Momordica cochinchinensis, widely known as gac fruit or spiny bitter gourd, is a perennial climbing vine in the Cucurbitaceae family. It is native to a broad region spanning from Southern China to Northeastern Australia, including Southeast Asia. The genus name Momordica refers to the "bitten" appearance of its seeds, while the species epithet cochinchinensis references Cochinchina, the historical name for the southern region of Vietnam. Unlike its relative Momordica charantia (bitter melon), which is consumed for its bitter flesh, Momordica cochinchinensis is prized primarily for the intensely pigmented, nutrient-dense oily arils (the deep red membrane) that surround its seeds. Historically, it has been revered as a "fruit from heaven" in Vietnamese culture, traditionally used to impart color and health-promoting properties to ceremonial dishes like xôi gấc, a vibrant red sticky rice served during weddings and Lunar New Year celebrations.

The plant is a vigorous, large-leafed vine that thrives in tropical climates, often found trailing over fences or trellises in rural gardens. It produces large, solitary, pale yellow flowers and distinctive, oblong fruits. As the fruit matures, it transforms from a vibrant green to a striking, deep orange-red, with a thick, firm skin covered in small, protective spines. Upon opening, the fruit reveals the edible red arils, which contain a very high concentration of lipophilic compounds. Momordica cochinchinensis is a perennial species that requires significant space for its large root system and canopy, and it is largely recognized for its medicinal applications as much as its culinary utility.

The fruit is not typically eaten as a raw, fresh snack. Instead, the red, oily arils are harvested and used as a potent natural food colorant and nutrient-rich ingredient. The flavor is mild, nutty, and savory, often likened to a subtle combination of avocado and carrot due to its high fat content. Beyond the xôi gấc application, the arils are frequently used to enrich sauces, stews, and porridges. The seeds themselves, while occasionally roasted, are more commonly used in traditional medicine, where they are known as mộc miết tử and are valued for their role in treating inflammatory conditions, topical wounds, and localized swelling.

Nutritionally, the gac fruit is a global botanical powerhouse, standing as one of the richest sources of carotenoids in the plant kingdom. The aril is exceptionally high in lycopene and beta-carotene (provitamin A), both of which are highly bioavailable because they are dissolved in the fruit’s natural fatty acids—a unique property that facilitates superior human absorption compared to many other plant sources. The biochemical matrix also includes specialized fatty acids, Vitamin E, and polyphenols. In traditional systems, it is used to support eye health, improve skin conditions, and boost immune function. Modern pharmacological research extensively investigates its role in managing chronic diseases, focusing on the high lycopene content and its potential to protect against oxidative damage at the cellular level.