This week we celebrate broccoli as our Food of the Week. Broccoli's unique flavor and incredible nutritional value have made it one of the most popular vegetables in the United States. Its unique health-promoting sulfur-containing compounds and concentration of vitamins and minerals make it a great choice to feature in your World's Healthiest Foods Way of Eating.
What's New and Beneficial About Broccoli
- Since our recommended cooking method for broccoli has always been Quick Steaming, we are excited to report on numerous recent studies that show nutritional benefits from the steaming of broccoli (versus other cooking methods). Included in these benefits are better retention of vitamin C and sulforaphane when broccoli is steamed rather than boiled. Also noted in these studies are better firmness and more vibrant green color from short-term versus long-term steaming. "Short-term" in this context typically means 5 minutes or less of steaming, and "long-term" means more than 5 minutes, and usually more like 15-20 minutes.
- Connected with these steaming results in recent studies are clearly noticeable differences in nutrient concentrations that occur when steaming times are changed by relatively small amounts. For example, researchers are finding nutrient differences in broccoli steamed for 1 versus 2 minutes or 3 versus 5 minutes. Many nutrients in broccoli are clearly sensitive to total steaming time, and as a general rule, all studies suggest that total steaming time is kept relatively short. At WHFoods, our recommended steaming time for broccoli florets and leaves is 4 minutes.
- The anti-inflammatory benefits of sulfur compounds in broccoli have a strong research track record. Adding to this track record is a recent study showing broccoli benefits in a small group of smokers who averaged at least 10 cigarettes per day. Participants in the study consumed steamed broccoli for a 10-day period. The daily serving size was about 1.66 cups per day, and the cooking method featured in the study was 10 minutes of steaming. Participants in the study experienced a drop in their blood level of C-reactive protein (CRP), which is a blood protein used to measure a general degree of inflammation. The participants also experienced an increase in their blood level of the carotenoid lutein and the B-vitamin folate. Since broccoli is our 16th best source of carotenoids and 5th best source of folate, these study findings definitely make good sense to us. But equally interesting for us is the amount of broccoli consumed in this study. At WHFoods, our "outstanding" level of cruciferous vegetable intake is at least 1.5 cups per day of cruciferous vegetables. The intake level in this study was very close to that outstanding amount.
- In a recent study on organically grown broccoli, researchers noticed an association between the deep green color of the broccoli florets and their total carotenoid content. In other words, the deeper and richer the florets were in color, the more carotenoids they contained. Since carotenoids are yellow-orange in color and do not contribute to the greenness of food, this finding may seem somewhat surprising. But it may give us a practical way to make our broccoli selections in the grocery if we are trying to choose broccoli with higher carotenoid content.
Studies have shown that even kids like broccoli and one way to ensure that they enjoy it is to cook it properly by using our Quick Steaming method. Overcooked broccoli becomes soft and mushy, and along with this loss in texture comes a loss in flavor and nutrients. Begin by cutting broccoli florets into quarters and let sit for several minutes before cooking to enhance its health-promoting benefits. Steam for 4 minutes. See the Nutrient-Rich Way of Cooking Broccoli below.
You'll want to include broccoli 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, we recommend 3/4 cup of cruciferous vegetables on a daily basis. This amount is equivalent to approximately 5 cups per week. A more optimal intake amount would be 1-1/2 cups per day or about 10 cups per week. You can use our Veggie Advisor for help in figuring out your best cruciferous vegetable options.
It's no coincidence that more than 300 research studies on broccoli have converged in one unique area of health science—the development of cancer—and its relationship to three metabolic problems in the body. Those three problems are (1) chronic inflammation (2) oxidative stress, and (3) inadequate detoxification. While these types of problems have yet to become part of the public health spotlight, they are essential to understanding broccoli's unique health benefits. Over the past 10 years, research has made it clear that our risk of cancer in several different organ systems is related to the combination of these three problems.
The Cancer/Inflammation/Oxidative Stress/Detox Connection
In health science research, there is a growing body of evidence relating cancer risk to a series of environmental, dietary, and body system factors. Understanding this set of factors can be very helpful in making sense of broccoli and its health benefits. Please see our article on The Cancer/Inflammation/Oxidative Stress/Detox Connection for more details in this important area of health research.
