Hairless mice developed 25 per cent fewer skin tumours following exposure to UV radiation and fed a the broccoli extract for 13 weeks, compared with mice receiving a standard protective agent, researchers from Johns Hopkins University report in Photochemistry & Photobiological Sciences, a journal from the Royal Society of Chemistry.
In addition, the tumours the broccoli-fed mice did develop were 70 per cent smaller, added the researchers.
If additional studies can repeat the results, and particularly human studies, it may see skin protection added to the long list of potential health benefits of broccoli and its extracts.
Benefits of broccoli
The tissue of cruciferous vegetables, like broccoli, cauliflower, cabbage and Brussels sprouts, contain high levels of the active plant chemicals glucosinolates. These are metabolised by the body into isothiocyanates, which are known to be powerful anti-carcinogens. The main isothiocyanate from broccoli is sulphoraphane.
Broccoli sprouts have previously been shown to reduce blood pressure in rats with hypertension due to the presence of a compound called glucoraphanin (Grn+). Sprouts are the richest source of Grn+, containing up to 50 times more than mature broccoli.
Glucoraphanin, also known as sulforaphane glucosinolate (SGS), is the precursor of sulforaphane.
For the new study, the Baltimore-based scientists exposed hairless mice to 17 weeks of chronic UV radiation and then divided them into two groups: One groups received an extract from broccoli sprouts providing a daily dose of 10 moles of glucoraphanin, while the other group received no extract.
After a further 13 weeks, the researchers noted an inhibition in the development of skin tumours, with the incidence of skin cancer reduced by 25 per cent, and the tumour volume by 70 per cent.
Skin cancer stats
According to Cancer Research UK, skin cancers are extremely common with almost 82,000 cases of non-melanoma skin cancer (NMSC) documented in the UK alone.
Source: Photochemistry & Photobiological Sciences
Published online ahead of print, DOI: 10.1039/b9pp00130a
“Dietary glucoraphanin-rich broccoli sprout extracts protect against UV radiation-induced skin carcinogenesis in SKH-1 hairless mice”
Authors: A.T. Dinkova-Kostova, J.W. Fahey, A.L. Benedict, S.N. Jenkins, L. Ye, S.L. Wehage, P. Talalay