Because most varieties of winter squash are characterized by their rich orange flesh, our recommendations for winter squash intake are based on our recommendations for yellow/orange vegetables. At WHFoods, our minimum daily goal for vegetable intake from the yellow/orange subgroup is 1/2 cup per day. A more optimal intake level would be one cup per day. Alongside of winter squash, yellow/orange vegetables like sweet potato, carrots, and yellow bell peppers can contribute to your daily intake from this yellow/orange subgroup.
Enjoyment of winter squash can help boost your nutrient intake in every major nutrient category. Among the macronutrients, you get about one-fourth of our daily recommended fiber from a single one-cup serving. You also get about 10% of our daily recommended intake level for a very important type of fat—namely, omega-3 fat—from this same one-cup serving. On our website, 27 of 100 foods rank as excellent, very good, or good sources of omega-3s. Among these 27 foods most concentrated in omega-3s, winter squash ranks 13th!
In the vitamin category, B vitamins are a winter squash specialty. Here we are talking about the role of winter squash as a very good source of vitamin B6, and a good source of vitamin B2, vitamin B3, folate, and pantothenic acid. Also important to mention in this vitamin category is vitamin C, which winter squash provides in a very good amount; and of course vitamin A, which winter squash provides in an excellent amount due to its rich array of carotenoids. Vitamin K is also provided in a good amount by winter squash.
One final piece of information in this vitamin category for winter squash involves its vitamin E content. While present in exceedingly small amounts in the flesh of winter squash, more substantial amounts of vitamin E are provided by the seeds of this vegetable. Included here are the members of the vitamin E family known as the gamma-tocopherols. These important forms of vitamin E are one reason to consider saving and lightly roasting the seeds of winter squash if you decide to scoop them out of this vegetable before cooking. We've found that an oven temperature of 160-170°F (about 71-77°C) for 15-20 minutes works well for this purpose. We've also found it helpful to make a single layer of the winter squash seeds across a cookie sheet when preparing the seeds for light roasting.
Minerals provided by winter squash also play an important role in its nutrient benefits. This vegetable achieves rankings of very good for manganese and copper, and ranking of good for potassium and magnesium. Smaller amounts of zinc, iron, and calcium are also provided by winter squash.
In terms of phytonutrients, the star quality of winter squash is definitely its carotenoids. The carotenoid-richness of winter squash is responsible for the placement of this vegetable in our WHFoods Top 10 for vitamin A. While the carotenoids beta-carotene and alpha-carotene usually account for the greater percentage of carotenoids in winter squash (especially in those varieties belonging to the Cucurbita moschata genus/species), the complete list of identified carotenoids in winter squash is a long one and spotlight carotenoids are listed below:
Studies have also confirmed the presence of antioxidant phenols in winter squash, including lignans like secoisolariciresinol. In terms of quantity, the amount of total phenols in winter squash usually ranges from 25-80 milligrams of total phenols (when measured as chlorogenic acid equivalents) in about 3.5 ounces (100 grams) of fresh, uncooked winter squash.
When all of these nutrient categories are combined—macronutrients, vitamins, minerals, and phytonutrients—what you end up with is very broad-based nutrient support from a vegetable that is all-too-often overlooked as too starchy and high-carb to be providing such comprehensive nutrient benefits.
Over recent years, several areas of nutritional research have overlapped to provide us with a clearer view of winter squash and its impact on our blood sugar. Winter squash has long been established as vegetable with a low or medium glycemic index (GI) value. The difference between medium GI and low GI depends on the GI cut point of 55 that is typically used to differentiate between low and medium GI. We've seen studies on winter squash that show GI values between 55-65 as well as studies that show lower GI values between 50-55. At WHFoods, we classify winter squash as a low-GI food based on a value of 51 that we believe best corresponds to our preferred method of cooking winter squash—namely, short-term steaming (7 minutes). It is worth noting here, however, that many factors that can influence the GI value for winter squash, including the variety of winter squash, season of harvest, length of storage, preparation method, and cooking method. Whatever the factors involved, however, it's clear that winter squash scores lower on the GI scale than other equivalently starchy vegetables (for example, potatoes). Its lower GI values make winter squash a vegetable that is relatively easy on our post-consumption blood sugar levels and beneficial in this regard.
