Vitamin D3 Product Buyer’s Guide (updated July 2024)

How To Find A High Quality Effective Vitamin D3 Product

An image of the site's  Senior Editor - Sally Harper.
Sally Harper
Senior Editor
Health & Wellness Advice

Even though Vitamin D is a nutrient that our bodies naturally produce, the majority of Americans have low levels or a deficiency. This stems from the fact that humans use sunlight to synthesize Vitamin D and with the growing “work culture” and the appeal of indoor air conditioning or heating, people aren’t spending enough time outside. Nevertheless, we still need to get our fill of Vitamin D for healthy skeletal, cardiovascular, and immune systems.

Supplementing with Vitamin D, specifically D3, has been shown to provide numerous health benefits such as promoting bone formation, improving immune function, and decreasing the risk of heart disease. When paired with K2, the benefits can be increased because the two vitamins are a synergistic pair that transport and direct calcium into the bones instead of leaving it to clog the arteries. However, if you want to reap the benefits of consuming Vitamins D and K, you need to be consuming the right forms in the right dosages, but of equal importance is that they are manufactured in a safe manner. 

Navigating the market to find a high quality Vitamin D+K supplement can be beyond confusing for consumers who don’t know which are worth buying and which are worthless fakes. Therefore, we carefully examined which products are backed up with real scientific explanations for why they were crafted the way they were and how exactly they work.

5 Things To Look For In An Effective D3 Supplement

Every Vitamin D3 supplement should:

  • Contain 5000 IU (125mcg) of Vitamin D3, as recommended by the Vitamin D Council for raising Vitamin D levels.
  • Also contain Vitamin K2, preferably as MK-7 which is more absorbable than MK-4.
  • Contain at least 80% Trans MK-7 which is more biologically active.      
  • Contain 180mcg of Vitamin K2 MK-7 which is the clinically studied dosage.
  • It should contain BioPerine® (or similar) to aid absorption, efficacy, and faster results.

What We Uncovered

With a little research, we were able to spot the supplement suppliers that were simply out to cash in on the latest trend versus the products that we consider to be high-quality and effective.

  1. In short, many Vitamin D3 supplements often do not have any scientific or clinical support as to why they would be effective. Many are not fully transparent about their ingredients and do not include a bioavailability enhancer such as BioPerine® for more effective results.
  2. Moreover, they are not 100% certified for purity and often include unnecessary ingredients that provide no benefit whatsoever. Some formulas do not contain the same potency as they claim on their labels with many companies even hiding their labels or supplement facts to prevent consumers from better understanding what is contained in the formulas.

Some companies think that sticking a label on their bottle with the words ‘D3 and K2’ is enough to make consumers want to buy their product, even if there is no justification for why the product should work. Unfortunately, many consumers fall for this scheme and are later disappointed by a lack of results.


Our Research

Our research identified key areas that we felt raised concerns when purchasing a Vitamin D3 supplement. With so many products out there, we felt that we needed clear parameters when investing in a Vitamin D3 and K2 product.

  • Will it be effective? Unfortunately, there are many products that simply don’t work, which is a real concern for many potential buyers. To determine which products we could rate as beneficial, we looked to see if they contained the correct ingredients, how potent they were, and their grade of purity. Consumers need to be aware that there is a precise science to creating an effective formula.
  • Will it be too expensive for me to purchase? Our research uncovered many manufacturers selling D3+K2 capsules for close to $100. People often think that by paying more, they will get better quality. This is not always the case. Don’t risk your hard-earned money on something that has a price which is over inflated and unrealistic.  
  • Is the company open and transparent? Manufacturers should be transparent and open, providing you with as much information and guidance as they can. You need to be consumer savvy in order to determine which are the best manufacturers to purchase from and which are not worth your while.

Finding Effective, Quality D3 Supplements

There are several key elements to look out for that can pretty much guarantee a product’s authenticity.

