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Vegetables
Lea Ann Holzmeister, R.D., C.D.E.
URL: http://www.diabetesselfmanagement.com/article.cfm?aid=1551
Many Americans could improve their diets by increasing their vegetable consumption. Studies
have shown that vegetable consumption by Americans is low and also that a diet high in
vegetables promotes good health and may help prevent some chronic diseases such as heart
disease and some forms of cancer.
Vegetables contain a wide variety of nutrients such as vitamins A, C, and K, beta-carotene, folic
acid, and potassium. Some vegetables also supply significant amounts of phytochemicals, plant
compounds that may have a role in promoting health and preventing disease, and many are good
sources of fiber.
When vegetables replace high-fat or high-carbohydrate foods in the diet, they help play a role in
controlling diabetes by lowering overall calorie, fat, and carbohydrate intake. Most vegetables
are naturally low in carbohydrate and therefore don’t raise blood glucose significantly. They also
add color, texture, and variety to meals.
Calories and carbohydrates
Nonstarchy vegetables, including asparagus, broccoli, green beans, mushrooms, cabbage,
cauliflower, eggplant, and celery, are naturally low in calories and carbohydrate, containing
approximately 25 calories and 5 grams of carbohydrate per one-cup raw or half-cup cooked
serving. Up to two servings of nonstarchy vegetables per day can be counted as “free foods” in a
diabetes meal plan.
Starchy vegetables, such as corn, peas, potatoes, sweet potatoes, and lima beans, contain closer
to 80–100 calories and 15 grams of carbohydrate per half-cup serving. In the Exchange Lists for
Meal Planning, starchy vegetables are counted as starch exchanges, not vegetable exchanges.
Likewise, in the Diabetes Food Pyramid, they are listed in the grains, beans, and starchy
vegetables group, not the vegetable group. Whatever meal-planning method you use, be sure to
count the carbohydrate in starchy vegetables toward your meal total.
Fiber
The Dietary Guidelines for Americans recommend that all Americans eat a variety of fibercontaining foods, including vegetables, each day, for a total of 20–35 grams of fiber per day.
(People with gastrointestinal problems should check with their health-care provider for
individual fiber recommendations.)
The National Cancer Institute recommends making at least one high-fiber vegetable selection
every day. Vegetables containing at least 3 to 4 grams of dietary fiber per serving include
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artichokes, broccoli, Brussels sprouts, raw carrots, cauliflower, peas, baked potato (with skin),
and spinach.
Fiber comes in two forms: insoluble fiber, which makes foods like broccoli crunchy; and soluble
fiber, which gives vegetables like okra a viscous texture. Other vegetable sources of soluble fiber
include carrots, eggplant, and parsnips. Insoluble fiber is valuable for preventing constipation,
while a diet high in soluble fiber has been shown to lower blood cholesterol levels. Increasing
overall fiber intake may also help reduce the risk of some types of cancer.
Fat and protein
Vegetables are naturally low in fat, with most containing less than 1 gram per serving. However,
when fat is added to vegetables in the form of dressings, sauces, or butter, the dish may no longer
be low-fat. To keep your fat intake low, buy frozen and canned vegetables without added fat or
sauces, and prepare and eat vegetables with little added fat.
Vegetables contain approximately 2–3 grams of protein per serving. Three to five servings of
vegetables per day would provide approximately 12 grams of protein per day. This would
provide approximately 25% of the protein needs for a 140-pound woman and 23% of the protein
needs for a 150-pound man.
Vitamins, minerals, and other nutrients
Vegetables are a great source of vitamins. Antioxidant vitamins such as vitamin A, betacarotene, and vitamin C may help in the prevention of cancer and the effects of aging by
neutralizing free radicals, or unstable oxygen molecules that can damage cells.
Vegetables are among the best sources of vitamin K. Vitamin K protects against hip fractures
that are caused by osteoporosis and helps blood clot. Because the body doesn’t store vitamin K
as long as other fat-soluble vitamins, eating a good source of the vitamin daily is recommended.
Good sources of vitamin K include Swiss chard, kale, spinach, and collards. People who take
anticlotting medicines such as warfarin are advised to speak with their physician before
increasing the amount of vitamin-K–rich vegetables in their diet.
