Solgar Vitamin D3 1000 IU (25mcg) Softgels - 250 Count vs Vitamin D-3, High Potency, 5,000 IU, 120 Softgels

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

Of 35 vitamin D products in our database, only 1 carries third-party certification. That means 97% of the vitamin D supplements sold in the UK have no independent verification of what's actually in the bottle. UK regulations don't require third-party testing for supplements, so most brands skip it to save money. If certification matters to you, NOW Foods and Thorne are the brands scoring highest in our rankings, with overall scores of 85-87/100.

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

Our data shows that Thorne Vitamin D + K2 Liquid is the only combination D3+K2 product scoring 87/100 in our database of 35 vitamin D supplements, tying with two NOW Foods D3-only products for the top spot. Clinical research suggests K2 helps direct calcium to bones rather than arteries, which may matter at doses above 4000 IU daily. If you already eat K2-rich foods like natto, hard cheese, or egg yolks, a standalone D3 product may be sufficient.

Side-by-side comparison of scores, ingredients, prices and real customer feedback for Solgar Vitamin D3 1000 IU (25mcg) Softgels - 250 Count and Vitamin D-3, High Potency, 5,000 IU, 120 Softgels.

Last verified: 07 Apr 2026 · Based on 106 reviews

Back to comparison hub View vitamin d guide

83.0

Quick Answer

Solgar Vitamin D3 1000 IU (25mcg) Softgels - 250 Count scores 83.0/100 vs Vitamin D-3, High Potency, 5,000 IU, 120 Softgels at 82.0/100. Solgar Vitamin D3 1000 IU (25mcg) Softgels - 250 Count wins on ingredient quality, side effects, certifications. Vitamin D-3, High Potency, 5,000 IU, 120 Softgels is stronger on effectiveness and value for money.

Which is better: Solgar Vitamin D3 1000 IU (... or Vitamin D-3, High Potency, ...?

NOW Foods Vitamin D-3, High Potency, 5,000 IU, 120 Softgels wins with a better score of 82.0/100 versus 83.0/100 and costs half the price at £6.74 to Solgar's £11.16. Pick Solgar Vitamin D3 1000 IU (25mcg) Softgels - 250 Count instead if you need a low 1000 IU maintenance dose with fewer ingredients like just safflower oil.

— AIScored Editorial Team

How Do the Scores Compare?

Solgar Vitamin D3 1000 IU (...

Vitamin D-3, High Potency, ...

	Solgar Vitamin D3 1000 IU (... Solgar	Vitamin D-3, High Potency, ... NOW Foods
Overall Score	83.0	82.0
Effectiveness	81.0/100	86.0/100 Best
Ingredient Quality	89.0/100 Best	83.0/100
Value for Money	86.0/100	90.0/100 Best
Side Effects	92.0/100 Best	87.0/100
Certifications	68.0/100 Best	58.0/100
Best Price	£11.16 Amazon UK →	£6.74 iHerb → Cheapest
Price per Serving	£0.04 250 servings	N/A
Form	Softgels	None
Dose	1000 IU (25mcg) Vitamin D3	None
Third-Party Tested	✗ No	✗ No
Reviews Analysed	56	50

Solgar Vitamin D3 1000 IU (25mcg...

Pros

✓Small, easy-to-swallow softgels with no taste or odour — universally noted across reviews
✓Exceptionally clean formulation: only safflower oil and gelatin shell, no magnesium stearate or silicon dioxide
✓250-count bottle offers excellent long-term value — up to ~8 months supply at 1/day
✓Reviewers consistently report improved energy, mood, and immunity — consistent with D3 research evidence

Cons

✗1000 IU is a maintenance dose only — insufficient to correct deficiency; those with low D levels typically need 2000–5000 IU under guidance
✗Not third-party tested (e.g. NSF, Informed Sport) — limits verification for athletes or those requiring assay confirmation
✗Contains bovine gelatin — not suitable for vegans, vegetarians, or some religious dietary requirements (halal concerns raised by reviewers)
✗Safflower oil carrier is functional but not as optimal as olive oil or MCT oil for fat-soluble vitamin absorption

Best For

Individuals maintaining adequate vitamin D levels rather than correcting deficiency Those in low-sunlight climates or who work indoors year-round People seeking a clean, minimal-ingredient daily supplement Older adults with reduced cutaneous D3 synthesis Budget-conscious buyers wanting a large-count reliable supply

Amazon UK £11.16

View full review →

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 →

What does the data say about Solgar Vitamin D3 1000... vs Vitamin D-3, High Pote...?

Solgar Vitamin D3 1000 IU softgels deliver a modest 25mcg dose in a simple safflower oil base inside a gelatin shell. NOW Foods Vitamin D-3 High Potency packs 5000 IU per capsule using olive oil and safflower oil with the same bovine gelatin. The big gap sits in strength. Solgar suits daily top-ups while the NOW version hits hard enough to shift blood levels in people who test low.