Broccoli's Anti-Inflammatory Benefits
When threatened with dangerous levels of potential toxins, or dangerous numbers of overly-reactive, oxygen-containing molecules, signals are sent within our body to our inflammatory system, directing it to "kick in" and help protect our body from potential damage. One key signaling device is a molecule called Nf-kappaB. When faced with the type of dangers described above, the NF-kappaB signaling system is used to "rev up" our inflammatory response and increase production of inflammatory components (for example, IL-6, IL-1beta, TNF-alpha, iNOS and COX-2). This process works beautifully in temporary, short-term circumstances when healing from injury is required. When it continues indefinitely at a constant pace, however, it can put us at risk for serious health problems, including the development of cancer.
Isothiocyanates (ITCs) in Broccoli
Research studies have made it clear that the NF-kappaB signaling system that is used to "rev up" our inflammatory response can be significantly suppressed by isothiocyanates (ITCs). ITCs—the compounds made from glucosinolates found in broccoli and other cruciferous vegetables—actually help to shut down the genetic machinery used to produce NF-kappaB and other components of the inflammatory system. These anti-inflammatory benefits of ITCs have been clearly demonstrated in lab and animal studies. However, it can sometimes be tricky to translate the results of these lab and animal studies in practical take-away recommendations for everyday eating.
The primary anti-inflammatory ITC provided by broccoli is sulforaphane. This ITC can be directly produced from broccoli's glucoraphanin content. Numerous anti-inflammatory mechanisms for sulforaphane are well known, including inactivation of the NF-kappa B pathway. In this context, it is interesting to note that the predominance of sulforaphane in broccoli is limited to the heading version of this vegetable. Also widely enjoyed worldwide is "non-heading" broccoli, often called sprouting broccoli, broccoli raab, broccoli rabe, or rapini. In these non-heading varieties of broccoli, iberin is the most common ITC, and it is derived from glucoiberin, which is one of the more common glucosinolates in non-heading broccoli). Yet another anti-inflammatory compound present in both heading and non-heading varieties of broccoli is glucobrassicin. (And in this case, the corresponding ITC derived from glucobrassicin is indole-3-carbinol.)
Omega-3s in Broccoli
Lack of omega-3 fat is dietary problem that can cause over-activation of the inflammatory system. The reason is simple: many key anti-inflammatory messaging molecules (like PGH3, TXA3, PGI3, and LTE5) are made from omega-3 fats. While we are not accustomed to thinking about non-fatty vegetables as sources of omega-3 fats, it would probably be a good idea for us to change our thinking in this area. While there are limited amounts of omega-3s in low-fat vegetables like broccoli, it is equally true that their levels of omega-3s can still play an important role in balancing our inflammatory system activity. In 100 calories' worth of broccoli (about 2 cups) there are approximately 400 milligrams of omega-3s (in the form of alpha-linolenic acid, or ALA). That amount of ALA falls into the same general ballpark as the amount provided by one soft gel capsule of flax oil. While we would not want to depend on broccoli as our sole source of dietary omega-3s, we still get important anti-inflammatory benefits from the omega-3s it provides.
Other Anti-Inflammatory Benefits of Broccoli
Broccoli is a rich source of one particular phytonutrient (a flavonol) called kaempferol. Especially inside of our digestive tract, kaempferol has the ability to lessen the impact of allergy-related substances (by lowering the immune system's production of IgE-antibodies). By lessening the impact of allergy-related substances, the kaempferol in broccoli can help lower our risk of chronic inflammation.
Broccoli's Antioxidant Benefits
Vitamins, minerals, and phytonutrients all contribute to the antioxidant benefits provided by our food. Broccoli is a premiere example of a vegetable providing all three types of antioxidants. In the vitamin category, among all 100 of our WHFoods, broccoli represents our 3rd best source of vitamin C,10th best source of vitamin E, and 16th best source of vitamin A (in the form of carotenoids). It also serves as our top source of chromium, a very good source of manganese, and a good source of selenium and zinc. But it is the phytonutrient category in which broccoli's antioxidant benefits stand out. Concentrated in broccoli are flavonoids like kaempferol and quercitin. Also concentrated are the carotenoids lutein, zeaxanthin, and beta-carotene. All three of these carotenoids function as key antioxidants. In the case of lutein and beta-carotene, broccoli has been shown not only to provide significant amounts of these antioxidants but to significantly increase their blood levels when consumed in the amount of 2-3 cups per day.
