Vitamin D Sources

The two main ways to get vitamin D are by exposing your bare skin to sunlight and by taking vitamin D supplements. You can’t get the right amount of vitamin D your body needs from food.

How do I get the vitamin D my body needs?

The most natural way to get vitamin D is by exposing your bare skin to sunlight (ultraviolet B rays). This can happen very quickly, particularly in the summer. You don’t need to tan or burn your skin to get vitamin D. You only need to expose your skin for around half the time it takes for your skin to begin to burn. How much vitamin D is produced from sunlight depends on the time of day, where you live in the world and the color of your skin. The more skin you expose the more vitamin D is produced.

You can also get vitamin D by taking supplements. This is a good way to get vitamin D if you can’t get enough sunlight, or if you’re worried about exposing your skin. Vitamin D3 is the best kind of supplement to take. It comes in a number of different forms, such as tablets and capsules, but it doesn’t matter what form you take, or what time of the day you take it.

Different organizations recommend different amounts of vitamin D supplement to take each day. The Vitamin D Council recommends taking larger amounts of vitamin D each day than other organizations, because smaller amounts aren’t enough to give you what your body needs. Most people can take vitamin D supplements with no problems. However, if you have certain health problems or take certain medicines, you may need to take extra care.

Your body gets most of the vitamins and minerals it needs from the foods that you eat. However, there are only a few foods that naturally contain any vitamin D. Most foods that contain vitamin D only have small amounts, so it’s almost impossible to get what your body needs just from food.

Because there are only small amounts of vitamin D in food there are only two sure ways to get enough vitamin D:

• Exposing your bare skin to sunlight to get ultraviolet B (UVB).
• Taking vitamin D supplements.

Exposing your bare skin to sunlight

Human skin can make large amounts of vitamin D when lots of skin is exposed and the sun is high in the sky.

Your body is designed to get the vitamin D it needs by producing it when your bare skin is exposed to sunlight. The part of the sun’s rays that is important is ultraviolet B (UVB). This is the most natural way to get vitamin D.

Large amounts of vitamin D3 (cholecalciferol) are made in your skin when you expose all of your body to summer sun. This happens very quickly; around half the time it takes for your skin to begin to burn. This could be just 15 minutes for a very fair skinned person, yet a couple of hours or more for a dark skinned person.

You don’t need to tan or to burn your skin in order to get the vitamin D you need. Exposing your skin for a short time will make all the vitamin D your body can produce in one day. In fact, your body can produce 10,000 to 25,000 IU of vitamin D in just a little under the time it takes for your skin to begin to burn. You make the most vitamin D when you expose a large area of your skin, such as your back, rather than a small area such as your face or arms.

There are a number of factors that affect how much vitamin D your body produces when your skin is exposed to sunlight. These include the time of year and time of day, where you live in the world and the type of skin you have.

The amount of vitamin D you get from exposing your bare skin to the sun depends on:

• The time of day – your skin produces more vitamin D if you expose it during the middle of the day.
• Where you live – the closer to the equator you live, the easier it is for you to produce vitamin D from sunlight all year round.
• The color of your skin – pale skins make vitamin D more quickly than darker skins.
• The amount of skin you expose – the more skin your expose the more vitamin D your body will produce.

The time of year and time of day

When the sun’s rays enter the Earth’s atmosphere at too much of an angle, the atmosphere blocks the UVB part of the rays, so your skin can’t produce vitamin D. This happens during the early and later parts of the day and during most of the day during the winter season.

The closer to midday you expose your skin, the better this angle and the more vitamin D is produced. A good rule of thumb is if your shadow is longer than you are tall, you’re not making much vitamin D. In winter, you’ll notice that your shadow is longer than you for most of the day, while in summer, your shadow is much shorter for a good part of the middle of the day.

Where you live

The further you live away from the equator, the less vitamin D you can make during the winter, if at all.

