Betalains

Betalains are the vivid red-violet and yellow pigments that give beetroot its dramatic colour, staining a chopping board and famously tinting the plate. This unusual family of nitrogen-containing pigments is found in only a handful of plants, beetroot being by far the most familiar, and replaces the anthocyanins that colour most other red foods. Beyond their use as a natural food dye, betalains are valued for their potent antioxidant activity, which survives surprisingly well through gentle cooking but leaches readily into water.

Foods that contain betalains

Betalains occur only in plants of one order, the Caryophyllales, and where a plant makes them they take the place of anthocyanins — the two pigment families are mutually exclusive. That keeps the list short. The foods you are most likely to come across:

• Beetroot — by far the most common source. Red beetroot is coloured mainly by betanin, a red-violet betacyanin; golden beetroot by yellow betaxanthins.
• Swiss chard — the same plant species as beetroot, grown for its leaves; the red, pink and yellow stems of rainbow chard carry the same pigments.
• Prickly pear — the fruit of the Opuntia cactus, in red-purple and yellow-orange forms.
• Red-fleshed dragon fruit (pitaya) — the magenta flesh is coloured by betalains; the more common white-fleshed kind is coloured only in its skin.
• Red amaranth — the red-leaved varieties of this leafy green.
• Coloured quinoa — red-violet grains contain betanin and amaranthin, and yellow-orange grains betaxanthins.

Red cabbage, red onions, radishes, cherries and most berries look similar but are coloured by anthocyanins instead, so they are not betalain sources. Beetroot is the only food with a betalain figure in our database so far, which is why the table below has a single row.

Sources: Polturak G, Aharoni A. “La Vie en Rose”: biosynthesis, sources, and applications of betalain pigments. Mol Plant 2018;11:7–22, doi:10.1016/j.molp.2017.10.008. Polturak G et al. Transcriptome and metabolic profiling provides insights into betalain biosynthesis and evolution in Mirabilis jalapa. Mol Plant 2018;11:189–204, doi:10.1016/j.molp.2017.12.002. Escribano J et al. Characterization of betalains, saponins and antioxidant power in differently colored quinoa varieties. Food Chem 2017;234:285–294, doi:10.1016/j.foodchem.2017.04.187.