Katuk (Sauropus androgynus) is one of the most nutritionally dense leafy greens in Southeast Asia, traditionally eaten as a vegetable and used in folk medicine for purposes ranging from boosting breast milk to managing blood sugar. The plant carries a genuinely impressive phytochemical profile, but it also has a dark chapter in its history: outbreaks of serious lung disease linked to overconsumption of raw katuk juice in the 1990s and 2000s. Understanding both sides of the story matters, because the difference between a healthful food and a harmful one often comes down to how much you consume and how you prepare it.
What Katuk Is and Why People Eat It
Katuk is a shrubby plant native to tropical and subtropical regions of South and Southeast Asia. It goes by many names depending on where you are: “sweet leaf bush” in English, “cekur manis” in Malay, “rau ngót” in Vietnamese, and various local names across India, Indonesia, and the Philippines. The young leaves and shoots have a mild, slightly sweet flavor, which is how it earned the English nickname. Communities across these regions have used katuk as both a daily vegetable and a traditional remedy for centuries.1Journal of Ethnic Foods. Sauropus androgynus (L.) Merr.: a multipurpose plant with multiple uses in traditional ethnic culinary and ethnomedicinal preparations
Katuk is sometimes described as a “superfood” in Indonesian and Malaysian wellness circles, and while that word gets thrown around loosely, the plant does pack a legitimate nutritional punch. The leaves are rich in protein for a green vegetable, and they contain meaningful amounts of vitamin A, vitamin C, calcium, and carbohydrates. One interesting wrinkle is that the nutrient profile shifts depending on when the leaves are harvested: vitamin C, protein, calcium, and carbohydrate content all increase as the plant matures from about 60 to 120 days of growth, while vitamin A content actually decreases over the same period.2International Journal of Chemical Studies. Estimation of nutritive composition of Sauropus androgynus (Multivitamin plant) at different growth stages and position of leaves The position of leaves on the plant matters too, with younger leaves near the top differing from older ones lower down. So “katuk” is not one fixed nutritional package; what you get depends on how the plant was grown and which leaves you pick.
Boosting Breast Milk Production
The most well-documented traditional use of katuk is as a galactagogue, a substance that promotes lactation. In Indonesia especially, nursing mothers have long consumed katuk leaves in soups, stir-fries, or as supplements to increase their milk supply. This is not just folk wisdom with no research behind it. A review of multiple studies found that supplementation with katuk leaf, whether as extract capsules, boiled water, or even katuk-infused biscuits, consistently increased milk production in healthy breastfeeding mothers compared to those who did not consume it. Two of the reviewed studies also reported increases in the baby’s weight and the mother’s prolactin levels, respectively.3Atlantis Press. Review on Katuk (Sauropus androgynus (L.) Merr.) and Milk Production of Breastfeeding Mothers in Indonesia
The mechanism appears to differ from other herbal galactagogues. Many milk-boosting herbs work by blocking dopamine receptors, which causes prolactin levels to rise. Katuk does contain papaverine, which can act on dopamine receptors, but it also contains steroids that are thought to increase the number of secretory cells in the mammary glands themselves. In other words, katuk may work partly by helping the breast tissue produce more milk at the cellular level, not just by tweaking hormone signals.4Biomedicine and Pharmacotherapy / Biomedical and Pharmacology Journal. The Potential of Medicinal Plants as Galactagogue in Indonesia: A Review from Medical Perspective Reported side effects in the lactation studies were minimal and self-limiting, though researchers have noted that longer-term safety data is still needed.
Antioxidant Activity
Katuk leaves contain a range of phenolic compounds and flavonoids, the same broad class of plant chemicals that make blueberries and green tea attractive to health-conscious eaters. Laboratory analysis has identified specific flavonoids including kaempferol, afzelin, and trifolin in ethanolic extracts of katuk leaves.5PubMed Central. Molecular docking of ethanol extracts of katuk leaf (Sauropus androgynus) on functional proteins of severe acute respiratory syndrome coronavirus 2 These compounds are known to scavenge free radicals, the unstable molecules that contribute to cell damage and chronic disease.
