Carrot

The carrot (Daucus carota subsp. sativus) is a biennial herb, usually grown as an annual. In its first year it forms only a ground-hugging rosette: the leaves are 2–3-pinnately compound, divided into many narrow segments so they look feathery, about 30–60 cm long; at the same time the taproot swells into a storage root, cylindrical to conical, 5–50 cm long, with skin coloured orange, yellow, white, red or purple and firm, crisp flesh. In the second year it sends up a branched flowering stem 30–100 cm tall; the flowers form compound umbels of many small white flowers (the central flower is sometimes purple-red), the simple umbels combining into the compound umbel typical of the carrot family. The fruit is a dry schizocarp that splits into two ridged, prickly mericarps, each with one seed; the whole plant is aromatic because of its essential oil. It is propagated mainly by seed.

According to Kew POWO, the species Daucus carota is native from Macaronesia to N. Africa and Ethiopia, and from Europe to S. China, whereas the cultivated subspecies Daucus carota subsp. sativus is a cultigen originating from Central Asia to Afghanistan. Wild carrot (Queen Anne's lace) is thought to have originated on the Iranian Plateau — an area now including Iran, Afghanistan and Pakistan. Carrot was domesticated once in Central Asia about 1,100 years ago (around the 10th century); a genetic-structure study by Iorizzo et al. (American Journal of Botany, 2013) confirmed a single origin in Central Asia, from where it spread to Asia Minor (10th–11th century), Spain (12th century), north-western Europe (15th century), and eastwards to China (13th–14th century) and Japan (17th century). The first carrot roots were purple and yellow; only in the 17th century did selection of yellow carrots in the Netherlands produce the β-carotene-rich orange carrot of today. Carrots are now grown worldwide; according to FAO, world output of carrots and turnips exceeded 42 million tonnes in 2022, with China accounting for about 44%. In Vietnam carrots are grown mainly around Da Lat (Lam Dong) and in the winter crop of the northern lowlands.

Chemically, the most notable components of the carrot root are the orange-pigmented carotenoids: in orange roots, β-carotene makes up about 75% of total carotenoids, α-carotene about 23%, and the rest are lutein (about 1.9%), β-cryptoxanthin, zeaxanthin and lycopene; both β-carotene and α-carotene are provitamin A. β-carotene accumulation is controlled by genes such as Y2, clarified by the high-quality carrot genome (Iorizzo et al., Nature Genetics, 2016). Carrots are also characterised by the C17 polyacetylenes typical of the carrot family, mainly falcarinol, falcarindiol and falcarindiol-3-acetate. The root further contains phenolic acids (notably chlorogenic acid), α-tocopherol (vitamin E), vitamin C, vitamin K1, potassium and fibre/pectin, together with soluble sugars (sucrose, glucose, fructose). Purple cultivars are rich in anthocyanins; carrot seeds yield an aromatic essential oil (geranyl acetate, sabinene, carotol…), so the seeds and leaves are also used as a spice. Cooking with a little fat markedly increases carotenoid absorption.

Carrot is a popular root vegetable: the root is eaten raw in salads, boiled, steamed, stir-fried, in soups and stews, roasted, juiced, and made into cakes, jams and baby food; young leaves are used as a herb, the seeds as a spice (similar to caraway) and for essential oil; industry makes juice, purée, carrot powder and a natural food colour from β-carotene. In Vietnam carrots are grown mainly around Da Lat and in the winter crop of the lowlands, used in soups, stir-fries and salads. In research, carrot is an important model for carotenoid accumulation: a high-quality genome was published in Nature Genetics (2016), and its origin and domestication were clarified in the American Journal of Botany (Iorizzo et al., 2013). The polyacetylenes falcarinol/falcarindiol were shown to inhibit the formation of neoplastic lesions in the rat colon (Kobaek-Larsen et al., Food & Function, 2017; earlier in mice, 2005) and were reviewed in J. Agric. Food Chem. (Dawid et al., 2015); a newly described polyacetylene, isofalcarintriol, extends lifespan and improves metabolism in the nematode C. elegans and in mice (Nature Communications, 2023). Carrot is also an important source of provitamin A for preventing vitamin A deficiency and has been studied for the link between carrot intake and cancer risk (Nutrients, 2023).

As food, carrot is healthy; because β-carotene is provitamin A, eating plenty of carrots does not cause vitamin A toxicity (unlike high-dose retinol), but very large intakes over a long time may tint the skin yellow (carotenemia) — a harmless effect that fades when intake falls. Note: polyacetylenes such as falcarinol and the furocoumarins in the leaves can cause contact dermatitis and photosensitivity in sensitive people; in particular, wild carrot (Queen Anne's lace) is very easily confused with poison hemlock (Conium maculatum) and other toxic umbellifers, so never harvest wild umbellifers to eat unless you are certain of the species. Carrot juice is high in sugar, so people with diabetes should watch portion size, and sprouted, mouldy or over-mature, fibrous roots should be discarded. On conservation, Daucus carota is Not Evaluated (NE) on the IUCN Red List and is not listed in the CITES appendices; the wild species is widespread, and Kew holds more than 80 seed samples in its Millennium Seed Bank. The main risk is erosion of local cultivar diversity (traditional purple, yellow and white varieties) when only a few commercial varieties are grown; conserving landraces and wild Daucus relatives is therefore important because they hold valuable genes for disease resistance and carotenoid content.