Introduction
Carotene-rich vegetables like carrots have been consistently associated with lowered cancer risk in observational studies(1). Beta-carotene, a phytochemical found in fruits and vegetables, is known for its antioxidant properties. In rodent trials, supplementation with carrot (containing both carotenes and polyacetylenes) significantly reduced tumour numbers in the APCMin/+ mouse model(2). However, human intervention trials with pure beta-carotene showed more adverse effects than benefits(3). This study aimed to investigate the impact of beta- and alpha-carotene supplementation (without polyacetylenes) on colorectal cancer using the APCMin/+ mouse model, which spontaneously develops intestinal tumours and an enlarged liver(4).
Methods
APCMin/+ mice were fed either a daily supplement of 10mg/kg mouse of a polyacetylene-free extract from carrots containing a beta- and alpha-carotene mixture, in a dose corresponding to the beneficial carrot supplementation, or the control diet, with a very low beta-carotene content (providing approx. 0.02mg/kg mouse/day). The 8-week supplementation commenced at 5 weeks of age. Tumour quantification in the small intestines of APCMin/+ mice was performed by histology of the entire small intestine, with one slide per 0.3mm, using the H&E staining method and Imagescope software.
Results
Supplementation with carotenes had no significant effect on the total number of tumours (≥0.5 mm), showing no discernible difference between the control (n=6) (20.5, 95% CI [14.69, 26.31]) and treatment (n=8) (24.5, [19.21, 29.79]) group (P=0.237). However, the liver weight, in % of body weight, showed a significant 25% decrease in the treatment group (n=7) (4.78 95% CI [4.45, 5.15]) compared to controls (6.42, [5.71, 7.13]) (P<0.0003), reaching a level comparable with wildtype mice (4.48, [4.13, 4.83].
Conclusion
These findings confirm the results from the human intervention trials by indicating that beta- and alpha-carotene do not confer any benefit for cancer prevention, while the decrease in liver weight suggests a potential beneficial effect on another aspect of liver health. Additional research is necessary to fully understand these relationships and uncover the underlying mechanisms behind these results. Specifically, beta-and alpha-carotene from carrots do not provide the reduction in tumour numbers in a mouse model of colon cancer found when feeding the corresponding dose of freeze-dried carrot. However, the carotenes significantly attenuate the liver enlargement also seen in this model.
1. Ojobor CC, O’Brien, GM, Siervo M et al. (2023) Crit Rev Food Sci Nutr Online doi:10.1080/10408398.2023.2287176
2. Almqbel M, Seal CJ & Brandt K. Proc Nutr Soc (2017) 76, E141
3. Bjelakovic G, Nikolova D & Gluud C (2013) Jama 310(11), 1178-1179
4. Benito I, Encío IJ, Milagro FI et al. (2021) Int J Mol Sci 22, 4906

OC167 - Effect of Beta- and Alpha-Carotene Intake on Tumour Formation in the Intestines of APCMin/+ Mice.

Unique to the new Congress (previously the Summer Conference) is that you will have greater opportunity to engage with more nutrition science than ever before. In 2024 the core programme will be delivered by the Irish Section of The Nutrition Society, supported by the Science Committee. The theme of these symposia will be ‘new data – focused approaches and challenges’. Outside of the core programme you will have the chance to hear the latest research from the Society’s partner organisations, universities, the private sector and more, on a diverse range of research.