Papaya Nutritional Values, Benefits and Side Effects
updated on October 05, 2012
Papaya, Carica Papaya

Probably, papaya is native to Central America. The papaya is a melon like fruit with
yellow-orange flesh enclosed in a thin skin that varies in color from green to orange to rose.
Today papaya can be found all year long with the peak season being early summer and fall.
Most of the papayas imported come from Hawaii, but smaller quantities from Florida,
California, Mexico, Puerto Rico, and Central and South American countries are becoming
more available.

Look for papayas that are partly or completely yellow in color. Papayas that are hard and
green are immature and will not ripen properly. Uncut papayas have no smell. Papayas that
are cut should smell sweet, not bad or fermented. Slightly green papayas will ripen quickly at
room temperature, especially if placed in a paper bag. As the papaya ripens, it will turn from
green to yellow. Place ripe papayas in a plastic bag and store in the refrigerator. Papayas will
keep for up to a week, but it's best to use them within a day or two.

There are two types of papayas, the Hawaiian and Mexican. The Hawaiian varieties also
known as Solo papayas, are found most often in supermarkets. These fruits are pear shaped,
weigh about a pound each, and have yellow skin when ripe. The flesh is bright orange or
pinkish, depending on the variety. The Mexican varieties are not as common but can be found
in Latino supermarkets. Mexican papayas are much larger then the Hawaiian types and can
weigh up to 20 pounds and be more than 15 inches long. Although the flavor is less intense
than the Hawaiian varieties, they are still delicious and enjoyable.

Papayas are a rich source of vitamin A and C. One half of a small papaya can provide 150%
of the recommended dietary intake of Vitamin C. It is low in calories, fat free, cholesterol free,
and a good source of potassium, folate, and fiber.

The papaya enzyme called papain, is used as a meat tenderizer. It breaks down tough meat
fibers. Its use is nothing new. South American cooks have been using papaya to tenderize
meat for ages. It is sold as a component in powdered meat tenderizer available in most

Consumption of papaya may cut risk of certain cancers. Various isothiocyanates are effective
anti-cancer agents in experimental animals. Several epidemiological studies also indicated
that the dietary consumption of isothiocyanates or foods containing isothiocyanates inversely
correlates with the risk of developing lung, breast, and colon cancers. [10]

Researchers conducted a study of 165 cases to evaluate the role of diet in gallbladder
carcinogenesis. They found that consumption of radish, green chilli, sweet potato, mango,
orange, melon, papaya, cruciferous vegetables, beans, onion and turnip are linked with low
risk of gallbladder cancer. [3]

Papaya is a good source of nutrients and some phyto-chemicals such as beta-cryptoxanthin
and benzyl isothiocyanates. It is believed that these phytochemicals may offer benefits on
certain chronic conditions such as cancers.

Dietary tocopherols and carotenoids have been believed to cut risks of certain cancer and
cardiovascular diseases. Researchers observed that subjects that frequently consumed
papaya, tangerine, orange or watermelon had high plasma beta-cryptoxanthin concentrations.

In vitro studies, isothiocyanates induced apoptosis in various cancer cell lines and
experimental rodents via modulation of multiple signal-transduction pathways and apoptosis
intermediates. Recently, Japanese researchers recently has shown the benzyl isothiocyanate
extracted from papaya could also induce toxicity more preferentially in the proliferating human
colon epithelial cells than in the quiescent cells. [1]

Recently, Otsuki N and co-workers from The University of Tokyo showed that Carica papaya
leaf extract mediated a Th1 type shift in human immune system; they believe it is an evidence
that the papaya leaf extract may benefit people at risk of cancer. [8]

Researchers from Mexico evaluated the antiproliferative effect of aqueous extracts of 14 plant
foods consumed in Mexico on the breast cancer cell line MCF-7. Only the papaya extract had
a significant antiproliferative effect measured with the methylthiazolydiphenyl-tetrazolium
bromide assay. [9]

Other possible benefits of papaya

Researchers suggested the use of Carica papaya to treat symptoms related to venous and
lymphatic vessel insufficiency, and other free-radicals conditions. [4,6] Fruit juice of Carica
papaya demonstrates blood pressure lowering activities via alpha-adrenoceptor route in a
study of mice. [5]

Side effects of Papaya Consumption
Though marketers suggest that papaya consumption lowers high cholesterol levels,
researchers actually noticed a significant increase of plasma total cholesterol and triglyceride
level after four weeks of excessive papaya consumptions in a study. [7] Definitely, more
studies are needed to confirm this observation.

[1] Nakamura Y, Miyoshi N. Cell death induction by isothiocyanates and their underlying molecular mechanisms. Biofactors.
2006;26(2):123-34. [2] Irwig MS, et al, Frequent intake of tropical fruits that are rich in beta-cryptoxanthin is associated with higher plasma
beta-cryptoxanthin concentrations in Costa Rican adolescents. J Nutr. 2002 Oct;132(10):3161-7. [3] Pandey M, Shukla VK. Diet and
gallbladder cancer: a case-control study. Eur J Cancer Prev. 2002 Aug;11(4):365-8. [4] Savickiene N, et al, Importance of biologically
active components and plants in the prevention of complications of diabetes mellitusMedicina (Kaunas). 2002;38(10):970-5. [5] Eno AE,
Owo OI, Itam EH, Konya RS. Blood pressure depression by the fruit juice of Carica papaya (L.) in renal and DOCA-induced hypertension
in the rat. Phytother Res. 2000 Jun;14(4):235-9. [6] Imao K, Wang H, Komatsu M, Hiramatsu M. Free radical scavenging activity of
fermented papaya preparation and its effect on lipid peroxide level and superoxide dismutase activity in iron-induced epileptic foci of
rats. Biochem Mol Biol Int. 1998 Jun;45(1):11-23. [7] Rahmat A, Abu Bakar MF, Faezah N, Hambali Z. The effects of consumption of
guava (psidium guajava) or papaya (carica papaya) on total antioxidant and lipid profile in normal male youth. Asia Pac J Clin Nutr.
2004;13(Suppl):S106. [8] Otsuki N, Dang NH, Kumagai E, Kondo A, Iwata S, Morimoto C. Aqueous extract of Carica papaya leaves
exhibits anti-tumor activity and immunomodulatory effects. J Ethnopharmacol. 2010 Feb 17;127(3):760-7. Epub 2009 Dec 2. [9]
Garcia-Solis P, Yahia EM, Morales-Tlalpan V, Diaz-Munoz M. Screening of antiproliferative effect of aqueous extracts of plant foods
consumed in Mexico on the breast cancer cell line MCF-7. Int J Food Sci Nutr. 2009 May 26:1-15. [10] Nakamura Y. Chemoprevention by
isothiocyanates: molecular basis of apoptosis induction. Forum Nutr. 2009;61:170-81. Epub 2009 Apr 7.