Vegetables are also high in phytochemicals such as carotenoids, flavonoids, indoles, and
isoflavones. Many of the bright colors in vegetables come from carotenoids. Generally, the
darker the color of the vegetable, the higher the nutrient content. Dark salad greens such as
spinach, watercress, and romaine lettuce contain more nutrients than pale greens such as iceberg
lettuce. For adequate intake of essential vitamins and minerals, include at least one vitamin-A–
rich vegetable (vitamin-A–rich vegetables include orange vegetables such as carrots and sweet
potatoes, dark green leafy vegetables such as spinach and collards, and tomatoes) at least one
vitamin-C–rich vegetable (vitamin-C–rich vegetables include broccoli, peppers, cabbage, and
leafy greens such as turnip greens) daily. Eat a variety of dark green leafy and deep yellow
vegetables, which provide a supply of carotenoids.
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Vegetables are also good sources of minerals such as calcium, potassium, and magnesium.
Minerals are essential nutrients, needed to regulate body processes such as muscle contractions
and nerve impulses. Vegetable sources of calcium include turnip greens, mustard greens, okra,
kale, broccoli, and rutabaga. Sources of potassium include potatoes, squash, tomatoes, and sweet
potatoes. Vegetable sources of magnesium include spinach, parsnips, and lima beans.
Vegetables are naturally low in sodium, but salt is often added to canned vegetables and
sometimes to frozen vegetables during food processing. Canned vegetables typically contain
200–300 milligrams of sodium per serving. Check frozen vegetable packages for sodium content.
The American Diabetes Association recommends that people with diabetes reduce their sodium
intake to 2400 milligrams (or less) per day to control blood pressure. Choosing fresh or unsalted
frozen vegetables as often as possible can help to lower your sodium intake. When buying
canned vegetables, look for low-sodium varieties. Foods labeled “low sodium” must contain 140
milligrams of sodium or less per serving.
The National Cancer Institute recommends eating cruciferous (cabbage family) vegetables
several times a week. A diet high in cruciferous vegetables may help protect against colon and
rectal cancers, and these vegetables are also good sources of calcium, iron, and folate.
Cruciferous vegetables include bok choy, broccoli, Brussels sprouts, cabbage, cauliflower,
collards, kale, kohlrabi, radishes, rutabaga, tur-nips, and watercress.
Increasing your intake
The Dietary Guidelines for Americans recommends 3–5 servings of vegetables per day. One
serving of vegetables is generally one cup of raw vegetables or one half-cup of cooked
vegetables or vegetable juice.
Vegetables should be an important part of your diabetes meal plan. However, you may find that
eating the recommended number of vegetable servings can be a challenge. Here are some ways
to increase your vegetable consumption:
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Make vegetables visible in your home. Store them so that you won’t overlook them in the
refrigerator or pantry.
Use your microwave (if you have one) to quickly cook vegetables to add to your meals.
Snack on vegetables like raw carrots, celery, bell pepper, and radishes and raw or
blanched (slightly cooked) broccoli and cauliflower.
Buy premixed, bagged salads (but skip the ones with dressing packets or high-fat
garnishes).
Pile spinach leaves and onion, tomato, and bell pepper slices on your sandwich or pizza.
Stir raw or lightly cooked vegetables into pasta, rice, or omelets.
Add chopped vegetables to soups or stews.
Add finely chopped vegetables such as carrots, onions, cooked eggplant, squash, or
chopped spinach to pasta sauce.
Keep a can of vegetable or tomato juice in your book bag or briefcase for a quick snack.
Top a baked potato with salsa or stir-fried vegetables.
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Canned vegetables
Canned vegetables offer a convenient, nonperishable vegetable option for your pantry shelves,
especially when fresh are not available or not in season. Although canned vegetables keep for
months, they don’t keep forever; look for and use before the “use by” dates for optimal quality.
Canned vegetables typically have added salt, which acts as a preservative and also adds
significant sodium to the food. Read the Nutrition Facts panel for sodium content, consider lowsodium varieties, or look for descriptions such as “no salt added.”
Stocking up on canned vegetables when they’re on sale may be an economical way of ensuring
your vegetable intake. Canned vegetable juice is also a convenient alternative. To avoid added
sugar or sweeteners, select 100% vegetable juice.
Frozen vegetables
Frozen vegetables are convenient and less perishable than fresh vegetables, since freezing retards
bacterial growth. Before they are frozen, vegetables are blanched. Blanching ensures that they
retain much of their appearance and flavor. Because frozen vegetables are often harvested at
their peak of ripeness and frozen within hours of harvesting, their quality and nutrient content is
equal or even superior to that of fresh vegetables, particularly fresh vegetables that have been
shipped long distances.
