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Whether via an adjustable kettlebell set or landmine attachment to immensely diversify your home gym, uniqueness paired with functionality truly excites us. And if there’s any nutrient that marries the two, it’s vitamin D—affectionately known as the “sunshine vitamin” and truly one-of-a-kind.
Yes, you can find vitamin D in foods (like any nutrient). But it’s also sourced from sweet sunshine (unlike any other nutrient). Unfortunately, vitamin D deficiency1 is an emerging health condition worldwide and available data2 points out that 25% to 50% (or more!) of patients in clinical practice are deficient in the vitamin. This can increase the risk of broken bones, muscle weakness, and seizures, just to name a few.
We absolutely encourage a foods-first approach and the great outdoors. But if you’re needing a vitamin D boost, like most of the world, look no further than this best vitamin D supplement round-up.
As a registered dietitian (RD), I personally evaluated the products on this list (as well as others our team researched). We had members of the GGR team, including personal trainers and certified nutrition coaches, personally test each of these products. Together, we rated each supplement on the formulation, dosage, price, and side effects.
Through applying our in-depth supplement testing methodology, we arrived at the best vitamin D supplements on the market by looking at these factors:
- Formulation: Does it have at least 1,000 IU (25 micrograms) of Vitamin D3 and contain no added sugars or unstable oils?
- Swallowability: Can it be easily swallowed?
- Third-party testing: Does the company use third-party testing to ensure there are no banned/harmful substances?
- Price per serving: Products gets a 4-5 out of 5 if the price per serving is $0.10 or lower.
Medical disclaimer: This article is intended for educational and informational purposes only. It is not intended as a substitute for medical advice. For health advice, contact a licensed healthcare provider.
Best Vitamin D Supplements for 2024
- Best Vitamin D Supplement Overall: Transparent Labs Vitamin D+K2
- Best High-Dose Vitamin D Supplement: Sports Research Vitamin D3
- Best Budget Vitamin D Supplement: Nutricost Vitamin D
- Best Vegan Vitamin D Supplement: Utzy Naturals Vitamin D3 + K2
- Best Multivitamin With Vitamin D: Ritual Essential Multivitamin 18+
- Best Chewable Vitamin D Supplement: Ora Organic Sol Food High-Potency Vitamin D3 + K2
- Best Vitamin D Supplement for Bone Health: True Nutrition Vitamin D3
- Best Liquid Vitamin D Supplement: Athletic Greens D3 + K2 Liquid
- Best Gummy Vitamin D Supplement: Bulletproof A+D+K Gummy
- Best Vitamin D Supplement Drops: Thorne Vitamin D/K2 Drops
- Best Organic Vitamin D Supplement: Garden of Life Raw Whole Food Vitamin D
- Best Vitamin D Supplement for Kids: Carlson Labs Kid’s Super Daily D3 + K2
Let’s Quickly Chat Vitamin D
Before diving straight into our top picks, let’s get a better understanding of vitamin D. At its essence, vitamin D is a fat-soluble vitamin3 essential for bone, immune, heart, and mental health. (The nutrient also plays other vital health roles that we’ll dive into in the next upcoming sections, so be sure to stick around.)
Vitamin D is also very unique in that not only is it sourced naturally from foods, but also from glorious sunshine—which is why vitamin D is also known as the “sunshine vitamin.” The vitamin D we get from sun exposure is known as vitamin D3, although vitamin D2 is another form of the vitamin.
Vitamin D2 vs Vitamin D3
Vitamin D primarily exists in two forms: vitamin D2 and vitamin D3. While their structures and uses are similar, the potency of vitamin D2 and vitamin D3 appears to be different. Bear with us here—while the differences are subtle, they make a world of difference in which form might be best to supplement with.
We’ll first discuss vitamin D3, also known as cholecalciferol, for explanation purposes. Vitamin D3 naturally occurs in a select few food sources—like fatty fish, egg yolks, and fortified products such as cereal—but is mainly synthesized by the human body, especially when skin is exposed to sunlight.
Vitamin D2, or ergocalciferol, is also synthesized by sunlight but by plants instead of the human body. What this means is that plants—such as mushrooms and yeasts—synthesize vitamin D from the sun and humans can obtain vitamin D2 by consuming the aforementioned foods.
Interestingly, both vitamin D2 and D3 are absorbed, metabolized, and used in the body similarly, However, older research4 shows vitamin D2 is much less effective in the body and that vitamin D3 is more effective in increasing blood levels of vitamin D in the blood.
Overall, both vitamin D2 and D3 are functional forms of vitamin D and you could certainly get enough vitamin D from either. But, you would have to consume a lot more vitamin D2 to reach an adequate level—and what this really comes down to is a “work smarter, not harder” approach, and why you’ll notice all of our top picks include vitamin D3 as its primary form.
All this said, let’s explore our (sun)shining vitamin D picks!
Best Vitamin D Supplement Overall: Transparent Labs Vitamin D+K2
Good for: Anyone looking for a high-quality vitamin D supplement with added benefits of vitamin K2
Best Overall
Transparent Labs D3 + K2
Product Highlights
- Vitamin D3 and K2 supplement
- 2 vitamins combined to provide maximum benefits
- Listed benefits: support immune system, bone health, and cardiovascular function
Pros & Cons
Pros
- Third-party tested and Informed Choice-certified
- No artificial sweeteners or colors
- Gluten-free and non-GMO
Cons
- Limited customer reviews
- Contains allergen: tree nut (coconut)
- Only available in 60-count containers
- Only 1 vitamin D3 + K2 dosage available
Bottom Line
Transparent Labs Vitamin D3 + K2 combines the two vitamins to maximize benefits. Each pill has 5,000 IUs of vitamin D3 and 100 mcg of vitamin K2. Customer reviews are limited but mostly positive for this product.
Transparent Labs Vitamin D3+K2 is a high-potency plant-based vitamin D3 supplement in softgel form. It uses lichen as its vitamin D3 source to provide 5,000 IU (125 mcg) of vitamin D, or 625% of the recommended daily value. The amount of vitamin D you need daily is listed in both micrograms (mcg) and international units (IU), in which 1 mcg of vitamin D equals 40 IU.
It’s also formulated with 1,000 mcg of vitamin K2 from chickpeas. Vitamin K25 is a necessary part of heart, bone, and cellular function. This combination of vitamin D3 and K2 earns the Transparent Labs supplement a 5-out-of-5-star rating when it comes to formulation.
To enhance the absorption of the fat-soluble vitamin, the vitamin D3 and K2 supplement contains extra virgin olive oil. The starch-based vegetable capsule—made up of tapioca, glycerin, and water—may also protect the vitamin D and K2 within it when compared to animal-based capsules.
GGR expert tester and senior editor, Erin Chancer, CNC, CPT, scores the Transparent Labs softgels 5 stars for taste, swallowability, and side effects. “These pills are totally inoffensive and don’t give off an aftertaste or oily burps,” says Erin.
While a tasteless and inoffensive pill is great, we also appreciate that Transparent Labs is well-known for their commitment to third-party testing and earns 5-stars in this category. Transparent Labs Vitamin D3+K2 formula is also free from artificial coloring, sweeteners, gluten, and GMOs.
