Research news on nutrition, environmental medicine and health
Sulfur in broccoli and other cruciferous vegetables may hold the key to healing genetic diseases(NaturalNews) Our mothers were right. Broccoli is good for us, but possibly in ways our mothers never knew. Health practitioners and fitness experts around the world have heralded the benefits of broccoli for decades. Scientists have long demonstrated the antioxidant properties of broccoli.
Research performed by scientists at the U.S. Department of Agriculture (USDA) and published recently in the journal Crop Science has demonstrated that mineral levels in new varieties of broccoli have not declined since 1975, and that the broccoli contains the same levels of calcium, copper, iron, magnesium, potassium and other minerals that have made the vegetable a healthy staple of American diets for decades.
“This research provides data on the nutritional content of broccoli for breeders to consider as they further improve this important vegetable,” said Edward B. Knipling, administrator of the Agricultural Research Service (ARS), USDA’s principal intramural scientific research agency. “The research demonstrates how ARS is helping to find answers to agricultural problems that impact Americans every day, from field to table.”
A team of three scientists evaluated the mineral content of 14 broccoli cultivars released over a span of more than 50 years: ARS geneticist and research leader Mark Farnham at the agency’s U.S. Vegetable Laboratory in Charleston, S.C.; plant physiologist Michael Grusak at the USDA-ARS Children’s Nutrition Research Center (CNRC) in Houston, Texas; and Clemson University scientist Anthony Keinath.
The researchers grew the 14 cultivars in two field trials in 2008 and 2009, and harvested florets for testing.
“Our studies show that not much has changed in terms of mineral content in the last 35 years in a crop that has undergone significant improvement from a quality standpoint and that was not widely consumed in the United States before the 1960s,” said Farnham.
Broccoli florets in the study were tested for levels of calcium, copper, iron, potassium, magnesium, manganese, molybdenum, sodium, phosphorous, sulfur and zinc. Results indicated significant cultivar differences in floret concentrations of calcium, copper, iron, magnesium, sodium, phosphorous and zinc, but not of potassium, manganese, molybdenum or sulfur. There was no clear relationship between mineral concentration and release year.
“For broccoli cultivars grown during the past 35 years, when hybrids became the standard cultivar, evidence indicates that mineral concentrations remain unchanged,” said Farnham. “As broccoli breeders continue to improve this crop in the future, data from this study can serve as a very useful guide in helping breeders understand the variation in mineral concentrations they should expect among their breeding stocks and also provide a realistic baseline that should be maintained as other characteristics are manipulated in the future.”
Reference
Farnham MW, Keinathb AP, Grusakc MA. Mineral Concentration of Broccoli Florets in Relation to Year of Cultivar Release. Crop Science 2011; 51: 2716-2720.
Researchers reporting online in the journal Cell, a Cell Press publication, on October 13th have found another good reason to eat your green vegetables, although it may or may not win any arguments with kids at the dinner table.
It turns out that green vegetables — from bok choy to broccoli — are the source of a chemical signal that is important to a fully functioning immune system. They do this by ensuring that immune cells in the gut and the skin known as intra-epithelial lymphocytes (IELs) function properly.
“It is still surprising to me,” said Marc Veldhoen of The Babraham Institute in Cambridge. “I would have expected cells at the surface would play some role in the interaction with the outside world, but such a clear cut interaction with the diet was unexpected. After feeding otherwise healthy mice a vegetable-poor diet for two to three weeks, I was amazed to see 70 to 80 percent of these protective cells disappeared.”
Those protective IELs exist as a network beneath the barrier of epithelial cells covering inner and outer body surfaces, where they are important as a first line of defense and in wound repair. Veldhoen’s team now finds that the numbers of IELs depend on levels of a cell-surface protein called the aryl hydrocarbon receptor (AhR), which can be regulated by dietary ingredients found primarily in cruciferous vegetables. Mice lacking this receptor lose control over the microbes living on the intestinal surface, both in terms of their numbers and composition.
Earlier studies suggested that breakdown of cruciferous vegetables can yield a compound that can be converted into a molecule that triggers AhRs. The new work finds that mice fed a synthetic diet lacking this key compound experience a significant reduction in AhR activity and lose IELs. With reduced numbers of these key immune cells, animals showed lower levels of antimicrobial proteins, heightened immune activation and greater susceptibility to injury. When the researchers intentionally damaged the intestinal surface in animals that didn’t have normal AhR activity, the mice were not as “quick to repair” that damage.
As an immunologist, Veldhoen says he hopes the findings will generate interest in the medical community, noting that some of the characteristics observed in the mice are consistent with those seen in patients with inflammatory bowel disease.
“It’s tempting to extrapolate to humans,” he said. “But there are many other factors that might play a role.”
