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How Is Vitamin D Made In The Body

Why Do Dermatologists Say Unprotected Sun Exposure Is Unsafe To Boost Vitamin D

How Our Bodies Make Vitamin D | Corporis

UVB radiation has the dual effect of promoting vitamin D3 synthesis in the skin 2D3) and increasing DNA damage, leading to skin cancer. Thus, although UVR may be an efficient means of providing the nutritional requirement for vitamin D, the advantage to the skin may be countered by the increased risk of mutations.1


  • Childhood is a critical period for reducing ultraviolet exposure and lifetime skin cancer risk.2
  • Responsiveness to UVB radiation varies among individuals, causing some to have low vitamin D status despite abundant sun exposure.3
  • The risks of high sun exposure leading to skin cancer cannot be counteracted by high vitamin D status.4
  • Although sunscreens could almost entirely block the solar-induced production of cutaneous previtamin D3 on theoretical grounds or if administered under strictly controlled conditions, in practice they have not been shown to do so.5
  • Exposure to a small amount of UV results in production of vitamin D without sunburn. Exposure to a higher dose does not result in higher amounts of vitamin D â instead, inactive luminsterol and tachysterol are produced. But exposure to large doses of UV results in sunburn with blistering and peeling.6

How To Get Vitamin D

You can make your vitamin D the old-fashioned way, by exposing your skin to UVB radiation in sunlight. It doesn’t take much, but people living north of the 37-degree-latitude line roughly the imaginary line between Philadelphia and San Francisco can’t get enough UVB in winter to do the trick. And many others will find it all too easy to overdose on UVB, increasing their risk of malignant melanomas and other skin cancers, as well as wrinkles and premature skin aging. All in all, most doctors recommend avoiding sunlight and getting vitamin D by mouth.

Diet can help, but it’s very hard to approach the new goals with food alone. Fish and shellfish provide natural vitamin D , but you’ll have to eat about 5 ounces of salmon, 7 ounces of halibut, 30 ounces of cod, or nearly two 8-ounce cans of tuna to get just 400 IU. An egg yolk will provide about 20 IU, but since it also contains nearly a day’s quota of cholesterol, you can’t very well use eggs to fill your tank with D. Other foods have even less D, which is why manufacturers fortify milk, some yogurt, some orange juice, and many cereals with vitamin D. In general, a serving will provide about 100 IU that means drinking a quart of fortified milk to get 400 IU.

What Causes Low Vitamin D

Anything that interferes with the bodys ability to make vitamin D through the skin, including liver or kidney disease, can cause deficiency. Malabsorption syndromes or a diet low in foods containing vitamin D can also lower vitamin D levels.

The following factors may interfere with our body’s ability to make vitamin D:

  • Chronic illness or disability that prevents regular sun exposure
  • Living at latitudes above 37 degrees north or below 37 degrees south of the equator over winter, although this is controversial, and studies have shown only Caucasians show a correlation with low vitamin D levels and latitude.
  • Skin color: Individuals with a darker skin produce less vitamin D with the same amount of sunlight exposure than individuals with lighter skin color.
  • Age: Older people are less efficient at making D3 and less likely to go outside in the sun.
  • Religion or culture: People whose beliefs require them to cover most of their skin and/or face usually do not receive adequate sunlight for their skin to make vitamin d.
  • Avoidance of the sun and use of sunscreen: Fears of skin cancer and skin aging mean people spend less time in the sun than in the past, although only 10 minutes of direct summer sun is necessary to make an adequate daily dose of vitamin D.

In addition, a poor intake of vitamin D through the diet may also contribute however, studies have shown less than 10% of the vitamin D in our body is obtained through diet, so it is not considered a major contributing factor.

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What Kind Of Vitamin D Is Best

The recommended form of vitamin D is vitamin D3 or cholecalciferol. This is the natural form of vitamin D that your body makes from sunlight. Supplements are made from the fat of lambs’ wool.

