Job’s tears, sometimes called “Job’s polish herb” for its skin-brightening reputation, is a grain-producing grass native to Southeast Asia that has been used for centuries in traditional medicine and skincare. What makes it special is a rare combination: it works as both a nutritious food grain and a source of bioactive compounds that affect everything from skin pigmentation to inflammation to blood sugar. Few plants pull double duty quite like this one.
What Job’s Tears Actually Is
Job’s tears (Coix lacryma-jobi) is a tropical perennial grass that grows 3 to 4 feet tall and produces distinctive tear-shaped seeds. It’s native to Southeast Asia but has naturalized across southern parts of the United States and other warm regions. The plant produces both male and female flowers on the same stalk, and its seeds come in two main types: hard-shelled varieties traditionally used for jewelry and beadwork, and soft-shelled varieties cultivated as a food crop and medicine.
The soft-shelled cultivar, known as var. ma-yuen, is the one that matters for health. Grown primarily across southern China, the Philippines, and peninsular Malaysia, this variety produces the edible, nutrient-dense seeds that show up in Asian grocery stores, traditional medicine cabinets, and increasingly in skincare products. In Japan it goes by “hatomugi,” in Chinese medicine it’s called “yi yi ren,” and in English you’ll sometimes see it labeled as coixseed.
The “Polish” Effect on Skin
The nickname “polish herb” likely comes from the seed’s ability to brighten and smooth skin, a property that has made it a staple in Japanese and Korean beauty routines. The mechanism behind this is specific: compounds in Job’s tears inhibit tyrosinase, an enzyme your skin needs to produce melanin. By slowing that enzyme down, the seed reduces melanin overproduction, which helps fade dark spots, sun damage, and uneven skin tone over time.
But the skin benefits go beyond just pigment control. The seeds contain polysaccharides that act as natural moisture-retaining agents, locking water into the outer layer of skin and preventing dehydration. Natural amino acids help maintain the skin’s moisture barrier, while vitamin E and other antioxidants promote collagen formation, improving firmness and elasticity. The seeds also have gentle exfoliating properties that encourage dead skin cell turnover, smoothing rough patches and reducing dullness. This combination of brightening, hydrating, and texture-refining effects is what earned Job’s tears its reputation as a “polishing” ingredient.
Compounds That Set It Apart
Job’s tears seeds contain an unusually diverse set of bioactive compounds. Two stand out as unique to this plant: coixol and coixenolide.
Coixol is responsible for much of the plant’s anti-inflammatory activity. It works by blocking several inflammatory signaling pathways in cells, suppressing the production of proteins that drive swelling and irritation. In skin specifically, coixol inhibits mucus overproduction and reduces inflammation triggered by common irritants. It’s also the compound behind the tyrosinase inhibition that gives the seeds their skin-brightening effect.
Coixenolide, which makes up less than 0.25% of the seed by weight, has attracted attention for its antitumor properties. It appears to work by blocking a key inflammatory pathway that certain cancers exploit for growth. A pharmaceutical formulation derived from Job’s tears extract, called Kanglaite, has been developed and studied for cancer support in clinical settings.
Beyond these signature compounds, the seeds are rich in polyphenols, lignans, flavonoids, and plant sterols (52 to 58 mg per gram). They also contain B vitamins including thiamine, riboflavin, and niacin, plus vitamin C. This chemical diversity is part of what makes the plant so versatile across different traditional medicine systems.
A Nutritional Powerhouse
As a food, Job’s tears holds its own against more familiar grains. The seeds contain 16 to 19% protein, which is notably higher than white rice. Starch makes up 50 to 79% of the dry weight, providing sustained energy, while fat content ranges from 2 to 7% and includes beneficial fatty acids like oleic acid and linoleic acid. Dietary fiber content varies depending on processing, ranging from 0.3 to 8.4 grams per 100 grams.
One particularly interesting nutritional feature is the seed’s ability to produce fructooligosaccharides, a type of prebiotic fiber that feeds beneficial gut bacteria. When gut microbes ferment these fibers, they produce short-chain fatty acids that improve insulin sensitivity and metabolism. This prebiotic action is part of why Job’s tears has shown promise for metabolic health.
Effects on Blood Sugar and Cholesterol
A randomized controlled trial in patients with type 2 diabetes tested Job’s tears mixed into yogurt against yogurt alone. The combination group saw a significant decrease in glycated albumin, a marker of blood sugar control over the previous two to three weeks. Yogurt alone did not produce this effect. Both groups saw improvements in total cholesterol and LDL (“bad”) cholesterol, but the Job’s tears group had a significantly greater increase in HDL (“good”) cholesterol, with levels rising by 25 mg/dL compared to just 0.9 mg/dL in the yogurt-only group.
The researchers attributed these results to the synbiotic effect of combining Job’s tears’ prebiotic fibers with the probiotics in yogurt, creating an environment in the gut that enhances metabolic function.
Anti-Inflammatory Properties
In animal studies modeling rheumatoid arthritis, Job’s tears extract significantly reduced blood levels of four major inflammatory signaling molecules at doses of both 100 and 200 mg per kilogram per day. The higher dose showed stronger effects. These inflammatory markers are the same ones elevated in many chronic conditions, from joint disease to metabolic syndrome, which helps explain why the plant has been used across so many different health complaints in traditional practice.
Its Role in Traditional Chinese Medicine
In Chinese medicine, Job’s tears is classified as a food that strengthens the spleen and removes “dampness,” a concept that roughly corresponds to fluid retention, sluggish digestion, and a feeling of heaviness in the body. It’s considered especially helpful for people experiencing edema, loose stools, urinary discomfort, or joint pain that worsens in humid weather.
Raw and roasted forms serve different purposes. Raw Job’s tears have a cooling nature and are used to clear what practitioners call “damp-heat,” conditions involving both fluid accumulation and inflammation. Roasted Job’s tears, prepared by dry-frying the seeds, have a milder, warmer character and are preferred for strengthening digestive function and stopping diarrhea. This distinction matters in practice: someone with a naturally cold constitution would typically be directed toward the roasted form.
How People Prepare and Eat It
Job’s tears is remarkably versatile in the kitchen. The most common preparation is simply boiling or steaming the peeled seeds and eating them like rice, often mixed into a bowl of cooked rice for added texture and nutrition. In China and Thailand, the seeds are boiled in water to make a lightly sweet drink sold as a health beverage in markets. In Japan, roasted seeds serve as a coffee substitute, and the grain is also processed into fermented drinks.
For medicinal purposes, the seeds are typically simmered into soups or porridges with other traditional ingredients. A classic combination pairs Job’s tears with hyacinth beans in a porridge meant to support digestion and reduce fluid retention. The ground flour can be mixed with cold water for a refreshing drink, and in Thailand, a popular dessert combines the cooked seeds with sugar and coconut milk. Western adaptations include using the hulled grains to bake biscuits, and the raw grains can be eaten similarly to peanuts. Brewing the seeds into a tea, by simmering them in water for 20 to 30 minutes, remains one of the simplest ways to extract their benefits.
Safety Considerations
Job’s tears is generally considered safe when consumed as a food in normal amounts. However, because of its cooling nature and traditional use for promoting fluid movement, it is typically avoided during pregnancy in Chinese medicine practice. Scientific safety data for pregnant or breastfeeding women is limited, and many medicinal herbs in this category lack rigorous human safety studies for these populations. People with known cold or deficient constitutions in the traditional medicine framework are generally advised to use the roasted form rather than raw, or to combine it with warming ingredients to offset its cooling properties.