Bok choy

As an increasingly popular member of the cruciferous vegetable family, bok choy is being recognized more and more often for its standout nutrient richness. This member of the cabbage family is one of our highest nutritionally ranked vegetables and it provides good, very good, or excellent amounts of 21 nutrients. Unlike some other members of the cabbage family, these ranked nutrients include omega-3s, as well as the antioxidant mineral zinc. Recent studies have identified over 70 antioxidant phenolic substances in bok choy. These phenolic antioxidants included numerous hydroxycinnamic acids, which have often been referred to as "chain-breaking" antioxidants due to their method of scavenging free radicals. In this context, bok choy has also been included in some current and ongoing large-scale human studies about dietary antioxidants and cancer prevention. Because of its strong beta-carotene content, bok choy ranks as our 11th richest food in vitamin A. This vitamin A richness places bok choy ahead of some of its fellow cruciferous vegetables, including cauliflower, cabbage, Brussels sprouts, and broccoli. Significant amounts of other carotenoids—for example, lutein—are also provided by bok choy. WHFoods Recommendations You'll want to include bok choy as one of the cruciferous vegetables you eat on a regular basis if you want to receive the fantastic health benefits provided by the cruciferous vegetable family. At a minimum, include cruciferous vegetables as part of your diet 2-3 times per week, and make the serving size at least 1-1/2 cups. Even better from a health standpoint, enjoy bok choy and other vegetables from the cruciferous vegetable group 4-5 times per week, and increase your serving size to 2 cups. We've found bok choy to be a delightful alternative among the cruciferous vegetables for its quick preparation, enjoyable and easy-to-chew texture, milder and somewhat sweet taste, and versatility in recipes. Enjoy the mild flavor of bok choy by using our Healthy Sauté method of cooking. Our 4-Minute Healthy Sautéed Bok Choy recipe will give you great tasting bok choy in a matter of minutes!

This chart graphically details the %DV that a serving of Bok choy provides for each of the nutrients of which it is a good, very good, or excellent source according to our Food Rating System. Additional information about the amount of these nutrients provided by Bok choy can be found in the Food Rating System Chart. A link that takes you to the In-Depth Nutritional Profile for Bok choy, featuring information over 80 nutrients, can be found under the Food Rating System Chart.

• Health Benefits
• Description
• History
• How to Select and Store
• Tips for Preparing and Cooking
• How to Enjoy
• Individual Concerns
• Nutritional Profile
• References

Health Benefits

Antioxidant Benefits

As an excellent source of vitamin C, vitamin A (in the form of carotenoids), and manganese, and a good source of zinc, bok choy provides us with a concentration of these core conventional antioxidants. Yet, its antioxidant support extends beyond these conventional antioxidants to a wide range of other phytonutrient antioxidants. These phytonutrients include flavonoids like quercetin, kaempferol, and isorhamnetin, as well as numerous phenolic acids (including significant amounts of hydroxycinnamic acids). It's important to understand the unique benefits provided by this diverse array of antioxidants. Different types of antioxidants function in different ways. While all types are helpful in preventing unwanted oxygen damage to our cells and body systems, different types of antioxidants go about this task in different ways, and it is the combination of these types in cruciferous vegetables—including bok choy—that make them so valuable in terms of their antioxidant support. (It is also a key reason why whole, natural foods like fresh bok choy provide you with benefits that antioxidant supplements cannot.)

