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Vitamin D is one of the most talked-about nutrients, so it can be surprising to find a multivitamin that leaves it out. There is a good reason some formulas do: the right amount of vitamin D varies from person to person more than almost any other vitamin.
Quick answer: your vitamin D needs depend on where you live, the season, your skin tone, your age, your body weight, and how much fortified food you eat. A fixed amount inside a multivitamin may be too little for some people and pile on top of other sources for others. A multivitamin without vitamin D lets you take D separately, at a dose that fits your situation and, when your clinician orders one, your blood test.
How Much Vitamin D Adults Need
The National Institutes of Health sets the Recommended Dietary Allowance at 600 IU (15 mcg) a day for people ages 1 to 70 and 800 IU (20 mcg) a day for adults over 70. The upper limit for adults is 4,000 IU (100 mcg) a day. If your label lists micrograms, multiply by 40 to get IU.
Blood levels are measured as 25-hydroxyvitamin D. In general terms:
- Below 12 ng/mL is considered deficient
- 12 to under 20 ng/mL may be inadequate for some people
- 20 ng/mL or higher is adequate for most people
- Above 50 ng/mL is linked to potential adverse effects
Why One Dose Does Not Fit Everyone
Your body can make vitamin D when UVB rays from the sun hit your skin, but how much it makes depends on several things you cannot always control.
- Where you live and the season. A classic study found that winter sunlight in Boston was too weak to produce vitamin D in the skin from November through February, and in Edmonton, Canada, from October through March. Our home of Bismarck, North Dakota, sits at about 47 degrees north, between those two cities. You can read more in our post on signs you are not getting enough vitamin D.
- Skin tone. Melanin reduces how much vitamin D the skin makes from the same amount of sun.
- Age. Older skin makes less vitamin D. Our guide on nutrient absorption after 50 covers other changes that come with age.
- Body weight. People with obesity tend to have lower blood levels, because more vitamin D is stored in body fat.
- Absorption. Conditions that affect fat absorption, gastric bypass surgery, and the weight-loss medication orlistat can all lower vitamin D levels.
- Time indoors. UVB does not pass through window glass, so sitting in a sunny room does not help.
Two people taking the same multivitamin can end up in very different places.
Vitamin D Adds Up From More Places Than You Think
Vitamin D shows up in more of your day than you might expect. In the U.S., a cup of fortified milk provides about 120 IU, and many breakfast cereals, plant milks, and orange juices are fortified too. Fatty fish like salmon and trout are natural sources.
Now add a calcium supplement with vitamin D, a separate vitamin D bottle someone recommended, and a multivitamin that also includes it. Each one looks modest on its own, but together they can add up to more than you meant to take. Keeping vitamin D in one place makes your total easy to see.
What the Latest Guidelines Say
In 2024, the Endocrine Society published a guideline on vitamin D for preventing disease in generally healthy people. Its main points:
- For healthy adults under 75, it suggests against vitamin D doses beyond the recommended daily intake.
- It suggests against routine vitamin D blood testing in the groups it studied.
- It suggests extra vitamin D for children and teens, adults 75 and older, pregnant people, and adults with high-risk prediabetes.
- For adults 50 and older who do need vitamin D, it suggests a daily, lower dose instead of large, infrequent doses.
The guideline focuses on prevention in people without a known deficiency. People with low blood levels or conditions that affect absorption are treated individually by their clinicians. Either way, the takeaway is the same: vitamin D works best when the dose fits the person, which is easier when it is not locked inside a multivitamin.
How to Take Vitamin D Separately
- Choose D3. Vitamin D3 raises blood levels more, and keeps them up longer, than vitamin D2. We compared them in vitamin D3 vs. D2.
- Take it with a meal. Vitamin D is fat-soluble, and dietary fat helps your body absorb it.
- Take it daily. Daily dosing is easier to remember and is what the Endocrine Society suggests for adults 50 and older.
- Count every source. Add up your supplements and fortified foods, and stay at or under 4,000 IU a day unless your clinician recommends more.
Where Vitamin Armor Fits
Our Vitamin100 Multivitamin leaves out vitamin D on purpose, along with iron and calcium, so you can decide on those separately. For people who need it, our Vitamin D3 provides 5,000 IU (125 mcg) per capsule. That is above the 4,000 IU upper limit, so it is meant for people whose clinician has confirmed a low level and recommended a higher dose, not as a default for everyone.
Not sure which dose fits? Our guide to vitamin D3 5,000 IU vs. 2,000 IU walks through the difference.
Frequently Asked Questions
Is it a problem to take a multivitamin with vitamin D and a separate vitamin D supplement?
Not necessarily, but it is easy to lose track of the total. Add up the vitamin D from every product you take, along with fortified foods, and talk with your clinician if the total goes above 4,000 IU a day.
Can I get enough vitamin D from the sun in winter?
In northern states, often not. Research from Boston, which is farther south than much of the northern U.S., found that winter sunlight was too weak to produce vitamin D in the skin for about four months of the year.
Should I get my vitamin D level tested?
The Endocrine Society suggests against routine testing in healthy people. Testing makes more sense when your clinician suspects a deficiency, you have a condition that affects absorption, or you are taking a higher dose.
Why is calcium also left out of some multivitamins?
Most adults need about 1,000 mg of calcium a day, far more than fits alongside everything else in a multivitamin, and much of it can come from food. Calcium may also interfere with the absorption of iron and other minerals, so it is often better taken on its own. Our post on calcium supplements and heart risk covers the details.
The Bottom Line
Vitamin D matters, but the right amount depends on your location, season, skin, age, weight, and diet. A multivitamin without vitamin D lets you keep your daily foundation simple and choose your vitamin D dose on its own, ideally with input from your clinician.
Sources
- Vitamin D: Fact Sheet for Health Professionals, NIH Office of Dietary Supplements, accessed 2026
- Endocrine Society recommends healthy adults take the recommended daily allowance of vitamin D, Endocrine Society, 2024
- Influence of season and latitude on the cutaneous synthesis of vitamin D3, Webb AR, Kline L, Holick MF, Journal of Clinical Endocrinology and Metabolism, 1988
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This article is for general education and is not a substitute for advice from your healthcare provider.