Vitamin D and the Sun

As most health experts have already begun to underline in studies and articles today, Vitamin D is one of the most essential substances we can get. It is crucial for healthy bones, fighting off disease, and assisting the body in absorbing phosphorus and calcium from our diet. Sunlight is by far the most effective way to stock up on Vitamin D, but many people today are actually vitamin D deficient, in part because they don’t know how to access proper exposure to the sun, and partially because they’ve been scared off by the idea that sunlight exposure of any kind poses extreme risks of skin cancer.

Why Do You Need Sunlight and Vitamin D?

It’s important to learn how you can get enough vitamin D in your system, without risking sun damage, as a lack of this substance in your system can lead to deficiency, which causes bones to become weak and brittle, skeletal deformities, and rickets in children. In adults, it can also cause a condition known as osteomalacia, which is responsible for bone tenderness and pain.

Vitamin D sufficiency, when combined with regular exercise and diet, has emerged as one of the most essential preventive factors in health today. In fact, hundreds of studies are linking the vitamin D that we absorb through sunlight with the ability to fight off dangerous conditions and diseases. Deficiency, on the other hand, links to higher rates of heart disease, numerous forms of cancer, as well as multiple sclerosis, and a number of other diseases.

Why the Sun Is the Best Source of Vitamin D

Generally, the body creates the majority of its vitamin D using direct sunlight on the skin. The best time for vitamin D to be produced in the body is between the months of March and October, particularly between the hours of 11am and 3pm, when the sun is closest to the earth. While other sources for vitamin D may exist, human beings currently get 90% of their vitamin D from sunlight exposure to the skin, specifically ultraviolet B exposure. This process naturally initiates the conversion of cholesterol within the skin cells into something known as “vitamin D3”. Although it’s obvious that dangerous overexposure to the sun carries a number of risks, it’s important to keep in mind that the skincare industry may have misled the public into thinking that any exposure to UV rays is harmful. The truth is that no research has yet shown that regular exposure to UV light leads to a significant risk of skin damage.

It is possible for individuals to get some of their Vitamin D intake from foods, including oily fish such as sardines, mackerel and salmon, as well as eggs and meat. However, the truth is that few foods are naturally fortified with, or contain enough supplemental vitamin D. For example, even an eight-ounce glass of whole milk that has been specifically fortified with Vitamin D contains only 100 IU, which is about one tenth of what experts suggest we need on a daily basis. On the other hand, simply stepping out into the sun is enough to produce thousands of units of natural vitamin D within a very short period of time.

According to the dietary recommendations produced by the government in regards to vitamin D intake, the current IU of vitamin D that individuals up to the age of 50 should get is only at 200 IUs a day. However, many experts have argued that these levels are ridiculously low, and not enough to maintain proper, healthy vitamin D levels. As a result, many experts have begun to advocate for the supplementation of around 2,000 IUs during the winter. Today, humans spend less of their time in direct sunlight than we have through any other point in history. This is perhaps a good reason why more than a billion people across the world are suffering with the repercussions of vitamin D deficiency.

How Long Do You Need to Spend in the Sun?

It’s obvious that sunlight is the best source of vitamin D – and perhaps the only truly natural source out there. Unlike supplementary or dietary vitamin D, when you soak up this vitamin directly from sunshine, your body will take exactly what it needs and de-metabolize the rest. The incredible results of exposure to the sun are crucial to think about, as many experts on vitamin D and health groups across the world are now advocating average intakes of around 1,000 to 2,000 IU of vitamin D a day, which is between five and ten times the old recommendations. However, because too much vitamin D taken from supplementary sources can force the body to over-process calcium, it’s difficult to know how much supplementary vitamin D is actually safe to take. In contrast, sunlight vitamin D doesn’t have that problem as it makes the substance exactly the way your body is intended to make it. What’s more, the difference between the amount of vitamin D you can obtain from sunlight and the amount taken from food is incredible.

Source  IU (International Units)
Sunlight (Full-body exposure)  3000 – 20000 IU
Salmon (3.05 oz. fresh)  100 – 250 IU
Fortified whole milk (8.oz)  100 IU
Fortified multi-vitamin  400 IU

From just a short period of time in the sun, the body can soak up all of the vitamin D it needs for good health. A “short period” means anything from a few minutes, as around 10-15 minutes of exposure is often enough for most lighter-skinned people to get the vitamin D they need. Keep in mind that exposing yourself for longer than necessary and potentially obtaining sunburn will not give you any extra benefits, and could lead to further problems. After all, the longer that you spend within direct sunlight, particularly during prolonged periods without sun protection, the greater risk you have of getting skin cancer. If you plan to be out in the sun for a significant amount of time, remember to seek shade, cover up with suitable clothing, and apply the right level of sunscreen.