Form | Softgel |
Dosing instructions | Take 1 softgel 1-2 times daily with food |
Cost per serving | $29.99/60 servings = $0.49/serving |
Best High-Dose Vitamin D Supplement: Sports Research Vitamin D3
Good for: Those seeking a high-quality, effective dose of vitamin D
Best High-Dose
Sports Research Vitamin D3
Product Highlights
- Vitamin D3 softgel supplement
- 10,000 IU
- Listed benefits: assisting calcium absorption, bone development, and supporting the immune system
Pros & Cons
Pros
- Gluten-free and Non-GMO
- Third-party tested
- Satisfaction guaranteed when purchasing directly from Sports Research
Cons
- Only available in 1 dosage: 10,000 IU
- Contains gelatin from softgel
- Contains allergen: tree nuts (coconut)
- Extremely limited reviews
Bottom Line
Sports Research Vitamin D3 is only available in one dosage, 10,000 IU. Be aware if you are allergic to tree nuts, as it also contains coconut MCT oil to help with absorption. This supplement is designed to support calcium absorption, bone development, and the immune system.
Sports Research high-dose vitamin D contains an impressive 5,000 IU per capsule which is ideal for folks who have limited access to sunlight. But if 5,000 IUs seems like a lot, you’re not wrong. The general recommendation for vitamin D is around 400 IUs. However, research published in the Journal of Bone and Mineral Research6 suggests that because sunshine can provide an equivalent of daily oral 10,000 IU, prolonged intake of high doses should not pose adverse risks.
Another study from Mayo Clinic Proceedings2 suggests people with malabsorptive conditions—such as from a gastric bypass surgery—may require 50,000 IU of vitamin D once weekly or even daily to maintain sufficiency. And, for people with severe vitamin D deficiency, a “loading dose” of 50,000 once weekly (for up to three months) is a commonly applied strategy.
The bottom line is that a high-dose vitamin D supplement can be both safe and effective, especially when vitamin D status is monitored. This high-dose supplement earns a 5-star rating from our testers in the formulation category.
Our tester scored the Sports Research vitamin D softgels at 5 out of 5 stars for swallowability because they are super small and have a smooth exterior. Plus, these softgels are tasteless and formulated with MCT oil for added absorption.
The Sports Research high-dose vitamin D supplement is certified gluten-free, non-GMO, third-party tested, and manufactured in a GMP compliant facility. Although it’s tested, it’s not done by one of the industry leading third-party labs, which is why it earns 4-star rating in this category.
Form | Softgel |
Dosing instructions | Take 1 softgel daily with food |
Cost per serving | $18.95/360 servings = $0.05/serving |
Best Budget Vitamin D Supplement: Nutricost Vitamin D
Good for: Anyone looking for quality vitamin D on a budget
Best Budget
Nutricost Vitamin D3 Softgels
Product Highlights
- Vitamin D3 softgels
- Available in 4 different dosages
- 240 servings per bottle
Pros & Cons
Pros
- Affordable
- Easy to swallow
- Non-GMO
Cons
- Not recommended with empty stomach
- Third-party testing lab not listed
Bottom Line
Nutricost offers an excellent price per serving value when it comes to Vitamin D3 supplementation.
Nutricost’s Vitamin D3 supplement is a softgel option with budget top of mind. And when we say budget, we mean it—you can purchase 240 servings for about $0.07 (and that’s even without the subscribe and save options on Amazon). Because the cost works out to less than $0.10 per serving, the Nutricost vitamin D earns a 5-star rating price.
Low cost also doesn’t mean low quality, as it provides a whopping 10,000 IU of vitamin D3. It also contains a touch of the fat source sunflower oil to help aid in the absorption of vitamin D, and taking with a meal (especially with a fat source) can enhance the absorption as well. When it comes to forumulation, this budget pick earns a 5-out-of-5-star rating.
The vitamin D supplement is protected by a softgel capsule produced from gelatin and glycerin, so it’s not a vegan-friendly option. Don’t worry, though, we hand-picked the best vegan vitamin D supplement which will be featured later in this roundup.
The Nutricost Vitamin D3 supplement is gluten-free and does not contain any added colors or artificial flavors. It’s also processed in a GMP-Compliant facility—meaning there are requirements on sanitation, personnel training, and quality control—and is recommended to be stored tightly closed in a cool, dry place to preserve vitamin D’s integrity.
“I found out a few months ago that I have low vitamin D so my doctor suggested I start supplementing,” says GGR Head of Content Nicole Davis, CPT, PN1-NC. “I’ve definitely noticed a difference in my energy levels since starting to supplement with Nutricost.”
Form | Softgel |
Dosing instructions | Take 1 softgel daily with 8-12 oz of water |
Cost per serving | $17/240 servings = $0.07/serving |
Best Vegan Vitamin D Supplement: Utzy Naturals Vitamin D3 + K2
Good for: Plant-based eaters seeking a high-quality, effective dose of vitamin D
Best Vegan
Utzy Naturals Vitamin D3 + K2
Product Highlights
Pros & Cons
Pros
- Well-reviewed by users
- Made in USA
- “Empty bottle” return policy
- Quality assurance guarantees
Cons
- Pricey
Bottom Line
Utzy Naturals contains a synergistic partnership of vitamins D3 and K2 in scientifically-backed dosages. It’s manufactured in the USA in an NSF-registered facility, is tested for purity and potency, and has an “empty bottle” guarantee.
Utzy Naturals Vitamin D3 + K2 provides an excellent way for plant-based eaters and vegans to supplement with vitamin D. The Pure Encapsulations supplement provides 125 micrograms (mcg)—or 5,000 international units (IU)—of vitamin D3 as cholecalciferol.
The National Institutes of Health7 (NIH) indicates adults should get about 15 mcg (600 IU) of vitamin D daily and increase intake to 20 mcg (800 IU) at age 70 and older. However, the Endocrine Society8 states that to maintain adequate vitamin D levels, adults might need at least 37.5 to 50 mcg (1,500–2,000 IU) per day of supplemental vitamin D, and children and adolescents might need at least 25 mcg (1,000 IU).
Vitamin D2 is typically a plant-based dietary supplement source, as vitamin D3 supplements9 are often manufactured from animal products—therefore, not naturally vegan-friendly. But as we’ve covered, vitamin D2 isn’t as effective as vitamin D3, which can present a real challenge for those following a vegan-based diet searching for an effective vitamin D supplement. A popular way of creating vegan-friendly vitamin D3 is through lichen10, a complex life form of fungus and algae.
Now, we can’t confirm nor deny that Utzy Naturals uses lichen in their D3 formula. While their ingredient lineup is all vegan, there’s no official declaration, so you may want to proceed cautiously. That said, this product is third-party tested, manufactured in the United States, and comes with an empty-bottle guarantee you won’t see with a lot of supplements.
Form | Capsules |
Dosing instructions | Take 1 capsule daily |
Cost per serving | $32.35/60 servings = $0.54/serving |
Best Multivitamin With Vitamin D: Ritual Essential Multivitamin 18+
Good for: Those seeking a high-quality, effective dose of vitamin D
Best Multivitamin With Vitamin D
Ritual Essential for Men Multivitamin 18+
Product Highlights
- Scientifically developed multivitamin
- 10 ingredients to support health
- Vegan, gluten- and major allergen-free, non-GMO, and no artificial colors
Pros & Cons
Pros
- Made Traceable with visible supply chain
- Free shipping and money back guarantee with subscription
- Delayed release capsule
Cons
- Customer complaints about the mint flavor
- Expensive at more than $1 per serving
- Only available from company website
- Limited number of customer reviews
Bottom Line
The Ritual Essential for Men Multivitamin 18+ is a well reviewed multivitamin with quality ingredients. The only notable complaint was the mint flavoring.
