Anticancer Fruits: Berries & Citrus
There are several compounds found in fruits that have significant anticancer potential. Few scientific studies so far have been carried out on the direct anticancer effect of fruits in the diet, partly because the fruits of interest (citrus and berries) make up a small amount of our diet so it is difficult to determine their significance.
However, if we look at the components in citrus and berries, and at the scientific studies that have been carried out on them, we start to see the huge potential that these foods have in the fight against cancer.
Berries contain three phytochemical compounds of particular interest, ellagic acid, anthocyanidins and proanthocyanidins.
Ellagic acid is present in strawberries and raspberries. Studies have shown ellagic acid to suppress tumour growth1,2 and prevent tumours from being able to grow new blood vessels (angiogenesis)3.
Anthocyanidins are the compounds that give many fruits their vibrant colours, they are present in high concentrations in raspberries, blueberries and strawberries. Anthocyanidins have proved to be very difficult to analyse in research studies, due to their complex structure, metabolic breakdown and interactions with other phytochemicals.
However, anthocyanidins that have been isolated from food have shown to be able to suppress tumour growth4, and provide protection against cancer5.
Proanthocyanidins (and anthocyanidins) are potent antioxidants. They absorb harmful free radicals in the bloodstream that can damage cell DNA and lead to cancer6,7. Cranberries and blueberries contain high levels of these antioxidants, as well as cinnamon and cocoa. Cranberries also contain anthocyanidins and catechins (the anticancer compound also present in green tea).
Currently, citrus fruits show more promise in protecting against cancer rather than acting directly on existing cancers. Studies have indicated that citrus fruit consumption can lower the risk of breast cancer8,9, stomach cancer10 and respiratory cancers11. In the studies carried out so far, it has not been possible to accurately determine which compounds are responsible for the protective effects of citrus fruits, however scientists have identified a number of important compounds, flavanoids, carotenoids and limonoids.
Flavanoids and carotenoids – the citrus flavonoids and carotenoids have strong antioxidant and anti-inflammatory activities which are thought to be the main contributing factors to their anticancer abilities12,13,14. It is possible, if not extremely likely, that these citrus compounds also have a more direct anticancer action, however more research is needed into this area to discover what the method of action might be.
Limonoids – there is an enduring myth that lemons can cure cancer. This is sadly not true, however there is a compound present in lemons that shows very promising anticancer activity. Extracted limonoids have been shown to have cytotoxic effects on tumour cells in studies outside of the body (in vitro)15,16,17. While it is not yet certain whether limonoids have a similar anticancer activity in the human body, these compounds will be much more extensively studied over the next few years.
Despite all of these promising anticancer activities, it should be mentioned that a link has been demonstrated between citrus fruits and an increased risk of melanoma18. The researchers involved in this study attributed this link to a compound present in citrus called psoralens which increase skin photosensitivity when applied topically to the skin and also when taken orally. However because this was the result of a single study, much further investigation is required to prove the correlation. Regardless, safe sun precautions such as wearing sun screen and keeping out of strong sunlight would be considered prudent.
There are clearly compounds present in fruit that have demonstrable cancer-preventative effects. The current research also indicates that these anticancer fruit compounds are likely to have some direct actions on cancer cells themselves. For this reason, fresh or frozen berries and citrus fruits should be included in the anticancer diet on a regular basis.
For more detailed information on the anti-cancer diet, the book ‘Food to Fight Cancer: What Your Doctors Aren’t Ready to Tell You’, is available to purchase from The Green Apple Club shop.
About the author:
Sonia Nicholas is a Biomedical Scientist and Freelance Clinical Science Writer & Editor. She has been working in the field of clinical science for fifteen years.
Sonia believes that everyone can improve their health by eating a clean diet – a claim that scientific research increasingly supports. Sonia also believes that healthy, clean eating is accessible to all and doesn’t have to be an expensive lifestyle choice.
All of the information on The Green Apple Club website is in line with current, recommended Government guidelines on nutrition. All of the articles on the website are evidence based and fully scientifically referenced.
Article tags: anti cancer diet, berries, citrus fruit, ellagic acid, phytochemicals, anti cancer food