Edible amaranth

Edible amaranth (Amaranthus tricolor L.) belongs to the family Amaranthaceae and is an annual herb with a stout, erect stem, growing 0.8–1.5 m tall; it is extremely variable, with ovate to lanceolate alternate leaves coloured green, lime, red-purple or blotched red/yellow depending on the cultivar. The inflorescences are dense axillary clusters and thick terminal panicles of tiny unisexual flowers, greenish to pink; the genus name comes from the Greek amarantos, 'unfading', because the dry flowers do not wilt. The circumscissile capsule holds 1–2 very small, glossy black seeds about 1 mm across; the seeds of grain-type amaranths are eaten as a staple.

According to Plants of the World Online (Kew, 2025) the native range is tropical Asia: India, Bangladesh, Assam, Nepal and Sri Lanka, through Indochina (Myanmar, Thailand, Laos, Cambodia, Vietnam) to Malesia (Malaya, Java, Sumatra, Borneo, Sulawesi, Maluku, the Lesser Sunda Islands, the Philippines) and New Guinea with the Solomon Islands. PROTA (Grubben, 2004) considers the species to originate in tropical Asia, domesticated in prehistoric times and the most important vegetable amaranth of South and Southeast Asia; the wild ancestor is unknown. Today it is cultivated and naturalised throughout tropical and subtropical regions, including China, Japan, Korea, Taiwan, East Africa and many African, Caribbean and American countries.

The characteristic pigments of red amaranth are betacyanins, dominated by amaranthin and its isomer isoamaranthin, with betanin/isobetanin and acylated derivatives (identified by MALDI-MS, J. Agric. Food Chem., 2006; a 52-compound profile of baby leaves in Molecules, 2023). In red cultivars, betalain content reaches about 1,122 ng/g fresh leaves, carotenoids about 55 mg/100 g and vitamin C about 122 mg/100 g (Scientific Reports, 2019). The leaves also contain 24 phenolic acids and flavonoids, including salicylic, vanillic, gallic, chlorogenic, caffeic, ferulic and p-coumaric acids and rutin, isoquercetin, hyperoside, quercetin, kaempferol, catechin, myricetin and apigenin (Scientific Reports, 2020) — together with iron, calcium, protein containing lysine and methionine, and dietary fibre.

In Vietnam, amaranth is boiled, cooked in shrimp or crab soup, or stir-fried with garlic — a familiar summer green; in China, Korea and Japan it is stir-fried with garlic or served as namul, while grain-type amaranths provide seed staples in Andean and Asian cuisines. In research, amaranth leaf extracts are potent inhibitors of cyclooxygenase and suppress the growth of several human cancer cell lines (Jayaprakasam et al., 2004); Sarker & Oba (Scientific Reports, 2019–2020) found strong correlations between betacyanins, carotenoids, vitamin C, polyphenols and DPPH/ABTS antioxidant activity. Baby leaves also show antimicrobial activity, especially against Gram-positive bacteria, and maleic acid displayed antifungal potential (Molecules, 2023).

On safety, like many leafy greens, amaranth contains oxalic acid and may accumulate nitrates, so it is best eaten cooked (boiled, souped or stir-fried) rather than raw in large amounts; discarding the cooking water reduces oxalate. People with a history of kidney stones should eat it in moderation. For conservation, the species is Not Evaluated on the IUCN Red List and is not in CITES; as one of the most important leaf vegetables of South and Southeast Asia (PROTA), widely grown throughout the tropics, it is not threatened. Germplasm is held by gene banks such as the NBPGR (India), the OGFR (USA) and the AVRDC (Taiwan), together with many national collections of local cultivars.