If you simply throw away your papaya seeds, you may be missing out on a nutrient-dense addition to your health regimen.
What Are Papaya Seeds?
Papaya seeds are the small, round, black seeds found in the center of the papaya fruit, which bears the scientific name Carica papaya. When you split open a papaya, there may be dozens or even hundreds of these black seeds in the middle, and the majority of people simply throw these seeds away. However, not only are they edible, but they have a huge wealth of nutrients, as well as a unique taste that makes them one of the more palatable fruit seeds. 
You can scoop out the seeds and rinse them off, as they are usually covered in a gelatinous casing. Once they are rinsed and dried, they can be eaten as is, providing a slightly spicy, peppery flavor, or they can be ground down to use as a spice, or added to salads, soups, sauces and dressings as a flavorful and nutritious addition.
Papaya Seeds Nutrition
Papaya seeds contain a surprisingly large amount of nutrients, including high levels of fat, protein, and magnesium, as well as dietary fiber, calcium, and phosphorous. Most importantly, however, these seeds are good sources of papain, the particular enzyme in papayas that is so closely linked to digestive health. These seeds also have various alkaloids, proteolytic enzymes, and other active ingredients that provide quite a few benefits to overall health. 
Papaya Seeds Benefits
The most impressive benefits of papaya seeds include their ability to boost kidney health, regulate digestion, treat inflammation and pain related to arthritis, strengthen the immune system, and aid in weight loss, among others.
Antioxidants and vitamins present in these seeds can help boost the free radical defenses of your body, reducing wrinkles, and signs of aging. 
Detoxify the Body
Studies have shown that these seeds and their enzyme components can help stimulate kidney function and reduce toxicity levels in the body.
Often used as a natural treatment for pain and inflammation related to arthritis and other chronic conditions.
Boost Immune System
The phenolic compounds and flavonoids found in these seeds will defend your body against foreign pathogens and potential infections. 
Research conducted by Dr. Mojica Henshaw MP, Francisco AD et al. have shown that papaya seeds have immunomodulatory components that can potentially slow, stop or reverse tumor growth for certain types of cancer. According to a report published in the Journal of Pharmacognosy and Phytochemistry, papaya seeds can stop the growth of cancer cell, halt metastasis and normalize cell cycle. However, more scientific study and research studies are required to support this claim.  
Aid in Digestion
Papain is a digestive enzyme that can regulate nutrient uptake, bowel movements and the bacterial environment of your gut. 
Papaya Seed Side Effects
Despite the many benefits, there are some side effects to consider, such as its effect on blood pressure, fertility, and heart health. Also, consuming an excessive amount of these seeds can result in toxicity due to the presence of ethyl benzothiocyanate, which can manifest as gastrointestinal problems and allergic reactions.
Studies have found that these seeds can lower blood pressure, but combined with other blood pressure medications, it can be dangerous.
These seeds have been traditionally known as a male contraceptive, so if you are trying to have a baby, avoid eating these seeds. 
There is a high level of fat in these seeds, so an excessive amount can throw off your cholesterol levels and increase your risk of certain cardiovascular issues.