Onnit Vitamin D3 Review – Is It Worth Using?

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By Jack Cincotta, MS

Reviewed by Juliana Tamayo, MS, RDN - Last Updated

Onnit Vitamin D3 Review

Let’s be blunt: most people need to get more vitamin D. After all, nearly half of Americans are deficient in this critical micronutrient, with anywhere from 15 to 60% of people in other countries vitamin D deficient too. 

This happens mainly because no one gets outside anymore; most people are stuck indoors all day with no access to the best form of vitamin D: good ol’ sunshine. 

That’s why many people are reaching for vitamin D supplements to try to correct these deficiencies and return to better health. But unless you’re choosing a high-quality supplement AND know what you’re doing, you’re unlikely to benefit. 

And in this article, we’ll look at a unique vitamin D supplement called Onnit Vitamin D3 Spray to see if it can aid your overall health. 

Ready to find out if this supplement spray is worth the purchase? Let’s jump into this Onnit Vitamin D3 review!

onnit vitamin d3 spray

About Onnit Vitamin D3

Onnit Vitamin D3 is made by Onnit, a reputable company with many other solid products, such as Total Human, New Mood, Active B Complete, and Total Gut Health

And their Vitamin D3 Spray is a unique vitamin D supplement for a few reasons. 

First, their vitamin D3 is dispensed as a spray, which they say makes it easier to ingest and absorb. And it’s also carried in a base of fractionated MCT oil to enhance bioavailability. 

Additionally, Onnit Vitamin D3 Spray contains vitamin K2 alongside vitamin D3, which they argue helps to diminish high levels of calcium that can sometimes occur alongside vitamin D3 supplementation. 

Plus, vitamin D3 works well together with vitamin K2 for optimal health. 

All in all, Onnit Vitamin D3 Spray is designed to be “liquid sunshine” to help support all the systems in your body for optimal health and wellness. 

Onnit Vitamin D3 Spray Benefits

The primary advertised benefits of Onnit Vitamin D3 Spray are:

  • Enhanced Bone Health
  • Better Heart Health
  • Improved Mood
  • Overall Vitality
onnit vitamin d3 spray overall vitality

Enhanced Bone Health

The combination of vitamin D3 and vitamin K2 in Onnit Vitamin D3 Spray is supposed to aid overall bone strength and health, while also improving calcium utilization. 

Better Heart Health

Onnit Vitamin D3 Spray is also advertised to improve heart health, given the role vitamin D3 plays in the cardiovascular system. 

Improved Mood

Another claimed benefit of Onnit Vitamin D3 Spray is improved mood, which they say the sunshine vitamin helps to benefit. After all, who doesn’t feel better on a sunny day, and that’s vitamin D for ya!

Overall Vitality

Lastly, Onnit Vitamin D3 Spray is advertised to simply boost overall vitality, which means you look, feel, and perform at a more optimal level. 

Onnit sure took a unique approach with this vitamin D supplement. But is Onnit Vitamin D3 Spray the real deal for vitamin D supplementation? Read on to find out.

Onnit Vitamin D3 Ingredients

Onnit Vitamin D3 Spray contains a basic formula with vitamin D3, vitamin K2, MCT oil, and other ingredients for flavor and preservation. 

onnit vitamin d3 spray supplement facts

Let’s take a closer look at each ingredient below.

Vitamin D3

So, you’ve heard us say vitamin D quite a bit already…so what exactly is it?

Well, vitamin D is an essential fat-soluble vitamin that has many roles in the body. In some instances, it actually acts like more of a hormone. 

Vitamin D is essential for calcium absorption as well as magnesium and phosphorus and plays a role in bone health and strength. 

Vitamin D also has a role in immune function, heart health, inflammation, and even mental health. 

Deficiencies in vitamin D can increase the risk for osteoporosis and other bone problems, depression, cardiovascular disease, type 2 diabetes, and other health problems. 

Fortunately, vitamin D supplementation appears to be beneficial for increasing serum vitamin D levels and warding off these negative effects. 

In particular, vitamin D3 is best since it appears to increase serum levels to a higher level, for longer, compared to vitamin D2. 

The most recent evidence shows that supplementing with vitamin D can reduce the risk of fractures, delay bone loss and type 2 diabetes, improve lung function, and decrease the risk of cancer mortality. 

However, the main benefits are seen in people who have severe deficiencies, and vitamin D supplementation doesn’t always bring health benefits.

Recommended Dose: 1,000 to 4,000 IU

Vitamin K2: Synergy with Vitamin D

As noted, Onnit Vitamin D3 Spray also contains vitamin K2. 

This is an important addition, since the fat-soluble vitamin K2 appears to have synergistic effects with vitamin D3. 