In fact, recent studies have shown that winter squash can help steady the release of sugar inside of our digestive tract after being eaten. (Researchers refer to this set of events as "post-prandial glycemic response.") Scientists are not yet completely certain about the reasons for this blood sugar-related benefit. But one key to this blood-sugar benefit may involve the pectin content of winter squash.
Pectin is an unusual fiber component that is built around special molecules called galacturonans. Galacturonans are polysaccharide-like molecules that contribute to the cell wall structure in many plants. The key galacturonans in pectin are homogalacturonan, rhamnogalacturonan, arabinogalacturonan, and xylogalacturonan. (In fact, these molecules are often referred to as the "pectic polysaccharides.") Research on pectin has shown it to have antidiabetic properties and to help lower the release of sugar from our food into our digestive tract following a meal. This research makes the pectin in winter squash a very likely candidate for the blood sugar-related benefits from this vegetable.
Yet, it's also important not to lose the forest through the trees here. As mentioned previously, winter squash achieves a ranking of "very good" in our WHFoods rating system and provides us with nearly 6 grams of fiber per cooked cup! Pectin definitely makes an important contribution to this total fiber content. At the same time, we would expect most foods that rank as "very good" fiber sources to be helpful foods for regulating blood sugar since fiber intake has long been known to help steady digestion and sugar metabolism in our digestive tract.
Before leaving this area of blood sugar benefits, it's also important to mention the great B-vitamin profile of winter squash. We're talking about a vegetable that we recognize as a very good source of vitamin B6 and a good source of vitamin B2, vitamin B3, folate, and pantothenic acid. These B vitamins play important roles in carbohydrate metabolism and are likely to provide us with blood sugar-related benefits for this reason.
Because winter squash is a vegetable that has not been studied extensively by food and health researchers, we only have bits and pieces of research evidence for other potential benefits from winter squash.
Several factors combine to suggest that winter squash may be a vegetable that provides us with important antioxidant benefits. These factors include its very good level of vitamin C, the vitamin E contained in its seeds, and of course its amazing carotenoid richness. Added to these factors would be its total phenol content and its antioxidant-related minerals including manganese and copper. However, we have yet to see any large-scale human studies that specifically link intake of winter squash to antioxidant benefits in the body. We fully expect future studies to demonstrate these benefits, however. In parts of the world where intake of winter squash plays an especially prominent role in overall food intake, these antioxidant benefits might be of special importance.
As described earlier, pectic polysaccharides are naturally occurring food fibers known to help benefit blood sugar events following a meal. These polysaccharides have also been shown to help increase satiety (food satisfaction after eating) and also to help lower total blood cholesterol levels. However, research studies have yet to clarify exactly how much food-based pectin would be needed to help lower total cholesterol levels over time. We suspect that future studies will show intake of winter squash to be helpful in this regard, but perhaps in an intermediate way.
The omega-3 fatty acids provided by winter squash—together with its carotenoids and phenols—also make anti-inflammatory benefits from this vegetable a distinct possibility. However, large-scale human studies are definitely needed in this area.
At the very outset of this Description section, we want to address the very name that is used to describe this vegetable—namely, winter squash. This name is simple and practical. But at the same time, it is somewhat misleading. Winter squash is not grown in the winter, nor harvested in the winter, nor primarily consumed in the winter.
