Does Citrus Consumption Increase Melanoma Risk?

Melanoma is a skin cancer that begins in cells called melanocytes, which give skin its color. Although uncommon, its incidence has increased in recent years. It is also called malignant melanoma or cutaneous melanoma. Its disease behavior is aggressive (an unfavorable disease course and rapid, frequent spread to surrounding tissue and other organs). Melanoma also has particular importance as a field that has driven the development of new cancer treatments (immuno-oncological treatments) in recent years.

The effect of the foods we consume on melanoma development has been studied for years. Scientific studies conducted to date have provided some evidence that many substances obtained through food, particularly vitamin C, protect against melanoma. However, a study by Wu and colleagues published in June 2015 drew attention to a different issue through its title: "Citrus Consumption and Risk of Malignant Melanoma" (Citrus Consumption and Risk of Cutaneous Malignant Melanom).

In this study, groups consuming citrus at different frequencies, more than two servings per week and fewer than two servings per week, were followed and compared. The study found a dose-dependent relationship between average citrus consumption frequency and the risk of developing melanoma. Consuming citrus fruits and juices at an average of more than 1,6 fruits per day was found to increase the risk of developing melanoma by %36. The research team attributes this to substances contained in citrus fruits, particularly grapefruit, called psoralen and furocoumarin .

These substances are potential carcinogens whose presence has also been demonstrated in humans and mice. Psoralen and furocoumarin interact with ultraviolet (UV) rays and trigger melanoma cell proliferation. However, there are inconsistencies regarding consumption of the fruit itself and its juice. For example, eating grapefruit is considered risky, whereas drinking grapefruit juice is not; drinking orange juice may pose a risk, while eating oranges themselves is considered a lower risk factor. Researchers explain this by the higher levels of psoralen and furocoumarin in grapefruit than in its juice, and lower levels in oranges than in their juice.

According to the study, the duration of UV exposure is also very important alongside citrus consumption. High consumption is reported to increase sun sensitivity and facilitate sunburn, particularly during childhood and adolescence, at times when sunlight is direct and strong.

However, these results should not lead people to avoid citrus consumption, and it should be remembered that citrus consumption protects against many diseases, particularly coronary heart disease and cancer.

In conclusion, the best advice available in light of current scientific studies is to include a variety of fruits and fruit juices in the diet and protect yourself from the sun.

Keywords: melanoma, malignant melanoma, skin cancer, cancer risk, citrus, grapefruit, fruit juice, orange, vitamin C, ultraviolet, psoralen, furocoumarin