Nutrition 2023: Vitamin D supplementation could inhibit effects of psoriasis, experts flag

26 Jul 2023 --- The potential for vitamin D supplementation or consumption of foods rich in the nutrient for healing the skin condition psoriasis has been posited in a recent analysis by the American Society for Nutrition and presented by a researcher from Brown University at the Nutrition 2023 symposium in Boston, Massachusetts, US.

The analysis, which included almost 500 psoriasis cases from the National Health and Nutrition Examination Survey (NHANES), demonstrated a linear relationship between increasing psoriasis severity and decreasing vitamin D levels measured through blood tests.

“Keratinocytes, which are cells in your skin, have vitamin D receptors. Currently, topical vitamin D analogs, which mimic the effects of vitamin D, are used to treat psoriasis because these analogs bind to vitamin D receptors on keratinocytes to prevent their proliferation,” Rachel Lim, an MD candidate at the Warren Alpert Medical School of Brown University tells Nutrition Insight. 

“This proliferation is what leads to the thick plaques characteristic of psoriasis. Vitamin D does not necessarily initiate a ‘healing process’ but rather prevents the proliferation of keratinocytes, resulting in fewer or less severe psoriasis plaques forming.” 

Eating foods rich in vitamin D or supplements could benefit people with psoriasis.

The promise of relief
More than eight million people in the US have psoriasis, where skin cells build up and form itchy, dry patches. According to the study’s findings, vitamin D levels could relieve the symptoms and their intensity.

Case studies were selected from more than 40,000 NHANES participants, with 162 cases from 2003-2006 and 329 from 2011-2014. The researchers also extracted data on vitamin D levels, self-reported psoriasis-affected body surface area and other factors, including age, gender, race, body mass index and smoking status.

“Our results suggest that a vitamin D-rich diet or oral vitamin D supplementation may also provide some benefit to psoriasis patients,” says Lim.

“To our knowledge, direct comparison of topical and oral vitamin D for psoriasis has not been extensively studied. Previous studies have found that serum vitamin D levels did not change significantly after treatment with topical vitamin D analogs. 

“As we found in our analysis, many people who have psoriasis are vitamin D deficient, based on their serum vitamin D levels. Further research, such as randomized trials, is warranted before any firm medical recommendations may be made.”

After adjusting for lifestyle factors such as smoking, the analysis showed that lower vitamin D levels and vitamin D deficiency were significantly associated with greater psoriasis severity. 

Patients with the least affected body surface had the highest average vitamin D levels, while those with the greatest affected area had the lowest average. 

“Only one previous study, published in 2013, has used NHANES data to analyze the relationship between vitamin D and psoriasis,” says Lim. “We were able to add more recent data, which more than tripled the number of psoriasis cases analyzed, making our results more up-to-date and statistically more powerful than previously available data.”
The study posits that oral intake of vitamin D can benefit people with psoriasis significantly.

Although dietary vitamin D toxicity is rare, the researchers advise people with psoriasis to consult their physicians and dermatologists before taking supplements.

Tinkering with the immune response
Vitamin D is believed to influence the development of skin diseases by affecting the body’s immune response and through direct effects on the cells involved in skin repair.

“With growing public interest in vitamin supplementation, we wanted to further examine the connection between vitamin D levels and psoriasis severity,” says Eunyoung Cho, research lead and associate professor, department of dermatology, Warren Alpert Medical School, Brown University. 

“Few studies have looked for this association in groups of people, especially in large US populations, or examined this relationship through a clinical nutrition lens.”

Lim presented the findings earlier this month at Nutrition 2023, the annual flagship meeting of the American Society for Nutrition.

The findings should be considered preliminary until a peer-reviewed publication is available.

More wonders of vitamin D
In other industry developments, adults with prediabetes who take vitamin D supplements are 15% less likely to develop diabetes demonstrated in a recent review of three clinical trials published in the Annals of Internal Medicine.

In addition, a decade-long study investigating vitamin D and its link to dementia found 40% fewer dementia cases in participants who took dietary supplements compared to the control group. Supplementation was also positively associated with postponing the development of the disease. However, the study is being criticized by experts as they spot several limitations.

By Inga de Jong