Added salt is not required to preserve frozen vegetables. However, salt, butter, or cream sauces
are sometimes added to frozen vegetables to enhance their flavor. Before buying frozen
vegetables with added flavorings, read the Nutrition Facts panel on the label to see how much fat
and sodium a product contains.
How long frozen vegetables stay safe and retain quality varies from food to food. Quality
depends on the vegetables being fresh when initially frozen and maintaining a constant freezing
temperature. Packages of frozen vegetables should be firm. Frozen vegetables should be used
immediately after defrosting to avoid loss of quality. If you buy frozen vegetables in loose-pack
plastic bags, pour out the amount you need, then return the remainder to the freezer immediately.
To maintain the quality of frozen vegetables for a longer period of time, store them in a freezer
that can maintain a temperature of 0°F or lower.
Vegetable grades
All canned and frozen vegetables sold in U.S. grocery stores are wholesome and nutritious, but
they can differ in quality. The USDA has established grade standards as measures of quality for
many canned and frozen vegetables. The grade, when present, is often displayed with a shield
design on the package. The USDA provides a voluntary inspection service where the quality of
processed vegetables is certified. The food manufacturer pays for the inspection service.
The USDA grades for canned and frozen vegetables are as follows:
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Grade A. Top quality in tenderness, flavor, appearance, and uniformity. They make the most
attractive servings for special luncheons or dinners.
Grade B. Very good quality, slightly more mature and not quite as tender as Grade A
vegetables.
Grade C. Not as uniform in color and flavor as the higher grades and usually more mature.
These vegetables are generally best used as ingredients in soups, soufflés, casseroles, or stews.
Fresh vegetables
When buying fresh vegetables, consider how well they store and when you will be eating them.
Root vegetables such as potatoes and onions can store well in a cool, dark place for several
weeks, while vegetables such as leafy greens may need to be refrigerated and used in a few days.
The freshest produce contains the most nutrients, so buy only the amount you need. Always look
for signs of quality to ensure peak nutritional content.
Here are some fresh vegetable selection tips:
Artichokes. Artichokes should be heavy for their size, compact, and firm with a soft green color.
Artichokes may exhibit a white, blistered or bronze appearance due to frost, which doesn’t affect
the quality.
Asparagus. Asparagus should be firm with compact, closed tips. Spears should be bright green,
straight, and round and should snap easily when bent. Spears with larger diameters are just as
tender as slender spears.
Beans (green). Good quality beans should be slender and crisp and have straight pods that are
bright colored. They should also be free of blemishes and snap easily when bent.
Beets. Choose small to medium-size beets with firm, smooth skins and purple-red color. Leaves,
if still attached, should be dark green.
Broccoli. Broccoli should have bud clusters of tightly closed, dark green florets (possibly with
some purple tinge). Look for light green stalks of consistent thickness.
Brussels sprouts. Choose Brussels sprouts with a fresh appearance and bright green color.
Texture should be firm and leaves compact.
Cabbage. Choose firm heads of cabbage that are heavy for their size. Outer leaves should have
consistent color and be free of blemishes.
Carrots. Fresh carrots will be firm and well shaped with smooth exteriors. Color should be
bright orange to orange-red. Carrots with their green tops attached will be the freshest.
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Cauliflower. Cauliflower should be creamy white with compact heads. Leaves should be bright
green, fresh, and firmly attached.
Celery. Choose celery with straight stalks with rigid, crispy ribs. Inside surface of ribs should be
clean and smooth. Leaves should be fresh with no signs of wilting.
Corn. Ears should have fresh-looking green husks, stems that are not dried out, and silk ends
that are free of decay or worm injury. Ears should be evenly covered with plump, consistently
sized kernels. When pierced, kernels should squirt juice.
Cucumbers. Fresh cucumbers should be firm and slender, with dark green color. Cucumbers are
frequently treated with an edible wax to prevent moisture loss.
Eggplant. Choose firm eggplants that are light for their size. Skin should be taut, glossy, free of
blemishes, and deeply colored.
Endive, escarole, and kale. These greens should be crisp with well-colored leaves. Avoid
bunches with wilted, cracked, yellowed, or coarse-veined leaves.
