Broccoli: A Superfood Vegetable With Great Health Benefits
Benefits of Broccoli
All green vegetables are nutritious and healthy, but broccoli is a true superfood. It's rich in nutrients and is thought to have many enticing health benefits. These include promoting eye health, improving the functioning of the immune system, and reducing inflammation and oxidative damage. They might also include improving the condition of arteries damaged by diabetes and reducing the risk of some forms of cancer.
Broccoli’s health benefits may be even more attractive now that researchers have bred a new form of the vegetable that they call “super broccoli”. This form of broccoli contains a much higher level of glucoraphanin than the regular vegetable. Glucoraphanin is converted into sulforaphane when we chew or chop broccoli. Sulforaphane is the chemical that is thought to be responsible for many of the vegetable's benefits.
The scientific name of broccoli is Brassica oleracea. Brussels sprouts, cabbage, cauliflower, kale, collard greens, and kohlrabi have the same scientific name, despite their different appearances. They are all cultivars of the same species.
Nutrients in Broccoli
Broccoli of any kind is rich in nutrients. The raw vegetable is an excellent source of vitamins C and K. In fact, one cup of fresh broccoli contains more than 100% of our daily requirement for these nutrients. Broccoli is a good source of vitamin A in the form of beta-carotene, which our bodies change into the type of vitamin A that we need. In addition, the vegetable contains folate (vitamin B9) and other vitamins.
Broccoli is also a good source of manganese. It contains useful amounts of other minerals, including potassium, magnesium, calcium, and iron. It provides us with dietary fiber and some protein in addition to vitamins and minerals. Broccoli is low in fat, sugars, calories, and sodium. Like all plants, it doesn’t contain cholesterol.
Broccoli belongs to the Brassicaceae family, which is also known as the cruciferous family. Some other nutritious vegetables in the family are Brussels sprouts, cauliflower, cabbage, kale, radishes, mustard, and horseradish.
Our bodies convert the beta-carotene in broccoli into vitamin A, which is necessary to make the visual pigments. These pigments are located in light-sensitive cells in the retina, which is found at the back of the eyeball. The retina sends a signal to the brain when the cells and their pigment are stimulated by light. The brain then creates the image that we see.
Two additional nutrients in broccoli are lutein and zeaxanthin, yellow pigments in the carotenoid family that also collect in the retina. These pigments aren't involved in vision but instead absorb high-energy blue and ultraviolet light. This absorption is thought to prevent the light from damaging the retina. Zeazanthin may help to prevent age-related macula degeneration (AMD). The macula is a spot on the retina that provides the most detailed vision and is the site where zeaxanthin collects.
Broccoli and other cruciferous vegetables have sulfur-containing chemicals called glucosinolates in their cells. (Glucoraphanin is a type of glucosinolate.) When the vegetables are chewed or chopped, an enzyme named myrosinase is released from the plant cells. This enzyme converts the glucosinolates into isothiocyanates, which have been shown to fight cancer in laboratory cell cultures and lab animals. Isothiocyanates may or may not work the same way inside the human body.
It’s hard to prove that cruciferous vegetables like broccoli help to prevent cancer in humans, but circumstantial evidence suggests that they are effective. In some population surveys, a diet rich in broccoli or its relatives has been linked to a significantly lower incidence of several types of cancer. Not all surveys show this benefit, however. Some show no link between cruciferous vegetable consumption and cancer risk.
The evidence for broccoli's benefit with respect to cancer is best described as "mixed". It's definitely intriguing, though. There's enough supportive evidence to make further research worthwhile.
Why Do the Results of Nutrition Surveys Vary?
There are many possible reasons why some surveys show that cruciferous vegetables reduce the risk of cancer while others don't. Some examples are given below.
- People may not describe their diet accurately to researchers.
- People who eat lots of cruciferous vegetables may be keen to follow other healthy habits as well. Avoiding unhealthy activities may have been responsible for at least some of the cancer reduction noted in surveys.
- Another possibility is that the benefit applies only to people with a particular gene or genes in their body.
- The benefit may depend on whether the vegetables are raw or cooked.
- The benefit may be received only if another food is eaten at the same time as the cruciferous vegetable.
- The vegetables may need to be eaten in a specific amount or frequency in order to be effective.
- Some cruciferous vegetables may be more effective than others.
Nutritional research in humans is complex. It's very important, though. Our diet can have powerful effects on our body.
Eating cruciferous vegetables may not be helpful for preventing disease if the rest of the diet is unhealthy. This may also be true if a person smokes, drinks an excessive amount of alcohol, or doesn't exercise.
Glucoraphanin and Sulforaphane
When broccoli is chewed or cut, its glucoraphanin is changed into an isothiocyanate called sulforaphane. In laboratory experiments with cell cultures, sulforaphane prevents the division of cancer cells and triggers their death.
