Abstract
Dietary intake of vitamin A (VA) and carotenes has shown beneficial effects for decreasing the risk of some types of cancer, but findings on the risk of primary liver cancer (PLC) are inconsistent. This case–control study explored the associations between the dietary intake of VA and carotenes and the risk of PLC. We recruited 644 incident PLC patients (diagnosed within one month of each other) and 644 age- and gender-matched controls in Guangzhou, China. A food frequency questionnaire was used to assess habitual dietary intake. Logistic regression analyses found that higher intakes of VA and carotenes were independently associated with decreased PLC risk (all P-trend < 0.001). The multivariable-adjusted ORs (95% CI) of PLC for the highest (vs. lowest) quartile were 0.34 (0.24–0.48) for vitamin A and 0.35 (0.25–0.49) for carotenes. The associations were not significantly modified by smoking, alcohol, or tea drinking (P-interactions: 0.062–0.912). Dose–response analysis showed a U-shaped VA–PLC relationship, with sharply decreased risks at the intakes of about 1000 μg retinol equivalent (RE)/day, and then slowly went down toward the flat-bottomed risks with the lowest risk at 2300 μg RE/day. Our findings suggest that greater intake of retinol, carotenes, and total VA may decrease PLC risk among the Chinese population at an intake of 1000 μg RE/day or greater from food sources.
Highlights
Primary liver cancer (PLC) is one of the most highly malignant tumors worldwide and is usually diagnosed at late stages with poor prognosis [1]
The present study examined the association between the dietary intake of retinol, carotenes, and their total retinol equivalent with primary liver cancer (PLC) risk in a Chinese population
PLC patients had lower values of BMI, waist-to-hip ratio (WHR), physical activity, and a lower proportion of tea drinkers, but higher proportions of smokers and alcohol users compared with the controls
Summary
Primary liver cancer (PLC) is one of the most highly malignant tumors worldwide and is usually diagnosed at late stages with poor prognosis [1]. Chronic viral hepatitis (HBV and HCV) infection may account for the majority of PLC cases, an increasing number of studies has shown that some dietary factors may be related to the development of PLC [3,4,5]. Vitamin A (VA) mainly comes from animal sources (retinol), and its precursor (carotenes) mainly from vegetables; it has substantial antioxidant effects and can increase the activity of detoxifying enzymes that combat the damage of reactive oxygen species [6] that may lead to oxidative DNA damage, followed by the initiation, promotion, and progression of carcinogenesis [7]. Inconsistent results were observed from human studies for the associations of vitamin A/retinol or its precursor with cancer risk
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