Many of us associate pumpkin with autumn, especially Thanksgiving. That's a shame because there's a wealth of goodness in that winter squash, and it deserves more than mere seasonal entertainment. It's low in calories and fat, and provides vitamins, minerals, fiber, and phytochemicals essential to a healthy diet. A cup has only 83 calories and one gram of fat, which is just enough to allow its use in recipes that call for shortening or oil. Measure for measure, you can use canned pumpkin puree for half the fat in a cake or cookie recipe. Some people even add it to their morning oatmeal with cinnamon and a little, like a teaspoon, of brown sugar. Here we're talking about the nutritive value of canned pumpkin, which is denser than what you would get from spending a few hours trying to hatchet out and distill the flesh from a fresh pumpkin. The only virtue realized from a fresh squash is the potential to roast the seeds for a snack later on… if you have the composure to separate the seeds from the stringy fibers in the core.
Because of its color, pumpkin is immediately identified as being a source of beta-carotene, the precursor to vitamin A that has no measurable level of liver burden. Beta-carotene is a molecule that the body easily changes to vitamin A in the intestine, and is found in plants, as opposed to pre-formed vitamin A common to animal products, as from butter and eggs. This fat-soluble vitamin is known to fight infections, to help treat skin disorders, to improve night vision and to ameliorate dry eyes, all the while performing anti-oxidant functions. Although beta-carotene does not, pre-formed vitamin A can lead to orange skin and yellow eyes, a state that disappears when levels are adjusted or intake is temporarily discontinued. The bioavailability of beta-carotene—the proportion that can be absorbed, transported and utilized by the body—is influenced by a few factors: supplemental beta-carotene is better absorbed that that from foods; food processing and cooking can enhance availability; the presence of fat in the gut aids absorption (only about three grams per meal is needed).
One cup of pumpkin yields more than 500 milligrams of potassium, an essential mineral in which most North Americans are shallow, often getting much less than the RDI of 4700 milligrams. In the body, potassium helps to keep blood pressure under control (Barri, 1997) (Hajjar, 2001) (Geleijnse, 1996), may help to encourage positive bone mineral density (New, 1997, 2000) (Tucker, 1999), and may reduce risk of stroke (Ascherio, 1998) (Fang, 2000) (Bazzano, 2001). Epidemiological evidence indicates that potassium intake and blood pressure are inversely correlated, with the greatest hypotensive effect found in those with the highest blood pressure. Inclusion of potassium in the management of hypertension was suggested in the late 90's (Barri, 1997). Knowing your potassium intake might be more important than you think.
Another of the vision-friendly carotenoids in pumpkin is lutein, a pigment for which spinach has been lauded. Concentrated in the macula, the part of the retina responsible for central vision, lutein rescues the eye from oxidative stressors and the high-energy photons of blue light that are known to increase risk for macular degeneration (Richer, 2004). Naturally combined with its isomer, zeaxanthin (the yellow pigment also in corn, saffron and paprika), lutein may also lower the risk of cataracts (Barker, 2010) (Moeller, 2008) (SanGiovanni, 2007).
Though the foregoing is reason enough to eat pumpkin more often than once a year, another virtue was made public earlier in this century. China has received some bad publicity in the recent past, with melamine in baby formula, toxic bean sprouts and contaminated pet foods, but its scientific community looks less toward dollar signs and more toward humanitarian ventures. While examining the medicinal properties of plants, pharmaceutical researchers in Shanghai found pumpkin to be among the species that exhibit hypoglycemic activity. Specific polysaccharides in pumpkin and a few other plants apparently are able to restore the function of pancreatic cells and cause an increase in insulin output by the functional beta cells. Scientists noticed that lower dosages of anti-diabetes drugs were needed when the plant compounds were concomitantly administered. Frequency of drug administration and its unwelcome side effects were also reduced (Jia, 2003). As with many natural approaches to the management of disease, dose makes the difference. Later study in Beijing found that 1000 mg/kg doses of protein-bound pumpkin polysaccharide were considerably more effective than half that amount (Quanhong, 2005).
Much of what we all learn as students is based on prior knowledge, using it as a springboard for additional investigation. One of the active pumpkin factors that eventually "sprang from the board" and found to be most effective in lowering glucose is trigonelline (TRG), an alkaloid also appearing in coffee, sea urchins and jellyfish, the latter two not being suggested as complementary to the pie. A derivative of vitamin B6, trigonelline is believed also to have anti-migraine, antiseptic, and anti-carcinogenic properties. If roasted at temperatures greater than 230° C (446° F), this alkaloid yields nicotinic acid—niacin. Experimental use of TRG attenuated triglycerides as well as serum glucose in laboratory animals bred to mimic human disorders (Yoshinari, 2009). Anti-oxidant status is severely compromised in diabetes, causing an increase in damage by free radicals. TRG was seen to ameliorate oxidative stress and to return related blood markers to near normal levels (Zhou, 2011, 2012).
You'd think that, as big as they can get, pumpkins are rough and tough. They're actually very tender, starting with seeds that don't do well in cold soil and seedlings that succumb to frost. If planted too early, they often rot before you're ready to pick them. What is truly surprising about pumpkins' cultivation is that they fare poorly if fertilized with the typical N-P-K fertilizers used in the garden. To ascertain initial results, researchers duplicated experiments five more times in order to remove doubts that high fertilizer rates decrease anti-oxidant concentrations in the fruits (Oloyede, Apr 2012 and May 2012).
Preparing fresh pumpkin is more work than fun unless you do it once a year, and just for the novelty of it. Uncut pumpkins can be stored for weeks in a well-ventilated space, but once you cut 'em you got to use 'em. Canned keeps seemingly forever. Fruit, leaves, flowers and seeds are edible. But we think of the flesh in pies, pancakes, muffins, custards, soups, soufflés, and yes, even ravioli. Now you can eat for health as well as flavor.
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