By pumpkin (Cucurbita pepo), we mean common large pumpkins, as well as smaller members of the pumpkin family with orange or deep yellow flesh such as butternut squash, acorn squash, winter squash, spaghetti squash, harlequin squash, Hokkaido pumpkins, red kuri squash, and other small orange squashes. Pumpkins are good sources of micronutrients with cancer fighting properties.
These include alpha-carotene, beta-carotene, various cucurbitacins, and the lignan enterolactone. Pumpkin polysaccharide has been shown to possess significant cytoprotective effect and antioxidative activity.
Pumpkin seeds are dietary sources of beta-carotene, copper, iron, magnesium, manganese, squalene, vitamin E, zinc and lignan phytoestrogens. The major fatty acids in pumpkin seeds are oleic acid, linoleic acid and palmitic acid.
Dietary intake of pumpkin was found to be protective against head and neck cancer in one Eastern European study. Studies have found that those with very low plasma levels of alpha-carotene and beta-carotene are at a higher risk of gastric cancer. Intake of orange and yellow vegetables may also be protective against prostate cancer and non-Hodgkin lymphoma.
Postmenopausal women with breast cancer and a high intake of enterolactone have been found to be less likely to die from their breast cancer than those with a low intake. Enterolactone has also been found to increase the sensitivity of breast cancer cells to radiation, thereby potentially enhancing the treatment effects of radiotherapy.
Cucurbitacin E has been shown to inhibit triple negative breast cancer metastasis in the laboratory by suppressing cell migration and invasion. Most of the population-based breast cancer studies performed to date that specifically included pumpkins were conducted in Japan (since pumpkin consumption is higher there than in the U.S. or Europe). One Japanese study found that consuming vegetables (specifically including pumpkins) reduced the risk of gastric, breast, lung and colorectal cancer, regardless of the family history of cancer. Another Japanese study found reductions in breast cancer risk associated with high intakes of green-yellow vegetables (green leafy vegetables, carrots and pumpkins) among both premenopausal and postmenopausal women.
Pumpkin flesh and seeds should be eaten cooked or roasted, not raw. One study found that raw pumpkin juice increased chromosomal damage in bone marrow cells of experimental rats treated with a carcinogen whereas boiled pumpkin juice significantly suppressed it.
Pumpkin seed oil appears to have estrogenic activities, conferred by its lignan content. One study found that pumpkin seed oil supplementation prevented changes in plasma lipids and blood pressure associated with inadequate estrogen availability in experimental rats that had had their ovaries removed. The copper content of pumpkin seeds is another reason to limit their consumption since copper has been shown to increase angiogenesis and metastasis of breast cancer.
Below are links to recent studies concerning this food. For a more complete list of studies, please click on pumpkin.