Bioactive substances in fruit and brassica vegetables protect against skin cancer. Cancer researchers at the University of Texas discovered this when they did experiments on mice. The researchers shaved the mice’s backs and rubbed the carcinogen DMBA into the bare patches. They did this twice a week for a period of four weeks. At the same time the researchers gave their animal subjects protective nutrients.
They mixed calcium-D-glucarate [CG] in the mice’s food. Calcium-D-glucarate is an analogue of D-glucaric acid, a substance in brassicas and apples that stimulates detoxification processes.
Another substance that the researchers mixed with the mice’s food was ellagic acid [ELA], a polyphenol found in strawberries, raspberries, cranberries and grapes. Animal studies have shown that ellagic acid protects against cancer by protecting the DNA from aggressive substances.
The researchers also gave the animals resveratrol [RES] and Grape Seed Extract [GSE]. Some was added to the animal’s food, and some was rubbed into the animals’ backs. The control group [ACT] was not exposed to DMBA, nor were they given any protective substances.
The figures below show that the combinations calcium-D-glucarate/Grape Seed Extract, ellagic acid/resveratrol and Grape Seed Extract/resveratrol gave protection against skin cancer.
The combinations prevented a rise in the level of Proliferating Cell Nuclear Antigen [PCNA], for example. Raised concentrations of this protein are an indication of rapidly dividing cancer cells.
The figure beneath shows that the combinations prevented the skin cells from absorbing high amounts of bromodeoxyuridine. The cells that did absorb the bromodeoxyuridine administered show up as dark patches. Bromodeoxyuridine resembles the DNA building block thymidine. If cells absorb large amounts of bromodeoxyuridine, it can be an indication of the presence of rapidly dividing cancer cells.
The combinations also inhibited the synthesis of COX-2, an enzyme that produces inflammatory factors that play a role in the development of cancer.
Skin cancer cells are damaged cells. A frequently found type of damage is the mutation of the Ha-ras gene. The combinations of protective nutrients prevented the development of the mutation.
“Combination regimens that use resveratrol as one of the constituents are potentially very effective in chemoprevention”, the researchers conclude. “Anti-initiation and antitumor properties of topical resveratrol may be significantly augmented by dietary agents such as ellagic acid, calcium-D-glucarate, or Grape Seed Extract.”
A recently published small epidemiological study suggests that Grape Seed Extract supplementation protects against skin cancer. The animal study suggests that the addition of resveratrol to a supplementation schedule like this can enhance the protective effect.
Cancer Prev Res (Phila). 2010 Feb;3(2):170-8.