Nothing says Fall like the arrival of pumpkins – just one of many gourd groups that arrive with the changing of the seasons. Most winter squashes are native to North America; hence, their prominent placement in the Thanksgiving cornucopia.

Although winter squashes are harvested in the Fall, they grow during the summer and are available well into winter. The most common varieties found in supermarkets, farmers’ markets, and health food stores are butternut, acorn, delicata, dumpling, carnival, kabocha, buttercup, kuri, turban, sugar pie pumpkins, and spaghetti squash. 

Nutritional Powerhouses

Winter squashes are naturally low in fat and calories but high in complex carbohydrates, fiber, vitamins, minerals, and a wealth of phytochemicals.

1. Phytonutrient stars – carotenoids and vitamin A

What makes winter squash really shine is their amazing concentration of carotenoids – with alpha- and beta-carotene making up the highest percentage – although many antioxidant carotenoids have been identified in winter squash, including lutein, zeaxanthin, beta-cryptoxanthin, flavoxanthin, neoxanthin, neurosporene, phytofluene, taraxanthin, and violaxanthin.

Carotenoids offers several health benefits via their potent antioxidant capacities. Lutein and zeaxanthin, although known for their support for the macula of the eye, have recently been shown to support cognitive function.1,2*

In addition, the body can make vitamin A from several of them – alpha-carotene, beta-carotene, and beta-cryptoxanthin. In fact, a one-cup serving of cooked butternut squash contains 1,144 mcg of vitamin A – much more than the RDA of 700 mcg for women and 900 mcg for men.3

2. Sources of other essential vitamins and minerals

Most of the winter squash varieties are great sources of vitamin C. Since vitamin C is sensitive to destruction by light, heat, and water cooking, cooked foods typically contain less than their raw counterparts.

But that’s not the case with winter squashes like butternut, which retain more vitamin C during cooking than other vitamin C-rich vegetables.4 In addition to vitamin C, winter squash tends to be a good source of vitamin E, B vitamins – riboflavin, niacin, vitamin B6 – and the minerals potassium, calcium, magnesium, and manganese.

3. Ideal choice for blood sugar support

Many individuals on low-carb diets avoid starchy vegetables. Although winter squashes contain complex carbohydrates, they contain less carbohydrate than most starchy vegetables.

For example, butternut squash has about half the carbohydrate content as the same amount of sweet potato (10 grams versus 20 grams, per 100 grams of food).In addition, the fiber content slows the breakdown of carbohydrates into simple sugars, thereby inhibiting blood sugar from rising after eating.

4. Filling and satisfying food to support weight management

Maintaining a steady blood sugar level helps the body moderate its insulin response and therefore regulate weight. In addition to helping maintain a sustained and steady level of blood sugar, the fiber in squash also helps ward off hunger for longer – it ranks high on the satiety scale despite being relatively low in calories. Staying fuller for longer means less snacking on high-calorie foods associated with weight gain.

5. Great for the gut

Fiber is essential for maintaining bowel regularity. There are two types of fiber – soluble and insoluble. Insoluble fiber is what we usually think of when we think of fiber – roughage – those indigestible fibers that act like a broom to sweep waste through the intestines and out of the body.

However, some individuals, such as those with irritable bowel syndrome (IBS), don’t tolerate large amounts of insoluble fiber. Soluble fiber, on the other hand, forms a gel that helps make stools more consistent and easier to pass. This “gentler” form of fiber tends to have a soothing effect on the gut, especially for individuals who have IBS.

In fact, registered dietitians often instruct individuals with IBS to start their day with soluble fiber-rich foods and avoid insoluble fiber. Winter squash is a great source of this gut-soothing soluble fiber, which makes it an ideal choice for those seeking gentle gut-supportive foods. Make a warming mash or puree of winter squash and ginger as an easy way to start the day with a nutrient-packed but soothing soluble fiber (see recipe below).