Both vitamin D and vitamin K2 play roles in calcium metabolism. And vitamin D promotes the production of vitamin K-dependent proteins, which of course require vitamin K in order to function properly. 

And overall, the current research shows that combined supplementation of vitamin D and vitamin K is more effective for cardiovascular and bone health compared to either supplement alone. 

Plus, the vitamin K form in Onnit Vitamin D3 Spray (menaquinone 7) is a very well-researched and highly bioavailable form. 

Recommended Dose: 100 to 200 mcg


The last ingredient we’ll go over is MCT (medium chain triglycerides) oil. The purpose of MCT Oil in Onnit Vitamin D3 Spray is to enhance the bioavailability of vitamin D3 and vitamin K2. 

And indeed, research has shown that MCT oil can increase the bioavailability of many different vitamins and nutrients, including vitamin D and vitamin K. 

Does Onnit Vitamin D3 Work?

Onnit Vitamin D3 Spray is likely to be an effective vitamin D3 supplement. 

onnit vitamin d3 spray benefits

It includes adequate doses of both vitamin D3 and vitamin K2, which have synergistic roles and can help with bone and heart health, among other things. 

And these forms of vitamin D and vitamin K are well-researched and highly absorbable. 

Plus, the inclusion of MCT Oil should further enhance the bioavailability of vitamin D3 and vitamin K2, leading to greater effects. 

This is a very simple product, but it certainly should be effective, especially for people with deficiencies. 

Claims vs. Reality

While Onnit Vitamin D3 Spray should work, the degree of these effects depends on how deficient one is, to begin with. 

But all in all, most people should see at least some improvement in bone, heart, and immune health, as well as a slight increase in mood and overall general well-being. 

Of course, people who are very deficient in vitamin D may need to take more than one serving, as some research shows up to 5,000 IU is sometimes needed. 

This supplement won’t work quickly either, as it takes time to build up. 

But if you’re deficient in vitamin D and take this on a consistent basis, you should notice some health improvements after a month or two. 

Who is Onnit Vitamin D3 Best For?

Ideally, Onnit Vitamin D3 is best for people who need to correct vitamin D deficiency and want to improve bone and heart health, since these are the most specific benefits of this particular vitamin D supplement. 

But it can be used by anyone who generally needs to increase their vitamin D levels and/or is at risk for a vitamin D deficiency, including office workers and anyone who doesn’t get enough sun. 

Darker-skinned individuals are more likely to need more vitamin D since they need to be out longer in the sun to get enough vitamin D production.

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How to Take Onnit Vitamin D3 Spray

The suggested use of Onnit Vitamin D3 Spray for adults is to take 5 sprays by mouth, then swallow, once daily. It is preferred to take with food. 

onnit vitamin d3 spray how to take

Is Onnit Vitamin D3 Safe?

Onnit Vitamin D3 Spray has doses of vitamin D3 and vitamin K2 within the tolerable intake zone, so side effects shouldn’t be too worrisome if they do occur. But some possible side effects include:

  • Diarrhea, nausea/vomiting, upset stomach
  • Increased urination
  • Mental/mood changes
  • Weakness
  • Loss of appetite
  • Bad taste in mouth

Onnit Vitamin D3 Spray is vegan, gluten-free, and soy-free, although it does contain tree nuts (coconut). 

It is also third-party tested for purity, Informed Sport Certified, and BSCG Certified Drug Free.

Where to Buy Onnit Vitamin D3 Spray

You can buy Onnit Vitamin D3 Spray on the official Onnit website at this link.

onnit vitamin d3 spray where to buy

Each container has 30 servings (150 sprays). And it comes in either Grapefruit or Passion Fruit Guava flavors.

The one-time purchase price is $24.95 ($0.83/serving). Or you can save 15% by choosing their Subscribe & Save option, which brings the price down to $21.21 ($0.71/serving). 

With the subscription, you can choose to get it delivered every 7, 15, 20, 30, 45, 60, or 90 days.

This is definitely an affordable vitamin D supplement, especially considering the ingredient quality, dosage, and bioavailability you’re getting. 

Final Verdict: Onnit Vitamin D3 Review

Onnit Vitamin D3 Spray is a very basic, but effective product. With well-researched vitamin D3 and added vitamin K2 for synergistic effects, plus MCT Oil for enhanced bioavailability, you can’t go wrong with this vitamin D spray. Plus, it’s affordable too. That’s why we recommend it to anyone looking for an alternative vitamin D supplement. 

Overall Rating:
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Jack Cincotta, MS

Jack Cincotta is a certified holistic health coach through AFPA and a board-certified holistic health practitioner through AADP. He has written hundreds of articles on nutrition and supplementation. Jack has a M.S. degree in Psychology and is passionate about researching the science behind nutrition. He often uses research-backed supplementation protocols for many of his clients to optimize results.

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