Best Multivitamin With Vitamin D
Ritual Essential for Women 18+
Product Highlights
- Clinically-backed formula for women age 18-49
- Made with 9 high-quality, traceable ingredients
- Patented beadlet oil technology
- Essenced with mint to maintain freshness
Pros & Cons
Pros
- Transparent ingredients
- Clinically studied
- Vegan
- Delayed-release
- Mild mint flavor
Cons
- Some users report they taste and smell like fish
- May cause indigestion
Bottom Line
Ritual Essential for Women is a clinically-backed, vegan multivitamin made with nine high-quality traceable ingredients.
Providing 50 micrograms of D3, Ritual Essential Multivitamin 18+ (which comes in formulas for men and women) is a great option for those looking to get vitamin D as well as other key minerals and vitamins. To put another way, 50 micrograms is 250% of the recommended daily value of Vitamin D3.
GGR Editor Frieda Johnson, CNC, tested these vitamins for our team. She said these were a great option because they didn’t hurt her stomach as much as other multivitamins usually do, which is why these earned a 5-star rating for side effects (because she didn’t experience any).
Depending on which version of the vitamin you get (for men or for women), you’ll also get:
- Vitamin A (men’s)
- Vitamin B12
- Vitamin E
- Folate
- Iron (women’s)
- Magnesium
- Zinc (men’s)
- Boron (men’s)
- Vitamin K2
- Omega-3
Frieda scored these multivitamins 5 out of 5 stars for taste and swallowability. Frieda was thrilled to find that these capsules have a minty flavor. “It’s quite pleasant; definitely preferable to a typical pill flavor!”
We should point out that Ritual is a subscription-based company, meaning you have to sign up for a subscription for the vitamins (monthly). They do offer a money-back guarantee, and you can cancel your subscription at any time.
These vitamins are also more expensive than other multivitamins. However, they are third-party tested.
Form | Capsules |
Dosing instructions | Take 2 pills daily |
Cost per serving | $33/30 servings = $1.10/serving |
Best Chewable Vitamin D Supplement: Ora Organic Sol Food High-Potency Vitamin D3 + K2
Good for: Those looking for a chewable vitamin D supplement made with organic, vegan ingredients
Best Chewable
Ora Organic Sol Food High Potency Vitamin D3 + K2
Product Highlights
Pros & Cons
Pros
- Meets daily requirement of vitamin D
- Uses MK-7 vitamin K2
- Most users enjoy the flavor
- Third-party tested
- 100% satisfaction guarantee
Cons
- Only 1 flavor (Slightly Sweet)
- Contains xylitol which can cause stomach upset
Bottom Line
Featuring 5,000 IU of vitamin D3 naturally-sourced from lichen and 100 mcg of vitamin K2 from chickpeas, Ora Organic Sol Food High Potency Vitamin D3 + K2 is a once-daily chewable vitamin with a satisfaction guarantee. Users love the ease of use and the fresh citrus flavor.
When you think chewable, you probably think gummy. But not all want a chewable supplement in gummy form, especially if it’s chock-full of added sugars. Ora Organic Sol Food High-Potency Vitamin D3 + K2 is a chewable tablet sweetened with xylitol, a natural plant-based sugar alcohol with fewer calories and a smaller effect on blood sugar levels. (Keep in mind that xylitol may cause stomach upset in some users.)
This doesn’t mean they aren’t sweet. GGR Senior Staff Writer Caine Wilkes, OLY, USAW-L1, gave these chewables a try and was pleasantly surprised, calling out its distinct citrus flavor and ultimately giving it a 4 out of 5 for taste.
As for solubility, non-gummy chewables can have a reputation for being gritty or chalky and getting stuck in your teeth. That wasn’t the case with Ora Organic. Caine even gave the chewables a perfect score of 5 out of 5, saying, “It chews right up easily and dissolves in your mouth, too. I had no issues.”
We went a step further and asked GGR Expert Contributor Dr. Bob Iafelice, MS, RDN, LDN, for his opinion on the formula and shared, “The dosage of 5,000 IU vitamin D is consistent with the top supplements out there, and what most adults need. The addition of vitamin K2 (especially MK7—the best form) is very important as it directs the calcium (absorbed by D) to the right places in the body. I give it a 5.”
High praise aside, Dr. Bob did have a statement (or two) about how Ora Organic promotes its products that we thought was too interesting not to share:
“Plant-based supplements are an alternative—they are not better than supplements that the vast majority of people take. Case in point here: They state, ‘The cleaner source of vitamin D3.’ So, are we led to believe that the thousands of other D and K products are unclean? They even disparage lanolin as ‘wool grease.’ Maybe they should be reminded that many lip balms, skin and hair care products, cosmetics, etc., are made from lanolin. It’s fine to promote plant-based products as an alternative, but to say that they are superior to non-plant-based is unsubstantiated—just my two cents.” End rant.
Apart from branding, we really like that Ora Organic High-Potency Vitamin D3 + K2 is gluten-free, certified vegan, USDA-organic, soy-free, dairy-free, and third-party tested. It also comes with a satisfaction guarantee and will grant you a full refund within 60 days if you’re unsatisfied with your purchase.
Form | Chewable tablets |
Dosing instructions | Chew 1 tablet in the morning or by mid afternoon |
Cost per serving | $24.99/30 servings = $0.83/serving |
Best Vitamin D Supplement For Bone Health: True Nutrition Vitamin D3
Good for: Active individuals looking to preserve the density and strength of their bones
Best For Bone Health
True Nutrition Vitamin D3
Product Highlights
Pros & Cons
Pros
- Incredibly budget-friendly at $0.08/serving
- Serving size is just 1 softgel (with food)
- Third-party tested and soy-free
Cons
- Product is manufactured in a facility that handles milk, soy, egg, peanut, nut, tree, fish, crustaceans/shellfish, and wheat products
Bottom Line
True Nutrition Vitamin D3 is a single-serving, potent vitamin D3 softgel, backed by third-party testing. It’s also budget-friendly and comes with 120 servings per bottle.
As established, vitamin D can be an important part of bone health as it helps the body better absorb the calcium needed to support healthy bones and potentially prevent osteoporosis.
So what makes True Nutrition Vitamin D3 our pick for the best vitamin D for bone health? Its value lies in its simplicity. True Nutrition Vitamin D3 contains 125 mcg (5,000 IU) of D3 from cholecalciferol (a fat-soluble compound) and is third-party tested. Quality aside, the daily dosage is one softgel, and you get 120 servings via each $9.99 bottle. That makes your cost per serving less than a dime.
Supplementation—much like diet and exercise—is most effective when you’re consistent, so the cost, amounts of servings, and ease of use all add up to a potent vitamin D3 you can take every day with minimal effort to elevate your vitamin D levels and maintain the health of your bones.
