or molasses to make a treat called alegría (literally "joy" in Mexican Spanish).

Amaranth was used in several Aztec ceremonies, where images of their gods (notably Huitzilopochtli) were made with amaranth mixed with honey. The images were cut to be eaten by the people. This looked like the Christian communion to the Roman Catholic priests, so the cultivation of the grain was forbidden for centuries.

Because of its importance as a symbol of indigenous culture, and because it is very palatable, easy to cook, and its protein particularly well suited to human nutritional needs, interest in grain amaranth (especially A. cruentis and A. hypochondriaca) was revived in the 1970s. It was recovered in Mexico from wild varieties and is now commercially cultivated. It is a popular snack sold in Mexico City and other parts of Mexico, sometimes mixed with chocolate or puffed rice, and its use has spread to Europe and North America. Besides protein, amaranth grain provides a good source of dietary fiber and dietary minerals such as iron, magnesium, phosphorus, copper, and especially manganese.

The flowers of the Hopi Red Dye amaranth were used by the Hopi Indians as the source of a deep red dye. This dye has been supplanted by a coal tar dye known as Red No. 2 in North America and E123 in the E.E.C., also known as amarynth.

The genus also contains several well-known ornamental plants, such as A. caudatus (love-lies-bleeding), a native of India and a vigorous, hardy annual with dark purplish flowers crowded in handsome drooping spikes. Another Indian annual, A. hypochondriacus (prince's feather), has deeply-veined lance-shaped leaves, purple on the under face, and deep crimson flowers densely packed on erect spikes.

Amaranths are recorded as food plants for some Lepidoptera species including The Nutmeg and various case-bearers of the genus Coleophora: C. amaranthella, C. enchorda (feeds exclusively on Amaranthus), C. immortalis (feeds exclusively on Amaranthus), C. lineapulvella and C. versurella (recorded on A. spinosus).

Use as a leaf vegetable
Amaranth species are cultivated and consumed as a leaf vegetable in many parts of the world. In Indonesia, Malaysia, and China it goes by the name "bayam". In Andhra Pradesh in India the leaf is added in preparation of popular dal called thotakura pappu. In Congo it is known as "lenga lenga" or "biteku teku".

The leaves are also used in a Caribbean soup called Callaloo.

It is commonly but incorrectly translated to and from English as spinach (including in Popeye cartoons).

Amaranth as weed
Not all amaranth plants are cultivated. Some appear as weeds. A new strain of the Palmer amaranth has appeared which is glyphosate-resistant and as a result cannot be killed by the widely used Roundup herbicide. Also, this hardy plant can survive in tough conditions. This could be of particular concern to cotton farmers using Roundup Ready cotton. Some people are very allergic to amaranth.

Nutritional value
Amaranth greens, also called Chinese spinach, hinn choy or yin tsoi (Simplified Chinese: 苋菜; pinyin: xiàncài), callaloo, thotakura (telugu) , tampala, or quelite, are a common leaf vegetable throughout the tropics and in many warm temperate regions. It is very popular in Andhra Pradesh. They are a very good source of vitamins including vitamin A, vitamin B6, vitamin C, riboflavin, and folate, and dietary minerals including calcium, iron, magnesium, phosphorus, potassium, zinc, copper, and manganese. Because of its valuable nutrition, some farmers grow amaranth today. However their moderately high content of oxalic acid inhibits the absorption of calcium, and also means that they should be avoided or eaten in moderation by people with kidney disorders, gout, or rheumatoid arthritis. Reheating cooked amaranth greens is often discouraged, particularly for consumption by small children, as the nitrates in the leaves can be converted to nitrites, similarly to spinach.

Amaranth seeds, like buckwheat and quinoa, contain protein that is unusually complete for plant sources. Most plants do not contain a complete set of amino acids, and thus different sources of protein must be used.