to normal after consistent use, including doctor-prescribed cases of significant deficiency
  • ✓Small softgels praised consistently as easy to swallow, tasteless, and gentle on the stomach
  • ✓5,000 IU therapeutic dose in a single capsule — practical for deficiency correction without splitting doses

Cons

  • ✗Not third-party tested — no independent lab has verified potency or purity; specs confirm this
  • ✗Not vegan or vegetarian: bovine gelatin capsule
  • ✗5,000 IU exceeds standard maintenance levels and is not appropriate for unsupervised long-term use without periodic blood monitoring
  • ✗Does not include K2, which several reviewers note is needed for proper calcium routing — requires a separate purchase

Best For

Adults with confirmed vitamin D deficiency, especially those prescribed 5,000 IU by a doctor People in low-sunlight climates or spending most of the year indoors Budget-conscious buyers wanting a clean single-ingredient D3 without unnecessary additives Those who already take a separate K2 supplement and want a standalone high-dose D3
iHerb £6.74
View full review →

Nutravita Vitamin D3 4000 iu - 4...

Pros

  • ✓Small, easy-to-swallow softgels praised by virtually every reviewer, including those with tablet-swallowing difficulties
  • ✓Excellent value for money — 400 softgels lasts over a year at one-per-day dosing
  • ✓Clean formula with no fillers, bulking agents, or anti-caking agents — just D3, sunflower oil, and gelatin
  • ✓High 4000 IU dose meets medically recommended therapeutic levels for deficiency without needing multiple capsules

Cons

  • ✗Gelatin (bovine) capsule — not suitable for vegetarians or vegans
  • ✗No independent third-party certification (no USP, NSF, or equivalent)
  • ✗4000 IU exceeds general population guidelines; those without confirmed deficiency should consult a doctor before use
  • ✗Not recommended for under-18s per product labelling, limiting household sharing

Best For

UK residents with limited sun exposure during autumn and winter People diagnosed with or at risk of vitamin D deficiency Adults who struggle to swallow large tablets or capsules Those wanting a clean-label supplement with minimal additives Budget-conscious buyers seeking a long-lasting supply
Amazon UK £8.99
View full review →

What does the data say about Vitamin D-3, High Pote... vs Nutravita Vitamin D3 4...?

Vitamin D-3, High Potency, 5,000 IU, 120 Softgels Winner 82.0/100

5,000 IU of cholecalciferol per softgel puts this firmly in therapeutic territory — a dose multiple reviewers had validated by blood tests showing deficiency fully corrected.

Effectiveness
Vitamin D-3, Hig..
86.0/100
Nutravita Vitami..
80.0/100
Ingredient Quality
Vitamin D-3, Hig..
83.0/100
Nutravita Vitami..
77.0/100
Value for Money
Vitamin D-3, Hig..
90.0/100
Nutravita Vitami..
90.0/100
Side Effects
Vitamin D-3, Hig..
87.0/100
Nutravita Vitami..
88.0/100
Certifications
Vitamin D-3, Hig..
58.0/100
Nutravita Vitami..
62.0/100

What are the key differences?

Vitamin D-3, High Poten.. is best for: Adults with confirmed vitamin D deficiency, especially those prescribed 5,000 IU by a doctor, People in low-sunlight climates or spending most of the year indoors
Nutravita Vitamin D3 40.. is best for: UK residents with limited sun exposure during autumn and winter, People diagnosed with or at risk of vitamin D deficiency