For the rest of us, he says, “it’s already a good idea to eat your greens.” Still, the results offer a molecular basis for the importance of cruciferous vegetable-derived phyto-nutrients as part of a healthy diet.
Reference
Li Y, Innocentin S, Withers DR, Roberts NA, Gallagher AR, Grigorieva EF, Wilhelm C, Veldhoe M. Exogenous Stimuli Maintain Intraepithelial Lymphocytes via Aryl Hydrocarbon Receptor Activation. Cell 2011 Oct 13. [Epub ahead of print]
New research has found that if you want some of the many health benefits associated with eating broccoli or other cruciferous vegetables, you need to eat the real thing – a key phytochemical in these vegetables is poorly absorbed and of far less value if taken as a supplement.
The study, published by scientists in the Linus Pauling Institute at Oregon State University, is one of the first of its type to determine whether some of the healthy compounds found in cruciferous vegetables can be just as easily obtained through supplements.
The answer is no.
And not only do you need to eat the whole foods, you have to go easy on cooking them.
“The issue of whether important nutrients can be obtained through whole foods or with supplements is never simple,” said Emily Ho, an OSU associate professor in the OSU School of Biological and Population Health Sciences, and principal investigator with the Linus Pauling Institute.
“Some vitamins and nutrients, like the folic acid often recommended for pregnant women, are actually better-absorbed as a supplement than through food,” Ho said. “Adequate levels of nutrients like vitamin D are often difficult to obtain in most diets. But the particular compounds that we believe give broccoli and related vegetables their health value need to come from the complete food.”
The reason, researchers concluded, is that a necessary enzyme called myrosinase is missing from most of the supplement forms of glucosinolates, a valuable phytochemical in cruciferous vegetables. Without this enzyme found in the whole food, the study found that the body actually absorbs five times less of one important compound and eight times less of another.
Intensive cooking does pretty much the same thing, Ho said. If broccoli is cooked until it’s soft and mushy, its health value plummets. However, it can still be lightly cooked for two or three minutes, or steamed until it’s still a little crunchy, and retain adequate levels of the necessary enzyme.
The new study was published in the Journal of Agricultural and Food Chemistry. It was supported by the National Institutes of Health.
Broccoli has been of particular interest to scientists because it contains the highest levels of certain glucosinolates, a class of phytochemicals that many believe may reduce the risk of prostate, breast, lung and colorectal cancer. When eaten as a raw or lightly-cooked food, enzymes in the broccoli help to break down the glucosinolates into two valuable compounds of intensive research interest – sulforaphane and erucin.
Studies have indicated that sulforaphane, in particular, may help to detoxify carcinogens, and also activate tumor suppressor genes so they can perform their proper function.
Most supplements designed to provide these glucosinolates have the enzyme inactivated, so the sulforaphane is not released as efficiently. There are a few supplements available with active myrosinase, and whose function more closely resembles that of the whole food, but they are still being tested and not widely available, Ho said.
Small amounts of the myrosinase enzyme needed to break down glucosinolates are found in the human gut, but the new research showed they accomplish that task far less effectively than does whole food consumption.
Although broccoli has the highest levels of glucosinolates, they are also found in cauliflower, cabbage, kale and other cruciferous vegetables. The same cooking recommendations would apply to those foods to best retain their health benefits, Ho said.
Many people take a variety of vitamins, minerals and phytochemicals as supplements, and many of them are efficacious in that form, researchers say. Higher and optimal levels of popular supplements such as vitamins C, E, and fish oil, for instance, can be difficult to obtain through diet alone. Some researchers believe that millions of people around the world have deficient levels of vitamin D, because they don’t get enough in their diet or through sun exposure.
But for now, if people want the real health benefits of broccoli, there’s a simple guideline.
Eat your vegetables.
Reference
Clarke JD, Riedl K, Bella D, Schwartz SJ, Stevens JF, Ho E. Comparison of Isothiocyanate Metabolite Levels and Histone Deacetylase Activity in Human Subjects Consuming Broccoli Sprouts or Broccoli Supplement. J Agric Food Chem 2011 Sep 19. [Epub ahead of print]
Teaming fresh broccoli with a spicy food that contains the enzyme myrosinase significantly enhances each food’s individual cancer-fighting power and ensures that absorption takes place in the upper part of the digestive system where you’ll get the maximum health benefit, suggests a new University of Illinois study.
“To get this effect, spice up your broccoli with broccoli sprouts, mustard, horseradish, or wasabi. The spicier, the better; that means it’s being effective,” said Elizabeth Jeffery, a U of I professor of nutrition.
In the study, when fresh broccoli sprouts were eaten with broccoli powder, the scientists were able to measure bioactive compounds in the blood 30 minutes later. When these peaked at three hours, they were much higher when the foods were eaten together than when either was eaten alone. Urine samples corroborated the blood results, said Jenna Cramer, lead author of the study.