The equator is an imaginary line on the Earth’s surface halfway between the North Pole and South Pole, which divides the Earth into the Northern Hemisphere and Southern Hemisphere. The further away you are from the equator, the more of an angle the sun will hit the atmosphere at, and the less UVB there will be available for you to produce vitamin D, particularly during the winter time.

In the summer, when the Earth rotates, the angle improves and more UVB reaches the places far away from the equator, allowing you to produce vitamin D outside of winter months.

For example, in the southern United States, in places like Florida, your body can produce vitamin D most of the year, while in more northern places, like New York City or Boston, you can’t produce much vitamin D from November through March. If you live even further north, like in Edmonton, Canada, you can’t produce vitamin D from October through April. These times are even longer (by a month or two) if you’re skin type is darker.

In Buenos Aires, you can’t produce vitamin D in June. In Cape Town, you can’t produce much vitamin D between mid-May and August. If you live as far south as the bottom tip of Chile and Argentina, you can’t produce vitamin D April through October! If you’re skin is darker, these windows are even longer by a month or two.

Live in Johannesburg? You can produce vitamin D all year round.

Your skin type

Melanin is a substance that affects how light or dark your skin color is. The more melanin you have, the darker your skin color. The amount of melanin you have in your skin affects the amount of vitamin D you can produce.

Melanin protects against skin damage from too much UVB exposure, so darker skins with more melanin allow less UVB to enter the skin. With less UVB getting through the skin, less vitamin D is produced each minute. This is why if you’re dark skinned, you need more sun exposure to make vitamin D than if you’re fair skinned.

The table below shows the different skin types:

The paler your skin type the more easily your skin can produce vitamin D. So, if you have skin type I to III, you produce vitamin D more quickly than if you have skin type IV to VI. For example, if you have skin type I, it might take around 15 minutes of sun exposure to get the vitamin D you need, while if you have skin type V or VI, it might take up to six times longer (up to 2 hours).

Because of all these factors – your skin type, where you live and the time of day or season – it can be difficult to work out how much time you need to spend exposing your skin to the sun in order to get the vitamin D you need. A good rule of thumb is to get half the sun exposure it takes for your skin to begin to burn to get your vitamin D and expose as much skin as possible.

Specific recommendations are not easy! Skin types are different and depending on the day of year, place and time of day, recommendations vary. Let’s see how complicated it can get if we expose a quarter of our body to the sun:

• At noon in Miami, an individual with skin type III would probably need about 6 minutes of exposure to the sun to make 1,000 IU of vitamin D in summer and 15 minutes in winter.
• Someone with skin type V would probably need around 15 minutes in summer and 30 minutes in winter.
• At noon in Boston during summer, an individual with skin type III would probably need about 1 hour of exposure to the sun to make 1,000 IU of vitamin D.
• Someone with skin type V would probably need about 2 hours of exposure.
• During the winter months in Boston, it’s not possible for anyone to make vitamin D from the sun, no matter their skin type.

And that’s assuming you’re exposing a quarter of your body. As you can see, there are lots of things that factor into vitamin D production. The best recommendation is to get half the sun exposure it takes for your skin to begin to burn.

Other factors

There are other factors which can affect the amount of vitamin D your body makes from exposure to the sun. These are:

• The amount of skin you expose. The more skin you expose, the more vitamin D you can produce.
• How old you are. As you get older, your skin has a harder time producing vitamin D.
• Whether you’re wearing sunscreen. Sunscreen blocks a lot of vitamin D production.
• The altitude you’re at. The sun is more intense on top of a mountain than at the beach. This means you make more vitamin D the higher up you are (at higher altitudes).
• Whether it is cloudy. Less UVB reaches your skin on a cloudy day and your skin makes less vitamin D.
• Air pollution. Polluted air soaks up UVB or reflects it back into space. This means that if you live somewhere where there is lots of pollution, your skin makes less vitamin D.
• Being behind glass. Glass blocks all UVB, so you can’t make vitamin D if you’re in sunlight, but behind glass.

