Unless you live in a sunshine climate like southern California, winter is usually associated with darkness and a shortage of fresh produce. The farmer’s markets are all packed up and everyone’s holed up at home, waiting it out.
But just because fresh produce isn’t growing where you live during the winter, doesn’t mean you can’t enjoy autumn’s bounty of nutrient-dense, cancer-fighting foods all through the dark, cold months.
There’s one fruit in particular, found in half a dozen varieties with names like “delicata,” “turban” and “hubbard,” that’s abundant all winter long and is packed with nutrients that keep your cells healthy and help to fight off cancer…
This powerhouse food is winter squash. Winter squash (a fruit in the gourd family (Cucurbitaceae, but which we commonly refer to as a vegetable) is called such because it’s harvested in late fall into early winter, and its hard outer shell makes it good for curing and storing over the winter.
Types of winter squash include the above-mentioned, plus butternut, acorn and spaghetti squash. Pumpkins too, are winter squash, and they’re great for more than just carving.
They’re packed with nutrients that nourish your cells and help to keep cancer away…
Important minerals in winter squash
Winter squash contains a large amount of fiber so you feel full faster when you eat. Plus, it’s full of potassium and minerals like magnesium, niacin and most importantly, zinc.
The trace mineral zinc is crucial to protecting men’s health, especially from prostate cancer. Prostate cells have a unique ability to store large amounts of zinc, which they use in secreting prostatic fluid.
Studies have shown that high levels of zinc in the prostate inhibit invasive activity of malignant prostate cancer cells, and exert anti-tumor activity.(1)
Incidents of prostate cancer have been associated with zinc deficiencies as well,(2) so it’s important for men to get enough dietary zinc to maintain a healthy prostate. The Institute of Medicine has established adequate intake (AI) levels of zinc at 11 milligrams (mg) a day for boys and men age 14 and older.(3)
One cup of dried, roasted pumpkin seeds, also known as pepitas, contains 16.9 mg of zinc. You can make them yourself at home (see below) or buy them at the grocery store. Just be sure to check the label, as some store-bought kinds contain unhealthy oils and excess salt.
The best source of cancer-fighting carotenoids
Winter squashes contain carotenoids, important phytochemicals with antioxidant properties that give certain fruits and veggies their red, yellow and orange colors. Carotenoids – which include nutrients such as vitamin A, beta-carotene and beta-Cryptoxanthin – have been shown to help the body prevent the development of cancer.(4)
Not only that, but winter squash has some of the highest concentrations of beta-Cryptoxanthin, which protects against lung and colon cancer, of any fruit around (only red peppers have more).
In a study published in the Japanese Journal of Cancer Research, dietary beta-Cryptoxanthin was shown to reduce the risk of colon carcinogenesis in an animal model.(5) And another study of Chinese men in Shanghai, China supported previous evidence that beta-Cryptoxanthin helps to reduce the incidence of lung cancer in humans.(6)
Researchers have found that beta-Cryptoxanthin works to minimize lung cancer incidence by reducing both the proteins and cell receptors that have been implicated in lung tumorigenesis.(7)
While there isn’t a hard and fast recommendation for a daily intake, the general consensus is that getting between 2 and 6 mg of carotenoids a day is enough to keep chronic illnesses and cancer at bay.(8)
Eating just one cup of cooked pumpkin provides
- 763% of your daily needs for vitamin A(9) and
- 50 mg of beta-Cryptoxanthin(10)
One cup of cooked butternut squash provides
- 457% of your vitamin A needs(11) and
- 58 mg of beta-Cryptoxanthin(10)
I can’t think of an easier way to get these crucial cancer-fighting elements.
Cucurbitacins in winter squash help fight cancer
Cucurbitacins are chemicals found throughout the plant kingdom that protect organisms from outside harm. They also have potent antioxidant, anti-inflammatory and anti-cancer effects on humans.(12) And fruits in the Cucurbitaceae family are chock full of them.
