Too low zinc consumption is quite rare in developed countries. However, people with atopic eczema are particularly at risk of zinc deficiency for three reasons:

1. Atopic eczema often coexists with intestinal disorders, which may lead to reduced zinc absorption in the small intestine (especially in inflammatory bowel diseases).

2. People with atopic eczema often follow restrictive diets that eliminate many important sources of zinc.

3. Zinc plays a key role in maintaining the proper functioning of the skin barrier and wound healing, therefore the demand for zinc in people with atopic eczema may be higher than in healthy people.

Zinc deficiency results in immune dysfunction and promotes systemic inflammation. For this reason, too low zinc levels may exacerbate the symptoms of eczema or even play a role in the pathogenesis of this disease. Diagnosing and treating zinc deficiency is one of the key elements of nutritional therapy of eczema. It works as follows:

  1. The first step is to assess the concentration of zinc in the blood serum. If the values are below normal, it will be necessary to use zinc supplementation in a dose that will correct the deficiency. It is also worth paying attention to the symptoms of zinc deficiency, such as decreased immunity, deterioration of taste and smell, slow wound healing, brittle nails and the development of inflammation of the oral mucosa.

2. The second step is to find the cause of the deficiency. In order to do so, it’s important take a close look at habitual diet to see if it’s providing you with enough zinc. It is also worth looking into the health of the gut and assess whether the deficiency may have been the result of insufficient absorption. In eczema, reduced absorption often coexists with a restrictive diet – as a result, the risk of zinc deficiency becomes very high.

3. The third step is to prevent the recurrence of the deficiency by ensuring adequate supply from the diet or supplementation and improving the condition of the small intestine. It’s best to assess zinc levels twice a year to make sure that they remain in a healthy range.

It’s important to note currently there are no indications that zinc supplementation, in the absence of a deficiency, would lead to a further improvement in eczema symptoms or other positive effects. On the contrary, consuming excessive amounts of zinc can lead to undesirable effects, including dysfunction of the immune system (1,2). While zinc supplementation is not for everyone, everyone should make sure to include zinc-rich foods in their diet, such as fish and seafood, beef and lamb, pumpkin seeds, almonds, dairy, legumes and other.

How common is zinc deficiency in atopic eczema?

According to a 2019 systematic literature review and meta-analysis of 15 studies (including 2 randomized controlled trials, 11 case-control studies, 1 cohort and 1 cross-sectional study), atopic eczema is associated with significantly lower levels of zinc in the serum, hair, and erythrocytes (3). However, there are no studies analyzing the diet of eczema patients – therefore it is difficult to assess whether the lower levels of zinc are the result of dietary restrictions, reduced absorption or higher demand.

In a 2014 randomized controlled clinical trial, the level of zinc in the hair was measured in 58 pediatric eczema patients and 43 healthy controls (study population aged 2-14) (4). Forty-one (70.7%) patients were deficient in hair zinc concentration (less than 130 μg / g) as opposed to 18 (41.9%) in the control group. Atopic patients with low zinc levels were divided into 2 groups. Group A received oral zinc oxide supplementation (12 mg daily) for 8 weeks and standard treatment with oral antihistamines and moisturizing creams. Patients in group B received standard treatment, but no zinc supplementation. After 8 weeks of supplementation, hair zinc levels increased significantly in group A. In group B, there were no significant changes in hair zinc levels. Moreover, scores on the symptoms severity scale (EASI), epidermal water loss and itching intensity improved significantly more in group A than in group B.

In 2017, the same research group conducted a case-control study to further investigate the levels of hair minerals (including zinc) in children with eczema. Sixty-six children aged 1 to 14 were enrolled in the study. The sex and age matched control group consisted of 25 healthy children. Once again, zinc levels were significantly lower in the eczema group compared to the healthy group. It was also observed that the levels of calcium, magnesium, copper, and phosphorus were lower in the patients, while the levels of sodium, potassium, manganese, chromium, and molybdenum were higher in the patients compared to healthy controls (5). These findings suggest that the diets of eczema patients may differ from those of healthy people.

Why is zinc important in atopic eczema?

Firstly, zinc is a key component of matrix metalloproteinases involved in the remodeling of the epidermis (6). For this reason, people with zinc deficiency often have specific eruptions on the skin, hair falls out, and wound healing is very slow (7).

