Salt Intake and Eczema 钠与湿疹

Research from the International Study of Asthma and Allergies in Childhood highlights the impact of diet on the development and persistence of Atopic Dermatitis (eczema). A notable finding is that adolescents who frequently consume fast food are at a 20% increased risk of developing AD, with the risk of severe AD jumping to 70% [1]. Although the exact dietary elements contributing to this increase were not pinpointed, high sodium intake—a common characteristic of fast food—has been implicated.

Sodium1

Sodium MRI studies have revealed that a significant portion of the body’s sodium that can be exchanged is stored within the skin. This is noteworthy because such sodium deposits are often found in association with autoimmune and chronic inflammatory diseases, including AD. In fact, one study reported that the sodium levels in the skin lesions of AD patients were 30 times greater than those in individuals without the condition [2].

The research conducted by Chiang and colleagues [3] aimed to explore the link between sodium intake and the prevalence, activity, and severity of AD on a population scale. They utilized data from over 500,000 individuals, aged 37 to 73, from the UK Biobank cohort. The average 24-hour urinary sodium excretion among participants was 3.01 grams per day, which surpasses the National Health Service’s (NHS) recommended limit of 6 grams of salt (equivalent to 2.3 grams of sodium) per day. The study found that for every 1-gram increase in urinary sodium excretion, there was an 11% increase in the likelihood of being diagnosed with AD, a 16% increase in the likelihood of having active AD, and an 11% increase in the likelihood of experiencing more severe AD symptoms. Interestingly, individuals whose sodium intake was within the NHS guidelines did not show an increased risk of AD. The study also noted that the correlation between sodium intake and AD was more pronounced in females and varied according to age.

These findings are consistent with those from the US NHANES cohort, which observed a 22% increase in the odds of having current AD with each additional gram of dietary sodium consumed per day. This body of evidence supports the theory that sodium accumulation in the skin may trigger immune responses that contribute to the development of AD [4-7].

sodium2

国际儿童哮喘和过敏研究的数据表明，饮食是影响特应性皮炎（湿疹）发病和持续的重要因素。研究发现，青少年频繁食用快餐与湿疹发病风险增加20%，严重湿疹风险增加70%有关[1]。尽管没有指出具体的饮食元素，但高钠摄入量–快餐的常见特点–已被认为与湿疹有关。

钠MRI研究显示，身体可交换的钠大部分储存在皮肤中。这一发现值得注意，因为这种钠沉积通常与自身免疫和慢性炎症性疾病相关，包括湿疹。实际上，一项研究报告称，湿疹患者皮损处的钠水平是无病状个体的30倍[2]。

Chiang及其同事的研究[3]旨在探索钠摄入量与湿疹发病率、活动性和严重程度之间的联系。他们利用来自英国生物银行队列的超过500,000名37至73岁个体的数据。参与者平均每天24小时尿钠排泄量为3.01克，超过了英国国家卫生署（NHS）推荐的限制（每天6克盐，相当于2.3克钠）。研究发现，尿钠排泄量每增加1克，被诊断为湿疹的可能性增加11%，有活跃湿疹的可能性增加16%，湿疹症状加重的可能性增加11%。有趣的是，那些钠摄入量符合英国NHS摄入量指南范围内的个体并未显示出湿疹风险的增加。该研究还指出，钠摄入量与湿疹之间的关联在女性中更为明显，并且随年龄变化。

这些发现与美国NHANES队列的观察结果一致，后者发现每天饮食钠摄入量每增加1克，当前湿疹的几率增加22%。这一研究佐证了这种理论，即皮肤中的钠积累可能触发导致湿疹发展的免疫反应。这些研究为我们提供了关于饮食、钠摄入量和特应性皮炎之间联系的重要见解[4-7]。

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Reference

  1. Ellwood  P, Asher  MI, García-Marcos  L,  et al; ISAAC Phase III Study Group.  Do fast foods cause asthma, rhinoconjunctivitis and eczema? Global findings from the International Study of Asthma and Allergies in Childhood (ISAAC) phase three.   Thorax. 2013;68(4):351-360
  2. Chattopadhyay  A, Tully  J, Shan  J,  et al.  Sodium in the skin: a summary of the physiology and a scoping review of disease associations.   Clin Exp Dermatol. 2023;48(7):733-743.
  3. Chiang BM, Ye M, Chattopadhyay A, Halezeroglu Y, Van Blarigan EL, Abuabara K. Sodium Intake and Atopic Dermatitis. JAMA Dermatol. Published online June 05, 2024. doi:10.1001/jamadermatol.2024.1544
  4. Matthias  J, Maul  J, Noster  R,  et al.  Sodium chloride is an ionic checkpoint for human TH2 cells and shapes the atopic skin microenvironment.   Sci Transl Med. 2019;11(480):eaau0683.
  5. Kopp  C, Linz  P, Dahlmann  A,  et al.  23Na magnetic resonance imaging-determined tissue sodium in healthy subjects and hypertensive patients.   Hypertension. 2013;61(3):635-640.
  6. Linz  P, Santoro  D, Renz  W,  et al.  Skin sodium measured with 23Na MRI at 7.0 T.   NMR Biomed. 2015;28(1):54-62
  7. Selvarajah  V, Mäki-Petäjä  KM, Pedro  L,  et al.  Novel mechanism for buffering dietary salt in humans: effects of salt loading on skin sodium, vascular endothelial growth factor C, and blood pressure.   Hypertension. 2017;70(5):930-937.