High vitamin A intake is linked to a lower risk of oestrogen receptor-positive breast cancer risk in premenopausal Black women, a new observational study has found.
According to the study, premenopausal women with the highest total vitamin A intakes, including retinol, beta-carotene, and lutein, have a 40% lower risk of oestrogen receptor-positive cancer than women with the lowest intakes. Interestingly, there was no link between total vitamin A intake and oestrogen receptor-negative breast cancer risk.
Vitamin A, comprising retinol and carotenoids, are a group of fat-soluble micronutrients with anti-breast cancer activities. Retinol blocks breast cancer growth, while carotenoids such as beta-carotene and lutein prevent cancer by reducing free-radical damage to DNA, fats and proteins in cells.
Past studies show a link between high vitamin A intakes, high blood vitamin A levels and lower breast cancer risks in premenopausal White women.
However, black women tend to have lower vitamin A intake and blood vitamin A levels, with a higher risk of oestrogen-negative breast cancer than White women. So, whether vitamin A intake is linked to oestrogen-negative breast cancer risk in Black women is unknown.
To learn more, researchers in the United States collated dietary data from three studies that were part of the African American Breast Cancer Epidemiology and Risk (AMBER) consortium: Black Women’s Health Study (BWHS), the Multi-ethnic Cohort Study (MEC), and the Women’s Circle of Health Study (WCHS).
The researchers assessed the participants’ intake of retinol and carotenoids, including alpha-carotene, beta-carotene, beta-cryptoxanthin and lutein, via food frequency questionnaires.
A total of 15,407 women – 3,564 with breast cancer and 11,843 controls – were included in the study. The mean age of the participants was 56 years. Of the participants with breast cancer, 39.4% were premenopausal, and 32.6% had oestrogen-negative breast cancer. A total of 15.9% had a family history of breast cancer, 62.4% were currently taking multivitamin supplements, 42.6% had obesity, and 43.7% were current or past smokers.
Amongst the controls, 36.7% were premenopausal, and 9.8% had a family history of breast cancer. A total of 64.7% were currently taking multivitamin supplements, 41.4% had obesity, and 45.3% were current or past smokers.
After analysing the data, the researchers found that higher total vitamin A intake was linked to a lower risk of oestrogen-positive breast cancer. However, there was no link between total vitamin A intake or individual carotenoids with oestrogen-negative breast cancer.
Further analysis of the data by menopausal status showed that premenopausal women with a higher total vitamin A intake had a lower oestrogen-positive breast cancer risk. Notably, women with the highest total vitamin A intakes had a 40% lower risk of oestrogen-positive breast cancer than women with the lowest intakes.
And when the researchers assessed the vitamin A subtypes individually, they found that women with the highest intakes of beta-carotene and lutein had a 30% and 27% lower risk of oestrogen-positive breast cancer, respectively than women with the lowest intakes. There was insufficient data to assess retinol’s effect.
“Our results that the highest quintile of dietary beta-carotene intake was associated with a 30% lower risk of oestrogen receptor-positive breast cancer among premenopausal women compared with the lowest quintile of intake are consistent with previous findings that utilised dietary intake measurements. Among carotenoids, beta-carotene is consistently observed to be associated with breast cancer risks, and our study strengthens the evidence by adding data from Black women,” the researchers wrote.
Notably, there was no link between total vitamin A intake and oestrogen-positive breast cancer risk in postmenopausal women. And irrespective of menopausal status, there was no significant link between total vitamin A intake and the risk of oestrogen-negative breast cancer.
Finally, multivitamin supplements intake did not influence breast cancer risk since the researchers found that regardless of multivitamin use, women with higher total vitamin A, beta-carotene and lutein had a lower oestrogen-positive breast cancer risk.
Study limitations were the use of food frequency questionnaires and the inability to assess the participants’ blood concentrations of retinol and carotenoids.
“Data from the AMBER Consortium show an inverse association of dietary intake of vitamin A, including carotenoids, with oestrogen-receptor positive breast cancer risks among premenopausal Black women,” the researchers concluded.
However, more research is needed to determine why the associations between vitamin A intake and oestrogen receptor-positive breast cancer risk is limited to premenopausal women.
A Nutritionist’s Perspective – What this study means for you?
Eating foods rich in vitamin A, particularly beta-carotene, may lower your risk of oestrogen-positive breast cancer if you’re a premenopausal woman. Beta carotene is rich in orange-coloured fruits and vegetables, including carrots, pumpkin, butternut squash, mangoes and apricots.
Autumn is the perfect season for orange foods so ensure you eat as many of them as possible. Remember that overconsuming beta-carotene can cause orange skin, so enjoy them in moderation.
This study found that taking multivitamin supplements were not necessarily beneficial for lowering breast cancer risk. Rather than taking unnecessary supplements, focus on eating a wide range of whole, natural foods. Supplements are only necessary if recommended by a health professional. Please seek advice before using them and only use them as recommended.