Form | Softgels |
Dosing instructions | Take 1 softgel with food |
Cost per serving | $9.99/120 servings = $0.08/serving |
Best Liquid Vitamin D Supplement: Athletic Greens D3 + K2 Liquid
Good for: Vitamin D seekers who prefer a liquid, mixable option
Best Liquid
Athletic Greens Vitamin D3 + K2
Product Highlights
- 2 drops provide 1,000 IU of vitamin D3 and 200 µg of vitamin K2
- Each bottle contains 600 servings, so it will last a while
- MCT coconut oil base to enhance absorption and natural vitamin E to preserve freshness
- Formulated to support vascular, respiratory, nerve, muscular, and immune health
- Reported benefits also include a positive mood
Pros & Cons
Pros
- Unflavored
- 1 bottle will last a long time
- Provides both vitamin D3 and K2
- Reportedly very effective
- Non-GMO, no soy, allergen-free
Cons
- Dropper may make measuring dosage tricky
Bottom Line
If you are looking for an easy way to boost levels of vitamin D3 and K2, Athletic Greens’ Vitamin D3 + K2 liquid is a flavorless supplement that can easily be put in any beverage.
Athletic Greens put itself on our map as one of the best greens powders on the market. But the brand also made its way as the best liquid vitamin D supplements, specifically in liquid form that provides 1,000 IU of vitamin D3 and 200 mcg of vitamin K2. This combination earns Athletic Greens a 5-star formulation rating.
According to the official Athletic Greens website, vitamins D and K2 “work synergistically to support the heart, vascular system, immune system, and respiratory system.” A 2017 study published in the International Journal of Endocrinology11 supports this, suggesting that joint supplementation of vitamins D and K might be more effective for bone and heart health rather than consuming either alone.
While vitamins K1 and K2 are both beneficial, vitamin K1 is more involved with blood clotting and Vitamin K25 has pronounced roles in heart, bone, and really overall health. Vitamin K2 is under-consumed, though supplying high doses via supplementation could help consumers reach the required daily intake and improve their health.
The D3+K2 liquid drops are also made with an olive oil base to augment the absorption of both fat-soluble vitamins, as well as vitamin E to preserve freshness. GGR Senior Staff Writer Lauren Strong, CPT, said the liquid does feel a little viscous like olive oil, but because you only have to swallow a few drops, it’s not too bad. She gave it a 4.5-star swallowability rating.
“I honestly didn’t really notice much for side effects, but I fell off the wagon taking this supplement daily and I got sick about two weeks later,” Lauren says. “With the lack of sun in the winter I think supplementing with Vitamin D where I live plays a huge role in overall immune system health.”
Form | Liquid drops |
Dosing instructions | Take 2 drops daily or as directed by a healthcare professional; may be put on a spoon or food or mixed in with other liquids |
Cost per serving | $52.50/600 servings = $0.09/serving*on-sale from $62.99 |
Best Gummy Vitamin D Supplement: Bulletproof A+D+K Gummy
Good for: Kids at heart with adult vitamin D needs
Best Gummy
Bulletproof Vitamins A+D+K Gummies
Product Highlights
- Sugar-free gummy vitamin combines 3 key vitamins in 1 product
- Each serving provides 900 micrograms of vitamin A, 50 µg (2,000 IU), and 1,000 µg of vitamin K1
- Formulated to support bone, heart, and immune health
- Combination of vitamins purported to enhance how the body absorbs and uses calcium
Pros & Cons
Pros
- No added sugar
- 3-in-1 supplement
- Science-backed ingredients
Cons
- Taste is not for everyone
- Difficult to open the jar
- May cause GI issues for some
Bottom Line
The Bulletproof Vitamin A+D+K Gummies provide potent doses of each vitamin in one gummy.
Bulletproof A+D+K Gummy is the one and only vitamin D gummy on our list. The Bulletproof A+D+K gummies provide the familiar ingredients vitamins D3 (50 mcg) and K2 (180 mcg), which we’ve learned could be a synergistic power duo. But how do vitamins A and K1 fit in?
Bulletproof’s website details the “three essential vitamins that help your body work better when taken together. Instead of taking a separate vitamin A gummy, vitamin K gummy, and vitamin D gummy, this is your one-stop-shop for bone, heart, and immune support.”
Vitamin A12—also a fat-soluble vitamin—supports normal vision, the immune system, reproductive health, and growth and development. And as we just recently touched on, vitamins K1 and K2 are both beneficial but vitamin K14 plays a larger role in blood clotting and is often administered as a medication. This is why newborns receive a vitamin K1 injection shortly after birth: to prevent the potentially lethal vitamin K deficiency bleeding.
Vitamins aside, the orange strawberry-flavored gummies do not contain any added sugars. Instead, they are sweetened with the sugar alcohols xylitol and erythritol, as well as the natural sweeteners monk fruit and stevia leaf extracts. Bulletproof earns a 5-star rating from our testers when it comes to forumulation due to the low-sugar profile and unique vitamin combination.
“These are SO GOOD,” says GGR expert contributor Amanda Capritto, CPT, CES, CNC, CF-L1, CSNC, who scored the Bulletproof gummies 5 out of 5 stars for taste.
“I’m almost out of these gummies and I’m really sad about it. The Orange Strawberry flavor is so tasty and tropical. I look forward to taking these every day.”
While not totally obvious on the vitamin D’s product page, a little poking around the Bulletproof site tells us their supplements only contain high-quality and “clean” ingredients provided in science-backed doses. They’re also free of GMOs, dyes, soy, gluten, and artificial fillers.
Form | Gummies (Orange Strawberry-flavored) |
Dosing instructions | Take 2 gummies daily, preferably with food |
Cost per serving | $24.95/30 servings = $0.83/serving |
Best Vitamin D Supplement Drops: Thorne Vitamin D/K2 Drops
Good for: Vitamin D-rop searchers who prefer liquid over capsules and chewables
Best Drops
Thorne Vitamin D/K2 Drops
Product Highlights
- Each serving provides 25 µg (1,000 IU) of vitamin D3 and 200 µg of vitamin K2
- Formulated to support bone, muscle, cardiovascular, and immune health
- Self-dispensing top designed to provide exact dosing
- Manufactured in a GMP facility and certified by NSF International yearly
Pros & Cons
Pros
- Easy-to-take and convenient
- Flavorless
- Made in GMP facility
- Quality assurance process
- Clean ingredients
- Affordable price
Cons
- Dispenser may be tricky
- Reports of damaged packaging
Bottom Line
Thorne Vitamin D/K2 liquid supplement is a convenient and affordable way to increase your intake of both vitamin D3 and vitamin K2.
Thorne Vitamin D/K2 Drops are a purposeful, synergistic blend of vitamins D and K2 to support bone, immune, and cardiovascular health. With each 2-drop serving, you’ll specifically be taking in 25 mcg (1,000 IU) of vitamin D3 and 200 mcg of vitamin K2.
The vitamin D drops also contain MCT oil to enhance absorption, as well as mixed tocopherols to preserve freshness. It’s also free of gluten and dairy-free, devoid of artificial flavors, and recommended to be stored in a cool, dry place (and not refrigerated).
To help ensure the accuracy of the dosed drops, the Thorne vitamin D supplement comes with a self-dispensing tip. The top disperses individual drops, which Thorne says you might experience a delay between them for safer dosing, though they also encourage dispensing onto a spoon before consuming can help you get the right dosage.
