Oil palm pollen exposure may trigger, aggravate allergic diseases in Asians

Exposure to oil palm pollen poses a heightened risk of developing diseases such as asthma and allergic rhinitis in Asians or risk of exacerbations in those who have these diseases already, according to a study.

Data from two independent cross-sectional cohorts involving participants from Singapore and Malaysia showed that oil palm sensitization was significantly associated with greater odds of asthma (odds ratio [OR], 1.47, 95 percent confidence interval [CI], 1.20–1.78; p=1.34x10^-4), allergic rhinitis (AR; OR, 2.01, 95 percent CI, 1.67–2.43; p=2.91x10^-13), and atopic dermatitis (AD; OR, 1.65, 95 percent CI, 1.35–2.00; p=6.95x10^-7). [World Allergy Organ J 2024;17:100853]

Additionally, oil palm sensitization among individuals with asthma significantly correlated with the presence of asthma-related symptoms and exacerbations within the past 12 months, including wheezing (OR, 1.68; p=0.00995), nocturnal cough (OR, 1.62; p=0.0122), daytime asthma attack (OR=2.07; p=5.03x10⁻⁴), night-time asthma attack (OR, 2.77; p=1.15x10⁻⁶), general practitioners/specialist visit for asthma (OR, 2.11; p=0.00112), and asthma-related hospitalization (OR, 3.55; p=0.0189).

The same was true for individuals with AR, with oil palm sensitization being associated with a greater likelihood of having moderate-to-severe AR symptoms (OR, 1.53; p=0.00113) and the presence of itchy nose symptoms in the past 12 months specifically (OR, 1.41; p=0.0181).

Meanwhile, results were not significant for individuals with AD.

These findings, according to the investigators, point to oil palm pollen exposure as a significant contributor to the incidence of various allergic disorders in Southeast Asia.

Tropical climate

With a tropical climate, Singapore and Malaysia have a flourishing plant life. But this translates to an abundance and diverse spectrum of airborne fungi, fern spore, and pollen. In Singapore, oil palm pollen concentrations in the atmosphere are especially high during the Northeast Monsoon season (December to March), resulting in a high frequency of oil palm sensitization (11.8 percent to 48.0 percent) among the local population. [Aerobiologia 2012;28:135-151; Allergy 2000;55:340-347]

In the present study, the oil palm sensitization rate was 9.6 percent in Singapore and Malaysia, similar to the 8.3 percent rate reported among children with asthma in Thailand but lower than the 22.43 percent rate reported in Indonesia. [Asian Pac J Allergy Immunol 2003;21:199-204; Asian Pac J Allergy Immunol 1999;17:9-12]

Given the cross-sectional design of the study and the inclusion of mostly young adults in the cohorts, the investigators stated that they were not able to look at whether seasons affect the link between oil palm allergy and the type of symptoms people have and whether age factors in the allergenicity of oil palm. More studies are needed to investigate these issues, they added.

In the meantime, primary prevention of sensitization against oil palm should be explored, the investigators said.

“In allergy patients with oil palm pollen sensitization, implementation of allergen-specific immunotherapy might help to reduce morbidity. This approach has been proven to be effective in the treatment of moderate-severe seasonal AR,” they noted. [JAMA 2017;317:615-625]

Alternatively, allergen avoidance can also help manage asthma-related phenotypes, they added. “By reducing the exposure of oil palm pollen allergen during the Northeast Monsoon season, the prevalence of oil palm allergy can be reduced in this population.” [Adolesc Med State Art Rev 2010;21:57-71; Front Pediatr 2017;5:103]

For the study, the investigators assessed the allergen sensitization profile in the Singapore/Malaysia population using serum samples from 564 participants from the Singapore/Malaysia Cross-Sectional Genetics Epidemiology Study (SMCGES; mean age 21.16 years, 49.1 percent men). They estimated the association of oil palm sensitization with the risk and severity of asthma, AR, and AD in a separate cohort of 13,652 young adults of Chinese ethnicity from Singapore/Malaysia (mean age 21.96 years, 41.5 percent men).