Pumpkins, and their seeds, are native to the Americas, and indigenous species are found across North America, South America, and Central America. The word “pepita” is consistent with this heritage, since it comes from Mexico, where the Spanish phrase “pepita de calabaza” means “little seed of squash.”
Pumpkin seeds were a celebrated food among many Native American tribes, who treasured them both for their dietary and medicinal properties. In South America, the popularity of pumpkin seeds has been traced at least as far back as the Aztec cultures of 1300-1500 AD. From the Americas, the popularity of pumpkin seeds spread to the rest of the globe through trade and exploration over many centuries. In parts of Eastern Europe and the Mediterranean (especially Greece), pumpkin seeds became a standard part of everyday cuisine, and culinary and medical traditions in India and other parts of Asia also incorporated this food into a place of importance.
Pumpkin seeds—also known as pepitas—are flat, dark green seeds. Some are encased in a yellow-white husk (often called the “shell”), although some varieties of pumpkins produce seeds without shells. Pumpkin seeds have a malleable, chewy texture and a subtly sweet, nutty flavor. While roasted pumpkins seeds are probably best known for their role as a perennial Halloween treat, these seeds are so delicious, and nutritious, that they can be enjoyed throughout the year. In many food markets, pepitas are available in all of the forms described above—raw and shelled, raw and unshelled, roasted and shelled, roasted and unshelled.
Most of the evidence we’ve seen about pumpkin seeds and prevention or treatment of diabetes has come from animal studies. For this reason, we consider research in this area to be preliminary. However, recent studies on laboratory animals have shown the ability of ground pumpkin seeds, pumpkin seed extracts, and pumpkin seed oil to improve insulin regulation in diabetic animals and to prevent some unwanted consequences of diabetes on kidney function. Decrease in oxidative stress has played a key role in many studies that show benefits of pumpkin seeds for diabetic animals.
Pumpkin seeds, pumpkin seed extracts, and pumpkin seed oil have long been valued for their anti-microbial benefits, including their anti-fungal and anti-viral properties. Research points to the role of unique proteins in pumpkin seeds as the source of many antimicrobial benefits. The lignans in pumpkin seeds (including pinoresinol, medioresinol, and lariciresinol) have also been shown to have antimicrobial—and especially anti-viral— properties. Impact of pumpkin seed proteins and pumpkin seed phytonutrients like lignans on the activity of a messaging molecule called interferon gamma (IFN-gamma) is likely to be involved in the antimicrobial benefits associated with this food.
Because oxidative stress is known to play a role in the development of some cancers, and pumpkin seeds are unique in their composition of antioxidant nutrients, it’s not surprising to find some preliminary evidence of decreased cancer risk in association with pumpkin seed intake. However, the antioxidant content of pumpkin seeds has not been the focus of preliminary research in this cancer area. Instead, the research has focused on lignans. Only breast cancer and prostate cancer seem to have received much attention in the research world in connection with pumpkin seed intake, and much of that attention has been limited to the lignan content of pumpkin seeds. To some extent, this same focus on lignans has occurred in research on prostate cancer as well. For these reasons, we cannot describe the cancer-related benefits of pumpkin seeds as being well-documented in the research, even though pumpkin seeds may eventually be shown to have important health benefits in this area.
Pumpkin seeds are generally available in prepackaged containers as well as bulk bins. Just as with any other food that you may purchase in the bulk section, make sure that the bins containing the pumpkin seeds are covered and that the store has a good product turnover so as to ensure the seeds’ maximal freshness. Whether purchasing pumpkin seeds in bulk or in a packaged container, make sure that there is no evidence of moisture or insect damage and that they are not shriveled. If it is possible to smell the pumpkin seeds, do so in order to ensure that they are not rancid or musty.
We recommend that you purchase certified organic raw pumpkin seeds and then light-roast them yourself (see next section on how to do so). By purchasing organic, you will avoid unnecessary exposure to potential contaminants. By purchasing raw, you will be able to control the roasting time and temperature, and avoid unnecessary damage to helpful fats present in the seeds. At the same time, you will be able to bring out the full flavors of the pumpkin seeds through roasting.
Pumpkin seeds should be stored in an airtight container in the refrigerator. While they may stay edible for several months, they seem to lose their peak freshness after about one to two months.