Key takeaways
  • Vitamin D deficiency is very common and the standard healthy limits are insufficient for people with eczema
  • Vitamin D modulates the immune system. More specifically, it modulates chronic inflammation
  • If you have chronic eczema, get your vitamin D tested

While Vitamin D is well known for enhancing calcium absorption and protecting bone health, you might be surprised to know that your vitamin D levels impact your skin in a number of ways. This is because Vitamin D is involved in downregulating inflammation, enhancing resistance to infections (which can happen in broken skin) and strengthening the skin barrier directly.

Why we need vitamin D for eczema and skin health

Eczema is primarily a condition related to the immune system. It is part of a group of immunologically driven disorders known as the atopic triad, which also includes asthma and hay fever.  

Vitamin D manipulates the immune system to reduce chronic inflammation, whilst at the same time defending us against opportunistic infections.

It also has a part to play in strengthening the skin barrier, which has many benefits, such as:

  • Reduces itching and irritation
  • Prevents secondary bacterial infections commonly complicate the condition
  • Reduces sensitisation events that occur through the skin

What is sensitisation?

Sensitisation describes how the immune system becomes activated or alerted to the presence of an allergen or irritating agent. This can happen through the airways, the digestive system and through the skin. Agents might include pollen, food, chemicals, and animal dander. Vitamin D helps to improve immune system competency, helping it be better equipped to deal with the triggers.

The research

The relationship between vitamin D and eczema, also known as atopic dermatitis, has been the subject of various studies, with some suggesting that vitamin D can play a role in managing, preventing or affecting the condition. Here's a summary of the connection:

  • Vitamin D is known to modulate the immune system. Since eczema is an inflammatory condition often linked with immune system dysregulation, adequate levels of vitamin D might help in reducing the severity of eczema by modulating immune responses and decreasing inflammation
  • Vitamin D plays a role in skin health, including the maintenance and repair of the skin barrier. Eczema sufferers often have compromised skin barriers, making them more susceptible to infections and allergens. By contributing to innate immunity, vitamin D may also assist by improving resistance to opportunistic skin infections, such as Staphylococcus aureas
  • Some studies have found correlations between vitamin D deficiency and increased severity of eczema
  • Eczema symptoms can exhibit seasonal variations, with many individuals experiencing worse symptoms during the colder, less sunny months. This pattern suggests a potential link with vitamin D levels, which naturally decrease during periods of reduced sunlight exposure

How can I get vitamin D?

Vitamin D is derived from certain foods, and it's made in the body in response to sunlight exposure.

How vitamin D is made from sunlight

When your skin gets sunlight, it makes vitamin D3 from a type of cholesterol. It's like the sun telling your skin to create vitamin D.

This vitamin D from your skin (or from foods or supplements you take) travels to your liver. Here, the liver adds a little piece to it, turning it into a new substance called 25(OH)D, or calcidiol. Think of it as the liver giving vitamin D a ticket to travel to the next stop.

Next, this substance goes to your kidneys. The kidneys add another piece to it, transforming it into its superhero form called 1,25(OH)2D, or calcitriol. This is the active form of vitamin D that your body can use to keep your bones strong, and do other important things.

So, in simple terms, vitamin D goes on a little journey in your body from the skin (with help from the sun), then hops on a bus to the liver, gets a ticket, and then makes a final transformation in the kidneys. Now, it's ready to help your body stay healthy!

How vitamin D is absorbed from food

First, you consume vitamin D either through foods that contain it (like fatty fish, fortified foods, or egg yolks) or through vitamin D supplements.

When you eat foods or take supplements containing vitamin D, they reach your stomach and then move into your intestines. In your intestines, vitamin D needs fats to be absorbed properly because it is a fat-soluble vitamin. This means it dissolves in fats and oils.

In the small intestine, vitamin D is absorbed into the walls of the intestine along with dietary fats. Bile acids, which are substances produced by your liver and stored in your gallbladder, help break down dietary fats and vitamin D so your body can absorb them more easily.

Once absorbed, vitamin D enters the bloodstream. However, because it is fat-soluble and not water-soluble, it needs a special protein to travel through the blood. This protein is called a vitamin D-binding protein. Think of this protein as a taxi that picks up vitamin D and takes it where it needs to go in the body.

Before vitamin D can be used by the body, it needs to be activated, as explained previously. This involves conversion in the liver and then in the kidneys into the form that the body can use to maintain bone health, support the immune system, and perform other important functions.

How much sunlight exposure do we need?

The need for adequate exposure to sunlight for vitamin D synthesis in the skin depends on several factors, including frequency, intensity, and duration of exposure, as well as skin type, age, geographic location, and time of year. Here's a general guideline on what's typically recommended for maintaining healthy vitamin D levels through sun exposure:

Frequency

Regular exposure is important because vitamin D synthesis from sunlight does not last long in the body. Generally, exposing your skin to sunlight 2-3 times per week can help maintain adequate vitamin D levels.