How much antioxidant activity you can extract from katuk depends heavily on preparation. Research comparing different extraction methods found that a 50% ethanol solvent yielded the highest levels of total phenolics and total flavonoids, along with the strongest ability to neutralize free radicals in a standard laboratory test.6IOP Conference Series: Earth and Environmental Science. The Effect of Ethanol Concentrations as The Extraction Solvent on Antioxidant Activity of Katuk (Sauropus androgynus (L.) Merr.) Leaves Extracts That is useful information for supplement manufacturers, but for the home cook, the practical takeaway is simpler: katuk leaves contain real antioxidant compounds, and cooking them in water-based preparations (soups, stews) is a reasonable way to get some of those benefits into your diet.
Effects on Blood Sugar and Cholesterol
Several lines of evidence suggest katuk may help with metabolic health, though the research ranges from animal studies to small human trials. In one study of patients with diabetes, a group receiving a combination of sago and katuk leaves saw an average blood glucose reduction of about 26 mg/dL, compared to roughly 6 mg/dL in a control group receiving standard medications alone.7Journal of Angiotherapy. Sago and Katuk Leaf Combination Treatment Reduces The Blood Glucose Levels in Diabetes Mellitus Patients Because that study used a combination of sago and katuk, it is hard to attribute the entire effect to katuk alone, but the direction of the result is encouraging.
Animal research adds further support. Chlorophyll extracted from katuk leaves showed a blood-sugar-lowering effect in diabetic rats over a 14-day treatment, though the researchers flagged that tissue analysis of the liver, kidney, and pancreas showed higher damage scores than in healthy animals, raising questions about long-term safety at therapeutic doses.8Pharmacognosy Journal. Hypoglycemic and Antianemia Effects of Chlorophyll from Sauropus androgynus (L) Merr Leaves in Rats Separately, an experiment with female rabbits found that adding katuk leaf meal to their diet lowered both cholesterol and glucose over three weeks, while also modestly increasing red blood cell counts.9Animal Production. The effect of katuk (Sauropus androgynus L. Merr) leaf meal on cholesterol, glucose, erythrocyte, leukocyte, and thrombocyte of female rabbits
The cholesterol-lowering potential has also been studied in poultry. Broiler chickens fed a diet containing 14% fermented katuk leaves had carcass cholesterol drop by nearly 28%, from about 72 mg/100g down to around 52 mg/100g. The proposed mechanism involves beta-carotene from katuk inhibiting an enzyme (HMG-CoA reductase) that is central to cholesterol production, the same pathway that pharmaceutical statins target.10Pakistan Journal of Nutrition. Effect of Fermented Katuk Leaf (Sauropus androgynus L. Merr.) in Diets On Cholesterol Content of Broiler Chicken Carcass That is a compelling biological story, but translating results from chickens or rabbits to humans requires caution. No large-scale clinical trial has yet confirmed that eating katuk reliably lowers cholesterol in people.
Wound Healing Properties
Traditional use of katuk for wound care has some laboratory backing. Researchers made a gel from the ethyl acetate fraction of katuk leaves and tested it on burn wounds in rats. At a 20% concentration, the gel achieved a healing rate of about 83%, slightly outperforming a standard positive-control treatment. Even lower concentrations (10% and 5%) showed meaningful healing activity, at roughly 67% and 56% respectively.11Strada Journal of Pharmacy. Activity Testing Of Katuk Leaf Ethyl Acetate Fraction Gel Preparation (Sauropus Androgynus (L.) Merr.) On Healing Wistar Strain White Rat Burns The active compounds thought to be responsible include flavonoids, alkaloids, tannins, and saponins, all of which have known roles in tissue repair and inflammation control. This is strictly preclinical work, so nobody should be slathering katuk paste on a burn just yet, but it represents a plausible direction for future wound-care products.