GGR Head of Content Nicole Davis, CPT—who was initially supplementing with the Nature Made Vitamin D3 softgels—has since switched to the Thorne liquid vitamin D. She scored both taste and swallowability of this liquid vitamin D at 5 out of 5 stars.
“These drops are tasteless, and I love that you can mix it into a beverage. I find them easier than taking a pill everyday. And, I haven’t noticed any difference in benefits from the softgels I was taking, which is a good thing as I definitely noticed better energy when I first started taking vitamin D,” says Nicole.
According to Thorne’s website, the US-manufactured and FDA-regulated supplement brand is trusted by 45K+ healthcare professionals, 100+ sports teams, 10K+ pro athletes, and U.S. Olympic teams. Thorne is also an official collaborator with Mayo Clinic, as well as the official supplement partner of CrossFit and UFC. However, Thorne doesn’t list any third-party testing labs or results, so it earns a 3-star rating for third-party testing.
Form | Liquid drops |
Dosing instructions | Take 2 drops one to three times per day or as recommended by your health-care practitioner; may be added to food or beverages |
Cost per serving | $28.00/600 servings = $0.05/serving |
Best Organic Vitamin D Supplement: Garden of Life Raw Whole Food Vitamin D
Good for: Whole food advocates looking for a boost of vitamin D, probiotics, and nutrients
Best Whole Food
Garden of Life Raw Vitamin Code Raw D3
Product Highlights
- Derived from raw whole foods
- Each serving provides 5000 IU of fat-soluble raw vitamin D3
- Lipid base consists of high omega-9 organic green cracked wall chlorella
- Added probiotics and enzymes include lactobacillus probiotics and digestive enzymes lipase, protease, bromelain, lactase, and papain
- Formulated to support bone, joint, breast, prostate, and immune health
Pros & Cons
Pros
- Raw
- 3rd-party certified
- Clean ingredients
- Vegetarian
- Added probiotics and enzymes
Cons
- Dosage too high for some
- Added probiotics may cause digestive problems for some
Bottom Line
The Garden of Life Vitamin Code Raw D3 is a gluten- and dairy-free whole food vitamin D complex that also contains a healthy dose of probiotics and digestive enzymes.
Garden of Life Raw Whole Food Vitamin D is formulated with whole food nutrition and contains a heavy dose of vitamin D3—5,000 IU to be exact. With such a large dose, compared to other products on our list, it’s urged to consult your healthcare practitioner before starting the supplement.
Vitamin D might be the nutrient of interest, but it cannot be overshadowed by the other 20+ whole food ingredients it contains. For that reason, it earns a 5-star rating for its formulation. Kate Meier, GGR editorial team member, said the capsules do taste a bit “plant-like,” but it’s not off-putting. She scored the taste 4 out of 5 stars.
We’ll first note the vitamin D supplement is joined with omega-9—a lipid base sourced from organic green chlorella (a type of algae)—to promote absorption. It also provides a raw organic blend of live probiotics and digestive enzymes to further enhance the absorption of nutrients, although we also recommend checking out the best probiotics to optimize your gut and overall health.
The robust vitamin D formulation also contains an organic fruit and vegetable blend of apple, beet, and broccoli, amongst many others down the colorful alphabet. Their addition is intended to provide antioxidants, vitamins, and nutrient cofactors that help drive essential chemical processes in the body.
The whole food supplement is also certified by the nonprofit B Lab to meet rigorous standards related to social and environmental performance, accountability, and transparency. It’s also certified non-GMO, gluten-free, and kosher and manufactured without high heat, synthetic binders, fillers, artificial flavors, artificial sweeteners, artificial colors, and other additives.
Garden of Life also prides itself on its traceability, meaning each ingredient can be traced back to its source, and partnering with charitable organizations and foundations. They were also the first vitamin and supplement brand to be Certified Carbon Neutral and are committed to sustainable practices. For this reason, Garden of Life earns a 5-star rating for third-party testing.
Form | Capsule |
Dosing instructions | Adults take 1 capsule daily or as directed by your healthcare practitioner; best when taken with a meal; capsule may also be opened and contents added to water or juice |
Cost per serving | $20.94/60 servings = $0.35/serving |
Best Vitamin D Supplement for Kids: Carlson Labs Kid’s Super Daily D3 + K2
Good for: Kiddos recommended to an effective and high-quality vitamin D supplement
Best for Kids
Carlson Kid’s Super Daily Vitamin D3 + K2
Product Highlights
- Children’s daily vitamin D3 liquid provides 25 µg (1,000 IU) and 22.5 µg of vitamin K2 per serving
- Easily add to food or beverage without altering the taste
- Made in an FDA-registered laboratory for potency and quality
- No added chemicals, flavors, or artificial coloring
- Euro-dispenser ensures accurate dosage
Pros & Cons
Pros
- Tasteless
- Has both vitamins K2 and D3
- No added chemicals
- Easy to measure
Cons
- Rosemary extract is too fragrant for some
Bottom Line
Made in an FDA-registered laboratory, Carlson’s Kid’s Super Daily Vitamin D3 + K2 liquid supplement provides 25 micrograms (1,000 international units) of concentrated vitamin D3 and 22.5 micrograms of vitamin K2 per serving.
Carlson Labs Kid’s Super Daily D3 + K2 is formulated for children aged four years or older, specifically providing 25 mcg (1,000 IU) of vitamin D. The amount of vitamin D matches some of our picks for adults, so is this too much or just right for the kiddos?
The NIH recommends7 infants from 0-12 months get 10 mcg (400 IU) of vitamin D each day and graduate to an adult dose of 15 mcg (600 IU) at age 1. However, the Endocrine Society says that children one year and older require at least 600 IU daily to maximize bone health.
The Endocrine Society further states at least 1,000 IU of vitamin D daily can help raise blood levels consistently. And under medical supervision, maintaining tolerable upper limits (UL) of vitamin D should be at least 3000 IU/d for children aged 4 to 8 and 4000 IU/d for everyone over 8 years of age. However, higher levels of 4000 IU/d for children 1 to 18 years old may be needed to correct vitamin D deficiency.
Preventing and correcting vitamin D deficiency is essential at all life stages, but especially in growing children to support their growing bones and bodies. Adequate vitamin D also reduces the risk of rickets, a condition described as the softening and weakening of the bones, particularly in children ages 6 to 24 months.
GGR Head of Content (and mom of three) Nicole Davis, is no stranger to Carlson vitamin D drops. “With my second we went through two different types of vitamin D before trying this brand…she had a bad reaction to others (we think), crying super duper hard, and was just so unhappy. Something did not sit right with her. In my delirium at 2 a.m. with a screaming newborn, I remember Googling vitamin D drops and reading reviews about these so I thought I’d try them. Voila!”
Nicole scored taste, swallowability, and side effects all at 5 out of 5 stars for these Carlson drops.
Carlson vitamin D supplement provides 22.5 mcg of vitamin K2 as well. While we’ve explored the benefits of vitamin K2 for adult health, a 2022 review13 examining the impacts of vitamin K2 on children’s health points out children have the highest vitamin K needs. Vitamin K2 is shown to be safe and effective for children and promotes bone health, blood clotting, and a healthy heart.
The review further suggests that 45 to 50 mcg of vitamin K2 is an appropriate intake range for children, although the supplement contains about half of the vitamin K2 recommendations. Parents and caregivers can help fill in the remaining needs with vitamin K2-rich food sources14, including cheese, milk, and other fermented foods and animal products.