Solgar scores 83/100 overall against NOW's 82/100 yet loses on effectiveness where NOW takes 86/100 to Solgar's 81/100. Ingredient quality favours Solgar at 89/100 over 83/100 and value sits with NOW at 90/100 compared to Solgar's 86/100. At £11.16 for 250 capsules Solgar gives eight months of use. NOW costs £6.74 for 120 doses so it works out cheaper per day for anyone who needs the higher amount. Pick Solgar if you want gentle maintenance and a cleaner label with fewer extras. Choose NOW if blood tests show deficiency or your GP suggests 5000 IU.

Both softgels measure small and slip down without flavour or smell. They stay gentle on the stomach. Neither suits vegans because of the animal gelatin. Store them away from heat to keep the oils fresh.

Solgar Vitamin D3 1000 IU (25mcg) Softgels - 250 Count Winner 83.0/100

Solgar Vitamin D3 1000 IU is a well-regarded maintenance-dose supplement in a 250-count softgel format, praised by reviewers for its small capsule size, easy swallowability, and clean formulation.

Effectiveness

Solgar Vitamin D..

81.0/100

Vitamin D-3, Hig..

86.0/100

Ingredient Quality

Solgar Vitamin D..

89.0/100

Vitamin D-3, Hig..

83.0/100

Value for Money

Solgar Vitamin D..

86.0/100

Vitamin D-3, Hig..

90.0/100

Side Effects

Solgar Vitamin D..

92.0/100

Vitamin D-3, Hig..

87.0/100

Certifications

Solgar Vitamin D..

68.0/100

Vitamin D-3, Hig..

58.0/100

What are the key differences?

Solgar Vitamin D3 1000 .. is best for: Individuals maintaining adequate vitamin D levels rather than correcting deficiency, Those in low-sunlight climates or who work indoors year-round

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

Frequently Asked Questions

Which is better, Solgar Vitamin D3 1000 IU (25mcg) Softgels - 250 Count or Vitamin D-3, High Potency, 5,000 IU, 120 Softgels? ▼

Solgar Vitamin D3 1000 IU (25mcg) Softgels - 250 Count scores 83.0/100 overall while Vitamin D-3, High Potency, 5,000 IU, 120 Softgels scores 82.0/100. Solgar Vitamin D3 1000 IU (25mcg) Softgels - 250 Count comes out ahead, scoring higher on effectiveness (81.0 vs 86.0). Solgar Vitamin D3 1000 IU (25m is best suited for Individuals maintaining adequate vitamin D levels rather than correcting deficiency and Those in low-sunlight climates or who work indoors year-round. Vitamin D-3, High Potency, 5,0 is better 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.

Is Solgar Vitamin D3 1000 IU (25mcg) Softgels - 250 Count worth the price compared to Vitamin D-3, High Potency, 5,000 IU, 120 Softgels? ▼

Solgar Vitamin D3 1000 IU (25mcg) Softgels - 250 Count costs £11.16 while Vitamin D-3, High Potency, 5,000 IU, 120 Softgels is £6.74. For value, Solgar Vitamin D3 1000 IU (25mcg) Softgels - 250 Count scores 86.0/100 vs Vitamin D-3, High Potency, 5,000 IU, 120 Softgels's 90.0/100. Vitamin D-3, High Potency, 5,000 IU, 120 Softgels delivers better value relative to its quality.

Which has fewer side effects? ▼

Solgar Vitamin D3 1000 IU (25mcg) Softgels - 250 Count scores 92.0/100 for side effects (higher means fewer reported issues) while Vitamin D-3, High Potency, 5,000 IU, 120 Softgels scores 87.0/100. Reviewers report fewer side effects with Solgar Vitamin D3 1000 IU (25mcg) Softgels - 250 Count. For certification and testing, Solgar Vitamin D3 10 scores 68.0/100 vs Vitamin D-3, High Po's 58.0/100. Always consult a healthcare professional before starting any supplement.

Related Product Comparisons

Nutri Advanced Vitamin D3 with K2 Liquid Drops 30ml

vs Solgar Vitamin D3 1000 IU (25mcg) Softgels - 250 Count

Nutri Advanced Vitamin D3 with K2 Liquid Drops 30ml

vs Vitamin D-3, High Potency, 5,000 IU, 120 Softgels

Solgar Vitamin D3 1000 IU (25mcg) Softgels - 250 Count

vs Vitamin D-3, High Potency, 2,000 IU, 240 Softgels

Solgar Vitamin D3 1000 IU (25mcg) Softgels - 250 Count

vs Vitamin D-3, High Potency, 5,000 IU, 240 Softgels

Solgar Vitamin D3 1000 IU (25mcg) Softgels - 250 Count

vs Vitamin D3, High Potency, 10,000 IU, 120 Softgels

Solgar Vitamin D3 1000 IU (25mcg) Softgels - 250 Count

vs Vegavero Vitamin D3 7000 IU + 200 µg Vitamin K2

View all Vitamin D comparisons →

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.

Feedback & Suggestions

Spotted an issue? Wrong price, incorrect data, or something else off? Let us know and we'll fix it.

Missing a product you'd like us to review? Tell us the product name and we'll consider adding it.