The areca nut (/ˈærɪkə/ or /əˈriːkə/) is the fruit of the areca palm (Areca catechu), which grows in much of the tropical Pacific (Melanesia and Micronesia), Southeast and South Asia, and parts of east Africa. This fruit is commonly referred to as betel nut so it is easily confused with betel (Piper betle) leaves that are often used to wrap it (paan). The term areca originated from the Malayalam word adakka (അടക്ക)[1] and dates from the 16th century, when Dutch and Portuguese sailors took the nut from Kerala to Europe. Consumption has many harmful effects on health and is carcinogenic to humans. Various compounds present in the nut, including arecoline (the primary psychoactive ingredient which is similar to nicotine), contribute to histologic changes in the oral mucosa. It is known to be a major risk factor for cancers (squamous cell carcinoma) of the mouth and esophagus. As with chewing tobacco, its use is discouraged by preventive efforts. Consumption by hundreds of millions of people worldwide – mainly with southern and eastern Asian origins – has been described as a "neglected global public health emergency".

The areca nut is not a true nut, but rather a fruit categorized as a berry. It is commercially available in dried, cured, and fresh forms. When the husk of the fresh fruit is green, the nut inside is soft enough to be cut with a typical knife. In the ripe fruit, the husk becomes yellow or orange, and as it dries, the fruit inside hardens to a wood-like consistency. At that stage, the areca nut can only be sliced using a special scissors-like cutter.

Usually for chewing, a few slices of the nut are wrapped in a betel leaf along with calcium hydroxide (slaked lime) and may include clove, cardamom, catechu (kattha), or other spices for extra flavouring. Betel leaf has a fresh, peppery taste, but it can also be bitter to varying degrees depending on the variety.

Areca nuts are chewed with betel leaf for their effects as a mild stimulant,[2] causing a warming sensation in the body and slightly heightened alertness, although the effects vary from person to person.

The areca nut contains the tannins arecatannin and gallic acid; a fixed oil gum; a little terpineol; lignin; various saline substances; and three main alkaloids—arecoline, arecaidine, and guvacine—all of which have vasoconstricting properties.[3] The betel leaf chewed along with the nut contains eugenol, another vasoconstrictor. Tobacco leaf is often added to the mixture, thereby adding the effect of nicotine.[4]

In parts of India, Sri Lanka, and southern China, areca nuts are not only chewed along with betel leaf, but are also used in the preparation of Ayurvedic and traditional Chinese medicines. Powdered areca nut is used as a constituent in some dentifrices.[5] Other traditional uses include the removal of tapeworms and other intestinal parasites by swallowing a few teaspoons of powdered areca nut, drunk as a decoction, or by taking tablets containing the extracted alkaloids.[5] According to traditional Ayurvedic medicine, chewing areca nut and betel leaf is a good remedy against bad breath.[6][unreliable source?] Diplomat Edmund Roberts noted that Chinese people would mix areca nut with Uncaria gambir during his visit to China in the 1830s.[7] After chewing a betelnut, the red residue, is generally spat out and is considered an eyesore. This has led many places to ban chewing this nut.[citation needed]

Systemic effects of areca nut
Areca nut affects almost all organs of the human body, including the brain, heart, lungs, gastrointestinal tract and reproductive organs. It causes or aggravates pre-existing conditions such as neuronal injury, myocardial infarction, cardiac arrhythmias, hepatotoxicity, asthma, central obesity, type II diabetes, hyperlipidemia, metabolic syndrome, etc. Areca nut affects the endocrine system, leading to hypothyroidism, prostate hyperplasia and infertility. It affects the immune system leading to suppression of T-cell activity and decreased release of cytokines. It has harmful effects on the fetus when used during pregnancy preparing betel leavesHabitual chewers of betel leaf and areca nut have a greatly increased risk of developing a range of serious diseases, including cancers of the mouth and esophagus.[13][14] It has many systemic effects (see box).[13]

Chewing areca nut alone has been linked to oral submucosal fibrosis.[15] According to Medline Plus, "Long-term use [of betel-areca preparations] has been associated with oral submucosal fibrosis (OSF), pre-cancerous oral lesions and squamous cell carcinoma. Acute effects of betel chewing include asthma exacerbation, hypertension, and tachycardia. There may additionally be a higher risk of cancers of the liver, mouth, esophagus, stomach, prostate, cervix, and lung with regular betel use. Other effects can include altered blood sugar levels, which may in turn increase the risk of developing type 2 diabetes."[16]

Use of areca nut has been associated with deterioration of psychosis in people with preexisting psychiatric disorders.[17] Areca nut consumption is also tied to chronic kidney disease in men.[18]

In 2003 the International Agency for Research on Cancer (IARC), a World Health Organization sponsored group, found sufficient evidence that the habit of chewing betel quid, with or without tobacco, causes cancer in humans.[4][19] Support for this conclusion is provided by a recent study which found that paan, even without concurrent tobacco use, is a risk factor for oral cancer. In October, 2009, 30 scientists from 10 countries met at IARC to reassess the carcinogenicity of various agents including areca nut, and mechanisms of carcinogenesis. They confirmed there is sufficient evidence that areca nut, with or without tobacco, can cause cancer.[20]

The harm caused by consumption of betel quid or areca nut by hundreds of millions of people worldwide (mainly with southern and eastern Asian origins and connections) has been characterized as a "neglected global public health emergency".[21]

During pregnancy
Chewing paan (and/or other areca nut and betel leaf formulations) during pregnancy significantly increases adverse outcomes for the baby.[22] The habit is associated with higher incidences of preterm birth and low birth weight and height.[13] Biologically, these effects may be a consequence of the arecoline that is found in areca nuts.[14] The habit also exposes the fetus to various other toxic components linked to cancer.[13]

Modern-day consumption
Paan
Hindi word for betel used for a stimulating and psychoactive preparation combined with areca nut and/or cured tobacco