Chemicals often have different effects inside a living body than they do on isolated cells, but sulforaphane has been found to slow the growth of tumors in mice. Sulforaphane may turn on tumor suppressor genes and may also make some carcinogens (chemicals that cause cancer) harmless. It seems to be the chief chemical being explored by researchers who are interested in broccoli's effect on health problems. Particular attention is being paid to broccoli sprouts, which contain a higher percentage of sulforaphane than mature broccoli.
Other Potential Health Benefits of Broccoli
Scientists are investigating sulforaphane in relation to other diseases in addition to cancer. It seems to be an anti-inflammatory substance and also seems to enhance the activity of antioxidants in the body. Antioxidants prevent the oxidation of molecules. Excessive oxidation is believed to damage cells.
Some research shows that broccoli is helpful in treating blood vessel damage caused by diabetes. There is growing evidence that broccoli helps the immune system to function better as well. A diet high in sulforaphane has been found to help mice with osteoarthritis by slowing cartilage damage in joints.
In one project, a group of researchers at John Hopkins University School of Medicine discovered an interesting effect of broccoli sprouts. In mice and a small group of humans, the consumption of broccoli sprouts significantly reduced—but didn't eliminate—a stomach infection caused by a bacterium named Helicobacter pylori. This is the bacterium that causes stomach and duodenal ulcers.
Fresh green broccoli that isn't wilting or turning yellow is the best type to buy. It may be available in supermarkets and grocery stores. An even better source might be a farmers market. The most nutritious broccoli might well be a homegrown version that has just been picked.
The new “super broccoli” contains two to three times more glucoraphanin than regular broccoli. It was created over many years by selectively breeding broccoli plants that had an increased glucoraphanin level. No genetic engineering was involved.
The super broccoli was bred by British scientists and is being sold to the public in the UK at the moment. It's available at selected supermarkets. The vegetable was created by the Institute for Food Research, which is also researching its health benefits.
Some nutritionists doubt that the enhanced variety of broccoli will be significantly helpful for the general population. They believe that for most people it's more important to improve overall diet and lifestyle than to search for nutritionally-enhanced varieties of food and drinks.
Whole Foods or Supplements?
Some of the protective substances present in broccoli can be bought as supplements. Researchers are finding that whole foods are often more beneficial than supplements, for several reasons.
- Sometimes supplements lack necessary "helper" nutrients that are found in the whole food.
- Many chemicals have been identified in cruciferous vegetables such as broccoli. It's not always clear which chemical is actually producing a particular effect in the body or which chemical to put in a supplement.
- Some substances in food may be helpful in small doses but harmful in the large doses found in certain supplements.
- The dose of a nutrient in a supplement may not be directly harmful but may cause an imbalance in essential body chemicals. This in itself may cause problems.
Supplements certainly have their place and are essential in some diseases or in some situations. For most of us, though, it's probably better to get our nutrients from whole foods instead of supplements.
Cooking Methods and Nutrient Loss
Broccoli is healthiest when it’s raw or lightly steamed. Broccoli should be slightly crunchy when it's removed from a steamer. The vegetable is also healthy when stir-fried or microwaved for a short time, but boiling has been shown to reduce its nutrient content dramatically. Water soluble vitamins such as vitamin C and folate enter the boiling water. In addition, boiling and prolonged cooking destroy the myrosinase enzyme that is needed to produce sulforaphane.
Broccoli in the Diet
I enjoy the taste of broccoli on its own, but some people may prefer to add a healthy sauce or dressing to the vegetable. The addition of an oil would enhance the absorption of the fat-soluble nutrients in the broccoli and the rest of the meal.
Broccoli can be incorporated into many recipes, including casseroles, soups, salads, and stir fry recipes. Some people even add it to bread recipes. There are many ways to sneak green vegetables into the diet of people who don't like them on their own. The effort is certainly worthwhile, since vegetables are very nutritious.
Many researchers are exploring the effects of broccoli and sulforaphane on the human body. Even if broccoli doesn't reduce cancer risk, it has other benefits that make it a worthy addition to the diet. It's an excellent food for everyone to eat regularly as part of a balanced diet.
- The SELF Nutrition Data site lists the nutrients in raw broccoli.
- Oregon State University gives facts about carotenoids (including lutein and zeaxanthin).
- The National Cancer Institute gives information about cruciferous vegetables and cancer prevention.
- John Hopkins University School of Medicine discusses broccoli sprouts and Helicobacter pylori.
- The University of East Anglia discusses broccoli and osteoarthritis.
- The University of Warwick gives facts about the effect of broccoli on arteries in diabetics.
- The phys.org news service provides a report about super broccoli.
- Oregon State University compares broccoli and supplements.
This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.
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© 2011 Linda Crampton