Frequently Asked Questions

Which is better, Vitamin D-3, High Potency, 5,000 IU, 120 Softgels or Nutravita Vitamin D3 4000 iu - 400 High Strength Easy to Swallow Premium Softgels - Over A Year's Supply - Max Strength Vitamin D3 Cholecalciferol Supplement - Manufactured in The UK? ▼
Vitamin D-3, High Potency, 5,000 IU, 120 Softgels scores 82.0/100 overall while Nutravita Vitamin D3 4000 iu - 400 High Strength Easy to Swallow Premium Softgels - Over A Year's Supply - Max Strength Vitamin D3 Cholecalciferol Supplement - Manufactured in The UK scores 80.0/100. Vitamin D-3, High Potency, 5,000 IU, 120 Softgels comes out ahead, scoring higher on effectiveness (86.0 vs 80.0). Vitamin D-3, High Potency, 5,0 is best suited for Adults with confirmed vitamin D deficiency, especially those prescribed 5,000 IU by a doctor and People in low-sunlight climates or spending most of the year indoors. Nutravita Vitamin D3 4000 iu - is better for UK residents with limited sun exposure during autumn and winter and People diagnosed with or at risk of vitamin D deficiency.
Is Vitamin D-3, High Potency, 5,000 IU, 120 Softgels worth the price compared to Nutravita Vitamin D3 4000 iu - 400 High Strength Easy to Swallow Premium Softgels - Over A Year's Supply - Max Strength Vitamin D3 Cholecalciferol Supplement - Manufactured in The UK? ▼
Vitamin D-3, High Potency, 5,000 IU, 120 Softgels costs £6.74 while Nutravita Vitamin D3 4000 iu - 400 High Strength Easy to Swallow Premium Softgels - Over A Year's Supply - Max Strength Vitamin D3 Cholecalciferol Supplement - Manufactured in The UK is £8.99. For value, Vitamin D-3, High Potency, 5,000 IU, 120 Softgels scores 90.0/100 vs Nutravita Vitamin D3 4000 iu - 400 High Strength Easy to Swallow Premium Softgels - Over A Year's Supply - Max Strength Vitamin D3 Cholecalciferol Supplement - Manufactured in The UK's 90.0/100. Both offer similar value for money.
Which has fewer side effects? ▼
Vitamin D-3, High Potency, 5,000 IU, 120 Softgels scores 87.0/100 for side effects (higher means fewer reported issues) while Nutravita Vitamin D3 4000 iu - 400 High Strength Easy to Swallow Premium Softgels - Over A Year's Supply - Max Strength Vitamin D3 Cholecalciferol Supplement - Manufactured in The UK scores 88.0/100. Reviewers report fewer side effects with Nutravita Vitamin D3 4000 iu - 400 High Strength Easy to Swallow Premium Softgels - Over A Year's Supply - Max Strength Vitamin D3 Cholecalciferol Supplement - Manufactured in The UK. For certification and testing, Vitamin D-3, High Po scores 58.0/100 vs Nutravita Vitamin D3's 62.0/100. Always consult a healthcare professional before starting any supplement.

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What the Data Says

Why do 97% of UK vitamin D supplements lack third-party certification?

Only 1 out of 35 vitamin D products we scored has independent certification. That's 97% without any third-party verification of purity, potency, or label accuracy.

This is worse than most supplement categories. The reason is simple: UK law doesn't require it, and testing costs money. Most vitamin D brands sell on price alone, especially in the D3-only space where the raw ingredient is cheap. Certification adds cost that budget brands won't absorb.

What does this mean for you? Without third-party testing, you're trusting the manufacturer's label claims. A 2021 study in Nutrients found that vitamin D supplements varied from 52% to 135% of their labelled dose. That's a problem if you're relying on a specific daily intake.

Among the 35 products we scored, the top performers are all from brands with strong manufacturing track records: NOW Foods D3 5000 IU and Thorne Vitamin D + K2 both score 87/100 overall. Thorne holds the highest certification score in the category at 85/100. If independent testing matters to you, that's the product to look at.

Do you need vitamin K2 with high-dose vitamin D?

Probably yes at high doses, and our data backs the pairing. Thorne Vitamin D + K2 Liquid is the only D3+K2 combo product in our 35-product database that scores 87/100 overall, matching the top-ranked D3-only options from NOW Foods. It also holds the highest certification score in the category at 85/100.

Here's the science behind it. Vitamin D increases calcium absorption from food. Vitamin K2 activates proteins that direct that calcium into bones and teeth, keeping it out of your arteries and soft tissue. At standard doses (1000-2000 IU daily), most people get enough K2 from diet to handle the extra calcium. At 4000-5000 IU daily, the calcium load increases enough that K2 becomes a more serious consideration.

The Endocrine Society doesn't yet include K2 in its vitamin D guidelines. But a growing body of research, including a 2019 meta-analysis in International Journal of Molecular Sciences, shows the D3+K2 combination improves bone mineral density more than D3 alone.

If you eat K2-rich foods regularly (natto, hard cheese, egg yolks, chicken liver), a standalone D3 product like NOW Foods D3 5000 IU 360 Softgels (87/100) is a solid choice. If your diet is low in K2, or you're taking 4000+ IU of D3 daily, Thorne D + K2 covers both bases in one product.

Disclaimer: AIScored provides data-driven comparisons based on publicly available reviews. This is not medical advice. Affiliate links may earn us a commission at no extra cost to you.

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