Overall, even though everyone benefits from seeking medical assistance regarding their vitamin D and nutritional needs, it’s a critical step for children. Before starting this product, or any other supplement for that matter, please consult with your child’s pediatrician for their utmost safety.
The D3+K2 supplement also contains MCT oil and an antioxidant blend—of d-alpha tocopherol and rosemary extract—to enhance absorption and freshness. The formulation comes in unflavored vegetarian drops, that can be added to food or a drink, to lower any intake resistance from the little recipient.
Also rest easy knowing the kid’s vitamin D supplement is free of GMOs, soy, gluten, dairy, and artificial preservatives. It’s also tested to meet potency and purity standards.
Form | Liquid drops |
Dosing instructions | Children 4 years of age or older: take one drop daily or as directed by your healthcare professional |
Cost per serving | $29.90/360 servings = $0.08/serving |
Other Vitamin D Supplements We Researched
Because there are hundreds of vitamin D supplements out, it’s nearly impossible to capture other great finds into one small, yet mighty list. Beyond our top picks, other vitamin D supplements we researched and approve include:
- Nordic Naturals Zero Sugar Vitamin D3 Gummies
- TheraCal D2000 Bone Health Supplement
- NATALIST Vitamin D3 Gummies
- Source Naturals Vitamin D-3 Liquid Drops
- Designs for Health Liposomal D Supreme Vitamin D
How We Picked and Tested the Best Vitamin D Supplements
We take our product reviews very seriously and the same goes for picking and testing the best vitamin D supplements on the market. To form our top picks, we specifically analyzed and factored in the following:
- Vitamin D type: As we’ve mentioned, vitamin D3 shows to be the most effective for increasing blood levels of vitamin D. This said, we are preferential towards vitamin D3 and each of our chosen products contains this form.
- Additional ingredients: If additional ingredients are formulated with vitamin D, what’s the intention? The inclusion of extra virgin olive oil is a great example of this, as the fat source can help enhance the absorption of the fat-soluble vitamin. We also favor products with cleaner formulas that are free of artificial ingredients, fillers, and other lower-quality, unnecessary ingredients.
- Supplemental form: Consumers differ on how they wish to take a supplement—such as a liquid or softgel—so we captured various supplemental forms to honor various preferences.
- Cost: While vitamin D supplements tend to be budget-friendly as a whole, we made sure to pick assorted price points to accommodate just about every personal budget.
- Manufacturing and testing: Because supplements are not tightly regulated, we always always prioritize products that have undergone tight manufacturing and testing practices. This includes compliance with the Current Good Manufacturing Practice (cGMP) set and monitored by the U.S. Food and Drug Administration (FDA).
- Brand loyalty: Is the company committed to high-quality products? Do they strive to keep customers both informed and satisfied? Just as we’re loyal to our review process and consumers, we place major weight on brands that do the same.
Benefits of Vitamin D Supplements
Some health benefits of vitamin D are familiar, but others are less obvious. Regardless, what vitamin D can do for the body and health is impressive and all backed by research.
Supports Bone Health
One of the most obvious and notable functions of vitamin D is its critical role to build and support healthy bones. Vitamin D deficiency also increases the risk of rickets in children, as well as osteomalacia and osteoporosis in adults.
This is because the body needs vitamin D15 for calcium absorption; and without enough of each, the body will start pulling available calcium in the skeletal system and eventually weaken bones. Supporting data16 clearly indicates that inadequate vitamin D over long periods of time can lead to bone demineralization.
A meta-analysis17 shows that vitamin D supplementation does not appear to improve bone health for those with adequate vitamin D levels. However, 2019 research18 advises that vitamin D intake of 800 IU per day—in tandem with sufficient calcium intake—is optimal for fracture prevention.
Protects from Several Chronic Diseases
Chronic diseases19 are conditions that last one year or more—like heart disease, Type 2 diabetes, and cancer—and are the leading causes of death and disability in the U.S. Lifestyle factors, including diet and exercise, mainly contribute to the risk of chronic disease but vitamin D also shows to protect from the following:
- Heart/cardiovascular disease: A 2014 meta-analysis20 suggests vitamin D supplementation might protect against heart failure in older adults. A supporting 2019 systematic review and meta-analysis21 shows supplementing with vitamin D may reduce blood cholesterol and triglyceride levels.
- Cancer: Research22 proposes that low blood vitamin D is associated with an increased risk of 15 different cancers—including breast, colon, lung, and prostate cancers—whereas adequate vitamin D may reduce the growth and spread of malignant (cancer) cells. Another systematic review23 also found that vitamin D supplementation could reduce the risk of cancer death by 15%.
- Type 2 diabetes: Because vitamin D deficiency is linked to insulin resistance and type 2 diabetes, researchers continue examining if vitamin D supplementation could prevent or help manage the chronic disease. Although a 2017 review24 advises vitamin D supplementation cannot be recommended to prevent or improve Type 2 diabetes at this time, a recent 2022 study25 hints vitamin D could be effective in decreasing diabetes in adults with prediabetes.
Bolsters Immune Function
The immune system helps the body defend against harmful invaders, and 2011 data26 suggests lower levels of vitamin D may increase the risk of infections. Cells of the immune system—like B cells, T cells, and monocytes—may also positively respond to vitamin D, thus bolstering immune function, especially in individuals managing an autoimmune disease.
A more recent 2020 review published in Nutrients27 tells us that vitamin D shows to exert immunological activities on many immune system responses. There have also been associations between low levels of vitamin D and greater risks of immune-related health conditions, including psoriasis, multiple sclerosis, type 1 diabetes, and rheumatoid arthritis.
Boosts Mental Health
Have you ever felt down in the dumps, only to get an instant mood and energy jolt after basking in the sweet sunshine? Well, not only can getting out in the sun boost your mood, but vitamin D supplementation might as well.
A 2020 systematic review and meta-analysis28, covering 25 trials and 7,500+ participants, found that vitamin D supplementation can reduce negative emotions. The benefits may be more pronounced in patients with major depressive disorders and individuals with vitamin D deficiency, though the evidence appears promising.
Supports Weight Loss
Fat loss is the byproduct of lifestyle factors, especially diet, and vitamin D might surprisingly play a role. Interestingly, obesity can increase the risk of vitamin D deficiency whereas weight loss can increase vitamin D levels according to a 2011 study published in The American Journal of Clinical Nutrition29.
In a 2018 study30, researchers conducted a double-blind clinical trial on 50 overweight and obese women: one group received 50,000 IU of vitamin D per week while the other group received a placebo for six weeks. The group receiving vitamin D significantly reduced weight, waist circumference, and body mass index while increasing blood levels of vitamin D.
A less recent, yet larger 2014 study31 prescribed over 200 overweight and obese women (aged 50-75 years) with a calorie-restricted diet and exercise routine—and half of the women received 2,000 IU daily of vitamin D3, or and the other half took a placebo. After one year, the researchers found women who repleted vitamin D stores experienced greater improvements in their weight loss.
Dosing and Interactions
While vitamin D supplements are mostly considered to be safe, you should still dose accordingly. Vitamin D can also interact with certain medications, which could pose serious risks and/or reduce the efficacy of the supplement or prescription.