Anti-Inflammatory Benefits

Many of the antioxidant nutrients listed above also provide anti-inflammatory benefits. They not only lower the risk of oxygen-based damage to your cells and body systems, but they also lower your risk of unwanted chronic inflammation. While it is a good thing for your body's inflammatory system to respond promptly to dangers or actual damage, it is not a good thing for it to continuously trigger inflammatory responses when there is not danger or actual damage. Anti-inflammatory phytonutrients in bok choy help prevent this type of continuous and unwanted inflammation from occurring. Yet in addition to these phytonutrients, bok choy also provides you with two additional anti-inflammatory nutrients. The first of these nutrients are omega-3s. Bok choy ranks as a good source of omega-3s in our rating system due to its significant amount of alpha-linolenic acid (ALA). About 70 milligrams of ALA are found in one cup of cooked bok choy. While this amount does not put bok choy anywhere close to the top of our omega-3 plant vegetable list, it does qualify bok choy as being about one-half as concentrated in omega-3s as walnuts on a calorie-for-calorie basis. We have yet to see research on bok choy's omega-3 content and inflammation, but we would expect this kind of research to show bok choy omega-3s as being helpful in lowering risk of unwanted inflammation.

Another anti-inflammatory nutrient provided by bok choy is vitamin K. Bok choy ranks in our Top 15 vitamin K-rich foods and is an excellent source of this fat-soluble vitamin. While best know for its role in bone health and blood clotting, vitamin K has also been shown to help regulate our body's inflammatory responses, especially in relationship to our cardiovascular system.

Other Health Benefits

Bok choy has been included in human studies of cruciferous vegetables that have shown decreasing risk of certain cancers when these vegetables were consumed on a frequent basis, usually involving one or more daily servings. At least part of this protection has been associated with the glucosinolate content of the cruciferous vegetables, including bok choy. (Glucosinolates are unique sulfur-containing compounds that have been shown to have cancer-protective properties.) However, we have yet to see a study exclusively focused on bok choy in comparison to its fellow cruciferous vegetables, and we suspect that it would rank on the lower end in terms of its glucosinolate-related benefits since it contains a significantly lower amount of these sulfur-containing compounds than other vegetables in the cruciferous family like Brussels sprouts or mustard greens.

Description

Bok choy is a member of the cruciferous family of vegetables, which also includes broccoli, kale, collard greens, cabbage, mustard greens, cauliflower, and Brussels sprouts. Bok choy is a type of cruciferous vegetable in which the leaves of the plant do not form a head. For this reason, it is often referred to as "non-heading" and you will sometimes see bok choy being referred to as "non-heading Chinese cabbage." Because "bok choy" means "white vegetable" in Chinese, you may also hear it being referred to as "white cabbage" or "white-stem cabbage." However, as a practical matter, not all bok choy is white-stemmed. While often white or cream-colored, bok choy stalks can also be varying shades of green. (In fact, it is also possible to find yellow-stemmed and purple-stemmed bok choy.) But regardless of stem color, you can recognize bok choy as a non-headed cabbage with distinct individual leaves that cluster together in a way that is similar to celery stalks.

Just as you can find more than one recognizable form of bok choy, you can also find more than one scientific name for this cruciferous vegetable. The most common name is Brassica rapa L. subsp. chinensis. But you may also find bok choy being scientifically referred to as Brassica chinensis (where "chinensis" is used as a species name rather than a subspecies name). Also, you may occasionally see bok choy being identified as Brassica campestris L. subsp. chinensis.

Finally, the English spelling of this vegetable's name can also take several different forms. You might see the first word in this food name being spelled as buk, pok, or pak. And you might see the second word being spelled as choi. But like the science names and common names, all of these variations in spelling refer to the same delicious vegetable that has smooth, glossy, spoon-shaped leaf blades that cluster together without forming an actual head. Baby bok choy is also available, and it has a more tender texture and milder flavor.

History

Bok choy—and other forms of Chinese cabbage—has been enjoyed in China and other parts of Asia for over 1,500 years. And bok choy is by no means a total newcomer to North America either, having been cultivated on the continent for over 100 years.

In the U.S., Florida, California, Hawaii, and New Jersey are key states in the commercial production of both headed and non-headed Chinese cabbage, including bok choy. For example, about 4,500 acres of these Chinese vegetables are grown in Florida each year. When evaluated in the marketplace, bok choy is typically included among other Oriental vegetables that include both headed and non-headed varieties of cabbages, mustards, and other cruciferous vegetables.

