Home / Nieuws / ...

 

Broccoli nog beter tegen kanker door goede bereiding*
Uit twee studies blijken weer eens de grote voordelen van broccoli en de jonge spruiten van broccoli.

Uit de eerste studie blijkt hoe broccoli kanker bestrijdt. In eerdere studies hadden de onderzoekers al laten zien dat de bioactieve stoffen, de isothiocyanaten die veel gevonden worden in kruisbloemige groenten, de groei van kanker konden doen stoppen. Het tumor onderdrukkende gen P53 speelt een sleutelrol in het gezond houden van cellen en het voorkomen van een abnormale groei van de cel. Als dit gen P53 gemuteerd raakt is de bescherming weg, iets wat bij de helft van alle kankerpatiënten gebeurt. In de studie bij verschillende kankerweefsels bleek nu dat isothiocyanaten dit gemuteerde gen doen uitschakelen.
Uit de tweede studie blijkt dat een goede bereiding van broccoli van wezenlijk belang is om de grote voordelen te kunnen benutten. De in broccoli (en andere kruisbloemige groenten) aanwezige glucosinolaten worden met het ook in broccoli aanwezige enzym myrosinase omgezet tot isothiocyanaten zoals sulforafaan. Het koken van broccoli doet veel myrosinase verdwijnen zodat weinig isothiocyanten als sulforafaan gevormd kunnen worden. Rauw of tot 5 minuten stomen of roerbakken doet alle myrosinase behouden zodat de maximale hoeveelheid isothiocyanaten gevormd kunnen worden. In de jonge spruiten van broccoli zit extreem veel van het enzym myrosinase. Uit de studie blijkt dat het eten van van jonge broccoli spruiten samen met broccoli of zelfs met broccolipoeder (waar wel veel glucosinolaten in zitten doch weinig van het enzym myrosinase) binnen 2-3 uur na inname de hoeveelheid in het lichaam gevonden isothiocyanaten als sulforafaan wel twee keer zo groot is als wordt gevonden na het eten van alleen broccoli of broccolipoeder alleen. De onderzoekers adviseren daarom kruisbloemige groenten te combineren met de jonge spruiten van broccoli zodat veel meer sulforafaan in het lichaam zijn werk kan doen.
Biochemical Basis Discovered For Broccoli's Cancer-Fighting Ability
Scientists are reporting discovery of a potential biochemical basis for the apparent cancer-fighting ability of broccoli and its veggie cousins. They found for the first time that certain substances in the vegetables appear to target and block a defective gene associated with cancer. Their report, which could lead to new strategies for preventing and treating cancer, appears in ACS' Journal of Medicinal Chemistry. 
Fung-Lung Chung and colleagues showed in previous experiments that substances called isothiocyanates (or ITCs) - found in broccoli, cauliflower, watercress, and other cruciferous vegetables - appear to stop the growth of cancer. But nobody knew exactly how these substances work, a key to developing improved strategies for fighting cancer in humans. The tumor suppressor gene p53 appears to play a key role in keeping cells healthy and preventing them from starting the abnormal growth that is a hallmark of cancer. When mutated, p53 does not offer that protection, and those mutations occur in half of all human cancers. ITCs might work by targeting this gene, the report suggests. 
The scientists studied the effects of certain naturally-occurring ITCs on a variety of cancer cells, including lung, breast and colon cancer, with and without the defective tumor suppressor gene. They found that ITCs are capable of removing the defective p53 protein but apparently leave the normal one alone. Drugs based on natural or custom-engineered ITCs could improve the effectiveness of current cancer treatments or lead to new strategies for treating and preventing cancer. 
Notes: 
The authors acknowledged funding from the Ruth L. Kirschstein National Research Service Award and a grant from the National Cancer Institute of the National Institutes of Health. 
ARTICLE: "Selective Depletion of Mutant p53 by Cancer Chemoprevention Isothiocyanates and Their Structure-Activity Relationships" 
Source: Michael Bernstein American Chemical Society 

Sprouts? Supplements? Team them up to boost broccoli's cancer-fighting power
A new University of Illinois study provides convincing evidence that the way you prepare and consume your broccoli matters, and also suggests that teaming broccoli with broccoli sprouts may make the vegetable's anti-cancer effect almost twice as powerful. 
"Broccoli, prepared correctly, is an extremely potent cancer-fighting agent--three to five servings a week are enough to have an effect. To get broccoli's benefits, though, the enzyme myrosinase has to be present; if it's not there, sulforaphane, broccoli's cancer-preventive and anti-inflammatory component, doesn't form," said Elizabeth Jeffery, a U of I professor of nutrition. 
According to Jeffery, many people destroy myrosinase by overcooking their broccoli. And health-conscious consumers who use broccoli powder supplements in recipes to boost their nutrition are also missing out. These supplements often do not contain this necessary enzyme, she said. 
"There is a way to boost that powder's effectiveness, though. Broccoli sprouts contain myrosinase in abundance. And broccoli powder often contains the precursor to sulforaphane without the enzyme that would boost its healthful benefits," said Jenna Cramer, co-author of the study. 
The scientists hypothesized that myrosinase from the sprouts would enhance sulforaphane formation and absorption from the broccoli powder if the two were eaten together. 
In a small pilot study, they recruited four healthy men who ate meals that contained broccoli sprouts alone, broccoli powder alone, or a combination of the two. The researchers then measured levels of sulforaphane metabolites in the mens' blood and urine after feeding. 
"We were looking at biomarkers--plasma and urine levels--that are associated with cancer prevention," Cramer said. 
Three hours after feeding, a definite synergistic effect was noted between the powder and the sprouts. 
"We saw almost a twofold increase in sulforaphane absorption when sprouts and powder were eaten together. It changed the way the subjects metabolized the powder. We saw plasma and urine metabolites much earlier and at much higher levels than when either was eaten alone," Jeffery said. 
This indicates that myrosinase from the broccoli sprouts produced sulforaphane not only from the sprouts but also from the precursor present in the broccoli powder, she said. 
Other foods that contain sulforaphane and can be teamed with broccoli to boost its benefits are mustard, radishes, arugula, and wasabi, Jeffery said. 
"To increase the vegetable's benefits, you could sprinkle broccoli sprouts on your broccoli or make a mustard sauce to serve with broccoli," she added. 
People who prefer to eat broccoli without sauce or sprouts should know that overcooking is the kiss of death for the important enzyme myrosinase, she said. 
"Steaming broccoli for two to four minutes is the perfect way to protect both the enzyme and the vegetable's nutrients," she said. 
The study was published in Nutrition and Cancer. Caudill Seed Company funded the research and provided broccoli products. (Februari 2011) 

 

 

Printen

Reageer hier op dit artikel  Mail dit bericht naar een kennis

 

Reacties: