Background: Folic acid fortification program has been established to prevent tube defects.
However, concern has been raised among patients using anti-folate drug, i.e. psoriatic patients, a
common, chronic, autoimmune inflammatory skin disease associated with obesity and smoking.
Objective: To investigate dietary and circulating folate, vitamin B12 (B12) and homocysteine (hcy) in
psoriatic subjects exposed to the national mandatory folic acid fortification program.
Methods: Cross-sectional study using the Food Frequency Questionnaire, plasma folate, B12, hcy and
psoriasis severity using the Psoriasis Area and Severity Index score. Median, interquartile ranges
(IQRs) and linear regression models were conducted to investigate factors associated with plasma folate,
B12 and hcy.
Results: 82 (73%) mild psoriasis, 18 (16%) moderate and 12 (11%) severe psoriasis. 58% female,
61% non-white, 31% former smokers, and 20% current smokers. Median (IQRs) were 51 (40, 60)
years. Only 32% reached the Estimated Average Requirement of folate intake. Folate and B12 deficiencies
were observed in 9% and 6% of the blood sample respectively, but hyperhomocysteinaemia
in 21%. Severity of psoriasis was negatively correlated with folate and B12 concentrations. In a multiple
linear regression model, folate intake contributed positively to 14% of serum folate, and negative
predictors were psoriasis severity, smoking habits and saturated fatty acid explaining 29% of circulating
Conclusion: Only one third reached dietary intake of folate, but deficiencies of folate and B12 were
low. Psoriasis severity was negatively correlated with circulating folate and B12. Stopping smoking
and a folate rich diet may be important targets for managing psoriasis.