Papaya Seed for Intestinal Parasites

Papaya seeds are a traditional remedy for intestinal parasites, and two trials in children support that use, weakly. In Nigeria, one dose of a seed and honey elixir cleared parasites from the stools of 23 of 30 children (76.7%), against 5 of 30 (16.7%) given honey alone (P = .0000109) (Okeniyi 2007). In Kenya, daily porridge made with ground seed cut roundworm egg counts by 63.9% over two months (Kugo 2018).

The catch is quality. The Nigerian study was a 60-child pilot with a 7-day follow-up, and the Kenyan study put one whole school in each arm, so the schools themselves could explain part of the gap (Kugo 2018). In Kenya, a single 400 mg dose of albendazole reduced egg counts by 78.8%, more than two months of papaya porridge (Kugo 2018). The CDC describes standard drug treatment for common worms as highly effective, with courses of one to three days (CDC 2024).

Papaya seeds hold more than 1 mmol of benzyl glucosinolate per 100 g of fresh seed, while the fruit's flesh has an undetectable amount (Nakamura 2007). When the seed is crushed, its own myrosinase enzyme turns this into benzyl isothiocyanate (BITC), yielding about 460 micromol per 100 g of seed (Nakamura 2007).

A lab study that tested seed extracts against a model worm (C. elegans, not a human parasite) found anti-worm activity tracked BITC content in every preparation (Kermanshai 2001). Extracts of heat-treated seeds had neither BITC nor any anti-worm effect unless the seed enzyme was added back, and crude extracts lost some activity after standing 10 hours at room temperature (Kermanshai 2001). The authors concluded BITC is best explained as the main or sole anti-worm agent (Kermanshai 2001).

In rats infected with a tapeworm, papaya seed at 0.6 or 1.2 g/kg body weight cut egg output by about 96% and worm counts by 91-94% (Sapaat 2012). In infected mice, a dried seed extract at 1.2 g/kg reduced worm burden and damaged the worms' outer surface, though more slowly than the drug praziquantel (Abou Shady 2014).

Animal doses don't translate directly to people, and none of these studies tells us the right human dose. Because heat stopped BITC forming in the lab (Kermanshai 2001), it is also unclear how much active compound children got from the cooked Kenyan porridge (Kugo 2018).

No dose of papaya seed has been established for anyone. The Kenyan trial milled maize, millet and papaya seeds in a 5:1:2.5 ratio, so each child's 300 mL of daily porridge held about 10 g of seed, given for two months (Kugo 2018). The Nigerian trial gave a single 20 mL dose of an elixir of air-dried seed and honey (Okeniyi 2007).

The trial authors themselves said the most effective dose and frequency were not known (Kugo 2018). No trial has tested adults or capsule products, so a label dose on a supplement has no trial behind it.

Sixty asymptomatic Nigerian children with parasites on stool microscopy were randomised to one 20 mL dose of an elixir of air-dried papaya seed and honey, or honey alone (Okeniyi 2007). Seven days later, stools were clear in 23 of 30 children given papaya (76.7%) and 5 of 30 given honey (16.7%), with no harmful effects reported (Okeniyi 2007).

Clearance by parasite type ranged from 71.4% to 100% with papaya and 0-15.4% with honey (Okeniyi 2007). The trial was small, followed children for one week, and the authors called for larger studies against standard drugs (Okeniyi 2007).

In Nandi County, Kenya, three primary schools were each assigned to one arm: porridge with ground papaya seed daily, plain porridge, or plain porridge plus one 400 mg albendazole dose (Kugo 2018). Of 326 children aged 4-12, 243 had complete data at 8 weeks (Kugo 2018).

Mean roundworm egg counts fell 63.9% in the papaya school (209.7 to 75.7 eggs per gram, p < 0.002) and 78.8% in the albendazole school, while counts rose slightly in the control school (Kugo 2018). Haemoglobin rose about 2 g/dL in the papaya group, but every arm received micronutrient-fortified porridge, and the authors attributed the rise mostly to that fortification (Kugo 2018).

The authors listed the limits themselves: one school per arm, roundworm only, and an unknown best dose (Kugo 2018). The control school also started with significantly more roundworm infection than the others, and the trial was registered only after it ended (Kugo 2018).

There is no trial in adults, no trial of a capsule or powder supplement, and no comparison with mebendazole or a repeat albendazole course. Neither trial tested whipworm or hookworm in enough children to judge, and neither followed children long enough to look at reinfection.

The Nigerian trial reported no harmful effects after its single dose (Okeniyi 2007); the Kenyan two-month trial did not report on side effects (Kugo 2018). The safety concerns come from animal and lab studies, which used concentrated extracts at doses well beyond food amounts.

In male rats, an oral aqueous seed extract reduced sperm count and motility and brought fertility to zero at the higher dose after 60 days; fertility returned within 45 days of stopping (Lohiya 1994). In langur monkeys, a chloroform seed extract at 50 mg/kg a day caused a complete lack of sperm after day 90, reversing about 150 days after stopping (Lohiya 2002). Seed extracts also killed or slowed human sperm in the test tube (Lohiya 2000; Ghaffarilaleh 2019).

In pregnant rats, an aqueous extract at 800 mg/kg caused vaginal bleeding and resorption of about 30% of fetuses, while at 100 mg/kg there were no fetal deaths or malformations but fetal weight was significantly lower (Oderinde 2002). An ethanol seed extract damaged isolated rat uterine tissue at high concentrations (Adebiyi 2003).

No study has tested papaya seed alongside medicines, including the antiparasitic drugs used to treat worms.