Thailand’s markets fill with the scent of som-o, the pomelo, especially during the cool season when large, grapefruit-like fruits line the stalls. Thais enjoy its sweet-tart segments at temple fairs and as merit offerings during New Year. But pomelo peel, the thick aroma-filled layer around the fruit, has long been used in Thai traditional medicine for coughs, swelling, skin issues, and indigestion. How much of this old wisdom holds up under scientific scrutiny? We explore the evidence with respect for heritage and a cautious, critical eye.
In Thai herbal practice, pomelo peel is woven into daily life. The zest perfumes traditional soaps and balms, while dried peel is simmered in teas to address stubborn phlegm or bloating after festive meals. Folklore speaks of its use as an anti-itch remedy for insect bites and as a poultice for minor swelling. These uses reflect a living tradition shaped by faith, trial, and community knowledge within temples and households. Data from traditional Thai sources and herbal practitioners shows how these practices persist alongside modern health ideas.
Globally, the pomelo is a large citrus species believed to be an ancestor of grapefruit and native to Southeast Asia. Beyond Thailand, dried peel is used in various ways: in China, a variety known as chen pi supports digestive comfort; in Vietnam, essential oil from the peel features in folk remedies and rituals. Modern pharmacology has begun to examine these traditional claims, with focus on the thick outer layer of the fruit and its rich chemistry.
Scientific analyses reveal that pomelo peel contains bioactive compounds such as flavonoids (including naringin, naringenin, and hesperidin), vitamins, coumarins, carotenoids, polyphenols, essential oils (mainly limonene), and natural polysaccharides. These components contribute to the peel’s aroma and may underlie traditional healing effects. Reviews of the literature identify antioxidant, anti-inflammatory, antimicrobial, anticancer, and metabolic-regulating properties in the peel.
Antioxidant power is a major area of interest. Flavonoids and polyphenols in the peel help neutralize free radicals linked to aging, cancer, and heart disease. In lab tests, pomelo peel often shows high antioxidant activity, sometimes exceeding that of other citrus parts. Local Thai cultivars, such as Thong Dee and Kao Nampueng, are noted for higher levels of beneficial compounds, according to studies conducted in the region.
In Thailand, decoctions of pomelo peel are sometimes used to ease coughs and phlegm. Laboratory evidence supports antimicrobial activity against pathogens associated with respiratory and gastrointestinal issues. A clinical trial conducted in the Philippines compared a 12.5% pomelo peel ointment with standard mupirocin for impetigo and found the peel ointment similarly effective and well tolerated, suggesting potential for complementary use where antibiotics are less accessible. This aligns with a broader interest in integrating herbal remedies with conventional care, particularly in rural Thai communities.
Anti-inflammatory effects are another area where traditional uses meet science. Animal and cell studies show that peel extracts—especially polysaccharides and coumarins like auraptene—can reduce inflammatory markers and swelling. While human trials are needed to confirm these results on a larger scale, the findings resonate with long-standing Thai remedies for swelling and skin irritation.
Digestive benefits also appear in line with traditional practice. Flavonoids and bitter compounds in the peel can stimulate digestion and modulate gut motility, with supporting evidence from animal and laboratory studies. This mirrors the decoctions used in households to ease bloating and abdominal discomfort.
Beyond health effects, the chemistry of pomelo peel offers practical applications. Essential oils from the peel show antifungal and antimicrobial activity, can help preserve foods, and may have roles in sustainable packaging. Researchers also explore environmental uses, underscoring a modern echo of the Thai ethos of using every part of the plant.
Investigations into anticancer potential focus on limonoids found in the seeds and peel. Laboratory studies indicate these compounds can induce cancer cell death and hinder tumor blood vessel growth. Although these results are preliminary, they support the idea of pomelo peel as a functional component within a balanced diet. Some studies also suggest benefits for blood sugar and lipid regulation in animal models, tied to flavonoids and polysaccharides.
Cautious use remains essential. Pomelo peel is non-toxic in typical culinary or traditional medicine amounts, but concentrated extracts can be risky. The peel’s bitterness can irritate sensitive stomachs, and there can be interactions with certain medications, similar to grapefruit. Thai health professionals advise consulting a medical provider before using concentrated pomelo remedies, especially for those with chronic illnesses or who take prescription drugs.
Culturally, pomelo holds significance in Thai life beyond healing. The fruit symbolizes good fortune and merit-making, and peeling som-o at temple fairs is a family activity that reflects patience and community spirit. The enduring folk wisdom around its uses emphasizes care, context, and respect for tradition as much as chemistry.
In summary, pomelo peel illustrates how traditional knowledge and modern science can inform one another. Many classic uses—cough relief, swelling reduction, cleansing benefits, and digestive support—receive some scientific backing, while further research is needed to confirm safety and efficacy at medicinal doses and across diverse populations. The rich mix of phytochemicals in the peel offers real potential within a Thai diet that values plant foods.
Practical guidance for readers curious about pomelo peel: incorporate moderate amounts of zest or dried peel in cooking or tea. For skin or household applications, maintain good hygiene and avoid applying raw peel to open wounds. Seek advice from qualified traditional Thai medicine practitioners or healthcare providers, especially if you have underlying conditions or take prescription medications.
Ultimately, pomelo peel stands as a testament to Thai traditional medicine’s blend of culture, cuisine, and care. As research progresses, this “giant of citrus” may yield new insights that benefit Thai health and well-being.