What Is the Correct Dosage of Vitamin D for Adults?

Everyone needs proper amounts of vitamin D, but we seldom get enough of it from food or sunlight. How much do we actually need, and can you take too much of it?

By Stephen C. George; Medically Reviewed by Dr. Ahmad Talha Azam
Feb 23, 2024 8:15 PMApr 4, 2024 7:19 PM
Vitamin D keeps you healthy while lack of sun. Yellow soft shell D-vitamin capsule against sun and blue sky on sunny day. Cure concept.
(Credit: FotoHelin/Shutterstock)


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It’s a universal truth: If you have a skeleton, you absolutely need vitamin D. Without this critical vitamin, your body wouldn’t be able to absorb calcium, the primary ingredient we all require for strong, healthy bones.

Of course, vitamin D’s value to your body is more than simply skeletal. It’s a crucial nutrient for your muscles, your nervous system, and even your immune system.  The sunshine vitamin is known to help with infections and inflammation and may also help inhibit the growth of certain types of cancer cells.

But how much vitamin D should adults get every day? When and how should you take it? Is there a big difference between vitamin D2 and D3? Can you take too much — and what would happen if you did? We’ve got your answers in this quick and easy guide to optimum vitamin D dosage.

Where Can You Find Vitamin D?

(Credit: morisfoto/Shutterstock)

Unlike some vitamins and minerals, vitamin D is not found naturally in a lot of foods. That said, you will find it in fatty and oily fish like salmon and sardines, as well as egg yolks and red meat. The form of vitamin D found in these sources is known as cholecalciferol, or vitamin D3, the same form that the human body can produce when our skin is exposed to sunlight.

Vitamin D2, or ergocalciferol, is synthesized from plant or fungus sources. It’s mainly used in supplements and to fortify various foods. Milk and dairy products, orange juice, and cereals are common foodstuffs fortified with vitamin D. Still, as beneficial as these food sources are, they may not be enough to ensure adequate daily intake of this important nutrient.

Read More: Full Vitamin D Deficiency Guide

How Much Vitamin D Do You Need Daily?

(Credit: Gang Liu/Shutterstock)

Both forms of vitamin D do an excellent job of helping your body absorb calcium, and dietary guidelines typically do not offer different recommended amounts for either form of the vitamin.

According to the National Institutes of Health’s Office of Dietary Supplements, the current recommended daily amount for vitamin D (in micrograms or International Units) is mainly determined by age as follows:

  • Children under 12 months: 10 mcg or 400 IU

  • Children/Teens 1-18: 15 mcg or 600 IU

  • Adults 19-70: 15 mcg or 600 IU

  • Adults 71 and older: 20 mcg or 800 IU

  • For people who are pregnant or breastfeeding, the recommendation is 15 mcg or 600 IU.

Why You Should Consult a Health Professional

Of course, these guidelines assume you are not suffering from a vitamin D deficiency or health condition that might inhibit your ability to absorb the vitamin. In those cases, a doctor or nutrition expert may determine that you need a higher dose of supplementary vitamin D, which the average healthy person doesn’t need.

In fact, in some cases, people with significant health issues may need doses of vitamin D that would be downright dangerous for the average person to consume. Again, if you think you may benefit from higher-than-recommended doses of this vitamin, you absolutely should consult a professional first.

Read More: 20 Best Vitamin D Supplements

What Factors that Impact Vitamin D Dosage?

(Credit: Roman Samborskyi/Shutterstock)

As with many supplements, when and how you consume vitamin D depends on a number of factors.

For starters, most experts recommend taking vitamin D with food rather than on an empty stomach. Vitamin D is famously known among nutrition and medical experts as a fat-soluble vitamin, meaning that it is better absorbed by your body when consumed with a bit of fat and is not especially water-soluble.

When Is the Best Time to Take Vitamin D?

Morning, noon, or night doesn’t play much of a factor in the optimum absorption of vitamin D. What really matters is that you take your supplement with a meal, especially the largest meal of your day, or at least one that contains fat to aid with absorption. Taking vitamin D on an empty stomach — late at night or first thing when you wake up, for example — won’t really harm you, but it won’t give you the same benefit as taking your vitamin with a bit of food.

Read More: Strange Side Effects From Supplements and What You Need to Know

Can You Overdose on Vitamin D?

(Credit: angellodeco/Shutterstock)

As necessary as vitamin D is to the proper functioning of a healthy body, you can have too much of a good thing. Excessive dosing of vitamin D in any form can lead to health problems ranging from nausea and vomiting to potentially fatal health conditions.

As a rule, NIH’s Office of Dietary Supplements warns that you should not exceed the following vitamin D dosages without the explicit guidance of a doctor:

  • Children under 6 months: 25 mcg or 1,000 IU

  • Children 7-12 months: 38 mcg or 1,500 IU

  • Children 1-3: 63 mcg or 2,500 IU

  • Children 4-8: 75 mcg or 3,000 IU

  • Children/Adults 9 and older: 100 mcg or 4,000 IU

  •  who are pregnant or breastfeeding, the recommendation is not to exceed 100 mcg or 4,000 IU without a doctor’s diagnosis or recommendation.

What are the Symptoms of Vitamin D Overdose?

Symptoms of vitamin D overdose include:

  •  Nausea and vomiting

  •  Constipation

  •  Dehydration and increased thirst

  •  Frequent urination

  •  Confusion and irritability

  •  Sluggishness and fatigue

  • Bone-deep pain

  • Kidney pain or kidney stones

In extreme cases, excessive dosing of vitamin D can lead to muscle weakness or difficulty walking, kidney failure, heart arrhythmia, and even death. Again, taking vitamin D supplements in excess of the recommended dosage without consulting your doctor practically guarantees any or all of the above side effects.

So don’t do it.

Read More: Here’s Why You May Want To Take Vitamin D and Magnesium Together

Article Sources

Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:

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