Intensity

The intensity of sunlight, particularly its UVB component, is critical for vitamin D synthesis. The sun's intensity varies with the time of day, season, and latitude. UVB rays are strongest around midday (between 10 AM and 3 PM) and during the late spring, summer, and early autumn months in most temperate regions. People living closer to the equator receive more intense UVB radiation year-round.

Duration

The amount of time needed in the sun varies significantly depending on skin type, location, and the environment.

As little as 10-15 minutes of midday sun exposure is sufficient for lighter-skinned individuals. People with darker skin may need longer exposure, sometimes up to 20-30 minutes or more, because melanin (which gives skin its colour) reduces the skin's ability to produce vitamin D from sunlight.

Exposing larger areas of skin, such as the back, arms, and legs, can help increase vitamin D production.

Other factors to consider include age and environmental conditions. Older adults often require longer exposure to produce sufficient vitamin D, as their skin becomes less efficient at synthesising it over time. Additionally, UVB exposure tends to be higher at higher altitudes and in clear weather, while pollution, clouds, and smog can reduce the amount of UVB that reaches the skin.

It's important to balance sun exposure for vitamin D with sun safety guidelines. If you’re concerned about UV exposure, consider alternatives like dietary sources or supplements. Additionally, you can protect your skin by using broad-spectrum sunscreen on exposed areas after sufficient sun exposure and incorporating antioxidant-rich foods to help counteract free radical damage caused by UV rays.

You can also take other steps to minimise UV-related free radical damage. (link to skin article)

What do the test ranges mean?

Before supplementing, you need to test your vitamin D levels in your blood, through what’s called a serum vitamin D test.

In Australia, the only reliable method for testing vitamin D levels is through a blood draw. As of the time of writing, no finger prick (blood spot) test is considered accurate for measuring vitamin D levels in the blood.

The Medicare policies in Australia have changed around the public funding of vitamin D tests in the last few years. Therefore in most instances, general practitioners are constrained in ordering publicly funded serum D tests. I recommend you ask your GP for the test and offer to privately pay for it. Typically this costs between $50 and $75 dollars. Alternatively, if already seeing a functional medicine practitioner, ask them to order a private test for you.

The broadly accepted Australian vitamin D ranges are:

  • Mild deficiency: 30 – 49 nmol/L
  • Moderate deficiency: 13 – 29 nmol/L
  • Severe deficiency: <13 nmol/L
  • Total deficiency: <50 nmol/L
  • Adequate levels: ≥50 nmol/L

Functional Medicine practitioners typically have a different perspective or lens through which they regard vitamin D metabolism, and while 50 nmol/Ls may be regarded by Australian health authorities to be adequate, from the perspective of a functional medicine practitioner, I see this as only just enough for all the physiological functions that rely on vitamin D. If my patient has a deficiency or a condition that requires a high requirement for vitamin D, such as eczema and atopy, then I encourage them to keep their serum D levels above 75 nmol/L.

It's always good practice when supplementing with any nutrient that you measure yourself at baseline, which is before treatment, and then after treatment. This gives an indication of your responsiveness to the supplementation. If you don’t respond in a predictable way to supplementation, then it's important to start considering factors that might be contributing to that, such as intestinal malabsorption issues or genetic susceptibilities.

If I supplement, how much should I take?

A daily intake of 1000-2000 IU of vitamin D for adults is considered safe and well within the recommended range for general maintenance.

In cases of vitamin D deficiency, or where an individual needs more (e.g. eczema/atopy) higher doses may be required, but this should be determined and supervised by a healthcare provider.

Upper Intake Levels of Vitamin D

The upper intake levels (the maximum daily intake unlikely to cause adverse health effects) for vitamin D are as follows:

Infants 0-6 months: 1,000 IU

Infants 6-12 months: 1,500 IU

Children 1-3 years: 2,500 IU

Children 4-8 years: 3,000 IU

Individuals 9 years and older: 4,000 IU

Exceeding these levels for an extended period can lead to adverse effects such as hypercalcaemia (high levels of calcium in the blood), which can damage the heart, blood vessels, and kidneys, hence it’s vital to have a practitioner monitor your levels over time.

So if you’re experiencing eczema and you haven’t had your vitamin D test in a while, speak with your practitioner. This can help you determine whether suboptimal vitamin D levels might be contributing to your symptoms, and explore appropriate next steps for improving your skin health.

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About 
Rebecca Hughes
Rebecca is committed to high-quality, results-driven health care to her patients. She brings a wealth of clinical experience to the treatment of a range of health conditions such as acne, eczema, psoriasis, period pain, PMS, menopause, thyroid conditions, IBS and metabolic conditions.
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{ "datePublished": "Jan 31, 2025" }