Of special interest in this antioxidant area are broccoli sprouts. In the U.S., broccoli sprouts are not consumed nearly as often as mung bean, alfalfa, or pea sprouts. However, in other countries broccoli sprouts are more widely consumed, and they show up as concentrated sources of broccoli antioxidants. Broccoli sprouts also contain concentrated amounts of glucosinolates and have become especially interesting to researchers in this regard.
Consumption of Broccoli Can Improve Detoxification
Many toxins that pose a risk to our cells must be detoxified in our body by a two-step process. The isothiocyanates (ITCs) made from the glucosinolates in broccoli have repeatedly been shown to improve our detoxification ability. The bulk of the research on broccoli intake and detoxification has focused on a component of this process called Phase 2. Phase 2 of detoxification is the component of the detox process in which activated toxic substances get hooked together with nutrients or nutrient components to allow excretion from the body. Importantly, the glucosinolates in broccoli (and their isothiocyanate derivatives) are known to activate Phase 2 detox activity in our cells. (This activation is typically mediated through a pathway called Nrf2.) Because broccoli components can activate Phase 2 detoxification, they can help us prepare potentially toxic substances for elimination from our body. This enhancement of Phase 2 detoxification appears to occur with commonly consumed amounts of broccoli falling in the 1-2 cups per day range.
Broccoli and Cancer Prevention
The unique combination of antioxidant, anti-inflammatory, and pro-detoxification components in broccoli make it a unique food in terms of cancer prevention. Connections between cancer development and oxidative stress, chronic inflammation, and inadequate detoxification are so well-documented in the research that any food improving all three of these metabolic problems would be highly likely to lower our risk of cancer. In the case of broccoli, the research is strongest in showing decreased risk of prostate cancer, colon cancer, breast cancer, bladder cancer, and ovarian cancer. We expect that risk reduction for other types will also eventually be shown to take place from regular consumption of broccoli.
How Much Broccoli Is Needed for Cancer Prevention?
Recent studies have also provided us with a much better idea about the amount of broccoli that we need to lower our cancer risk. At the lower end of the spectrum, it looks like an average of 1/2 cup of broccoli per day—only 22 calories' worth of broccoli - is enough to provide some measurable benefits. Few people have broccoli on a daily basis. But a 2-cup serving twice a week would still meet this minimum average amount. It's important to remember how little this amount actually in within the context of one week's food. A person eating 2,000 calories per day would be consuming 14,000 calories per week. A 2-cup serving of broccoli twice a week would provide about 178 calories—only 1% of the total weekly calories! At the higher end of the spectrum, studies show that more broccoli might be needed to accomplish other cancer-preventing tasks. For example, one study showed significantly higher urinary excretion of potential carcinogens from well-done, grilled meats given daily consumption of broccoli in the range of 9 ounces (250 grams) per day. That gram amount corresponds to approximately 1.6 cups of broccoli on a daily basis. We've also seen a study showing that "generous" amounts of broccoli can help optimize levels of antioxidants in the blood, especially beta-carotene and lutein. (Optimal antioxidant levels can help lower the risk of oxidative stress in healthy cells, which also helps lower their risk of becoming cancerous.) In this study, the term "generous" was used to describe the consumption of broccoli in the amount of 3 cups daily. Once again, that amount would not be ridiculously high in terms of calories—3 cups would provide about 132 calories or 6-7% of a 2,000-calorie diet. But it might be a greater amount that many people would want to consume on a regular basis. At WHFoods, our minimum recommendation for cruciferous vegetables is 3/4 cup per day, and our outstanding intake level is 1.5 cups per day. Of course, these recommendations are for intake of all cruciferous vegetables combined, and not only broccoli.
