Kirkland Signature Vitamin D3 1000 iu supplement bottle
Kirkland Signature

Vitamin D3 1000 iu

What We Researched
1 active ingredient analyzed · 6 inactive ingredients decoded · 6 brand certifications checked · Last updated: Mar 2026
100
Product Score Excellent
82
Brand Score Good

Product Analysis

Transparency Excellent

Supplement Facts

IngredientAmount% DV
Vitamin D3 (Cholecalciferol) 25 mcg/1000 IU
Bioavailability Excellent

Absorption Rating

  • Vitamin D3 (Cholecalciferol) Good
Other Ingredients Excellent

Fillers & Additives

  • Croscarmellose Sodium
  • Dicalcium Phosphate
  • Hydroxypropyl Cellulose
  • Hypromellose
  • Microcrystalline Cellulose
  • vegetable nesium stearate
Efficacy Excellent

Dosage Analysis

  • Vitamin D3 (Cholecalciferol) 25 mcg/1000 IU Effective

Supplement Facts

Ingredient Amount % Daily Value
Vitamin D3 (Cholecalciferol) 25 mcg/1000 IU

Other Ingredients

Inactive ingredients used in manufacturing. All rated for safety.

Croscarmellose Sodium Safe

Helps tablets break apart and dissolve quickly in the stomach.

Dicalcium Phosphate Safe

Serves as both a filler and a supplemental source of calcium and phosphorus.

Hydroxypropyl Cellulose Safe

Binds tablet ingredients and can form tablet coatings.

Hypromellose Safe

Forms vegetarian capsule shells. Dissolves easily in the stomach.

Microcrystalline Cellulose Safe

Adds bulk to small-dose supplements to make tablets/capsules a manageable size.

vegetable nesium stearate Unknown
Brand Trust Report
Kirkland Signature

Founded 1995 · Issaquah, Washington, United States · 26 products · costco.com/kirkland-signature.html

Certifications

6 certifications
Consumerlab Verified
Non Gmo Project Verified
Usda Organic Verified
Usp Verified Verified Source
Gluten Free Gfco Verified
Vegan Certified Verified

Transparency

4 claims
Third Party Testing Claim — Verified Source
Testing Lab Disclosure — Claimed
In House Testing — Claimed

Violation History

3 incidents
Lawsuit Falsely advertising rotisserie chicken as containing 'no preservatives'2026Source
Recall Kirkland Signature B100 Complex Timed Release2025-03-31Source
Recall Kirkland Signature Severe Cold and Flu Plus Congestion2024-11-30Source
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Frequently Asked Questions
Is Kirkland Signature Vitamin D3 1000 iu a good supplement?

Kirkland Signature Vitamin D3 1000 iu received a product quality score of 100/100 in GoodSupp's independent analysis, placing it in the top tier of supplements we've analyzed. The product contains 1 active ingredients Of the 6 inactive ingredients, 5 are rated safe and 0 are flagged for review. The manufacturer, Kirkland Signature, holds a brand trust score of 82/100 with 6 verified certifications including Consumerlab, Non Gmo Project, Usda Organic, Usp Verified.

What are the ingredients in Kirkland Signature Vitamin D3 1000 iu?

Kirkland Signature Vitamin D3 1000 iu contains 1 active ingredients: Vitamin D3 (Cholecalciferol) (25 mcg/1000 IU). Each ingredient's dosage, form, and safety rating is analyzed independently in GoodSupp's full product breakdown.

Is Kirkland Signature Vitamin D3 1000 iu safe to take?

Kirkland Signature Vitamin D3 1000 iu has been analyzed for ingredient safety across all its components. Always consult your healthcare provider before starting any new supplement, especially if you take medications or have underlying health conditions.

Is Kirkland Signature a trustworthy supplement brand?

Kirkland Signature receives a brand trust score of 82/100 based on GoodSupp's independent analysis of certifications, regulatory history, and transparency practices. Founded in 1995 and headquartered in Issaquah, Washington, United States, the company offers 26 products in their lineup. They hold 6 verified certifications including Consumerlab, Non Gmo Project, Usda Organic, Usp Verified. Third-party certifications are independently verified and indicate the brand meets specific quality, purity, and manufacturing standards. Note: Kirkland Signature has 3 historical regulatory incidents on record, which are factored into the trust score.

How much vitamin d3 should i take daily?

The optimal dosage depends on your individual health needs, age, sex, and current nutrient levels. Recommended daily amounts are established by health authorities but may vary from therapeutic doses used in clinical research. It's important to check the Supplement Facts label for the exact amount per serving and compare it against the % Daily Value. Some supplements provide mega-doses well above the Daily Value, which may not be necessary and in some cases could be harmful — particularly for fat-soluble vitamins (A, D, E, K) that accumulate in the body. GoodSupp's efficacy analysis evaluates whether a product's dosages align with clinically studied amounts. Always consult your healthcare provider for personalized dosage recommendations.

What does vitamin d do?

This is an important question for supplement consumers. The dietary supplement industry is largely self-regulated, which means product quality, ingredient transparency, and safety practices vary significantly between brands and products. The most reliable way to evaluate any supplement is to check for third-party testing certifications, review the full ingredient list and dosages, and research the brand's regulatory track record. GoodSupp's database of over 250,000 analyzed products provides independent quality scores, ingredient safety ratings, and brand trust reports to help you make evidence-based decisions.

How much vitamin d3 per day for a woman?

The optimal dosage depends on your individual health needs, age, sex, and current nutrient levels. Recommended daily amounts are established by health authorities but may vary from therapeutic doses used in clinical research. It's important to check the Supplement Facts label for the exact amount per serving and compare it against the % Daily Value. Some supplements provide mega-doses well above the Daily Value, which may not be necessary and in some cases could be harmful — particularly for fat-soluble vitamins (A, D, E, K) that accumulate in the body. GoodSupp's efficacy analysis evaluates whether a product's dosages align with clinically studied amounts. Always consult your healthcare provider for personalized dosage recommendations.

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Disclaimer: GoodSupp provides independent supplement quality analysis for informational purposes only. Scores are generated algorithmically based on ingredient profiles, brand certifications, and public records. This is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Product data is sourced from manufacturer labels and public databases. GoodSupp is not affiliated with any supplement brand.