Green onions. Choose green onions with crisp, bright green tops and clean, white bottoms.
Avoid discolored or wilted tops.
Jicama. Choose jicama with firm, well-formed tubers with smooth, unblemished skin. Larger
tubers tend to have a coarse texture.
Kohlrabi. Young kohlrabi will have smooth, tender bulbs that are free of cracks or blemishes.
Leaves should be firm and green. Small bulbs offer a more delicate flavor and texture.
Leeks. Good-quality leeks will have clean, blemish-free white bottoms with fresh-looking green
tops.
Lettuce. Heads should have crisp, even-colored leaves without signs of discoloration or decay.
Avoid lettuce that appears wilted or has yellow- tipped leaves or leaves showing cracks.
Mushrooms. Fresh mushrooms will be blemish-free and well-shaped in appearance and have a
firm texture without slimy spots or signs of decay.
Okra. Choose small to medium, well-shaped pods that are deep green and free of blemishes.
Pods should be crisp and should snap or puncture easily with pressure.
Onions. Good quality onions will be firm with short, tight necks and brittle outer papery skins.
Avoid those that feel soft or have sprouting green shoots or dark spots.
Parsnips. Choose well-shaped small to medium parsnips that are firm and have smooth, white
skins. Avoid large roots or those that have growth cracks, bruises, or discoloration.
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Peas. Choose plump peas with bright green color in well-filled pods. Snap peas and snow peas
should have crisp, firm pods.
Peppers, bell. Good quality bell peppers will be bright, glossy, firm, and well-shaped. Avoid
peppers with soft spots or dull-looking skin.
Potatoes. Choose potatoes that are firm and smooth without wrinkles, sprouts, cracks, bruises,
decay, or green areas. Green areas are caused by the potato’s production of a natural insecticide
in response to exposure to light. These green areas should be cut out before use because they can
be toxic if eaten in large amounts.
Rutabagas. Choose small to medium-size rutabagas that are heavy for their size. Select those
that are well-shaped and fairly smooth without shriveling or growth cracks.
Sprouts. Look for sprouts with a crisp texture without decay. Avoid those with a slimy
appearance. Remember that sprouts may carry bacteria and have been linked to outbreaks of
food poisoning, so cook sprouts before eating them.
Sweet potatoes. Good quality sweet potatoes will have bright, uniformly colored skin. Select
those that are firm and well-shaped with smooth skins.
Tomatoes. Choose tomatoes with smooth, firm flesh and bright, shiny skins. Avoid tomatoes
that are mushy or have blemishes.
Turnips. Choose small to medium turnips that are firm, fairly smooth, and heavy for their size.
Avoid turnips with signs of shriveling or growth cracks.
Storing, handling, and cooking vegetables
Proper storage and handling of fresh vegetables enhances their flavor and keeps nutrient loss to a
minimum. Store potatoes, tomatoes, and onions in the pantry out of any plastic wrappers. Store
vegetables such as leeks, celery, carrots, lettuce, and mushrooms unwashed, in the refrigerator in
plastic bags until ready for use. Too much moisture tends to cause rotting.
To remove dirt, bacteria, and pesticide residue, scrub and rinse vegetables with skins under cool
running water before use. Remove outer leaves of lettuce, cabbage, and other leafy vegetables.
To minimize preparation time, wash leafy greens and refrigerate them wrapped in a paper towel
inside a plastic bag a few hours before use. Otherwise you can refrigerate leafy greens unwashed
in a plastic bag and rinse right before use.
To retain most of the nutrients, steam vegetables or cook fresh or frozen vegetables in a small
amount of water. Cook vegetables only until tender-crisp. The shorter the time that vegetables
are cooked, the more nutrients that are retained. When longer cooking times are needed, cook
vegetables whole or cut into large pieces so fewer surfaces are exposed and fewer nutrients are
lost. Cover vegetables while cooking to speed up cooking time and to help retain nutrients that
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can be lost through the steam. Save the nutrient-rich cooking water from vegetables for soups,
stews, mashed potatoes, and sauces.
The table that accompanies this page provides nutrition information for fresh, canned, and frozen
vegetables available in most supermarkets. Canned and frozen vegetables must have a Nutrition
Facts panel on their labels but fresh vegetables sold loose (not in packages) do not require
nutrition labeling. The fresh and frozen vegetables listed contain no added salt. The canned
vegetables included in the table contain added salt.
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