Grapes, vegetables, and green tea: The role of nutrition in melanoma prevention

This review examined the role of nutrition in the prevention of melanoma.

Rates of melanoma have been rising, and while it’s usually curable in the early stages, once it metastasizes (spreads to other areas of the body), it is generally uncurable. Therefore, interest in preventative measures is increasing, particularly those provided by diet. 

Ultraviolet light from the sun can cause the creation of free radicals, dangerous by-products of how the body reacts to oxygen. If the production of free radicals becomes excessive it can lead to cell wall damage, protein damage, and even damage to our DNA. This damage is known as oxidative stress and it has been linked to the development of melanoma. Free radicals can be neutralized (their activity is blocked) by antioxidants, molecules that are found in many foods. However, it is not clear whether antioxidants play a role in the prevention of melanoma development.

This study reviewed the role nutrition and supplements play in melanoma prevention. Overall, 87 articles were examined, with research focusing both on the effects of diet in general and the effects of more specific nutrients and antioxidents.

Generally speaking, the Mediterranean diet, which is high is fish, vegetables, and vegetable oils, was found by multiple studies to have preventative effects against melanoma. Shellfish and daily tea consumption were also found to be beneficial. 

Grape seed proanthocyanidins are antioxidants found in grapes, which have been found to reduce damage from ultraviolet light, and to reduce the number of mutated p53-positive skin cells following sunburn (p53 is a protein that works to suppress, or block, tumor cells. If p53 is mutated and not working correctly, tumors cannot be suppressed). Grape seed proanthocyanidins were also found to be non-toxic, making them promising candidates against melanoma.

Green tea, particularly one antioxidant it contains, epigallocatechin-3-gallate, has been shown to be effective at reversing damage done by ultraviolet light, reducing oxidative stress, and reducing inflammation. However, there are insufficient studies examining the preventative benefits of green tea consumption on cancers in humans.

Other antioxidants, including resveratrol (found in peanuts, fruits, grape skins, and wine), lycopene (found in red fruits and vegetables), and rosmarinic acid (found in rosemary) have all been found in non-human studies to have preventative effects on melanoma cells, however, human studies must be carried out.

Vitamins D and E, despite showing protective effects against melanoma in animal studies, do not have a clear role in reducing the risk of melanoma in humans.

This study concluded that while there are positive results highlighting the preventive role diet can play in the risk of melanoma, more human studies are needed to make the role of nutrition clear.