Researchers have discovered that these compounds can help fight breast cancer. A study published in a 2012 issue of the journal Breast Cancer Research and Treatment found that cucurbitacin E (found in high doses in pumpkin seeds) blocks breast cancer metastasis by suppressing tumor cell migration to the lungs, without harming nearby healthy cells.(13)
And another study published in 2013 found cucurbitacin E induced both apoptosis (programmed cell death) and cell cycle arrest in human breast cancer cells.(14)
In addition to breast cancer, researchers isolated cucurbitacin E from sprouted pumpkin seeds and found that it induced apoptosis of lung and prostate cancer cells as well.(15)
Pumpkins have one other cancer-fighting component. They’re rich in a unique water-soluble protein called pumpkin 2S albumin. It’s been shown to induce apoptosis in breast cancer, ovarian and testicular cancer, prostate cancer and hepatocellular (liver cancer) carcinoma cell lines.(16)
How to reduce your cancer risk with winter squash
When winter squash is in season, you can find a wide variety at farmer’s markets and local pumpkin patches. Once the snow flies you should be able to find it in any grocery store.
Choose organic squash whenever possible, with a firm skin and without visible blemishes. Store in a cool, dark place (not the refrigerator) for up to a month. If the squash has been cured it can be stored longer.
Winter squash, including pumpkin, tastes great roasted, baked, braised or steamed. Eat them mashed with a little coconut oil and nutmeg, stuffed with nuts and veggies or in a pureed soup.
Pumpkin seeds can be roasted in a single layer at low heat (usually under 170 degrees). Roasting them low, slow and for only 15 minutes or so preserves the delicate linoleic and oleic acids that make up about 75% of the fat found in the seeds.
When it comes to pumpkins, canned is an option as well. Check the label to ensure the only ingredient is “pumpkin,” and doesn’t contain any added sugar, fillers or preservatives.
Just because the growing season is over doesn’t mean you can’t still enjoy nutrient-dense whole foods all winter long. By including winter squashes in your diet as winter gets settles in, you’ll ensure your body continues to get the nutrients it needs to stay healthy and prevent cancer.
- Zinc as an anti-tumor agent in prostate cancer and in other cancers. http://www.sciencedirect.com/science/article/pii/S000398610700118X
- Zinc transporters in prostate cancer. http://www.sciencedirect.com/science/article/pii/S0098299712001343
- The role of carotenoids in human health. http://www.ncbi.nlm.nih.gov/pubmed/12134711
- Chemoprevention by the oxygenated carotenoid beta-cryptoxanthin of N-methylnitrosourea-induced colon carcinogenesis in F344 rats. https://www.ncbi.nlm.nih.gov/pubmed/10595732
- Dietary cryptoxanthin and reduced risk of lung cancer: The Singapore Chinese Health Study. https://www.ncbi.nlm.nih.gov/pubmed/14504200
- β-Cryptoxanthin reduced lung tumor multiplicity and inhibited lung cancer cells motility by down-regulating nicotinic acetylcholine receptor α7 expression. http://cancerpreventionresearch.aacrjournals.org/content/early/2016/09/13/1940-6207.CAPR-16-0161.abstract
- Daily intake of carotenoids (carotenes and xanthophylls) from total diet and the carotenoid content of selected vegetables and fruit. https://www.ncbi.nlm.nih.gov/pubmed/8815648
- Pumpkin, canned, without salt. http://nutritiondata.self.com/facts/vegetables-and-vegetable-products/2602/2
- List of winter squashes, pumpkins and other foods rich in Beta-cryptoxanthin. http://nutritiondata.self.com/foods-011136000000000000000.html?maxCount=112
- Squash, winter, butternut, cooked, baked, without salt. http://nutritiondata.self.com/facts/vegetables-and-vegetable-products/2648/2
- Cucurbitacins – A promising target for cancer therapy. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3612419/
- Cucurbitacin E inhibits breast tumor metastasis by suppressing cell migration and invasion. http://link.springer.com/article/10.1007/s10549-012-2175-5
- Growth inhibitory effect of Cucurbitacin E on breast cancer cells. https://www.ncbi.nlm.nih.gov/pubmed/24040444
- Isolation of cucurbitacin E from pumpkin seed and analysis of its anti-cancer and anti-inflammatory activities. http://www.fasebj.org/cgi/content/meeting_abstract/22/1_MeetingAbstracts/889.6
- Characterization of anticancer, DNase and antifungal activity of pumpkin 2S albumin. https://www.ncbi.nlm.nih.gov/pubmed/24814706