The Association Between Citrus Consumption and Melanoma Risk in the UK Biobank

A.R. Marley; M. Li; V.L. Champion; Y. Song; J. Han; X. Li

Disclosures

The British Journal of Dermatology. 2021;185(2):353-362. 

In This Article

Results

In the UKBB population, total citrus intake significantly varied by several demographic and sun exposure variables (Table 1). Relative to those with no total citrus consumption, participants with higher citrus intake were more likely to be older, be male, have a higher education and income, be less likely to smoke, and be more physically active. A number of sun exposure variables also varied by citrus intake. Relative to those with no citrus consumption, participants who consumed more citrus were less likely to use sunlamps or solariums, more likely to report sunburns during childhood, and less likely to describe themselves as olive skinned.

There were a total of 1592 cases of melanoma among the 198 964 participants included in this analysis. Total citrus consumption was significantly associated with melanoma risk, as participants consuming the most total citrus were at a significantly increased risk for melanoma (Table 2). In the fully adjusted model, the ORs (95% CIs) were 0·98 (0·82–1·16) for > 0–0·5 serving, 1·07 (0·91–1·25) for > 0·5–1 serving, 1·13 (0·93–1·36) for > 1–2 servings, and 1·63 (1·24–2·12) for > 2 servings of total citrus per day relative to no citrus consumption (P-value for trend = 0·0051).

On analysis of individual citrus products, consumption of oranges and orange juice was independently associated with melanoma risk (Table 3). In the fully adjusted models, participants in the highest category of orange and orange juice consumption (> 1 serving per day) had a significantly increased risk of melanoma relative to those with no consumption. Relative to no consumption, ORs (95% CIs) were 1·79 (1·07–2·78) and 1·54 (1·10–2·10) for the highest consumption of oranges and orange juice, respectively (P-values for trend = 0·043 and 0·021). No other orange or orange juice serving categories were significant in either of the multivariable-adjusted models, and no significant results were seen for any other citrus product. Respective associations for high intake of total citrus, oranges and orange juice were larger than associations for all citrus fruit and all citrus juice analysed separately (Table S1; see Supporting Information). Relative to no consumption, those in the highest category (> 1 serving per day) of citrus fruit intake and citrus juice intake had ORs (95% CIs) of 1·33 (1·06–1·64) and 1·43 (1·05–1·90), respectively.

We tested for interactions between total citrus consumption and other melanoma risk factors, including coffee intake, tanning ability, childhood sunburn occasions, natural hair colour, skin colour, average time outdoors in summer, solarium or sunlamp use, and use of sun or UV protection. Before adjustment for multiple comparisons, we found statistical evidence of interaction only for skin colour (P-value for interaction = 0·019) and then conducted stratified analyses to evaluate this potential interaction (Table 4). A linear relationship between citrus consumption and melanoma risk was observed among participants with a fair or very fair skin complexion, with a significantly increased melanoma risk associated with those in the highest category of total citrus consumption. Relative to no citrus consumption, ORs (95% CIs) of 1·05 (0·87–1·26), 1·10 (0·93–1·30), 1·17 (0·96–1·42) and 1·75 (1·31–2·29) were observed among fair or very fair participants with total citrus consumptions of > 0–0·5, > 0·5–1, > 1–2, and > 2 daily servings, respectively (P-value for trend = 0·0015).

A decreased risk of melanoma was observed among olive-skinned participants consuming half a serving of citrus per day (OR 0·48, 95% CI 0·23–0·89). As citrus consumers and non-citrus consumers differed in several key demographic categories (Table 1), and as some commonly used medications are known to interact with certain citrus products,[38–40] we considered that non-consumers of citrus may systematically differ from citrus consumers. Therefore, we repeated our aforementioned analyses using the lowest category of citrus consumption (> 0–0·5 serving) as the referent to see if our results differed when only considering citrus consumers (Tables S2–4; see Supporting Information). No appreciable differences were observed.

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