Vitamin D is beneficial to health, but guidelines on how much to take are not always clear. Some people will be able to get enough vitamin D from sunlight alone, but others may need to make lifestyle changes or take supplements.
In this article, we provide more information about getting vitamin D from sunlight, food, and supplements.
Vitamin D is a nutrient that is important for health. Certain foods contain a small amount, but people can make most of the vitamin D that they need from sunlight.
Some of the benefits of vitamin D include:
Vitamin D is different from most other vitamins. When the body processes it, vitamin D becomes a hormone called calcitriol, which makes bones in the body absorb calcium.
Some people will be able to get enough vitamin D just from sunlight. However, it depends on where in the world they live, the time of year, the time of day, and their skin color.
People who live nearer the equator get more sun exposure. In the Northern Hemisphere, a person may not get sufficient vitamin D from sunlight during the winter.
The sun is usually strongest between 11:00 a.m. and 3:00 p.m. In the summer, a person does not need to be out in the sun for very long during this period to make enough vitamin D.
The amount of melanin a person's skin contains affects how much vitamin D they can make. Less melanin results in lighter skin, which does not protect as well against harmful ultraviolet (UV) rays.
People with more melanin in their skin have better protection from the sun, but take longer to make vitamin D. In the United States, the Centers for Disease Control and Prevention (CDC) found that Mexican-Americans and non-Hispanic black people are
These varied factors make it difficult to recommend how much sunlight a person should get to make the vitamin D that their body needs.
The Vitamin D Council gives some examples:
Some people may not absorb enough vitamin D from sunlight because of specific lifestyle factors. For example, individuals who work at night, stay indoors during daylight hours, always cover their skin, or use a high-factor sunscreen every day.
The body can only make a certain amount of vitamin D at once. After this, it is vital to protect the skin from UV rays. UV rays can cause burning, aging of the skin, and increase a person's risk of skin cancer.
Scientists use nanograms per milliliter (ng/mL) to measure the level of vitamin D in the blood. There is currently no set level for vitamin D deficiency.
Some experts classify deficiency as having less than 12 ng/mL of vitamin D in the blood, and state that levels below 20 ng/mL are too low for healthy bones and general wellbeing. However, others believe that the level should be higher, and classify deficiency as anything less than 30 ng/mL.
Vitamin D deficiency in children can cause rickets. This is a condition that makes bones soft, causing them to bend. A deficiency can also cause bone pain and weak muscles in adults.
There may be a connection between vitamin D and other medical problems and diseases, but more research is necessary to confirm this.
The recommended dietary intake for vitamin D is difficult to judge, as it is dependent on sun exposure. This varies from person to person according to where they live and the time of year, among other factors.
For this reason, guidelines base their recommended intakes on the assumption that a person gets minimal sun.
The recommended dietary intake is in IU, which is International Units. The Food and Nutrition Board (FNB) recommend the following intake per day to maintain a healthy level of vitamin D:
|Age||Recommended daily intake of vitamin D|
|0 to 12 months||400 IU|
|1 to 70 years||600 IU|
|70 years and above||800 IU|
For adults with vitamin D levels below 30 ng/mL, the Endocrine Society guidelines recommend a daily intake of 1,500–2,000 IU to restore healthy levels of vitamin D. There are also treatment options where people with vitamin D deficiency receive 50,000 IU weekly or monthly instead of taking a daily dose.
Many foods in the U.S. are fortified, meaning that the manufacturers add vitamins to them. Breakfast cereals, milk, and orange juice often contain added vitamin D. The nutrition label should make it clear when this is the case.
Breast-fed babies and young children will often need a vitamin D supplement. This is because breast milk does not give a baby all of the vitamin D that they need. Vitamin D drops are available over-the-counter (OTC).
Babies and young children who have formula, which contains added vitamin D, should not need supplements.
There are two forms of Vitamin D found in supplements and fortified foods:
These two forms are generally equivalent, and both raise a person's vitamin D levels effectively. However, at higher doses, vitamin D2 is less potent.