Dose Recommendations
The amount of vitamin D you need each day is based on Recommended Dietary Allowances (RDAs), or the average daily intake level to meet nutrient requirements. Provided by the National Institutes of Health7, the RDAs below indicate daily intakes sufficient to maintain bone health and calcium metabolism in healthy metabolism:
Age | Male | Female | Pregnancy & Lactation |
0-12 months* | 10 mcg (400 IU) | 10 mcg (400 IU) | |
1-13 years | 15 mcg (600 IU) | 15 mcg (600 IU) | |
14-18 years | 15 mcg (600 IU) | 15 mcg (600 IU) | 15 mcg (600 IU) |
19-50 years | 15 mcg (600 IU) | 15 mcg (600 IU) | 15 mcg (600 IU) |
51-70 years | 15 mcg (600 IU) | 15 mcg (600 IU) | |
>70 years | 20 mcg (800 IU) | 20 mcg (800 IU) |
*Recommendation based on Adequate Intake (AI)
Interestingly, too, a 2020 review22 hints there’s still debate on what level of vitamin D in the blood is optimal to achieve the health benefits of vitamin D. However, it’s likewise advisable to increase vitamin D intake—and have sensible sunlight exposure—to maintain levels.
To add more complexity to the matter, vitamin D testing can be expensive and not always supported as a screening tool2. For successful repletion of vitamin D, it’s prudent to mention who might be at the greatest risk of deficiency which includes:
- People who cannot tolerate or avoid dairy products or follow a vegan diet
- Those who are classified as obese
- Individuals condition that impacts the digestive system, including Crohn’s disease and conditions that interfere with normal fat digestion
- People who have undergone gastric bypass surgery
- Darker-skinned individuals or those who are regularly fully-clothed/use sunscreen that blocks vitamin D absorption from the sun
- Older adults, especially who spend more time indoors
- Those who live in the northern hemisphere, especially when winter arrives and sun exposure lessens
All this said, recommended intake values also vary based on an individual’s vitamin D level. Someone with a significant vitamin D deficiency will require more vitamin D to replete those vitamin D stores.
Interactions & Safety
It’s smart to consult with your doctor before taking any sort of supplement, especially if you’re taking medication. This is because there’s always a risk of drug interactions, which can make the prescription less effective and/or lead to unwanted—and sometimes dangerous and fatal—side effects.
Mayo Clinic32 counsels the following medications can lead to possible interactions, including:
- Aluminum
- Anticonvulsants, specifically phenobarbital and phenytoin
- Atorvastatin
- Calcipotriene
- Cholestyramine
- Cytochrome P-450 3A4 substrates
- Digoxin
- Diltiazem
- Orlistat
- Thiazide diuretics
- Steroids
- Stimulant laxatives
- Verapamil
Beyond medication interactions, vitamin D supplementation shows to be safe and toxicity is rare12. Severe adverse effects have only been reported with very extreme intakes of vitamin D ranging from 15,000-42,000 mcg, which is well above natural intakes from food or supplements.
Still, most of the risks are related to vitamin D’s function of increasing calcium absorption—the more vitamin D available, the more calcium that’s absorbed, which can cause hypercalcemia. Defined as high calcium in the blood, hypercalcemia33 can cause bone pain, digestive complications, kidney stones and failure, depression, and other worrisome health concerns.
It might sound like a broken record, but it’s genuinely important to seek medical guidance to help determine your unique nutrient needs.
Buying Guide: What to Look for in Vitamin D Supplements
Whether you’re looking for additional guidance to choose between our top picks or venturing outside the list, lean on these expert tips to decide which vitamin D supplement is right for you.
Review the Formulation
The formulation is what you’ll actually be consuming, so it’s important to review it. Here’s what to look out for in a vitamin D supplement:
- Vitamin D form: Vitamin D supplements mostly contain one of two forms, including vitamin D2 (ergocalciferol) or vitamin D3 (cholecalciferol). Both are great sources of vitamin D but we do recommend choosing a supplement with vitamin D3 since it’s more effective in raising vitamin D levels in the blood.
- Vitamin D content: Most vitamin D supplements provide 1,000-2,000 IUs of vitamin D, although some offer higher doses. Ultimately, you and your doctor should explore together how much vitamin D might be best for your individual needs and select a dosage to match.
- Added ingredients: Beyond vitamin D, review and consider additional ingredients in the supplement. For instance, some vitamin D supplements contain other nutrients such as vitamins A and K while others (outside of our picks) might contain unwanted fillers.
Consider the Supplement Form
Would you rather consume the vitamin D supplement as liquid drops, softgels, or gummies? Pick a supplement form based on your preferences, as you’ll be more consistent in taking it if it’s in a preferential form.
Factor in Your Dietary Needs and Preferences
Do you follow a vegan diet? Or perhaps you’re managing Celiac disease and needing a gluten-free option. Consider your dietary needs and/or preferences and choose a vitamin D supplement to match.
Explore Verifications and Certifications
Exploring the product verification and certifications can give you great insight into what’s actually in the supplement. (And what’s not in the product.)
Look out for third-party testing verifications to best validate the product’s safety, purity, and quality. Also, check to see if the product holds verifications that are important to you like certified gluten-free and/or vegan.
Investigate the Brand Behind the Product
Investigating the brand behind the product of interest can deepen your understanding of the brand’s standards and reputation. Areas that can provide great insight include:
- Return policies and 100% money-back guarantees
- Customer reviews on the site’s main webpage, as well as on Amazon and other third-party seller sites if available
- Customer service access or at minimum a contact form you can fill out—and actually get a response back
Taking this extra step can help you decide if you’re willing to support a company (and acquire your hard-earned dollars)!
FAQs About Vitamin D Supplements
Which form of vitamin D is best absorbed?
Research suggests vitamin D3 is the best form to take rather than vitamin D2. Both forms act and function similarly in the body, although vitamin D3 shows to be effective in increasing vitamin D levels.
How much vitamin D should you take every day?
How much vitamin D you should take depends on many factors, including your age and current vitamin D status. As a general rule, most males and females should consume 15 mcg (600 IU) of vitamin D daily and increase to 20 mcg (800 IU) after age 70.
Is it better to take vitamin D in the morning or at night?
When it comes to timing your vitamin D supplements, all that matters is to follow the dosing instructions. Some supplements require you take with a meal or a certain amount of water.
What are signs of low vitamin D?
There are a wide range of signs that may indicate low vitamin D levels including muscle pain, weakness, mood swings, and fatigue. According to the Mayo Clinic and the Cleveland Clinic, there are some populations more at risk to vitamin D deficiency including:
– The elderly
– Postmenopausal women
– People who are obese
– People who have been on steroids for an extended time
– People who have darker skin
References
- Amrein K, Scherkl M, Hoffmann M, et al. Vitamin D deficiency 2.0: an update on the current status worldwide. Eur J Clin Nutr. 2020 Nov;74(11):1498-1513. doi: 10.1038/s41430-020-0558-y. Epub 2020 Jan 20. PMID: 31959942; PMCID: PMC7091696.