The Taiwan Lung Disease Outbreak
No honest discussion of katuk can skip what happened in Taiwan in 1995. An outbreak of severe respiratory distress struck people who had been consuming large quantities of uncooked katuk juice, typically as a weight-loss remedy. Clinicians documented 23 patients with strikingly similar symptoms, and open lung biopsies in four of them confirmed bronchiolitis obliterans, a serious condition where the small airways become scarred and permanently narrowed.12The Lancet. Reversible airflow obstruction associated with Sauropus androgynus consumption A second outbreak was reported in Japan in 2005, reinforcing that this was not a one-off event.13PubMed Central. Sauropus androgynus (L.) Merr. Induced Bronchiolitis Obliterans: From Botanical Studies to Toxicology
The common thread in these cases was excessive consumption of raw or lightly processed katuk, often as concentrated juice rather than as a cooked vegetable in normal food portions. Studies on the topic describe a pattern of symptoms including drowsiness, constipation, and progressive breathing difficulty, with the worst cases leading to respiratory failure.13PubMed Central. Sauropus androgynus (L.) Merr. Induced Bronchiolitis Obliterans: From Botanical Studies to Toxicology The exact toxic compound responsible has been debated, with papaverine and other alkaloids among the suspects. What matters for anyone considering katuk is the distinction between traditional culinary use, which involves moderate amounts of cooked leaves, and the concentrated raw juice that caused these outbreaks.
How Preparation Changes the Risk
The question of raw versus cooked is central to katuk safety. Animal research has explored this directly. In one study, rats given katuk leaf juice at high doses (5,000 mg/kg body weight) showed significant narrowing of the bronchial airway compared to controls, confirming that concentrated juice can damage the lungs. Interestingly, the researchers noted that the toxic necrosis appeared to be dose-independent at certain thresholds, meaning that even moderate doses of the raw juice caused some airway changes, though the most severe damage occurred at the highest dose.14Academia.edu. ACUTE LUNG TOXICITY OF JUICE AND SOUP OF KATUK (Sauropus androgynus) LEAVES AS BREASTMILK BOOSTER RELATED TO BRONCHIOLITIS OBLITERANS
In contrast, a 28-day subchronic toxicity study in female rats fed katuk leaf soup (the cooked form) found no significant changes in liver enzyme levels (SGOT and SGPT) and no concerning histopathological changes in the liver or lungs. Creatinine levels did rise at higher doses (500 and 1,000 mg/kg body weight), suggesting some kidney stress, but overall the researchers concluded that katuk soup consumed for under 30 days was relatively safe.15Asian Journal of Pharmaceutical and Clinical Research. Subchronic Oral Toxicity Test For 28 Days Of Sauropus Androgynous L. Merr. Leaves Soup In Wistar Female Rats The practical implication is clear: cooking katuk, as traditional cuisine has always done, appears to reduce or eliminate the pulmonary risk that raw juice carries. The outbreaks were driven by a modern trend of juicing large quantities of raw leaves, not by centuries of eating them in soup.
Liver and Kidney Considerations
Beyond the lungs, researchers have looked at whether katuk affects the liver and kidneys. The results are mixed but generally reassuring at normal dietary levels. When katuk extract was combined with another plant extract and given to pregnant mice infected with E. coli, the combination at appropriate doses did not cause liver toxicity, with the lowest levels of necrotic cells observed in the liver.16Journal of Ayurveda and Integrative Medicine. Hormone-balancing and protective effect of combined extract of Sauropus androgynus and Elephantopus scaber against Escherichia coli-induced renal and hepatic necrosis in pregnant mice That finding fits with the broader theme: at sensible doses and in combination with other ingredients, katuk does not seem to be a liver problem.
