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Date of release: 10 October, 2016

Eating more fiber appears to lower future breast cancer risk

There has been a hypothesis that a diet high in fiber can reduce future risk of breast cancer by inhibiting estrogen reabsorption. One meta-analysis has shown a weak effect that eating fiber reduces breast cancer risk [1]. However, other studies, including the Nurses’ Health Study, did not show this association [2]. It is also known that factors in childhood and early adult life can affect future breast cancer risk. A recently published study has analyzed data from the Nurses’ Health II Study which allowed analysis of fiber intake during adolescence or early adulthood (which is a younger age range than other studies) for a longer follow-up time than other studies [3].

This study analyzed questionnaires from over 44,000 women which documented information about their diet and alcohol intake during high school. There was also an evaluation of the influence of adjustment for alternate healthy-eating index score as well as red meat, animal fat, or β-carotene, as these can also affect future breast cancer risk. Their results demonstrated that, among all women, total fiber intake in early adulthood was associated with significantly lower breast cancer risk. Each 10 g/day increase in total fiber intake during early adulthood was associated with a 13% decrease in breast cancer risk among all women (relative risk 0.87; 95% confidence interval 0.80–0.95). There was a stronger association for premenopausal breast cancer than for postmenopausal breast cancer, although this was not significant.

Comment

There are numerous risk factors for the development of breast cancer and many of these are modifiable. Many of my patients do not realize that being overweight or drinking moderate amounts of alcohol increases their risk of developing breast cancer in the future. More focus in the past has been on the body mass index of the patient rather than their actual diet.

This group have shown previously that a higher red meat intake in early adulthood may be a risk factor for breast cancer, and that replacing red meat with a combination of legumes, poultry, nuts and fish may reduce the risk of breast cancer [4]. Carotenoids, a group of fat-soluble pigments that give red, orange, and yellow fruits and vegetables their colours, may also reduce risk of breast cancer due to their antioxidative or antiproliferative properties [5]. However, diets high in glycemic index, glycemic load, insulin index and insulin load during adolescence or early adulthood have not been shown to be associated with an increased risk of breast cancer [6].

The type of food eaten has an effect on health in numerous ways and general advice is to eat a diet rich in fiber. This advice should be given to young children and adolescents as eating a diet high in fiber has many health benefits such as reducing future risk of cardiovascular disease and diabetes. Another health benefit appears to be reducing risk of breast cancer.

Louise R. Newson


Solihull, West Midlands, UK



    References

  1. Aune D, Chan DS, Greenwood DC, et al. Dietary fiber and breast cancer risk: a systematic review and meta-analysis of prospective studies. Ann Oncol 2012;23:1394-402


    http://www.ncbi.nlm.nih.gov/pubmed/22234738

  2. Holmes MD, Liu S, Hankinson SE, Colditz GA, Hunter DJ, Willett WC. Dietary carbohydrates, fiber, and breast cancer risk. Am J Epidemiol 2004;159:732-9


    http://www.ncbi.nlm.nih.gov/pubmed/15051582

  3. Farvid MS, Eliassen AH, Cho E, Liao X, Chen WY, Willett WC. Dietary fiber intake in young adults and breast cancer risk. Pediatrics 2016;137:e20151226


    http://www.ncbi.nlm.nih.gov/pubmed/26908709

  4. Farvid MS, Cho E, Chen WY, Eliassen AH, Willett WC. Dietary protein sources in early adulthood and breast cancer incidence: prospective cohort study. BMJ 201410;348:g3437


    http://www.ncbi.nlm.nih.gov/pubmed/24916719

  5. Boeke CE, Tamimi RM, Berkey CS, et al. Adolescent carotenoid intake and benign breast disease. Pediatrics 2014;133:e1292-8


    http://www.ncbi.nlm.nih.gov/pubmed/24709924

  6. Farvid MS, Eliassen AH, Cho E, Chen WY, Willett WC. Adolescent and early adulthood dietary carbohydrate quantity and quality in relation to breast cancer risk. Cancer Epidemiol Biomarkers Prev 2015 24:1111-20


    http://www.ncbi.nlm.nih.gov/pubmed/25805068