Psoriasis and Diet ?

Diet and nutrition in psoriasis: analysis of the National Health and Nutrition Examination Survey (NHANES) in the United States.
Johnson JA, Ma C, Kanada KN, Armstrong AW.
J Eur Acad Dermatol Venereol. 2014 Mar;28(3):327-32. doi: 10.1111/jdv.12105. Epub 2013 Feb 25.

• Psoriasis is a chronic dermatological disease and its etiology is genetic and environmental. Although sometimes controversial, associations between acne and diet seem to be more and more accepted…however very little can be said when the patient asks: “does diet influence psoriasis ?”
• In this study, the authors used data from the National Health and Nutrition Examination Survey (NHANES, USA) between 2003 and 2006. 6290 patients answered in the questionnaire that they had psoriasis. Lab exams were done.
• Based on multivariate regression analysis psoriasis was associated with:
  • increased vitamin A blood level (Odds ratio (OR)= 1.01, Confidence interval (CI)=1-1.02, p=0.03)
  • increased alpha-carotene blood level (OR=1.02, CI=1.01-1.04, p=0.01)
  • lower sugar intake (OR=0.998, CI=0.996-1, p=0.04)
  • increased body mass index (BMI) (OR=1.04, 95% CI=1.02-1.07, p=0.03)
  • No differences were seen regarding intake of calories, protein, carbohydrates, total fat, total saturated fat, monounsaturated fat, polyunsaturated fat…nor levels of folate, vit B12, vitamin C, vitamin D, high density lipoprotein (HDL), cholesterol, total cholesterol, albumin, calcium, trans-beta-carotene, cis-beta-carotene, beta-cryptoxanthin, lutein, xeaxanthin, trans-lycopene, retinyl palmitate, retinyl stearate and total lycopene.
• The results suggest that results suggest that the strength of these dietary associations is comparable to that of an increased BMI. However these associations are a lot less strong than that of psoriasis with arthritis (OR=2.31, CI=1.37-3.90, p=0.02).

• Comment: the results coming out of this questionnaire suggest that low sugar intake and higher vitamin A/precursor* levels could be associated with psoriasis and it could begin the investigative process of a link between diet and psoriasis. However statistical epidemiological analysis is not enough to determine a causal relationship and more studies are definitely needed.

*Vitamin A and its precursors are important for the normal differentiation of keratinocytes and thse elevated blood levels could be a compensatory mechanism.

Contributors

Dr Christophe Hsu – dermatologist. Geneva, Switzerland