However, a clinical study reported in 2008 suggested that vitamin D2 works as well as vitamin D3.

Many supplements contain vitamin D as vitamin D2 or calciferol. It’s derived from irradiated fungus. Because this is not the form of vitamin D naturally made by your body, WebMD nutritionist Kathleen M. Zelman, MPH, RD, recommends using the D3 form for those taking vitamin D supplements.

Because of its potency, different forms of vitamin D are used in prescription medications. If you have a prescription for one of these medications, do not switch to another form of vitamin D without checking with your doctor.

What Should My Blood Levels Be

Vitamin D  Heading Healthy

Now, while vitamin D is fun to talk about, what really matters is our circulating 25-hydroxyvitamin D concentration. It lets us know how much vitamin D has been produced in our body from sun, food and supplements. Its half-life is 15 days. 1,25 2D is not a good indicator of vitamin D status, as it has a short half life of only 15 hours and levels in the blood are regulated tightly by hormones and minerals. 1,25 2D only starts to decline when a severe deficiency of vitamin D is present.

The most advantageous serum concentrations of 25D seem to begin at 60 nmol/L, with the optimal levels being between 75 and 100 nmol/L. Most people will be unable to reach these levels with an intake between 200 and 600 IU of vitamin D.

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What Is The Rda Of Vitamin D

RDA stands for recommended dietary allowance.

In the United States, for an adult with, or under, 70 years of age, the recommended dietary allowance for vitamin D is 600 IU. If you are over 70, the RDA for vitamin D is set at 800 IU.

However, if you look at a bottle of a bestselling vitamin D supplement, youll most likely find a much larger number like 5,000 or 10,000 IU.


This raises two important questions:

  • 1Why is there such a large gap between what is officially recommended and what people are routinely supplementing with?
  • 2How much vitamin D should you take?

In this article, youll learn the answer to this question and the science behind it.

In a Hurry?

At the end of this article you can find a nice summary of the answers to these questions.

Natural Analogs Of Vitamin D

  • Vitamin D1 is a molecular compound of ergocalciferol with lumisterol in a 1:1 ratio.

  • Vitamin D2 is produced by invertebrates, some plants, and fungi. Biological production of D2 is stimulated by ultraviolet light.

  • Vitamin D3 is synthesized in the skin by the reaction of 7-dehydrocholesterol with UVB radiation, present in sunlight with an UV index of three or more.

  • Vitamin D4 is an analog scientifically known as 22-dihydroergocalciferol.

  • Vitamin D5 is an analog created from 7-dehydrositosterol.

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What Is The Difference Between Vitamin D2 And D3

Vitamin D2 and D3 are two important forms of vitamin D. D2 comes from plants and D3 comes from mainly animal sources or it is made by our bodies when our skin is exposed to sunlight. D3 is better absorbed and more potent than D2. Fortified milk or juice is more likely to contain D2 because it is cheaper to produce.

If You Live Far From The Equator

VITAMIN D: Its Role, Function, and Levels

People living in areas farther away from the equator make less vitamin D in their skin.

In these areas, more of the suns rays, especially UVB rays, are absorbed by the earths ozone layer. So people who live farther away from the equator usually need to spend more time in the sun to produce enough .

Whats more, people who live farther from the equator may not produce any vitamin D from the sun for up to six months a year during the winter months.

For example, people who live Boston, USA and Edmonton, Canada struggle to make any vitamin D from sunlight between the months of November and February (

14 ).

During this time of year, its important that they get their vitamin D from foods and supplements instead.


People who live farther away from the equator need more time in the sun, as more UVB rays are absorbed by the ozone layer in these areas. During winter months, they cannot make vitamin D from sunlight, so they need to get it from foods or supplements.

Vitamin D is made from cholesterol in the skin. That means you need to expose lots of skin to the sunlight to make enough.

Some scientists recommend exposing around a third of the area of your skin to the sun .

