Study: Carotenoids and Vitamin C May Reduce Lung Cancer Risk

In a recent study, researchers found that certain dietary antioxidants might reduce the risk of lung cancer in smokers and in women who have never smoked.

The study, which included data from a case-control study of lung cancer, examined the role of β-carotene, α-carotene, β-cryptoxanthin, lutein/zeaxanthin, lycopene, and vitamin C in lung cancer risk.
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The researchers conducted in-person interviews with 1105 individuals aged 35 to 75 years who were diagnosed with lung cancer and living in the Montreal area, as well as 1449 population controls. Food frequency questionnaires were used to determine the usual frequency of consumption of 49 fruits and vegetable in the 2 years prior to the interview or lung cancer diagnosis.

The odds ratios (ORs) and 95% confidence intervals (CIs) between dietary intake variables and lung cancer risk were estimated with logistic or polytomous regression and were adjusted for potential confounding factors, including a detailed smoking history.

“ORs associated with upper versus lower tertiles of intake were 0.66 (95% CI = 0.51–0.84) for β-carotene, 0.70 (95% CI = 0.55–0.90) for α-carotene, 0.65 (95% CI = 0.51–0.84) for β-cryptoxanthin, 0.75 (95% CI = 0.59–0.95) for lycopene, and 0.74 (95% CI = 0.58–0.96) for vitamin C,” the researchers wrote.

Overall, the researchers found that high dietary intakes of β-carotene, α-carotene, β-cryptoxanthin, lycopene, and vitamin C were associated with a decreased risk of lung cancer. High intakes of β-carotene, α-carotene, β-cryptoxanthin, and lycopene were associated with a reduction in lung cancer risk among male heavy smokers, and vitamin C was associated with reduced risk of lung cancer in female heavy smokers.

“Furthermore, our data suggest a preventive effect of vitamin C against lung cancer in women who have never smoked, an association which, to our knowledge, has not been reported previously,” the researchers wrote.

The researchers caution against a close association between the carotenoids and vitamin C, because other protective compounds in select fruits and vegetables could also reduce the risk of lung cancer.

“Overall, our findings contribute both new knowledge and confirmatory data to the as yet inconclusive body of evidence on the hypothesized associations between high intakes of individual carotenoids and vitamin C, and lung cancer risk,” the researchers wrote. “Even though smoking remains the strongest predictor of lung cancer risk, it appears desirable, in light of these findings, to further promote consumption of fruits and vegetables rich in carotenoids and vitamin C to reduce the lung cancer burden among both smokers and non-smokers.”

—Melissa Weiss

Reference:

Shareck M, Rousseau M-C, Koushik A, Siemiatycki J, Parent M-E. Inverse association between dietary intake of selected carotenoids and vitamin C and risk of lung cancer [published online February 28, 2017]. Front Oncol. doi: doi.org/10.3389/fonc.2017.00023.