Indoor tanning

Your skin can also make vitamin D if you use an indoor tanning bed. As with natural sunlight, making the vitamin D you need from a tanning bed happens within minutes. You don’t need to tan your skin, or use a tanning bed for a long time to get the vitamin D you need.

If you choose to use a tanning bed, the Vitamin D Council recommends using the same common sense you use in getting sunlight. This includes:

• Getting half the amount of exposure that it takes for your skin to begin to burn.
• Using low-pressure beds that has good amount of UVB light, rather than high-intensity UVA light.

Exposing your skin to UVB and the risk of skin cancer

Exposing your skin to the sun for too long, so that your skin starts to burn can be dangerous. This is because it can increase your risk of developing skin cancers. Research to date shows that moderate but frequent sun exposure is healthy but overexposure and intense exposure can increase your risk of skin cancer.

After you have exposed your skin for half the time it takes for you to begin to burn, cover up with clothing and go into the shade. Using sunscreen is not as recommended as using shade and clothing to protect your skin, because it hasn’t consistently been shown to prevent all types of skin cancers. But if you do want to use sunscreen, use a sunscreen that blocks both UVA light and UVB light.

While covering up to prevent too much sun exposure is an important step in protecting yourself from skin cancer, research has not always shown that sunscreen is the safest and most effective method.

Research has shown that sunscreen helps prevent squamous cell carcinoma, but has no effect in preventing basal cell carcinoma. For melanoma, research has been contradictory. Some research shows that sunscreen prevents melanoma, while other research shows that it increases your chance of getting melanoma.

For these reasons, the Vitamin D Council believes that covering up with clothing and/or going into the shade (after you get a little bit of sun exposure), is a safer way to protect yourself from too much sun exposure.

Infants have delicate skin which burns more easily, so it’s important to use extra care with your baby. This is why most doctors recommend giving your infant vitamin D supplement and not exposing your baby’s skin to the sun at all. See our pregnancy and breastfeeding page for more information on how to get the vitamin D your baby needs.

For older children, the advice is the same as for adults. You can expose your child’s skin for half the time it takes to burn in order to get the vitamin D they need. After that, make sure they cover up with clothes, shade and if you wish, sunscreen.

If you have had skin cancer or if you’re worried about exposing your skin to the sun, or that of your child, you can take vitamin D supplements instead.

Vitamin D supplements

In the 21st century, it’s hard to get daily full body sun exposure. On the days that you can’t get enough sun exposure, taking a supplement is an effective way to get the vitamin D your body needs. It‘s also a good way to get vitamin D if you’re worried about exposing your skin to the sun.

How much vitamin D do I need to take?

Different organizations recommend different daily intakes. Here are the recommendations from some organizations in the United States:

Recommended daily intakes from various organizations:

The Food and Nutrition Board recommended daily intakes are the official recommendations by the United States government.

Why are the recommendations so different? Some researchers believe that there isn’t enough evidence to support taking higher amounts of vitamin D yet. On the other hand, some researchers believe that research is proving, or will prove, that taking lower amounts isn’t enough.

Can I take more than the recommended amounts?

Yes, you can, but attention and care is needed if you choose to take more supplement than in the recommendations above. Here are the safe maximums set by the same organizations:

Upper limits set by various organizations:

Vitamin D is fat-soluble, which means your body has a hard time getting rid of it if you take too much. The Vitamin D Council recommends taking no more than the upper limit, meaning do not take anymore than 10,000 IU/day for adults.

While these amounts seem like a lot, keep in mind that your body can produce 10,000 to 25,000 IUs of vitamin D after a little bit of full body sun exposure. Vitamin D toxicity, where vitamin D can be harmful, usually happens if you take 40,000 IU a day for a couple of months or longer.