  1. Monitoring By A Third Party: There are organizations that will independently monitor and track the reputation of a company and assess their customer satisfaction levels. A company’s reputation is incredibly important within the health industry. Make sure you select a top provider, one that has an impeccable reputation and is backed by an independent third-party monitoring organization.
  2. 100% Money-Back Guarantee: Many companies offer you a money-back guarantee if their products do not bring the results that you are looking for. Some are better than others. Choose a company that has a solid satisfaction guarantee. A strong guarantee demonstrates a manufacturer’s confidence that their product will deliver the desired results.
  3. External Testing: This is not the same as a monitoring company. Third-party testing substantiates and verifies the quality of the manufacturer’s product. It can be very expensive for manufacturers to undertake and even disqualify entire shipments of products that don’t reach the correct standards. That said, when manufacturers don’t have independent quality control and testing, there is no way of knowing if their products are effective, or indeed, safe.

Our Research Results

Thorough research takes time and money, which most people don’t have an endless supply of. So we did the work for you – saving you both!

An effective Vitamin D supplement should contain top quality, clinically proven ingredients in significantly potent doses for optimal effect. There are significant doses of Vitamin D3 that can raise Vitamin D levels when paired with a significant dose of Vitamin K2. We also looked for the inclusion of BioPerine® which has been clinically researched for its ability to increase nutrient absorption and deliver more effective results. 

Most products failed to pass our specific criteria.

There are some manufacturers who actually include some of the right ingredients in their formulas. However, they fail when they weaken the potency by adding an unnecessary blend of useless ingredients. Other manufacturers simply failed by using a weaker potency of certain ingredients than what has been proven effective in scientific studies. Others filled their pills with binders, additives, or preservatives. All but a few of them avoided quality control testing.

We are very confident in the brands that we did pick. Given our stringent parameters and reasons for choosing our top products, we are sure our top picks will help you achieve the results you are looking for.

Why Did We Select Our #1 Choice As Our Top Vitamin D3 Supplement?

Our top pick not only met all of our strict criteria for a quality Vitamin D3 supplement, but it also beat it!

Look at what it contains:

  • 125mcg Vitamin D3 – The clinically studied amount.
  • 180mcg Vitamin K2 MK-7 – The recommended dosage of the optimal vitamin form
  • Vitamin K2 that is 80% Trans – Most products don’t share this information which indicates how active the K2 is. 8o% is a very high percentage that leads to great results.    
  • BioPerine® – Most do not include this bioavailability enhancer
  • GMP certification – Certification that many products neglect to obtain. 

Our Top Pick For A Vitamin D3 Product

We think you will agree that our top choice stands above and beyond the competition. Approved Science Vitamin D3+K2 is a top quality product manufactured by a company with an excellent reputation that uses external independent monitoring and testing. Combine that with an incredible money-back guarantee policy and this an undoubtedly solid pick for our #1 choice.

Vitamin D3 Report

Approved Science Vitamin D3+K2

Rating: Excellent


Money-Back Guarantee
Consumer Feedback
Company Reputation

Editor’s Choice

Approved Science Vitamin D3+K2

If you are looking to improve your bone, cardiovascular, and immune health then Approved Science Vitamin D3+K2 is something that deserves your undivided attention. Of all the Vitamin D supplements currently available on the market, this is the one that deserves a closer look and very likely, the one that will change your life!

It contains the recommended dosage of 5000 IU of Vitamin D3 combined with Vitamin K2 for a synergistic combination to ensure calcium is directed to the bones in an efficient and optimal manner. In addition to having the right vitamins, this formula uses the ideal forms of the vitamins (Vitamin D as D3 and K as K2 MK-7) in clinically researched amounts. It was the only product we found that contains BioPerine® to enhance nutrient absorption and consequent utilization for better results. It does not contain any additives or preservatives and is totally 100% safe to use with no long-term side effects.

