Case–control study on beneficial effect of regular consumption of apples on colorectal cancer risk in a population with relatively low intake of fruits and vegetables

Special Authors Introduction
Jedrychowski et al.

It is assumed that potential cancer-inducing oxidative damage may play an important role in the etiology of colorectal cancer, the second-most common malignancy in both genders in developed countries. Experimental studies provided evidence that this oxidative damage might be prevented or restricted largely by the presence of dietary antioxidants of plant origin, such as fruits or vegetables.

The protective antioxidant effect of fruits and vegetables has been attributed to flavonoids, a major class of phytochemicals naturally occurring in fruits, vegetables, and various foods of plant origin. Yet, epidemiologic studies relating flavonoid intake to risk of colorectal cancer have been sparse and inconclusive. A recent reanalysis of several case-control studies in Italy demonstrated a consistent inverse association between apple consumption and the risk of various cancers, and among them of colorectal cancer. Here we assessed the potential protective impact of apples on risk of colorectal cancer in the course of a newly performed hospital-based case-control study in a country with dietary habits very different from those of Mediterranean region. The risk of colorectal cancer was inversely correlated with daily number of apple servings, but the most significant reductions of OR estimates were observed for an intake one or more apple servings daily (OR = 0.37, 95%CI : 0.15-0.91). No other fruit was significantly associated with altering the risk of colorectal cancer. The study findings provides a strong epidemiologic evidence in favor of much stronger promotion of apples as an effective preventive measure against colorectal cancer.

It seems that the preventive effect of apples on the occurrence of colorectal cancer may result from the fact that apples are a rich source of flavonoids and have the second highest level of antioxidant power among all fruits. Apples are also ranked as the second for total concentration of phenolic compounds, and have the highest content of free phenolics in comparison with other fruits. Interestingly, apple peels have a stronger antioxidant activity than apple flesh and apple peels alone, inhibiting the growth and cell proliferation of liver cancer and colon cancer cells more significantly than whole apples. Although vitamin C which is present in many fruits and vegetables is a powerful antioxidant, the major part the antioxidant activity attributed to apples comes from other compounds.

This Article was published in The European Journal of Cancer Prevention
The Full Article is available on the registered area of our website