Carrot intake reduces cancer risk by 10 to 20 per cent, meta-analysis reveals

A meta-analysis of 80 prospective cohort studies showed that carrot intake lowers cancer risk by 10%-20%. Findings apply across a wide range of exposure types, geographical regions, and cancer types.

"Carrot intake across 50 prospective cohorts with 52,000 cancer cases revealed a relative risk reduction of 10% (relative risk, 0.90) compared to controls," reported Charles C Ojobor, Newcastle University, Newcastle upon Tyne, UK, and colleagues reported.

Carrots are the main dietary source of potential anti-cancer compounds, including polyacetylenes, while β-carotene showed no benefits in controlled cancer trials.

The meta-analysis was performed to quantify the association between carrot intake and cancer incidence across all types of cancer focusing on high-quality (prospective) data. Secondarily, the researchers sought to estimate dose dependency, to facilitate the development of quantitative recommendations, and also to allow comparison of separate datasets to assess the robustness of the outcomes.

Specifically, the analysis aimed to ‘provide evidence for a dose–response relationship and for consistency of the association across studies’, as required by the European Food Safety Authority (EFSA) as one prerequisite for a health claim for carrot consumption to lower the cancer risk.

For this purpose, the researchers performed a meta-analysis of 50 prospective cohort studies capturing a wide variety of cancer types (colorectal, breast, prostate, lung, and other types), geographic regions (Asia, Europe, USA, other regions), and exposure types (alpha-carotene intake by plasma level and carrot intake from Food Frequency Questionnaire).

The intake of beta-carotene (another compound in carrots) was not evaluated because previous randomized clinical trials showed limited benefits in cancer reduction.

The researchers reported the following key findings:

• Compared to controls, carrot intake across 50 prospective cohorts with 52,000 cancer cases finds a relative risk reduction of 10% (relative risk, 0.90).
• Alpha-carotene (another compound found in carrots) plasma levels evaluated in 30 prospective cohorts with 9331 cancer cases found a relative risk reduction of 20% (relative risk, 0.80).
• Studies of both types of exposure (carrots and alpha-carotene plasma levels) showed a significant linear dose-response relationship whereby one serving per week lowers risk by 4±2% and five servings per week lowers risk by 20±10%.

"These results provide enhanced support for cost-effective and safe public health recommendations and interventions to increase carrot intake, as part of the overall consumption of vegetables and fruits, to reduce the risk of cancer and other diet-related diseases," the researchers wrote.

"The results also underscore the need to determine the roles of a wider range of vegetable phytochemicals, specifically isocoumarins and polyacetylenes, in pre-clinical studies regarding cancer-related effects," they concluded.

Reference:

Ojobor CC, O'Brien GM, Siervo M, Ogbonnaya C, Brandt K. Carrot intake is consistently negatively associated with cancer incidence: A systematic review and meta-analysis of prospective observational studies. Crit Rev Food Sci Nutr. 2023 Dec 17:1-13. doi: 10.1080/10408398.2023.2287176. Epub ahead of print. PMID: 38104588.