According to this recommendation, wearing a tank top and shorts for 1030 minutes three times per week during the summer should be sufficient for most people with lighter skin. People with darker skin may need a bit longer than this.

Below are some consequences of too much sunlight:

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Storing Enough Vitamin D

Can you tell me if the vitamin D you get from sun exposure during the summer is stored in the body for use in winter months when sunlight is less available? Also, should African-Americans use sunscreen since it blocks the ultraviolet rays needed for the body to make vitamin D?

Andrew Weil, M.D. | July 28, 2016

Most adults are not getting enough vitamin D, which we need for bone health and, more and more research suggests, for protection against a number of diseases including many types of cancer. We get vitamin D from fortified milk and cereals as well as from eggs, salmon, tuna, mackerel and sardines, and our bodies make it with exposure to sunlight. Unfortunately, many people dont get optimal sun exposure, particularly in northern latitudes during the gray winter months. In addition, sunscreen blocks vitamin D synthesis in the skin, and dermatologists have made us so fearful about UV damage to skin that many people dont get enough direct exposure to sunlight regardless of where they live.

Because so many people dont get sufficient vitamin D from sun exposure or their diets, I recommend a daily supplement of 2,000 IU. Use the D3 form and take it with a fat-containing meal to ensure absorption. There are no concerns about toxicity with this dose of supplemental vitamin D .

Andrew Weil, M.D.

Advice For Adults And Children Over 4 Years Old

During the autumn and winter, you need to get vitamin D from your diet because the sun is not strong enough for the body to make vitamin D.

But since it’s difficult for people to get enough vitamin D from food alone, everyone should consider taking a daily supplement containing 10 micrograms of vitamin D during the autumn and winter.

Between late March/early April to the end of September, most people can make all the vitamin D they need through sunlight on their skin and from a balanced diet.

You may choose not to take a vitamin D supplement during these months.

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Should Everyone Get Their Vitamin D Levels Checked Generally No

Karl Insogna, MD, director of Yale Medicines Bone Center

Most people should be fine. Testing is important only for certain populations: for people who are institutionalized for patients with a gastrointestinal disorder or osteoporosis those who have had weight loss surgery those on anti-convulsant medications and children who are immobilized and not outside and active. If youre over 70, I recommend getting your levels checked at least one time.

People whose cultural or religious beliefs require them to be fully clothed, especially if theyre living in northern climates, and whose dietary habits include little or no dairy , may also be vitamin D-deficient and should be tested.

Vitamin D2 Versus Vitamin D3

Vitamin D: A Key Player in Bone Health, Sports Performance, &  Recovery

Vitamins D2 and D3, as described previously, differ only in their side chain structure. Physiological responses to both forms of the vitamin include regulation of calcium and phosphate homeostasis and regulation of cell proliferation and cell differentiation of specific cell types, as described above. Qualitatively, vitamins D2 and D3 exhibit virtually identical biological responses throughout the body that are mediated by the VDR .

Regarding the potency of the two forms of vitamin D, there are reports that certain animals, such as avian species and New World monkeys , discriminate against vitamin D2 However, it has been assumed for several decades that the two forms are essentially equipotent in humans . Recent reports involving human dietary studies have argued for or against a metabolic discrimination against vitamin D2, compared with vitamin D3. Part of the apparent conflict between these different studies is almost certainly due to differences in size and frequency of dose the differences reported suggest a difference in pharmacokinetic parameters between vitamin D2 and vitamin D3.

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How Much Vitamin D Do You Really Get From The Sun

Quick Health Scoop

  • Vitamin D helps your body absorb calcium, aids in supporting healthy teeth and bones, and plays an important role in immune and muscle health
  • 40% of the U.S. population have a blood level indicating Vitamin D deficiency
  • You can get Vitamin D from three main sources: the sun, food, and supplements
  • To avoid the damaging effects of the suns rays, many health experts recommend the best way to take Vitamin D is through food and supplements

Not many vitamins get a nickname, but Vitamin D does. Known as the sunshine vitamin, this key nutrient can be obtained by the body through sunlight exposure. But the obvious dilemma is, how do you balance getting enough Vitamin D through the sun with practicing sun-safe habits to protect the skin? How much Vitamin D do you get from the sun? And how long do you need to be in the sun to get Vitamin D?