Moreover, mice fed a zinc-deficient diet develop eczema-like skin rashes, with an increased number of bacteria characteristic for eczema (s. aureus) on the skin surface, and elevated serum IgE levels (8). Moreover, the so-called „zinc finger motifs” (small structural proteins consisting of one or more zinc ions) are needed for the expression of filaggrin, an epidermal protein that plays a key role in maintaining the integrity of the skin barrier (9). Filaggrin is needed for the formation of corneocytes and the production of intracellular metabolites that help to moisturize the stratum corneum and maintain the proper pH of the skin. As many as 50% of eczema patients are carriers of the loss-of-function mutations of the FLG gene encoding filaggrin, which is the main genetic predisposition for developing eczema (10, 11).

Secondly, in eczema the level of pro-inflammatory cytokines such as IL-1 and IL-6 is increased. Topical application of zinc oxide to mechanically damaged skin in mice has been shown to inhibit pro-inflammatory cytokines and increase levels of anti-inflammatory cytokines such as IL-10 (12).

Thirdly, it has been shown that zinc oxide exhibits antimicrobial activity against s. aureus, i.e. the pathogenic bacteria that most often dominates the skin microbiome in eczema (13). It is worth noting that the relationship between endogenous zinc in humans and S. aureus is still not clear. However, looking at the evidence as a whole, it seems that antimicrobial properties may be one of the ways, in which zinc can improve eczema symptoms.

Bibliography

  1. Plum L. M., Rink L., Haase H., The essential toxin: impact of zinc on human health. Int J Environ Res Public Health. 2010;7(4):1342-1365
  2. Chandra R. K., Excessive intake of zinc impairs immune responses. JAMA. 1984; 21;252(11):1443-6.
  3. Gray N. A., Dhana A., Stein D. J., Khumalo N. P., Zinc and atopic dermatitis: a systematic review and meta-analysis. J Eur Acad Dermatol Venereol. 2019; 33(6):1042-1050.
  4. Kim J. E., Yoo S. R., Jeong M. G., Ko J. Y., Ro Y. S., Hair zinc levels and the efficacy of oral zinc supplementation in patients with atopic dermatitis. Acta Derm Venereol. 2014; 94(5):558-62.
  5. Kim, J., Shin J. M., Ko J. Y., Ro Y. S., Hair Mineral Analysis in Children with Atopic Dermatitis. Ann Dermatol. 2017; 29(2):251-153.
  6. Cui, N., Hu, M., & Khalil, R. A. (2017). Biochemical and Biological Attributes of Matrix Metalloproteinases. Progress in molecular biology and translational science, 147, 1–73.
  7. Lansdown, A. B., Mirastschijski, U., Stubbs, N., Scanlon, E., & Agren, M. S. (2007). Zinc in wound healing: theoretical, experimental, and clinical aspects. Wound repair and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society, 15(1), 2–16.
  8. Takahashi H., Nakazawa M., Takahashi K., Aihara M., Minami M., Hirasawa T., et al. Effects of zinc deficient diet on development of atopic dermatitis-like eruptions in DS-Nh mice. J Dermatol Sci. 2008; 50: 31–39.
  9. Cassandri, M., Smirnov, A., Novelli, F. et al. Zinc-finger proteins in health and disease. Cell Death Discov. 3, 17071 (2017)
  10. Palmer, C., Irvine, A., Terron-Kwiatkowski, A. et al. Common loss-of-function variants of the epidermal barrier protein filaggrin are a major predisposing factor for atopic dermatitis. Nat Genet 38, 441–446 (2006).
  11. Irvine, A. D., & McLean, W. H. (2006). Breaking the (un)sound barrier: filaggrin is a major gene for atopic dermatitis. The Journal of investigative dermatology, 126(6), 1200–1202.
  12. Maarouf, M., Vaughn, A. R., & Shi, V. Y. (2018). Topical micronutrients in atopic dermatitis-An evidence-based review. Dermatologic therapy, 31(5).
  13. Kadiyala U., Turali-Emre E. S., Bahng J. H., Kotov N. A., VanEpps J. S., Unexpected insights into antibacterial activity of zinc oxide nanoparticles against methicillin resistant Staphylococcus aureus (MRSA). Nanoscale. 2018; 10: 4927–4939.

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