Carotenoid intake may lower CRC risk

Total and selected carotenoids are inversely associated with the risk of colorectal cancer (CRC), suggests a recent study.

The highest quintile of intake for α-carotene (odds ratio [OR], 0.72, 95 percent confidence interval [CI], 0.60–0.87), β-carotene (OR, 0.60, 95 percent CI, 0.49–0.73), β-cryptoxanthin (OR, 0.83, 95 percent CI, 0.69–0.99), lutein plus zeaxanthin (OR, 0.64, 95 percent CI, 0.53–0.78), and total carotenoids (OR, 0.59, 95 percent CI, 0.48–0.73) correlated with a reduced CRC risk. [Eur J Clin Nutr 2025;79:1154-1159]

Significant trends were observed across quintiles, but no significant association was noted for lycopene.

"[O]ur findings indicate an inverse association between most carotenoids and the risk of CRC, supporting a variety of fruits and vegetables in dietary recommendations for CRC prevention,” the researchers said.

The major sources of carotenoid in this population are carrots, citrus fruits, leaf vegetables, tomatoes, and peas. Foods rich in carotenoids are also a good source of dietary fibre, which has been shown to be associated with a lower risk of CRC and can act as a confounder.

"However, in our study, further adjustment for fibre intake did not materially modify the association,” the researchers said. 

Heterogeneity between studies could be explained by the differences in dietary carotenoid sources in other populations. For instance, in countries such as Germany and the UK, industrially processed foods are relevant carotenoid sources but are deemed risk factors for CRC. [Front Nutr 2023;10:1170992; J Natl Cancer Inst 2023;115:155-164]

Antioxidants

Furthermore, carotenoids have antitumour effects due to their antioxidant properties and their ability to modulate cell signalling, inhibit cell cycle progression, modulate immune responses, and promote apoptosis. [Molecules 2012;17:3202-3242]

Studies in rats have shown that supplementation with α-carotene, lycopene, and lutein was protective against the development of aberrant crypt foci. [Cancer Lett 1996;107:137-142]

Moreover, studies in human colon cancer (CC) cells and in mouse CC models exhibited the cell proliferation inhibition properties of β-carotene through the suppression of M2 macrophage markers expression. [J Nutr Biochem 2020;82:108402]

β-carotene can likewise upregulate BCMO1 and inhibit MMP7 and MMP28 expression, which reduce the invasiveness and migration ability of human CC cells. [Am J Clin Nutr 2013;98:413-422]

In another animal study, citrus juices and pulp rich in β-cryptoxanthin prevented CC progression; reduced the expression of the mRNAs of inflammatory factors, such as COX-2, TNF-α, IL6, and IL1-β; and promoted the expression of mRNA of Nrf2, a cytoprotective transcription factor, in rats. [Molecules 2012;17:3202-3242]

Lycopene

A previous study also found lycopene to reduce Akt activation and non-phosphorylated β-catenin expression in human CRC cells, as well as increase phosphorylated β-catenin levels, which correlated with reduced CRC growth and proliferation. [Mol Nutr Food Res 2008;52:646-654]

"Moreover, in humans mucosal β-carotene, β-cryptoxanthin, lycopene and zeaxanthin were lower in adenoma tissue compared to non-involved mucosa,” the researchers said. “Serum carotenoids were found to be lower in adenoma as compared to healthy [participants].” [Clin Nutr 2003;22:65-70; Eur J Gastroenterol Hepatol 1999;11:305-308]

The present study used data from a case-control study on CRC conducted in Italy, which included a total of 1,953 histologically confirmed incident cases of CRC and 4,154 controls. Carotenoid intake was estimated in each participant through a food frequency questionnaire, using an Italian food composition database.

The researchers calculated the ORs and corresponding 95 percent CIs of CRC for the highest vs the lowest quintiles of carotenoid intakes using multiple logistic regression models, including terms for total energy intake and other selected confounding factors.