How Much Vitamin D per Day?

how to tackle your immune system function in winter

Vitamin D is of great importance to the human body. It is commonly known as the “sunshine vitamin” and it is obtained when the skin is exposed to sunlight. Nevertheless, it remains to be among the most common nutrition deficiencies around the world.

About 42% of the adult population in the US comprises people with low levels of this essential vitamin. This is dangerous because it can contribute to numerous health problems.

In this article, you will find out what is this vitamin, its importance to your body, and the amount of it that your body requires per day. So, keep reading to learn more about this crucial vitamin.

What is Vitamin D?

It is a vitamin that is soluble in fat and is used to perform numerous essential functions in the body. When your skin is exposed to the UV rays from the sun, it can produce significant quantities of this vitamin. Furthermore, if excess of it is produced, it will be stored in the body fat to be used later.

Why is it important?

It helps in regulating the amount of phosphate and calcium in the body. These nutrients are necessary for keeping muscles, teeth, and bones healthy. The human body can absorb calcium and phosphate only in the presence of vitamin D. Inadequate levels of this vitamin could result in bone deformities like rickets in children. In adults, it causes osteomalacia which is accompanied by bone pain.

More so, it regulates several other cellular functions in the body. Its neuroprotective, antioxidant, and anti-inflammatory properties help to promote brain cell activity, immune health, and muscle function properly.

How do you know if you are deficient?

Being deficient means that your body is missing adequate vitamin D2 or D3. Severe deficiency results in rickets in children because of weak muscles, inappropriate growth patterns, deformities in joints, and pain in bones. In adults, the symptoms are not quite obvious.

foods to add to your diet for more sunshine vitamin

Deficiency can be discovered when blood tests are carried out to determine the levels of this vitamin. These values are provided by the IOM (Institute of Medicine) for measuring your status:

  • High. Levels are higher than 50 ng/ml
  • Sufficient. Levels range between 20 and 50 ng/ml
  • Insufficient. Levels range between 12 and 20 ng/ml
  • Deficient. Levels are lower than 12 ng/ml

Read More: What Foods Have Vit D

How Much should I Take?

How much vitamin D you should intake will depend on several factors. Some of them include;

  • Sun exposure
  • Age
  • Clothing
  • Season
  • Ethnicity
  • Latitude and air pollution

The recommended average intake per day is 10 to 20 micrograms or 400 to 800 IU. However, this amount could be higher if you have limited exposure to sunlight or have a darker skin tone. Also, obese or overweight people require higher doses of this vitamin.

However, if all things are considered, a daily intake of 25 to 100 micrograms or 1000 to 4000 UI should be adequate to maintain normal blood levels in the majority of people. Ensure that you do not intake higher amounts than that before you consult your healthcare professional.

How do I calculate my vitamin intake?

As mentioned above, the human body requires at least a daily intake of 25 to 100 micrograms or 1000 to 4000 IU. One microgram is 1,000 times smaller than one milligram. A microgram is mostly written using μg.

In most cases, this amount can be expressed in IU (international units). One microgram is the same as 40 IU. Therefore, 20 micrograms are equal to 800 IU.

How much is too much?

The maximum amount that normal people should intake is 4,000 IU. This applies to children between 11 to 18 years, adults, pregnant and breastfeeding women, and the elderly. Children who are under 10 years should not intake more than 2000 IU in a day. Infants who are under a year old should not intake more than 1000 IU in a day.

When should vitamin D2 or D3 be taken?

During winter and autumn, you must obtain this vitamin from foods because the sun is not adequate for your body to manufacture vitamin D. However, it can be challenging to obtain it in sufficient amounts from your diet. That is why it is recommended that people, even pregnant and breastfeeding women, take a daily supplement that contains 10 micrograms of the vitamin during the winter and autumn seasons.

What is the difference between vitamin D2 and D3?

Two main types can be obtained from diet and supplements and they include:

  • Vitamin D2. Also known as ergocalciferol, vitamin D2 is found mainly in plants such as certain types of mushrooms.
  • Vitamin D3. Also known as cholecalciferol, vitamin D3 is found mainly in animals and it includes egg yolks, oily fish, and fish liver oil.

Should I take vitamin D2 or vitamin D3?

Of the two types, vitamin D3 is stronger and increases the levels of vitamin D twice as much as vitamin D2. Vitamin D2 requires a prescription whereas D3 is widely available over the counter. D3 is absorbed far easily than D2 and it lasts in the body longer dose-for-dose. You need to work closely with your healthcare provider to determine if you require a vitamin supplement and the amount that you need if needed.

Is it better to take this supplement every day or once a week?

There is no one-size-fits-all dosage interval for vitamin supplements. Also, there is no adequate research to prove that taking these supplements daily is more effective than taking them weekly or vice-versa. Some healthcare providers will advise that you take larger doses per week or lesser doses per day. This decision will depend on numerous factors. Therefore, consult your medical service provider on which is your ideal interval for taking the supplements.

Who can take Vitamin D2 or D3 supplements?

Normally, people do not require taking vitamin supplements because the body can produce them on its own. However, it is recommended to take these supplements during the autumn and winter seasons when the sunlight’s angle that hits the earth blocks off UV rays from entering into the atmosphere. During these seasons, people should take vitamin supplements throughout the period. This also applies to people with darker skin tones and those with higher risks of lower levels of the vitamin.

Who cannot take Vitamin D2 and D3 supplements?

People who are taking anti-HIV, anti-cancer, and anti-seizure treatments, as well as certain antibiotics, should not take these supplements. The reason behind this is that these medications can activate or catalyze the enzymes that convert vitamin D2 and D3 into their inactive forms; thus, reducing the vitamin levels.

Final Note

Vitamin D deficiency is quite common and the majority of people are usually not aware of it. If you suspect that you have a deficiency, you must see your doctor and have your blood levels measured. The good thing is that it is relatively easy to fix this deficiency.


  1. Zittermann, A., Gummert, J. F., and Borgermann, J. Vitamin D deficiency and mortality. Curr Opin.Clin Nutr Metab Care 2009;12(6):634-639.
  2. Amrein K, Schnedl C, Holl A, et al. Effect of high-dose vitamin D3 on hospital length of stay in critically ill patients with vitamin D deficiency: the VITdAL-ICU randomized clinical trial. JAMA. 2014;312(15):1520-30. DOI: 10.1001/jama.2014.13204. Erratum in: JAMA. 2014 Nov 12;312(18):1932.
  3. Armas LAG, Heaney RP, Hollis BW. Vitamin D2 is much less effective than vitamin D3 in humans (abstract OR22-2). The Endocrine Society 86th Annual Meeting, June 16-19, New Orleans, LA.

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