Importantly, people who have darker skin tones will need to spend longer in the sun if they want to produce the same amount of vitamin D. Cancer research has a useful tool that allows you to find out your skin type and discover how long you should be out in the sun without exposing yourself to risk of burning. Remember that it is not possible to make vitamin D simply by sitting close to a window indoors, as the ultraviolet B or UVB rays that you need to provoke a reaction cannot get through the glass, but you can still burn.

Calculating How Much Sun Is Enough

The amount of exposure you need to UV rays in order to maintain the right vitamin D levels will depend on a number of crucial factors, including your skin type, the time of year that you are exposing your skin to the sun, your day-to-day activities, and your individual circumstances. Crucially, vitamin D levels can vary naturally throughout the seasons. For example, during the winter months when levels of UV rays are lower and more people are likely to cover up their skin to protect against the cold, vitamin D levels will naturally be lower. On the other hand, in the summer, when UV levels are high and people are more likely to stay active outdoors, their vitamin D levels increase.

When calculating the amount of sun exposure you need to maintain healthy vitamin D levels, it’s worth noting that the body is only capable of storing so much vitamin D at any given time. Once a person has received the amount of sun exposure needed, spending extra time outdoors will not increase the vitamin D level, but it can heighten the chances of skin cancer.

Scientists have recently devised a calculator that takes numerous factors about your personal circumstances into account, and uses data entered about you to estimate the exact number of minutes you’ll need to spend in the sun to produce the equivalent of around 1,000 International Units of vitamin D. At this point in time, the calculator doesn’t have a very user-friendly interface, and it’s often quite easy to get confused and enter the wrong information. However, once you work your way through the technicalities, it can be interesting to see how the answers change according to skin type and time of year.

Keep in mind that whether you’re using this calculator, or attempting to figure out exactly how much sun exposure you need each day manually, the information you will receive will be what is considered enough to maintain a healthy status of vitamin D. This means that if you’re already starting out with a vitamin D deficiency, you may need to get more exposure than you originally thought. If you do have vitamin D deficiency, you may find that it is worth speaking to your doctor about how you can improve your intake of vitamin D, and how much time you might have to spend outdoors to benefit from better health.

After all, the sunshine vitamin can be responsible for protecting people against a wide host of different diseases, including cancers of the colon, prostate, and breast, heart disease, osteoporosis, and more. At the same time, spending time in the sun has a number of other hidden benefits, such as protecting you against insomnia, depression, or an overactive immune system. Due to the many benefits that can come from basking in the sun even for a brief amount of time, many experts are beginning to worry that the public-health messages generally given out about skin cancer and staying out of the sun have gone too far, and may be making people more vitamin D deficient. Indeed, the research suggests that far more lives may be lost to diseases as a result of lack of sunlight, than to those caused by too much sun exposure.

Points to Consider

Children under the age of six months should not be exposed to direct sunlight whenever possible between the months of March and October when the sun is at its highest. When exposed to sunlight, children should be sure to cover up with suitable clothing, wear at least SPF15 sunscreen, and spend some time in the shade to avoid overexposure. However, in order to make sure that they get enough vitamin D into their system, children under the age of five may be advised to take vitamin D supplements, even when they do get plenty of time in the sun.

Crucially, people who take supplements are advised to not take any more than 25 micrograms a day of vitamin D, as intakes of supplements above this amount can be harmful according to experts on minerals and vitamins. Often, this is one of the reasons why exposure to sunlight is the best way to get the right amount of vitamin D in your system, as there is no risk that the body will make more than it needs. However, it is recommended that you protect your skin or get into shade before your skin starts to burn or turn red.

Resources and References:

Determining Sunburn Risk – A resource that allows you to determine how “at risk” you are for sunburn. (Cancer Research UK)
Sun Exposure Calculator – A calculator to help determine that right amount of sun exposure for healthy vitamin D absorption. (Zardoz)
NHS Info on Vitamin D – Information about vitamin D supplements and how much to take. (
Research on Sunlight and Vitamin D – A study about sunlight and vitamin D and the effects on bone health and prevention of autoimmune diseases, cardiovascular disease, and cancers. (