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In the news: Healthy Diet for Breast Cancer Prevention, AREDS2 Formula Safer, More Effective

Diet Quality Counts for Preventing Breast Cancer

Studies have suggested that diet can influence cancer risk, but it hasn’t always been clear which eating habits or foods are best for cancer prevention.

Some research has pointed to diets with less or no meat as a risk-lowering healthy choice. A plant-based diet (as opposed to a vegan or vegetarian diet) is one that doesn’t exclude meat but focuses on plant foods over animal-based foods.

Now, the findings of a new study(1) show that not all plant-based diets are equal. The quality of those plant foods counts, with whole or unprocessed foods trumping refined foods when it comes to lowering the risk of breast cancer.

The new research concentrated on the quality of plant foods, differentiating between healthy plant-based foods such as whole grains, fruits, veggies, nuts, healthy oils, tea and coffee, and plant-derived foods classified as less health – largely processed foods including refined grains, fruit juices, potatoes, sugary drinks, and deserts

The researchers looked at data from over 65,500 postmenopausal women who were followed for more than 20 years. They compared breast cancer rates with how closely the women adhered to a mostly plant or animal diet, and whether they ate healthier vs. less healthy foods.

The study found that eating a healthy plant-based diet was linked to a 14% lower risk of breast cancer, while the “unhealthy” plant-based diet was associated with a 20% higher risk. These findings were consistently observed for all breast cancer subtypes (which are mostly defined by hormone receptors and other types of proteins).

Safety, Effectiveness of AREDS2 Supplements Confirmed at 10-Year Mark

The first Age-Related Eye Disease Study (AREDS) established that a dietary supplement can slow the progression of age-related macular degeneration (AMD).

However, the beta carotene component tested in the original AREDS study was found to up the risk of lung cancer for smokers – a risk that persisted through the second AREDS trial (AREDS2).

AREDS2 examined whether replacing beta carotene (15 mg) with lutein and zeaxanthin (10 and 2 mg), would allow the researchers to create a supplement formula that was equally effective at lowering the risk for age-related macular degeneration (AMD) and that could be used by anyone whether or not they smoke or formerly smoked.

At the end of the 5-year AREDS2, all participants were given the revised formulation with lutein/zeaxanthin, vitamins C and E, and zinc plus copper and were followed for an additional five years. The researchers wanted to know whether the increased risk of lung cancer seen in those assigned to beta carotene in AREDS continued beyond the end of AREDS2, and whether they could see any long-term benefit of adding lutein/ zeaxanthin to the AREDS2 formula.

In a new report(2), the researchers looked at 10 years of data and concluded that the revised formula with lutein and zeaxanthin not only reduces the risk of lung cancer due to beta carotene but is also more effective at reducing the risk of AMD progressing to late AMD.

The follow-up continued to show that beta carotene nearly doubled the risk of lung cancer for those who had smoked, while there was no increased lung cancer risk for those taking lutein/zeaxanthin. And after 10 years, those originally receiving these two carotenoids in AREDS2 and beyond had an additional 20% reduced risk of AMD progression vs. those assigned to beta carotene.

References

1. Shah S, et al. (OR07-03-22) Adherence to Healthy and Unhealthy Plant-Based Diets and Risk of Breast Cancer Overall and by Hormone Receptor and Histologic Subtypes Among Postmenopausal Women. Presented at the American Society for Nutrition Annual meeting, June 14, 2022
2. National Institutes of Health News Release. NIH study confirms benefit of supplements for slowing age-related macular degeneration. June 2, 2022.