- Kennel KA, Drake MT, Hurley DL. Vitamin D deficiency in adults: when to test and how to treat. Mayo Clin Proc. 2010;85(8):752-758. doi:10.4065/mcp.2010.0138
- Harvard T.H. Chan School of Public Health. (2024, May 9). Vitamin D. The Nutrition Source. https://nutritionsource.hsph.harvard.edu/vitamin-d/
- Armas LA, Hollis BW, Heaney RP. Vitamin D2 is much less effective than vitamin D3 in humans. J Clin Endocrinol Metab. 2004 Nov;89(11):5387-91. doi: 10.1210/jc.2004-0360. PMID: 15531486.
- Halder M, Petsophonsakul P, Akbulut AC, et al. Vitamin K: Double Bonds beyond Coagulation Insights into Differences between Vitamin K1 and K2 in Health and Disease. Int J Mol Sci. 2019;20(4):896. Published 2019 Feb 19. doi:10.3390/ijms20040896
- Vieth R. Vitamin D Toxicity, Policy, and Science. J Bone Miner Res. 2007;22(S2):V64-V68. doi:https://doi.org/10.1359/jbmr.07s221
- National Institutes of Health. (Updated July 26, 2024). Office of Dietary Supplements – Vitamin D. Nih.gov. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
- Holick MF, Binkley NC, Bischoff-Ferrari HA, et al. Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2011 Jul;96(7):1911-30. doi: 10.1210/jc.2011-0385. Epub 2011 Jun 6. Erratum in: J Clin Endocrinol Metab. 2011 Dec;96(12):3908. PMID: 21646368.
- Hirsch, L. Arnold. Industrial Aspects of Vitamin D. Academic Press. 2011. doi.org/10.1016/B978-0-12-381978-9.10006-X.
- USDA. (n.d.). U.S. Forest Service. Forest Service Shield. https://www.fs.usda.gov/wildflowers/beauty/lichens/about.shtml
- van Ballegooijen AJ, Pilz S, Tomaschitz A, Grübler MR, Verheyen N. The Synergistic Interplay between Vitamins D and K for Bone and Cardiovascular Health: A Narrative Review. Int J Endocrinol. 2017;2017:7454376. doi: 10.1155/2017/7454376. Epub 2017 Sep 12. PMID: 29138634; PMCID: PMC5613455.
- National Institutes of Health. (Updated August 12, 2022). Office of Dietary Supplements – Vitamin A. Nih.gov. https://ods.od.nih.gov/factsheets/VitaminA-Consumer/
- Kozioł-Kozakowska A, Maresz K. The Impact of Vitamin K2 (Menaquionones) in Children’s Health and Diseases: A Review of the Literature. Children (Basel). 2022;9(1):78. Published 2022 Jan 5. doi:10.3390/children9010078
- Fu X, Harshman SG, Shen X, et al. Multiple Vitamin K Forms Exist in Dairy Foods. Curr Dev Nutr. 2017 Jun 1;1(6):e000638. doi: 10.3945/cdn.117.000638. PMID: 29955705; PMCID: PMC5998353.
- U.S. Department of Health and Human Services. (2023, July 13). Bone Health and osteoporosis. National Institute of Arthritis and Musculoskeletal and Skin Diseases. https://www.niams.nih.gov/health-topics/bone-health-and-osteoporosis
- Laird E, Ward M, McSorley E, et al. Vitamin D and bone health: potential mechanisms. Nutrients. 2010;2(7):693-724. doi:10.3390/nu2070693
- Bolland MJ, Grey A, Avenell A. Effects of vitamin D supplementation on musculoskeletal health: a systematic review, meta-analysis, and trial sequential analysis. Lancet Diabetes Endocrinol. 2018;6(11):847-858. doi:https://doi.org/10.1016/s2213-8587(18)30265-1
- Yao P, Bennett D, Mafham M, et al. Vitamin D and Calcium for the Prevention of Fracture: A Systematic Review and Meta-analysis. JAMA Netw Open. 2019;2(12):e1917789. doi:https://doi.org/10.1001/jamanetworkopen.2019.17789
- CDC. (2024, October 04). About chronic diseases. Centers for Disease Control and Prevention. Accessed October 17, 2024 from: https://www.cdc.gov/chronic-disease/about/index.html
- Ford JA, MacLennan GS, Avenell A, et al. Cardiovascular disease and vitamin D supplementation: trial analysis, systematic review, and meta-analysis. Am J Clin Nutr. 2014;100(3):746-755. doi:https://doi.org/10.3945/ajcn.113.082602
- Dibaba DT. Effect of vitamin D supplementation on serum lipid profiles: a systematic review and meta-analysis. Nutr Rev. 2019;77(12). doi:https://doi.org/10.1093/nutrit/nuz037
- Holick MF. Cancer, sunlight and vitamin D. J Clin Transl. Endocrinol 2014;1(4):179-186. doi:https://doi.org/10.1016/j.jcte.2014.10.001
- Zhang Y, Fang F, Tang J, et al. Association between vitamin D supplementation and mortality: systematic review and meta-analysis. BMJ. Published online August 12, 2019:l4673. doi:https://doi.org/10.1136/bmj.l4673
- Lips P, Eekhoff M, van Schoor N, et al. Vitamin D and type 2 diabetes. J Steroid Biochem Mol Biol. 2017 Oct;173:280-285. doi: 10.1016/j.jsbmb.2016.11.021. Epub 2016 Dec 5. PMID: 27932304.
- Pittas AG, Kawahara T, Jorde R, et al. Vitamin D and Risk for Type 2 Diabetes in People With Prediabetes. Ann Intern Med. Published online February 7, 2023. doi:https://doi.org/10.7326/m22-3018
- Aranow C. Vitamin D and the immune system. J Investig Med. 2011;59(6):881-886. doi:10.2310/JIM.0b013e31821b8755
- Charoenngam N, Holick MF. Immunologic Effects of Vitamin D on Human Health and Disease. Nutrients. 2020 Jul 15;12(7):2097. doi: 10.3390/nu12072097. PMID: 32679784; PMCID: PMC7400911.
- Cheng Y, Huang Y, Huang W. The effect of vitamin D supplement on negative emotions: A systematic review and meta‐analysis. Depress Anxiety. Published online May 4, 2020. doi:https://doi.org/10.1002/da.23025
- Mason C, Xiao L, Imayama I, et al. Effects of weight loss on serum vitamin D in postmenopausal women. Am J Clin Nutr. 2011;94(1):95-103. doi:10.3945/ajcn.111.015552
- Khosravi ZS, Kafeshani M, Tavasoli P, et al. Effect of Vitamin D Supplementation on Weight Loss, Glycemic Indices, and Lipid Profile in Obese and Overweight Women: A Clinical Trial Study. Int J Prev Med. 2018;9:63. Published 2018 Jul 20. doi:10.4103/ijpvm.IJPVM_329_15
- Mason C, Xiao L, Imayama I, et al. Vitamin D3 supplementation during weight loss: a double-blind randomized controlled trial. Am J Clin Nutr. 2014 May;99(5):1015-25. doi: 10.3945/ajcn.113.073734. Epub 2014 Mar 12. Erratum in: Am J Clin Nutr. 2014 Oct;100(4):1213. PMID: 24622804; PMCID: PMC3985208.
- Mayo Foundation for Medical Education and Research. (2023, August 10). Vitamin D. Mayo Clinic. https://www.mayoclinic.org/drugs-supplements-vitamin-d/art-20363792
- Sadiq NM, Anastasopoulou C, Patel G, et al. Hypercalcemia. [Updated 2024 May 7]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK430714/
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