It’s no secret that many people cook the benefits right out of broccoli instead of steaming it lightly for two to four minutes to protect its healthful properties, she said.
“However, this study shows that even if broccoli is overcooked, you can still boost its benefits by pairing it with another food that contains myrosinase,” she said.
Myrosinase is the enzyme necessary to form sulforaphane, the vegetable’s cancer-preventive component, co-author Margarita Teran-Garcia explained.
Note what happened with the fresh broccoli sprouts and broccoli powder eaten in this experiment. The powder doesn’t contain myrosinase, but it does contain the precursor to the anti-cancer agent sulforaphane. Eaten together, the sprouts were able to lend their myrosinase to the powder. As predicted, both foods produced sulforaphane and provided greater anti-cancer benefit, Jeffery said.
Other foods that will boost broccoli’s benefits if they are paired together include radishes, cabbage, arugula, watercress, and Brussels sprouts.
“Here’s another benefit of protecting and enhancing the myrosinase in your foods,” Jeffery said. “If myrosinase is present, sulforaphane is released in the ilium, the first part of your digestive system. Absorption happens well and quickly there, which is why we saw bioactivity in 30 minutes.”
An earlier Jeffery study showed that microbiota are capable of releasing sulforaphane in the lower gut, but absorption happens more slowly in the colon than in the upper intestine, she said.
Scientists say that as little as three to five servings of broccoli a week provide a cancer-protective benefit.
“But it pays to spice it up for added benefits and find ways to make it appealing so you don’t mind eating it if you’re not a broccoli fan. I add fresh broccoli sprouts to sandwiches and add them as one of my pizza toppings after the pie is out of the oven,” Cramer said.
Reference
Cramer JM, Teran-Garcia M, Jeffery EH. Enhancing sulforaphane absorption and excretion in healthy men through the combined consumption of fresh broccoli sprouts and a glucoraphanin-rich powder. Br J Nutr. 2011 Sep 13:1-6. [Epub ahead of print].
CORVALLIS, Ore. – Sulforaphane, one of the primary phytochemicals in broccoli and other cruciferous vegetables that helps them prevent cancer, has been shown for the first time to selectively target and kill cancer cells while leaving normal prostate cells healthy and unaffected.
The findings, made by scientists in the Linus Pauling Institute at Oregon State University, are another important step forward for the potential use of sulforaphone in cancer prevention and treatment. Clinical prevention trials are already under way for its use in these areas, particularly prostate and breast cancer.
It appears that sulforaphane, which is found at fairly high levels in broccoli, cauliflower and other cruciferous vegetables, is an inhibitor of histone deacetylase, or HDAC enzymes. HDAC inhibition is one of the more promising fields of cancer treatment and is being targeted from both a pharmaceutical and dietary approach, scientists say.
“It’s important to demonstrate that sulforaphane is safe if we propose to use it in cancer prevention or therapies,” said Emily Ho, a principal investigator in the Linus Pauling Institute, lead author on the study and associate professor in the OSU Department of Nutrition and Exercise Sciences.
“Just because a phytochemical or nutrient is found in food doesn’t always mean its safe, and a lot can also depend on the form or levels consumed,” Ho said. “But this does appear to be a phytochemical that can selectively kill cancer cells, and that’s always what you look for in cancer therapies.”
The findings were published in Molecular Nutrition and Food Research, a professional journal. Research was supported by the National Cancer Institute, National Institute of Environmental Health Sciences and the OSU Agricultural Experiment Station.
The Linus Pauling Institute has conducted some of the leading studies on sulforaphane’s role as an HDAC inhibitor – one, but not all, of the mechanisms by which it may help prevent cancer. HDACs are a family of enzymes that, among other things, affect access to DNA and play a role in whether certain genes are expressed or not, such as tumor suppressor genes.
Some of the mechanisms that help prevent inappropriate cell growth – the hallmark of cancer – are circumvented in cancer cells. HDAC inhibitors can help “turn on” these silenced genes and restore normal cellular function.
Previous OSU studies done with mouse models showed that prostate tumor growth was slowed by a diet containing sulforaphane.
“It is well documented that sulforaphane can target cancer cells through multiple chemopreventive mechanisms,” the researchers wrote in their study. “Here we show for the first time that sulforaphane selectively targets benign hyperplasia cells and cancerous prostate cells while leaving the normal prostate cells unaffected.”
“These findings regarding the relative safety of sulforaphane to normal tissues have significant clinical relevance as the use of sulforaphane moves towards use in human clinical trials,” they said.
The results also suggest that consumption of sulforaphane-rich foods should be non-toxic, safe, simple and affordable.
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