As the days grow shorter and colder in Seattle, we often hear the same questions: “What vitamin D product is the best?”, “How much vitamin D should I take?”, “Do I even need more vitamin D?” These are valid questions, especially when our northern climate does not give enough sunlight for our bodies to produce enough vitamin D during the fall and winter months. Therefore, it makes sense to think about boosting your health with a little extra vitamin D, since it plays such an important role in supporting your immune system, strengthening your bones, and even regulating your mood.
However, navigating the world of supplements can feel overwhelming. With so many vitamin D products, different forms, doses, brands, and labels that don’t always match up, it’s easy to get confused. What is most important is you really only need a few key pieces of information to make the right choice. This guide is here to help you break it all down and empower you to make informed decisions about your vitamin D supplement.
Vitamin D2 vs. Vitamin D3 – What is the difference?
There are two main forms of vitamin D you will encounter in supplements and food:
- Vitamin D2 (ergocalciferol): This form is usually derived from yeast or fungi and is often found in fortified foods.
- Vitamin D3 (cholecalciferol): This form is the same type of vitamin D that your body produces in response to sunlight. It’s mainly animal-based, derived from lanolin (sheep’s wool) or other animal sources (fatty fish).
While both work well in raising your vitamin D levels in the blood, studies suggest that vitamin D3 is more effective at raising and maintaining your levels compared to D2. Vegan D3 (lichen) alternatives do exist in the market, but the best practice is to contact the manufacturer about any ingredients that concern you.
Understanding Dosage – How Much Do You Need?
There are a lot of guidelines established by different health organizations about how much vitamin D should be taken daily. The general consensus is that the daily minimum requirements for most healthy patients are:
- Infants (age less than 12 months): 400 (10 mcg)
- Children and Adults (age 1-65): 600 IU (15 mcg)
- Pregnant and Breastfeeding: 600 IU (15 mcg)
- Older Adults (age 70+): 800 IU (20 mcg)
- Maximum daily dose: 4,000 IU per day for most healthy adults
However, these are general guidelines. In practice, many healthcare professionals may suggest taking 1000-2000 IU daily to maintain adequate levels of vitamin D. If you are vitamin D deficient, your doctor may recommend higher doses. A blood test for vitamin D (calcifediol) can determine your vitamin status and help guide your dosing. Screening for vitamin D is not done routinely at your annual check-up, so ask your doctor if you want a vitamin D test.
Delivery Forms – Which One to Choose?
Vitamin D is a fat-soluble vitamin, which means it needs to be dissolved in fat to be absorbed rather than water. This is why it is best to take vitamin D with fatty foods (e.g., eggs, fatty fish, yogurt, nuts, avocados). Some supplement products bypass this by pre-dissolving their vitamin D in oil. Here are some delivery forms that you will likely see in many vitamin D products:
- Softgels:
- Contain vitamin D already dissolved in liquid oil to enhance absorption in the gut.
- The type of oil used is typically olive oil, sunflower oil, or MCT oil. Some products may also use fish oil or soy oil.
- Softgel shells are made from gelatin typically derived from animal collagen (cow skin, pork skin) but there are alternatives made from seaweed or starch.
- Tablets:
- Solid, compressed powders that have longer shelf life compared to other forms.
- Cheaper but have lower absorption if taken on an empty stomach.
- Best taken with meals containing healthy fats (e.g., avocado, nuts, olive oil).
- Tablets are compressed with other ingredients along with vitamin D.
- Liquid Drops:
- Liquid-oil formulation similar to the liquid in softgels. Highly absorbable.
- Good option for those with swallowing and digestive problems.
- Liquid drops are easier to adjust based on specific needs.
- Many products come with droppers for precise dosing, but it is important to check the product label on how many drops are needed per vitamin D dose.
- Oral Sprays:
- Also liquid-oil formulation similar to softgels and drops.
- Sprays are absorbed through the soft tissue under the mouth and the sides of your cheek.
- Another good option for those with swallowing and digestive problems.
- Not very cost effective and the amount of sprays needed per dose may vary.
- Gummies:
- Chewable, flavored, and kid-friendly formulation of vitamin D.
- Generally less stable overtime, especially the vitamin D content.
- May have high added sugars which will contribute to daily sugar intake.
- Unreliable dosing between products may require multiple gummies to be taken daily.
- Gummies are made of gelatin and may contain artificial flavorings and dye.
Choosing the Right Supplement – What Should I Look For?
With countless vitamin D supplements on the market, it is hard to know which one is a quality, trusted product. Here are some tips to consider:
- Check the labels: Verify the dosage per serving and any additional nutritional information at the “Supplement Facts” panel. The label should be able to tell you about additional ingredients such as binders, fillers, artificial colors, hydrogenated oils, or allergens like gluten and soy. For vegetarians and vegans, check whether the source is listed to be from fungal, yeast, or lichen.
- Third-Party Testing: There are third-party organizations like U.S. Pharmacopeia (USP) and National Sanitation Foundation (NSF) International that perform independent quality testing for many supplement products. The tests verify that the products contain the ingredients listed on the label at the correct potency, are free from harmful contaminants, and will break down properly when consumed. Products that passed the tests will have a seal of verification on the label. You can also look up a product on their database as well.
Examples of verified seals on supplement products. Source: NSF and USP International
- Combination products: Vitamin D may also come in combination with other supplements (e.g, vitamin K2, calcium, multivitamins). Some products may contain high enough vitamin D that you won’t be needing an additional vitamin D product. Best to avoid taking more than you need by checking the label to see if they contain the right amount of vitamin D for you.
- Expiration dates and storage: Supplement’s potency can degrade over time. Check to see if the product you are getting is close to expiration or if there are any signs of damage (e.g. dampness, discoloration) caused by improper storage.
Talk To Your Doctor If You Need Any Help
It is a good idea to consult your doctor if you have any concerns about your vitamin D needs. They might be able to help you assess your individual needs, order a blood test to check your vitamin D levels, recommend the appropriate dosage and form, and advise you on any potential risks or interactions.
Prepared by Van Nguyen PharmD Candidate 2026
Reference:
- Demay, Marie B et al. “Vitamin D for the Prevention of Disease: An Endocrine Society Clinical Practice Guideline.” The Journal of clinical endocrinology and metabolism vol. 109,8 (2024): 1907-1947. doi:10.1210/clinem/dgae290
- Fleet, James C. “Differences in the absorption and metabolism of vitamin D2, vitamin D3, and 25 hydroxyvitamin D.” The Journal of steroid biochemistry and molecular biology vol. 249 (2025): 106718. doi:10.1016/j.jsbmb.2025.106718
- Limbaugh, Savannah. “Dietary Supplement Forms: Understanding the Pros, Cons, and Myths.” Wholistic Matters. https://wholisticmatters.com. Accessed Aug. 20, 2025.
- Vitamin D: Fact sheet for health professionals. Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional. Accessed Aug. 20, 2025.
- Vitamin D. NatMed. https://naturalmedicines.therapeuticresearch.com. Accessed Aug. 20, 2025.