In some diseases, researchers have studied the safety and benefits (if any) of these types of high doses of vitamin D. These diseases include multiple sclerosis and prostate cancer. If you have a disease for which research has shown there may be a benefit in taking larger amounts of vitamin D, and you would like to consider taking more than 10,000 IU/day, the Vitamin D Council recommends taking the following precautions:

• Work with your doctor
• Test your vitamin D [25(OH)D] levels every 3 months and make sure that your blood levels are within the safe and healthy range.

What form of vitamin D should I take and how should I take it?

Research shows that vitamin D3 is the better type of vitamin D compared to vitamin D2.

The Vitamin D Council recommends taking vitamin D3 rather than vitamin D2. Vitamin D3 is the type of vitamin D your body produces in response to sun exposure, while vitamin D2 is not. In the United States, most over-the-counter vitamin D supplements are D3, but check to make sure. Vitamin D2 is sometimes prescribed by doctors because that is what pharmacies have available. If your doctor prescribes you D2, ask them if you can take vitamin D3 instead.

Vitamin D3 supplements aren’t vegetarian and some part of the production in making them occur outside the United States. If you have ethical concerns with taking vitamin D3, then sun exposure is a good option and vitamin D2 can be an alternative.

Other than that, it doesn’t matter what form of vitamin D you take, whether it’s in a capsule, tablet or liquid drop. For most people, vitamin D is easily absorbed in the body and you don’t need to worry about what time of day you take it or whether you take it with meals.

Cod liver oil contains vitamin D. However, the Vitamin D Council recommends against taking cod liver oil because of the high amount of vitamin A there is in cod liver oil compared to vitamin D. Vitamin A is also a fat-soluble vitamin, so your body has a hard time getting rid of it and too much vitamin A can be harmful.

What if I’m having trouble absorbing vitamin D supplements?

Some people get tested for vitamin D and find, despite taking vitamin D regularly, that they’re still not getting enough vitamin D. This means your body is having a hard time absorbing your vitamin D supplements. The Vitamin D council recommends that if you’re having this problem, you can try these options:

• Take vitamin D under your tongue rather than swallowing it (sublingually).
• Try relying on more sun exposure.
• Increase your intake.

Be sure to test your vitamin D [25(OH)D] levels to make sure your new regimen is safe and effective. The Vitamin D Council recommends testing every 3-6 months if you’re trying different regimens.

Can anyone take vitamin D supplements?

Most people can take vitamin D supplements with no problems. However, care is needed in a few situations. These situations include:

• If you’re taking certain other medicines: digoxin for an irregular heartbeat (atrial fibrillation) or thiazide diuretics such as hydrochlorothiazide or bendroflumethiazide (commonly used to treat high blood pressure). In this situation, don’t take high doses of vitamin D. You should also have your digoxin level monitored more closely if you’re taking vitamin D.
• If you have one of these medical conditions: primary hyperparathyroidism, Hodgkin’s or non-Hodgkin’s lymphoma, a granulomatous disease, kidney stones, some types of kidney disease, liver disease or hormonal disease, you should get advice from a specialist. See our Hypersensitivity page for more information.
• Don’t take vitamin D if you have high blood calcium levels, unless under the care of your physician.
• You may need more than the usual dose of vitamin D if you’re taking certain medicines which interfere with vitamin D. These include: carbamazepine, phenytoin, primidone, barbiturates and some medicines used for the treatment of HIV infection.

Can I get sun exposure and take supplements?

Yes. In fact, that is the Vitamin D Council’s recommendation. On days that you do not get enough full body sun exposure, it is important to take a supplement. For most people on the Monday-Friday indoor work schedule, that means taking a supplement 5-6 days a week and getting sun exposure on a day or two during the weekend.

Can I get vitamin D from my diet?

There are small amounts of vitamin D in a few foods, which makes it nearly impossible to get what you need from food. However, these foods include:

• Fatty fish
• Beef liver
• Egg yolks
• Fortified milk and orange juice
• Fortified cereals
• Infant formula

The Vitamin D Council believes that trying to get enough vitamin D from your diet is unlikely to give you the vitamin D you need.

References

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