Dietary Intake of Vitamin E Linked with Decreased Risk of Atopic Dermatitis

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Dietary vitamin E consumption may potentially diminish the risk of developing atopic dermatitis, new research suggests, although similar intake of retinol, vitamin C, and carotene is not causally linked to the skin disease.¹

These data were the result of a new analysis led by Siqing Wang from the Beijing University of Chinese Medicine. Wang and a team of investigators noted the strong link observed between oxidative stress and atopic dermatitis, suggesting that raising one’s intake of antioxidants could lead to a risk reduction.

To further explore this possibility, the team carried out a Mendelian randomization (MR) analysis with the goal of analyzing such a causal link between dietary antioxidant vitamin intake and atopic dermatitis (eczema). This method involves genetic data and works by avoiding the possible confounders and reverse causation seen within typical observational research.²

“Based on the above evidence, we hypothesize that dietary antioxidant vitamin intake is a protective factor in (atopic dermatitis),” Wang and colleagues wrote. “It is beneficial to provide reasonable dietary guidance to patients with (atopic dermatitis) during their consultation. At the same time, it provides evidence for exploring the pathogenesis of oxidative stress in (atopic dermatitis).”¹

Trial Design

The investigators implemented 2-sample Mendelian randomization (MR) to examine the potential causal link between eczema and the intake of several different dietary antioxidants. Specifically, they looked at vitamin E, vitamin C, carotene, and retinol.

A set of 3 key assumptions were involved in the investigators’ MR analysis. The first assumption, namely the relevance assumption, necessitates that the genetic instruments implemented are associated substantially with the intake of the aforementioned antioxidants.

The next assumption was regarding independence, namely that it requires that such genetic instruments are not correlated with any confounders which could impact a relationship between atopic dermatitis and consumption of antioxidants. The last assumption is regarding exclusivity, specifically that genetic instruments can affect the outcome solely based on their impact on intake of antioxidants, without directly affecting the skin condition itself.

Following a period of screening the necessary data from public databases and eliminating any data labeled as abnormal, both the MR and sensitivity analyses were carried out. The investigators’ data needed for their genome-wide association study (GWAS) were sourced from the UK Biobank and the IEU OpenGWAS database.

The research team’s work was separated into 2 distinct phases: the MR analysis period in which sought to determine a causal connection between eczema and the antioxidants, and the sensitivity analysis period which helped to validate the robustness of the team’s conclusions.

Conclusions

The investigators concluded that there was a causal association identified in their analyses between the consumption of vitamin E and a diminished risk of atopic dermatitis (OR 95% CI = 0.745–0.992, P = .038). Despite these findings, they were unable to identify a causal connection between the skin disorder and patients’ consumption of the other three vitamins (vitamin C, carotene, and retinol), as their p-values and ORs did not suggest any statistical significance.

The research team’s sensitivity analysis indicated that there was no evidence of heterogeneity or pleiotropy observed among the single nucleotide polymorphisms (SNPs), given that all of the p-values exceeded 0.05.

“It is to be expected that the relationship between vitamins and (atopic dermatitis) will be visualized by conducting large MR analysis and clinical trials, especially between specific vitamins and different stages of (atopic dermatitis),” they wrote. “This could be significant in the treatment of AD and slash the cost to the healthcare system and individuals.”

References

1. ^{Wang S, Dan W, Wang Z, Sun Y, Zhang G. Causal relationships between dietary antioxidant vitamin intake and atopic dermatitis: A two-sample Mendelian randomization study. Skin Res Technol. 2024; 30:11111. https://doi.org/10.1111/srt.13883.}
2. ^{Davey Smith G, Hemani G. Mendelian randomization: genetic anchors for causal inference in epidemiological studies. Hum Mol Genet. 2014; 23(R1): R89-R98.}