What is true about winter squash is the longer growing season that it requires. Summer squash typically requires about 50–70 days of growth. Winter squash typically require about 90–120 days. This difference means that summer squash can be planted in the spring and harvested in the summer, while winter squash can also be planted in the spring yet it's not harvested until the fall. In other words, while summer squash can be freshly harvested and available in the summer, winter squash cannot; this difference lends some credence to the term "summer squash." But it doesn't help explain why we use "winter" to describe "winter squash."
Use of the word "winter" requires us to consider another typical difference between summer and winter squashes—namely, the thickness of their skins. While there is no hard and fast rule here, winter squashes are typically larger and have thicker skins than summer squashes. (Although some squashes often classified as winter squashes—for example, delicata squash—don't always fit this description.) Delicata is a variety of winter squash that can have a thinner and more tender skin than most winter squash varieties, even though it still typically requires a long growing season of about 110 days. Yet many familiar winter squash varieties—including butternut and hubbard—typically have thick skins. These thick skins allow winter squashes to be stored over a much longer period of time than summer squashes. We're talking about several months for winter squashes and perhaps a week or so for summer squashes. As a result, winter squashes can be stored over the winter months after being harvested in the fall: thus contributing to the use of "winter" in their name.
Some winter squash varieties grow on bushes, while others grown on vines. The difference here usually involves the final size and weight of the winter squashes at harvest. (The larger and heavier winter squashes need to rest on the ground, while the smaller-sized winter squashes can be supported growing on a bush.) The largest winter squashes that most people are familiar with in the U.S. are winter squashes typically just called "pumpkins." In some countries, the terms "winter squash" and "pumpkin" are used much more interchangeably than they are in the United States. But regardless of the terminology, we are talking about bush-grown or vine-grown vegetables that all share roughly similar nutrient profiles and health benefits.
The term "winter squash" does not refer to any single type of plant but to a very large and diverse plant family. At WHFoods, we think about winter squash as including many different varieties sometimes recognized by different colors, outer skin textures, overall size, or overall shape. Below is a list of different winter squash varieties with a brief description of each variety:
Other winter squash varieties include carnival squash, red kuri squash, sugar pumpkin squash, and sweet dumpling squash. And of course, what are commonly called "pumpkins" in the U.S. are considered varieties of winter squash.
From a science perspective, all of the winter squash varieties above belong to one of three botanical genus/species:
From this science perspective, it's also worth noting that you find summer squash varieties in each of these genus/species, making the research on summer and winter squash varieties both confusing and in some cases overlapping.
Both winter and summer squash varieties belong to the general plant family known as the Cucurbitaceae. This plant family is famous not only for squashes, gourds, and pumpkins, but for other popular foods as well. For example, watermelons, honeydew melons, crenshaw melons, and casaba melons are members of the Cucurbitaceae family. And so are cucumbers!
Before leaving this Description section, we want to post a reminder: when you are enjoying the beautiful orange shades of the flesh of your winter squashes, remember that you are getting amazing carotenoid benefits since carotenoids are responsible for this flesh color. From the deepest oranges to the paler yellows, winter squashes are providing you with a diversity of carotenoids that make them the Number 10 food on our website for vitamin A richness!
Scientists have traced the origins of winter squash to what is called a "center of diversity" in what is now Mexico. However, wild species of winter squash (belonging to all three genus/species groups, namely, Cucurbita pepo, Cucurbita maxima, and Cucurbita moschata) have been discovered as far south as southern Argentina. Butternut squashes and other members of the Cucurbita moschata group seem to have flourished especially in northwestern South America including Columbia and Peru, while varieties like Hubbard and kabocha seem to have favored the southern portion of South American in Argentina. Not surprisingly, winter squashes have played a historically important role in the cuisines of South America as well as Central America and the southernmost regions of what is now the United States. In addition to playing a direct role as vegetables enjoyed on their own, winter squashes have also traditionally served as the key ingredient in soups, pies, and casseroles.
