Vitamin D3 5000 IU 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 D3 5000 IU 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 27 reviews
Vitamin D3 5000 IU scores 81.0/100 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 D3 5000 IU wins on effectiveness, ingredient quality, certifications. 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 value for money and side effects.
How Do the Scores Compare?
Vitamin D3 5000 IU
Thorne
|
Nutravita Vitamin D3 4000 i...
Nutravita
|
|
|---|---|---|
| Overall Score | 81.0 | 80.0 |
| Effectiveness |
82.0/100
Best
|
80.0/100 |
| Ingredient Quality |
90.0/100
Best
|
77.0/100 |
| Value for Money | 66.0/100 |
90.0/100
Best
|
| Side Effects | 80.0/100 |
88.0/100
Best
|
| Certifications |
88.0/100
Best
|
62.0/100 |
| Best Price | View → |
£8.99
Amazon UK →
Cheapest
|
| Form | N/A | Softgel |
| Dose | N/A | 116 Grams |
| Third-Party Tested | ✗ No | ✗ No |
| Reviews Analysed | 10 | 17 |
Vitamin D3 5000 IU
Pros
- ✓Thorne Research is NSF Certified for Sport — independently tested for purity and label accuracy
- ✓Cholecalciferol (D3) is the most bioavailable and research-supported form of vitamin D
- ✓D3+K2 MK7 combination helps direct calcium to bones rather than arteries — evidence-backed synergy
- ✓Liquid format (30ml) allows flexible dosing and faster absorption than capsules
Cons
- ✗5000 IU is a high therapeutic dose — not appropriate for general daily use without a confirmed deficiency test
- ✗Premium price point compared to generic D3 supplements
- ✗Liquid format requires careful dosing to avoid over-supplementation
- ✗Fat-soluble vitamin — must be taken with a meal containing fat for optimal absorption
Best For
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
What does the data say about Vitamin D3 5000 IU vs Nutravita Vitamin D3 4...?
Thorne's Vitamin D3 5000 IU is a high-potency cholecalciferol supplement from one of the most rigorously tested supplement brands in the industry, known for NSF Certified for Sport status and clean formulations.
What are the key differences?
Frequently Asked Questions
Which is better, Vitamin D3 5000 IU 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? ▼
Is Vitamin D3 5000 IU 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? ▼
Which has fewer side effects? ▼
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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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