Some research links vitamin D to eczema due to its immune-regulating properties and ability to affect gene expression. Supplementing vitamin D may be helpful for those who are deficient, and a doctor can test and advise about this.
Eczema commonly affects infants and children but can persist into adulthood. Vitamin D may be a helpful therapy, but people should be careful not to exceed upper limits.
This article explains the link between vitamin D and eczema and looks at what the evidence says. In addition, it discusses how much vitamin D people need and those who are at risk of a deficiency.
Vitamin D and eczema
Elena Popova/Getty Images
Atopic dermatitis, the most common type of eczema, is an inflammatory skin condition. It affects around 30% of the United States population, primarily children and adolescents.
The word atopic means that there is a tendency to develop allergic diseases. Usually, eczema starts in the first few years of life. Around half of people with moderate to severe eczema also develop other allergic conditions such as asthma, hay fever, or food allergies.
Scientists know that vitamin D regulates the immune system and have conducted research to determine if a lack of vitamin D triggers the development of eczema and if supplementing it can help symptoms.
A 2015 review explains the “vitamin D hypothesis,” which proposes that lower levels of the vitamin have links to eczema. The hypothesis links to research showing that people who live at higher latitudes with less sunlight or have darker skin are more likely to be deficient in vitamin D. The review points out that eczema is also more prevalent in these geographical regions.
The review explains that vitamin D protects the skin’s barrier function, which helps to prevent infections. Additionally, vitamin D suppresses skin inflammation by increasing and regulating immune cells.
Furthermore, vitamin D affects gene expression, which scientists think may predispose children to eczema. The 2015 review also highlights that infants may become deficient by lacking vitamin D in their parent’s breastmilk, but more studies are needed to confirm this.
What the evidence says
The American Academy of Dermatology Association advises that there is not enough scientific evidence to recommend using any vitamin or mineral to treat eczema. It says vitamin D supplements may be helpful during the winter, but people should be careful about how much they take because higher doses can be toxic.
However, the American Academy of Allergy, Asthma & Immunology highlights that there has been a recent increase in studies associating vitamin D deficiency with eczema. Therefore, if a doctor diagnoses vitamin D deficiency, they may prescribe supplements.
A 2018 systematic review of 21 publications found that lower vitamin D levels were associated with eczema severity, and supplementation improved symptoms in 67% of people.
An older review in 2016 suggests that vitamin D supplements lessen the severity of eczema and are a safe and tolerable therapy. However, the researchers highlight that scientists need to conduct larger-scale, extended studies to confirm this.
What is vitamin D deficiency?
Doctors assess vitamin D levels by taking a blood test. They measure a form of vitamin D called 25-hydroxyvitamin D (25(OH)D) in either nanomoles per liter (nmol/l) or nanograms per milliliter (ng/ml). One nmol/l is the same as 0.4 ng/ml.
The National Institutes of Health’s Office of Dietary Supplements (ODS) advises that levels of 50 nmol/l (20 ng/ml) or above are adequate for most people for bone and overall health.
However, a 2020 update on the current status worldwide suggests that most authors consider a range below 75 nmol/l (30 ng/ml) as a deficiency. Furthermore, 25(OH)D levels of 25–30 nmol/l (10–12 ng/ml) increase the risk of osteomalacia and nutritional rickets, and doctors class this as a severe deficiency.
Supplementing Vitamin D
Adults need 15–20 micrograms (mcg), or 600–800 international units (IU), of vitamin D daily, and children need 10–15 mcg (400–600 IU) depending on their age. People get vitamin D from the sun or food, but they can also consider taking a supplement.
Two forms of vitamin D are available as a supplement. Vitamin D2 (ergocalciferol) and D3 (cholecalciferol) may be part of a multivitamin and mineral supplement. Alternatively, retailers sell them as single supplements.
However, some vitamin D3 is unsuitable for vegans because manufacturers derive it from sheep’s wool. Instead, vegans can opt for D3 made from lichen or D2.
Although both forms increase vitamin D in a person’s blood, the ODS advises that D3 may raise it higher and for longer than D2. Additionally, because vitamin D is fat-soluble, people absorb it best with a meal or snack that includes some fat.
Supplementing too much vitamin D can be harmful, and the ODS advises that very high levels of vitamin D in the blood (greater than 375 nmol/l or 150 ng/ml) can cause the following:
- nausea or vomiting
- muscle weakness
- confusion
- pain
- loss of appetite
- dehydration
- excessive urination and thirst
- kidney stones
Extremely high levels may even cause death, and vitamin D overdosing is almost always due to excessive supplementation.
Additionally, vitamin D supplements may interact with some medications, either reducing the amount of vitamin D that the body absorbs or affecting a medication’s effectiveness. These medications include steroids, statins, and thiazide diuretics. Therefore, individuals taking medication should check with a doctor to see if vitamin D supplements are appropriate.
What are the upper limits for vitamin D?
The ODS’s daily upper limits for vitamin D intake from all sources, including food, beverages, and supplements, are as follows:
- birth to 6 months: 25 mcg (1,000 IU)
- 7–12 months: 38 mcg (1,500 IU)
- 1–3 years: 63 mcg (2,500 IU)
- 4–8 years: 75 mcg (3,000 IU)
- 9 years and older, including pregnant and breastfeeding females: 100 mcg (4,000 IU)
Who is at risk of vitamin D deficiency?
Some groups of people may have a higher risk of vitamin D deficiency. According to the ODS, the following people may need a blood test:
- infants who solely consume breastmilk
- older adults
- people who seldom expose their skin to sunlight
- people with darker skin
- those with health conditions that limit the fat their body absorbs, such as Crohn’s disease, celiac disease, or ulcerative colitis
- people who are obese or have had gastric bypass surgery
Summary
Some evidence links vitamin D deficiency to eczema and suggests that supplementing it may relieve symptoms.
Because vitamin D regulates the immune system, it can protect the skin barrier and prevent inflammation.
Vitamin D also influences gene expression, and some research suggests that a lack of it in utero may predispose a person to eczema.
Some people may be at more risk of vitamin D deficiency, including those with darker skin, breastfed infants, and individuals who do not expose their skin to sunlight. People in these groups may need to see a doctor to test their vitamin D levels.
A person can supplement vitamin D if they are deficient but must be careful to stay within safe upper limits.
Leave a Reply