Highlights in Chemical Biology

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Broccoli sprouts slow cancer development


02 February 2010

If you want to prevent or slow down the progress of skin cancer eating broccoli sprouts regularly could help, claim scientists in the US. 

The most common kind of cancer in humans is non-melanoma skin cancer, which is often caused by ultra violet (UV) radiation. While avoiding exposure to low-level UV radiation and using sun-screen is the best way to avoid the cancer, for many the damage has already been done. But, reducing the harmful effects of previous exposure could be as simple as eating broccoli sprouts regularly, says Albena Dinkova-Kostova at John Hopkins University, Baltimore.

Broccoli, radish, and watercress produce highly reactive sulforaphane when digested, which are thought to trigger the synthesis of cell-protecting proteins and protect against cancer. Many groups have investigated the effects of sulforaphane on various chronic diseases such as epidemiology, and prostate cancer. Now Dinkova-Kostova's team have investigated the anti-skin-cancer effects of sulforaphane when eaten, rather than applied to the skin. 

Broccoli sprouts

Higher concentrations of sulforaphane are found in younger plants

Dinkova-Kostova extracted glucoraphanin - the precursor of sulforaphane - from broccoli sprouts and fed a daily dose to mice that had previously been exposed to UV radiation twice a week for 17 weeks. The number of mice that developed tumours or lesions was reduced by 25 percent, the number of tumours was reduced by 47 percent and the volume of the tumours was reduced by 70 percent. Analysing the urine of the mice confirmed that the glucoraphanin had been converted to the active ingredient sulforaphane. 

'The younger the plant, the sharper the taste because of the higher concentration of sulforaphane,' comments Dinkova-Kostova. Cooked broccoli still contains glucoraphanin, but unlike its raw form it is converted to sulforaphane in the gut rather than during chewing, with variable efficiency from person to person. However, eating boiled broccoli, or frozen broccoli which has been blanched is not likely to result in the positive results seen in this study because glucoraphanin is water soluble, adds Dinkova-Kostova. 

Elizabeth Jeffery, a professor of nutrition and toxicology from the University of Illinois, Urbana, US, says 'this is the first paper that shows that, without prior conversion to sulforaphane, a glucoraphanin-rich extract is slowing cancer incidence'. The findings are relevant because a lot of people take broccoli supplements which all contain glucoraphanin, rather than sulforaphane, or whole dried sprouts, she adds. 

Dinkova- Kostova hopes to develop a protective strategy for people with high risk of skin cancer, in particular people who have had organ donations. But in the meantime it probably wouldn't hurt to eat up your greens.

Aileen Day 

 

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Link to journal article

Dietary glucoraphanin-rich broccoli sprout extracts protect against UV radiation-induced skin carcinogenesis in SKH-1 hairless mice
Albena T. Dinkova-Kostova, Jed W. Fahey, Andrea L. Benedict, Stephanie N. Jenkins, Lingxiang Ye, Scott L. Wehage and Paul Talalay, Photochem. Photobiol. Sci., 2010, 9, 597
DOI: 10.1039/b9pp00130a

Also of interest

Stainless skin cancer diagnosis

An infrared imaging technique that can distinguish different types of skin cancer has been developed by scientists in France

Disease detection is skin deep

Body odour can be collected on skin patches and used to diagnose disease.

Where the sun does most damage

Skin cancer's location on the body depends on the body's distance from the equator