How to Select and Store

Look for bok choy with firm, bright green colored leaves and moist hardy stems. Bok choy should be displayed in a cool environment since warm temperatures will cause it to wilt and will negatively affect its flavor. The leaves should look fresh, be unwilted, and be free from signs of browning, yellowing, and small holes. Bok choy is available throughout the year, although it is more widely available, and at its peak, from the middle of winter through the beginning of spring.

To store, place bok choy in a plastic storage bag removing as much of the air from the bag as possible. Keeping bok choy cold will keep it fresh and help it retain its vitamin C content. Put the whole head in a plastic bag in the crisper of your refrigerator. Bok choy will keep for about 1 week if properly stored.

Tips for Preparing and Cooking

Tips for Preparing Bok Choy

Unlike some of the other cruciferous vegetables, you can consume virtually all parts of bok choy without much trimming or worrying about problematic textures or cooking times.

Chop leaf portion into 1/8" slices and the stems into 1/2" lengths for quick and even cooking.

To get the most health benefits from bok choy, let sit for a minimum of 5 minutes before cooking. Sprinkling with lemon juice before letting them sit can further enhance its beneficial phytonutrient concentration.

Want to learn more about how cutting, slicing, and chopping may affect fresh vegetables like bok choy? See our Q+A on this subject.

The Healthiest Way of Cooking Bok Choy

From all of the cooking methods we tried when cooking bok choy, our favorite is Healthy Sauté. We think that it provides the greatest flavor and is also a method that allows for concentrated nutrient retention.

To Healthy Sautébok choy, heat 5 TBS of vegetable or chicken broth, or water, in a stainless steel skillet. Once bubbles begin to form add bok choy stems on the bottom of the pan and the leaves on top, cover, and Healthy Sautéfor 3 minutes. (See our recipe for details on how to prepare this dish.)

How to Enjoy

A Few Quick Serving Ideas

• Healthy Sautébok choy with snow peas and mushrooms.
• Add a few drops of tamari soy sauce to bok choy recipe.
• Combine Healthy Sautéed bok choy with tofu or chicken for a complete meal.

WHFoods Recipes That Feature Bok Choy

• 15-Minute Steamed Halibut with Bok Choy
• 15-Minute Healthy Sautéed Chicken & Bok Choy
• 4-Minute Healthy Sautéed Bok Choy

Individual Concerns

Bok choy is sometimes referred to as a "goitrogenic" food. Yet, contrary to popular belief, according to the latest studies, foods themselves—bok choy included—are not "goitrogenic" in the sense of causing goiter whenever they are consumed, or even when they are consumed in excess. In fact, most foods that are commonly called "goitrogenic"—such as the cruciferous vegetables (including cabbage, broccoli, kale, and cauliflower) and soyfoods—do not interfere with thyroid function in healthy persons even when they are consumed on a daily basis. Nor is it scientifically correct to say that foods "contain goitrogens," at least not if you are thinking about goitrogens as a category of substances like proteins, carbohydrates, or vitamins. With respect to the health of our thyroid gland, all that can be contained in a food are nutrients that provide us with a variety of health benefits but which, under certain circumstances, can also interfere with thyroid function. The term "goitrogenic food" makes it sound as if something is wrong with the food, but that is simply not the case. What causes problems for certain individuals is not the food itself but the mismatched nature of certain substances within the food to their unique health circumstances. For more, see An Up-to-Date Look at Goitrogenic Substances in Food.

Nutritional Profile

Bok choy is an excellent source of vitamin K, vitamin C, vitamin A (in the form of carotenoids), potassium, folate, vitamin B6, calcium, and manganese. It is a very good source of iron, vitamin B2, phosphorus, fiber and protein as well as a good source of choline, magnesium, niacin, vitamin B1, copper, omega-3 fatty acids, zinc, and pantothenic acid. Boy choy also provides flavonoids including quercetin, kaempferol, and isorhamnetin, as well as numerous antioxidant phenolic acids, especially hydroxycinnamic acids.

In-Depth Nutritional Profile

In addition to the nutrients highlighted in our ratings chart, an in-depth nutritional profile for Bok choy is also available. This profile includes information on a full array of nutrients, including carbohydrates, sugar, soluble and insoluble fiber, sodium, vitamins, minerals, fatty acids, amino acids and more.

Introduction to Food Rating System Chart

In order to better help you identify foods that feature a high concentration of nutrients for the calories they contain, we created a Food Rating System. This system allows us to highlight the foods that are especially rich in particular nutrients. The following chart shows the nutrients for which this food is either an excellent, very good, or good source (below the chart you will find a table that explains these qualifications). If a nutrient is not listed in the chart, it does not necessarily mean that the food doesn't contain it. It simply means that the nutrient is not provided in a sufficient amount or concentration to meet our rating criteria. (To view this food's in-depth nutritional profile that includes values for dozens of nutrients - not just the ones rated as excellent, very good, or good - please use the link below the chart.) To read this chart accurately, you'll need to glance up in the top left corner where you will find the name of the food and the serving size we used to calculate the food's nutrient composition. This serving size will tell you how much of the food you need to eat to obtain the amount of nutrients found in the chart. Now, returning to the chart itself, you can look next to the nutrient name in order to find the nutrient amount it offers, the percent Daily Value (DV%) that this amount represents, the nutrient density that we calculated for this food and nutrient, and the rating we established in our rating system. For most of our nutrient ratings, we adopted the government standards for food labeling that are found in the U.S. Food and Drug Administration's "Reference Values for Nutrition Labeling." Read more background information and details of our rating system.

In-Depth Nutritional Profile for Bok choy

References

• Harbayum B, Hubbermann EM, Zhu Z et al. Free and bound phenolic compounds in leaves of pak choi (Brassica campestris L. ssp. chinensis var. communis) and Chinese leaf mustard (Brassica juncea Coss). Food Chemistry, Volume 110, Issue 4, 15 October 2008, Pages 838-846.
• Heimler D, Vignolini P, Dini MG et al. Antiradical activity and polyphenol composition of local Brassicaceae edible varieties. Food Chemistry, Volume 99, Issue 3, 2006, Pages 464-469.
• Lee WY Jr, Emmy Hainida KI, Abbe Maleyki MJ, et al. Antioxidant capacity and phenolic content of selected commercially available cruciferous vegetables. Malays J Nutr. 2007 Mar;13(1):71-80. Epub 2007 Mar 15.
• Lin LZ and Harnly JM. Phenolic component profiles of mustard greens, yu choy, and 15 other brassica vegetables. J Agric Food Chem. 2010 Jun 9;58(11):6850-7. doi: 10.1021/jf1004786.
• Reif C, Arrigoni E, Berger F, et al. Lutein and β-carotene content of green leafy Brassica species grown under different conditions. LWT - Food Science and Technology, Volume 53, Issue 1, September 2013, Pages 378-381.
• Reiss R, Johonston J, Tucker K, et al. Estimation of cancer risks and benefits associated with a potential increased consumption of fruits and vegetables. Food and Chemical Toxicology, Volume 50, Issue 12, December 2012, Pages 4421-4427.
• Samec D, Piljac-Zegarac J, Bogovic M, et al. Antioxidant potency of white (Brassica oleracea L. var. capitata) and Chinese (Brassica rapa L. var. pekinensis (Lour.)) cabbage: The influence of development stage, cultivar choice and seed selection. Scientia Horticulturae, Volume 128, Issue 2, 18 March 2011, Pages 78-83.
• Zamora-Ros R, Rothwell JA, Scalbert A, et al.Dietary intakes and food sources of phenolic acids in the European Prospective Investigation into Cancer and Nutrition (EPIC) study.Br J Nutr. 2013 Oct;110(8):1500-11. doi: 10.1017/S0007114513000688. Epub 2013 Mar 14.

• Much grattidtude to George Mateljan,and the George Mateljan Foundation for www.whfoods.com