Trans, saturated fat-heavy diets may trigger AD flares in Asians

High dietary consumption of trans fatty acids (TFAs) and saturated fatty acids (SFAs) appears to play some role in atopic dermatitis (AD) flare-ups among Chinese adults from Singapore and Malaysia, according to a large study.

Analysis of data from 13,561 Chinese adults who participated in the Singapore/Malaysia Cross-sectional Genetics Epidemiology Study (SMCGES) showed that diets high in total estimated TFAs and SFAs were strongly associated with exacerbations among individuals with either chronic or current moderate-to-severe AD.

In a multivariable model controlled for total fatty acids in diets and with false discovery rate correction, the adjusted odds ratios for AD exacerbation were 1.516 (95 percent confidence interval [CI], 1.094–2.097) with high TFAs (p<0.05) and 1.581 (95 percent CI, 1.106–2.25) with high SFAs (p<0.05). [Skin Health Dis 2024;4:e330]

“Fatty acids in diets do not interact to influence AD,” the investigators noted.

The mechanisms by which TFAs and SFAs contribute to AD exacerbation are complex and not fully understood, according to the investigators. But one possible pathway, they continued, is a dysregulation in D6D, an enzyme involved in fatty acid metabolism.

Impairment of D6D leads to imbalances in fatty acids, which can contribute to inflammation and immune dysregulation, the investigators explained. “Our epidemiological findings, while preliminary, may support the notion that excessive fatty acids in diets shape immune responses to encourage the development and even exacerbation of inflammatory diseases like AD.”

In the study, a standardized ISAAC questionnaire was used to collect information on the participants’ sociodemographic background, dietary and lifestyles habits, and personal/family medical histories. A total of 2,316 participants had AD (17.1 percent, 58.4 percent female), including 947 with moderate-to-severe disease and 809 with chronic disease. More than half (52.1 percent) had a healthy BMI range (18.0–23.0 kg/m²) and consumed alcohol occasionally (51.4 percent).

“Despite the possibility of recall bias, our large sample size minimizes the impact of individual measurement errors and enhances the study’s statistical power to detect associations between dietary fatty acid intake and AD,” the investigators said.

“However … we only studied five main types of dietary fatty acids by referencing the USDA database, and it might not fully capture the other subtypes of fatty acids consumed in diets. We seek to replicate these findings independently by cross-validating with other cohorts using a detailed food frequency questionnaire that surveys an exhaustive list of foods with known nutritional fatty acids content.

“Ultimately, we hope that our findings provide valuable insights into the potential role of dietary factors in terms of fatty acid consumption in the development and severity of AD. These insights may inform public health policies and dietary recommendations, as well as guide future research on the pathomechanisms underlying an association between intake frequencies of FAs and AD exacerbations,” they added.

Commercially produced deep-fried foods and pastries are primary sources of artificial trans fat, while naturally occurring trans fat is found in small amounts in dairy products and red meat. To reduce the risk of chronic inflammatory diseases, the Singapore Health Promotion Board recommends consuming foods with less than 0.50 grams of trans fat per 100 grams. In addition, a ban on partially hydrogenated oils in 2021 was introduced to eliminate artificial trans fat in Singaporeans’ diets.

Saturated fats, on the other hand, are more widely distributed in the Asian diet. The National Nutrition Survey has identified stir-fried vegetables, meat dishes with coconut milk, and fried noodles as significant contributors to high saturated fat intake among adults.