For us, the bottom line here is not to treat broccoli like garnish. In recipes like our Asian-Flavored Broccoli with Tofu or 5-Minute Broccoli with Feta Cheese and Kalamata Olives recipes, we use 1 pound of broccoli to provide two servings. That's approximately 1.5 cups of broccoli per serving. There is no reason to shy away from 2-3 cup servings of broccoli when enjoying this cruciferous vegetable, especially if you want to optimize its cancer-preventing benefits. But make sure you're not simply "decorating" your plate with single broccoli stalk and floret.
Broccoli and Digestive Support
The digestive support provided by broccoli falls into two basic categories: fiber support, and ITC (isothiocyanate) support. At approximately 1 gram of dietary fiber for every 10 calories, you don't have to eat much broccoli to get a large amount of your daily requirement! For 100 calories—only 5% of a 2,000-calorie diet—you get about 10 grams of fiber, or 40% of the Daily Value (DV). And, 250 calories of broccoli (about 12% of a 2,000-calorie diet) will give you the full daily requirement for this important nutrient! Few components of food support our digestive system as well as fiber. The speed that food travels through us, the consistency of food as it moves through our intestine, and bacterial populations in our intestine are all supported as well as regulated by dietary fiber.
Alongside broccoli's dietary fibers are its glucosinolates. These phytonutrients are converted by our bodies into isothiocyanates (ITCs). ITCs—and particularly sulforaphane—help protects the health of our stomach lining by helping prevent bacterial overgrowth of Helicobacter pylori or too much clinging by this bacterium to our stomach wall. Broccoli sprouts appear to have especially strong stomach support properties in this regard.
Broccoli and Cardiovascular Support
Recent studies continue to show intake of broccoli as being able to lower levels of LDL-cholesterol in our bloodstream. In fact, one recent study showed a drop of LDL-cholesterol by about 2.5% after intake of 1/3 cup of broccoli per day for 3 months. That's a fairly quick drop and a fairly small amount of broccoli—especially since our minimum daily recommendation at WHFoods for cruciferous vegetables (including broccoli) is 3/4 cup. This basic relationship between broccoli intake and LDL reduction holds true for both raw and steamed broccoli. However, recent studies also show a stronger link between intake of steamed broccoli and LDL-cholesterol reduction than between LDL reduction and intake of raw broccoli.
Yet, owing to the new transition in thinking about the role of LDL reduction for our health, the implication of this benefit isn't clear. The reason for this is that current
research on diet and cardiovascular disease is undergoing an unusual kind of transition when it comes to looking at LDL cholesterol. For example, one medical study has found that individuals with high LDL-cholesterol levels tend to live as long—and sometimes longer—than individuals with average or low LDL levels. In this general context, it is also worth pointing out that for the years 2015-2020, the Dietary Guidelines for Americans (issued jointly by the U.S. Department of Health and Human Services and U.S. Department of Agriculture) have eliminated a previous recommendation to restrict dietary cholesterol intake to a level of 300 milligrams per day. This change in the recommendations is the result of a changing medical perspective on the role of blood cholesterol (including LDL-cholesterol) as a factor in cardiovascular disease.
While we remain highly confident about the cardiovascular benefits of broccoli, we suspect that the reasons for these health benefits are going to start pointing less and less to cholesterol management and more and more to better control of inflammation and decreased oxidative stress within our blood vessels. We also suspect that the phytonutrients in broccoli will become increasingly important in our understanding of broccoli intake and reduced risk of cardiovascular disease and that these phytonutrients will become better understood in their role as modifiers of cell signaling and communications related to our cardiovascular health.
The B-complex vitamins in broccoli can also make a major contribution to our cardiovascular health. Especially with respect to the excessive formation of homocysteine—an event which raises our risk of atherosclerosis, stroke, and heart attack—B-complex vitamin deficiency intake can pose a major risk. Three B vitamins especially important for lowering our risk of hyperhomocysteinemia (excessive formation of homocysteine) are vitamin B6, vitamin B12, and folate. (And as mentioned earlier in this article, daily intake of 1.66 cups of steamed broccoli over a very short 10-day period has been shown to raise blood folate levels in a small group study of cigarette smokers.) By making an important contribution to our B6 and folate intake, broccoli can help us lower our risk of excessive homocysteine formation and cardiovascular problems that are related to excess homocysteine.
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