Lower dietary methionine linked to higher breast cancer survival
USA: According to a study published in the Nutrients, breast cancer survivors should decrease methionine intake after breast cancer diagnosis as it is associated with lowered risk of all-cause and breast cancer mortality. This is the first study of dietary changes in methionine about breast cancer survival and the findings of the study have suggested that restricting methionine intake is associated with longer survival after a breast cancer diagnosis.
Methionine is an essential amino acid for humans, meaning that it is not produced within the body and can only be obtained from the diet, usually from meats, nuts, eggs, and grains.As shown by previous experimental studies, limiting methionine animal diet or in cell culture media suppresses the proliferation of mammary cancer cells or metastasis. None of the studies has investigated the associations of methionine intake with survival among breast cancer survivors.
Yangbo Sun and colleagues investigated this association between dietary intake changes of methionine, folate/folic acid, and vitamin B12 from before to after breast cancer diagnosis and mortality.
The study methods and results can be summarised as follows:
- A total of 1553 postmenopausal women were included in the Women's Health Initiative study.
- These women had a history of invasive breast cancer and completed a questionnaire about food frequency before and after a breast cancer diagnosis.The Food Frequency Questionnaire was administered an average of 1.5 years after breast cancer diagnosis.
- To estimate the hazard ratio (HR), multivariable Cox proportional hazards regression models were used.
- The mean follow-up duration was 16.1 years.
The values recorded pre and following diagnosis are:
- 28% of women decreased their intake of methionine by ≥20%.
- 30% of women increased their intake of methionine by ≥20%
- 42% of women had a stable methionine intake (±19.9%).
- A total of 772 deaths were recorded.
- One hundred ninety-five deaths were due to breast cancer.
- Women who decreased methionine intake had lower risks of all-cause and breast cancer mortality with HR of 0.78 and 0.58, respectively.
- Increased methionine intake, folate/folic acid, or vitamin B12 changes were not associated with all-cause or breast cancer mortality.
To conclude, Women who cut their dietary intake of methionine after a breast cancer diagnosis showed a 22% reduction in all-cause mortality and a 42% reduction in breast cancer mortality compared with women whose methionine intake was stable.
The study's limitations included Observational design, dietary assessment is vulnerable to measurement error and Changes in dietary methionine intake may not be reflected in systemic methionine levels.
Further reading:
Sun Y et al. Changes in Dietary Intake of Methionine, Folate/Folic Acid and Vitamin B12 and Survival in Postmenopausal Women with Breast Cancer: A Prospective Cohort Study. Nutrients. 2022 Nov 10;14(22):4747. 10.3390/nu14224747. PMID: 36432434