First, understand why you need this key nutrient. Vitamin D, a fat-soluble vitamin, provides a variety of health benefits. It helps your body absorb calciumone of the main building blocks of boneand plays an important role in immune and muscle health. ,1

Learn More: Vitamin D Immune System Benefits

With all this in mind, you might be wondering what is the best way to get Vitamin Dand how can you do so safely?

What Is Vitamin D Deficiency

Vitamin D deficiency is when levels of vitamin D in your body fall below those recommended as necessary to ensure all the processes in your body that rely on vitamin D can function properly.

Currently, there is controversy regarding what is the cut-off level for vitamin D deficiency with recommendations ranging from less than 20 ng/ml of 25D to less than 12 ng/ml of 25D.

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What Type Of Vitamin D Is Best For Children

The government recommends a supplement of at least 10µg of vitamin D for children over the age of 1 and 8.5-10µg for babies under 1 year old.15

But getting children to take a supplement in tablet or capsule form is easier said than done we get it! Thankfully, there are some child-friendly supplements out there.

Vital Functions Of Vitamin D

Your body won’t work so well with Vitamin D deficiency

Vitamin D, which is technically a hormone rather than a vitamin, is a crucial nutrient. Unfortunately, many Americans even those who eat a good diet are vitamin D deficient.

Typically, we get a vitamin D boost from the sun, but because we are wearing more sunscreen and spending more time INSIDE our levels are falling, putting us at greater health risks. In fact, there is research linking vitamin D deficiency to over 200 diseases.

Although most people think of vitamin D as just the sunshine vitamin, they often do not fully understand the significant ways that vitamin D affects your brain, body and overall health. Here are just a few:


Vitamin D receptors are found all over the body, including the immune cells. Research has clearly shown that vitamin D deficiency is part of the seasonal nature of cold and flu outbreaks less sunlight means less vitamin D, which leads to lower immunity and more illness.


Its well-documented that vitamin D is essential for the proper absorption of calcium, and its been shown to greatly reduce fracture risk in two ways. First, it helps with the formation of stronger bones second, Vitamin D helps improve balance and prevent falls by enhancing muscle contraction.





Because vitamin D is a fat-soluble vitamin, it helps to regulate kidney function and plays a very beneficial role in treating kidney disease.


Weight Loss

Cognitive Function

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Vegan Vitamin D Spray

If you want a vegan source of the faster-acting vitamin D3 or simply cannot stand taking tablets or capsules, a vitamin D spray could be for you.

Vitamin D sprays act incredibly fast as they bypass the digestive system and deliver vitamin D directly into the bloodstream.

Beware however, that not all vitamin D sprays are vegan, but BetterYou Dlux Vegan Vitamin D Spray is. Give it a go and see if it works for you.

Do Babies Need Vitamin D

Yes, babies under the age of 1 need vitamin D too.

Babies up to 1 year of age who are being breastfed should be given a daily supplement that contains 8.5 10 µg every day to make sure they are reaching recommended levels.17

This still applies if the breastfeeding mother is taking a supplement herself.

However, babies fed infant formulas will not need a vitamin D supplement if they are having more than 500ml of formula a day, as it will already by fortified with vitamin D and other nutrients.

The easiest way to provide breastfed babies with vitamin D is with vitamin D drops.

We have a Vitamin D3 Drop formula that is specifically designed for babies to take daily from birth until they are 12 months old.


  • Yes, babies who are being breastfed need 8.5-10µg vitamin D a day
  • Babies drinking infant formula wont need to supplement as their milk will have been fortified with vitamin D already

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