The kidney signal is worth watching, though. As noted in the subchronic soup study, creatinine levels crept up at higher doses, which can indicate the kidneys are working harder to filter substances from the blood.15Asian Journal of Pharmaceutical and Clinical Research. Subchronic Oral Toxicity Test For 28 Days Of Sauropus Androgynous L. Merr. Leaves Soup In Wistar Female Rats And the rat study on chlorophyll extracts showed higher organ damage scores in the liver, kidney, and pancreas of diabetic animals given therapeutic-dose katuk, even though their blood sugar did improve.8Pharmacognosy Journal. Hypoglycemic and Antianemia Effects of Chlorophyll from Sauropus androgynus (L) Merr Leaves in Rats People with existing kidney disease or those considering katuk as a concentrated supplement rather than a food should be aware of this gap in the safety data.
Who Should Be Cautious
The overall safety picture for katuk breaks down along a few clear lines. If you are eating cooked katuk leaves as a vegetable in normal portions, the way people have done across Southeast Asia for generations, the existing evidence does not suggest meaningful risk. The nutritional value is real, and the lactation benefits have been demonstrated repeatedly in nursing mothers.
The risks rise sharply when people move beyond culinary use:
- Raw juice for weight loss: This is the preparation most strongly linked to bronchiolitis obliterans and should be avoided. The Taiwan and Japan outbreaks both involved concentrated raw juice consumed over weeks.
- High-dose supplements: Capsules and concentrated extracts deliver far more of katuk’s alkaloids per serving than a bowl of soup does. Without clear dosing guidelines from regulatory agencies, the margin of safety is unknown.
- Extended daily use: Even the relatively reassuring soup study only tested a 28-day window. There is no good data on what happens with months of continuous high-dose consumption.
- Pre-existing conditions: People with kidney problems, chronic lung conditions, or liver disease should treat katuk supplements with extra caution given the organ-specific signals in animal research.
Pregnant women represent a complicated case. Katuk is widely consumed during pregnancy and postpartum in Indonesia without widespread reports of harm, and the lactation studies generally report minimal side effects. But the long-term safety evaluations that would allow a definitive “safe in pregnancy” statement have not been done. If you are pregnant or nursing and want to try katuk for milk production, sticking with cooked leaves in food quantities, rather than concentrated supplements, is the more conservative approach.
Why Harvest Timing and Leaf Position Matter
One underappreciated aspect of katuk is how variable its composition can be. The study measuring nutritional content across different growth stages found that protein, vitamin C, calcium, and carbohydrate content all rose steadily as the plant matured from 60 to 120 days, while vitamin A moved in the opposite direction.2International Journal of Chemical Studies. Estimation of nutritive composition of Sauropus androgynus (Multivitamin plant) at different growth stages and position of leaves The position of leaves on the stem also made a real difference in nutrient concentrations.
This variability matters for anyone trying to use katuk intentionally, whether as a food, a supplement ingredient, or a research subject. Two batches of katuk leaf powder made from different-aged plants could have meaningfully different levels of the very compounds people are after. It also partly explains why traditional use emphasizes young shoots and tips for cooking: those tender leaves at the top of the plant have a different nutritional and chemical profile than the tougher, older leaves below. For supplement manufacturers, this kind of variability makes standardization genuinely difficult, and it is one reason why katuk products on the market may not deliver consistent results.
Where the Research Stands
Katuk sits in a frustrating middle ground that is common for traditional plants. The preliminary evidence for several benefits, lactation, antioxidant activity, blood sugar management, cholesterol reduction, and wound healing, is encouraging and spans multiple research groups and study designs. At the same time, almost all of this work consists of small trials, animal studies, and in-vitro experiments. No large randomized controlled trial has established katuk as a proven treatment for any condition in humans. The lactation evidence is the strongest, with multiple studies showing consistent results, but even there the sample sizes are modest by pharmaceutical standards.
The safety story is similarly incomplete. The lung disease outbreaks established a genuine danger from overconsumption of raw juice, and that warning stands. But the boundary between safe culinary use and risky overconsumption has never been precisely mapped in humans. Animal studies suggest cooked preparations at moderate doses are safe for at least a month, but the long-term picture remains an open question. For now, the most evidence-backed approach is the one that traditional cuisine already figured out: cook the leaves, eat them in reasonable amounts, and do not attempt to concentrate and juice them in large quantities for weight loss or any other purpose.