Quality: Approved Science Vitamin D3+K2 contains high-grade, natural, clinically-verified ingredients that are GMP-certified.

Reputation: Approved Science’s reputation is top quality. They are well known in the industry and are an established company that provides great customer support service, secure and easy checkout as well as prompt, efficient delivery. This manufacturer has several third-party monitoring services, including buySAFE, Norton, and Trustee, as well as an A+ rating from the quality monitoring company QualityTrusted. Approved Science’s commitment to the health industry and consumers is excellent, providing further legitimacy to their products by producing them in an FDA-registered laboratory.

Money-Back Guarantee: Every item sold is supported by a 60-day 100% money-back guarantee. Such guarantees from manufacturers show strong confidence in their products’ ability to deliver results. Great news for consumers.

Bottom Line: If you are looking for a product that ticks all the boxes for an effective Vitamin D supplement that comes from an established reputable company with an excellent money-back guarantee, then this is the supplement for you.

It would be good to note that, due to high demand, Approved Science Vitamin D3+K2 is often sold out. To avoid having to back order, don’t hesitate to make that purchase when you see it in stock.

See The Full Review


Rating: Good



Dr. Mercola Vitamins D3 & K2

Marketed as a supplement that improves bone & joint comfort, blood flow, and immunity, Dr. Mercola’s Vitamins D3 & K2 is our second choice. With 5000 IU of Vitamin D3 and 180 mcg of K2, this product seems to have it all, except a bioavailability enhancer. Nevertheless, there are a few reasons it didn’t rank higher.

The price on this is quite fair though there are some cheaper options. It was unclear to us whether or not the manufacturer offers a satisfaction guarantee. The return policy has two options depending on your membership with Mercola Market. Non-expired consumables can be returned for up to 90 days or 1 year depending. However, there is no clarification on whether this refers to opened or only unopened products.

Dr. Mercola’s Vitamins D3 & K2 is made according to the GMP guidelines and the manufacturer checks the product throughout the process. However, there is no mention of third-party testing which adds assurance that each element is what it’s supposed to be. We appreciate the claim that Dr. Mercola’s Vitamins D3 & K2 is made without any harmful fillers or binders. Yet, this doesn’t exclude the “non-harmful” binders, fillers, and anticaking agents that it does contain. Read our full review for a deeper understanding of this formula and its price.

Click here to read the full review


Rating: OK


Designs For Health Vitamin D Supreme

Our third pick is a Vitamin D supplement that is vegetarian, dairy-free, and soy-free. Providing the clinically recommended dosage of 125 mcg Vitamin D, Vitamin D Supreme also contains a combination of 500 mcg K1 and 50 mcg K2. But is it as effective as a product with only K2 but in a more significant dosage and no K1? 

When reviewing this product, we were pleased to see a price tag that suggests quality – not cheap, but affordable. We appreciate that this product is formulated with the optimal vitamin types according to clinical studies. However, we were a little puzzled that the K2 dosage wasn’t as high as other science-based products. Nevertheless, with 125 mcg of D3, this product had the right amount to qualify it for our top Vitamin D products. 

We also liked that the product comes from a well established brand and the overall reviews for this product were positive. The manufacturer follows the GMP guidelines and guarantees their products are what they are supposed to be. Yet, unlike our top pick, this product does not undergo third-party testing and there is no satisfaction guarantee. Read our full review for more about how this product stacks up.

Click here to read the full review

What You’ll Discover:

Which Vitamin D3 supplement is the BEST BUY and comes with a great GUARANTEE!
Which formula and ingredients are the most EFFECTIVE and work the fastest?
How NOT to get ripped off! BE AWARE of poor quality and cheap products.

Top 6 Items to Consider:

  1. Ingredients
  2. Cost Per Serving
  3. Product’s Testing Results
  4. Company’s Reputation
  5. Consumer Reviews
  6. Return Policy & Satisfaction Guarantee

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