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 have long been valued as a source of the mineral zinc, and the World Health Organization recommends their consumption as a good way of obtaining this nutrient. If you want to maximize the amount of zinc that you will be getting from your pumpkin seeds, we recommend that you consider purchasing them in unshelled form. Although recent studies have shown there to be little zinc in the shell itself (the shell is also called the seed coat or husk), there is a very thin layer directly beneath the shell called the endosperm envelope, and it is often pressed up very tightly against the shell. Zinc is especially concentrated in this endosperm envelope. Because it can be tricky to separate the endosperm envelope from the shell, eating the entire pumpkin seed—shell and all—will ensure that all of the zinc-containing portions of the seed will be consumed. Whole roasted, unshelled pumpkin seeds contain about 10 milligrams of zinc per 3.5 ounces, and shelled roasted pumpkin seeds (which are often referred to pumpkin seed kernels) contain about 7-8 milligrams. So even though the difference is not huge, and even though the seed kernels remain a good source of zinc, you'll be able to increase your zinc intake if you consume the unshelled version.
- While pumpkin seeds are not a highly rich source of vitamin E in the form of alpha-tocopherol, recent studies have shown that pumpkin seeds provide us with vitamin E in a wide diversity of forms. From any fixed amount of a vitamin, we are likely to get more health benefits when we are provided with that vitamin in all of its different forms. In the case of pumpkin seeds, vitamin E is found in all of the following forms: alpha-tocopherol, gamma-tocopherol, delta-tocopherol, alpha-tocomonoenol, and gamma-tocomonoenol. These last two forms have only recently been discovered in pumpkin seeds, and their health benefits—including antioxidant benefits—are a topic of current interest in vitamin E research, since their bioavailability might be greater than some of the other vitamin E forms. The bottom line: pumpkin seeds' vitamin E content may bring us more health benefits that we would ordinarily expect due to the diverse forms of vitamin E found in this food.
The diversity of antioxidants in pumpkin seeds makes them unique in their antioxidant support. Pumpkin seeds contain conventional antioxidant vitamins like vitamin E. However, not only do they contain vitamin E, but they contain it in a wide variety of forms. Alpha-tocopherol, gamma-tocopherol, delta-tocopherol, alpha-tocomonoenol and gamma-tocomonoenol are all forms of vitamin E found in pumpkin seeds. These last two forms have only recently been discovered, and they are a topic of special interest in vitamin E research, since their bioavailability might be greater than some of the other vitamin E forms. Pumpkin seeds also contain conventional mineral antioxidants like zinc and manganese. Phenolic antioxidants are found in pumpkin seeds in a wide variety of forms, including the phenolic acids hydroxybenzoic, caffeic, coumaric, ferulic, sinapic, protocatechuic, vanillic, and syringic acid. Antioxidant phytonutrients like lignans are also found in pumpkin seeds, including the lignans pinoresinol, medioresinol, and lariciresinol.
Interestingly, this diverse mixture of antioxidants in pumpkin seeds may provide them with antioxidant-related properties that are not widely found in food. For example, the pro-oxidant enzyme lipoxygenase (LOX) is known to be inhibited by pumpkin seed extracts, but not due to the presence of any single family of antioxidant nutrients (for example, the phenolic acids described earlier). Instead, the unique diversity of antioxidants in pumpkin seeds is most likely responsible for this effect.
Other Health Benefits
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.
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.