If probiotics are beneficial bacteria, then prebiotics are the foods that feed them. Some varieties of winter squash contain prebiotic oligosaccharides,6 which like other prebiotics such as  arabinogalactans, stimulate growth of the body’s own beneficial bacteria.*  This makes winter squash a good healing food choice for individuals suffering from gut disorders associated with an unbalanced microbiome.  

All parts are edible

The seeds of winter squash are edible and quite nutritious. In fact, before they were prized for their great tasting flesh, squash was cultivated for its seeds. Pumpkin seeds have been used historically for treating a variety of ailments – from an enlarged prostate to intestinal parasites.

Like other seeds, squash seeds are rich in the healthy omega-6 fatty acid, linoleic acid. However, oleic acid comprises most of the fat in the seeds – a mono-unsaturated fat that is the hallmark of olive oil and one of the nutrients that makes the Mediterranean diet so healthful.

Seeds of winter squash can also contain heart-healthy phytosterols, including beta-sitosterol, sitostanol, and avenasterol, and vitamin E in the form of alpha-, beta-, and gamma-tocopherol. And although lacking the vibrant colors that typically signify important sources of carotenoids, the seeds contain even higher concentrations than the colorful flesh. These little nutritious storehouses are packed with other nutrients too, including the minerals zinc and iron.

Squash seeds make a delicious snack and a healthy addition to salads and vegetable sides. Roast them at a low temperature to preserve the healthy unsaturated oils.

To enjoy the seeds from your winter squash:

  • Wash and dry the seeds with a paper towel
  • Spread in a single layer on a baking sheet lined with parchment paper  
  • Drizzle with a little avocado oil and mix to coat seeds well
  • Sprinkle a pinch of salt and any desired herbs and seasonings 
  • Roast at 275-300 degrees F for 20-25 minutes or until seeds start to brown 

Culinary hint: For sweeter seeds, try cinnamon, pumpkin pie spice, or nutmeg. For a savory version try truffle salt, Cajun spice, curry, or herbs de Provence. 

Ginger Squash Puree

Ingredients:

  • 1 large butternut squash
  • 2 tablespoons butter or plant-based buttery spreads at room temperature
  • ½ cup nut milk
  • 1½ tablespoons peeled and grated fresh ginger
  • Salt to taste

Preheat an oven to 400°F  

Bake squash whole until easily pierced with a knife (usually 45-50 minutes). Remove from oven and set aside until cool enough to handle. Cut in half and scoop out the seeds and fibers. Reserve seeds for another use.

Add flesh of the squash to a food processor fitted with the metal blade. Process until smooth, pulsing several times, about one minute. Add the nut milk, butter, and ginger and process again. Taste and adjust salt and seasoning as desired.  

If serving right away, then transfer the puree to a heavy saucepan. Reheat gently over low heat, stirring to prevent scorching. Spoon into a warmed bowl and serve immediately.


References

  1. Stringham N, Holmes P, Stringham J. Effects of macular xanthophyll supplementation on brain-derived neurotrophic factor, pro-inflammatory cytokines, and cognitive performance. Physiol Behav 2019 Aug 16:112650. doi: 10.1016/j.physbeh.2019.112650.
  2. Mewborn C, Lindbergh C, Robinson T, et al. Lutein and zeaxanthin are positively associated with visual-spatial functioning in older adults: An fMRI study. Nutrients 2018 Apr 7;10(4). pii: E458. doi: 10.3390/nu10040458
  3. What’s to know about butternut squash? https://www.medicalnewstoday.com/articles/284479.php [Accessed 10.9.19]
  4. Roura SI, Del Valle CE, Aguero L, Davidovich LA. Changes in apparent viscosity and vitamin C retention during thermal treatment of butternut squash (Cucurbita moschata Duch.) pulp: effect of ripening stage. J Food Qual 2007;30:538-551.
  5. FoodData Central. https://fdc.nal.usda.gov/fdc-app.html#/food-details/169296/nutrients
  6. Du B, Song Y, Hu X, et al. Oligosaccharides prepared by acid hydrolysis of polysaccharides from pumpkin (Cucurbita moschata) pulp and their prebiotic activities. Int J Food Sci 2011;46:982-987.