It's worth noting that winter squashes were anything but an optional food or "interesting vegetable alternative" in the development of many cuisines throughout South and Central and North America. Instead, winter squashes were been heavily relied on as staple foods and essential for attainment of both calories and nutrients. Early domestication of winter squashes—dating as far back as 10,000 years—showed the unique ability of squash plants to develop larger-sized fruits, resulting in some of the very large Hubbard winter squashes that are grown today. The larger-sized winter squashes were perfect for increasing available calories and nutrients, especially during the winter months that followed fall harvests. Here the historical record provides us a very helpful reminder: winter squashes are vegetables that we ourselves can rely on for key nutrients and health benefits, especially when we do not have peak season summer vegetables available.
Squashes (including both winter and summer squashes) are popular foods in the United States, which presently imports more squash than any country in the world. (Over 90% of current squash imports into the U.S. come from Mexico.) Within the U.S., California, Florida, Georgia and Michigan grow the largest volume of squashes (including both summer and winter squash). To give you a better idea of this amount, over 400 million pounds of squash were produced in the U.S. in 2016. On a worldwide basis, the largest winter squash-producing countries in the world are China and India, followed by the Ukraine.
Winter squash is easily prone to decay, so it is important to carefully inspect it before purchase. Choose ones that are firm, heavy for their size and have dull, not glossy, rinds. The rind should be relatively hard since soft rinds may indicate that the squash is watery and lacking in flavor. Avoid those with any signs of decay, which manifest as areas that are water-soaked or moldy.
At WHFoods, we encourage the purchase of certified organically grown foods, and winter squash are no exception. Repeated research studies on organic foods as a group show that your likelihood of exposure to contaminants such as pesticides and heavy metals can be greatly reduced through the purchased of certified organic foods, including winter squash. In many cases, you may be able to find a local organic grower who sells winter squash but has not applied for formal organic certification either through the U.S. Department of Agriculture (USDA) or through a state agency. (Examples of states offering state-certified organic foods include California, New York, Oregon, Vermont, and Washington.) However, if you are shopping in a large supermarket, your most reliable source of organically grown winter squash is very likely to be winter squash that display the USDA organic logo.
Winter squash has a much longer storage life than summer squash. Depending upon the specific variety and other factors, winter squash can be safely stored for a minimum of one week, and more likely for much longer. It's not uncommon to find winter squash being successfully and safely stored for a period of up to six months. Research studies show that the flesh of winter squash can actually increase its concentration of carotenoids during storage. In short, if you find it convenient to buy and store winter squash, by all means do so! In most studies, storage in a steady temperature range of 50-68°F (10-20°C) has been show to provide an optimal temperature condition. So you'll want to store your winter squash somewhere outside of the refrigerator—for example, inside a cabinet that is near the stove or a heater or exposed to a lot of direct sunlight.
Once your winter squash has been cut, however, cover the pieces in plastic wrap and store them in the refrigerator, where they will keep for one or two days. One good way to freeze winter squash is to first cut it into pieces of suitable size for individual recipes.
If you'd like even more recipes and ways to prepare winter squash the Nutrient-Rich Way, you may want to explore The World's Healthiest Foods book.
Winter Squash, cubed, cooked
|vitamin A||535.36 mcg RAE||59||14.1||excellent|
|vitamin C||19.68 mg||26||6.2||very good|
|fiber||5.74 g||21||4.9||very good|
|vitamin B6||0.33 mg||19||4.6||very good|
|copper||0.17 mg||19||4.5||very good|
|manganese||0.38 mg||17||3.9||very good|
|vitamin B2||0.14 mg||11||2.6||good|
|vitamin K||9.02 mcg||10||2.4||good|
|pantothenic acid||0.48 mg||10||2.3||good|
|omega-3 fats||0.19 g||8||1.9||good|
|vitamin B3||1.01 mg||6||1.5||good|
Density>=7.6 AND DRI/DV>=10%
Density>=3.4 AND DRI/DV>=5%
Density>=1.5 AND DRI/DV>=2.5%