To the Editor:
Lecithin supplements are one of the most commonly used nonvitamin, nonmineral supplements.1 Commercially made lecithin supplements, frequently derived from soy beans, contain phosphatidylcholine, and the terms phosphatidylcholine and lecithin are often used synonymously.2 Phosphatidylcholine is one of the primary forms of choline and is an essential component of cell membranes, important for cell-membrane signaling.3 Phosphatidylcholine is endogenously produced in the liver and converted to choline, but additional choline is needed from dietary sources (eg, egg yolk, liver). In 1998, an Adequate Intake (Dietary Reference Intake) for choline was recommended at 425 mg/d for adult women.2 Laboratory studies suggest that choline deficiency may promote carcinogenesis through uncontrolled apoptosis and DNA damage.3 Recent epidemiologic studies found that choline intake from foods is associated with reduced breast cancer risk4 and mortality,5 although findings are inconsistent.6,7 To the best of our knowledge, no previous studies have evaluated lecithin supplement use and breast cancer risk.
We evaluated the association between lecithin supplement use and breast cancer risk in the Ontario Women's Diet and Health Study. Methods for this population-based case-control study have been described previously.8 Briefly, 3101 breast cancer cases aged 25–74 years were recruited from the Ontario Cancer Registry (2002–2003), and 3471 controls (frequency age-matched 1:1 to cases) were identified through random digit dialing of Ontario households. Study participants completed self-administered risk-factor and food-frequency questionnaires that queried exposures 2 years earlier (before cancer diagnosis among cases). The risk factor questionnaire listed 40 nonvitamin, nonmineral supplements suspected to contain phytoestrogens, and asked participants to report which, if any, they had ever used, for how long (less than 1 year; 1–5 years; more than 5 years), and with what frequency (less than 1/week; 1–6/week; daily). Lecithin was included since it is often derived from soy beans, a major phytoestrogen source. However, later laboratory analysis revealed that lecithin contains no phytoestrogens.9 Multivariate logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). More than 40 potential confounders (including known breast cancer risk factors and alcohol intake) were evaluated. None was found to confound the association (OR did not change by more than 10%), and thus results are presented with adjustment for age only.
Ever-use of lecithin supplements was associated with reduced breast cancer risk (age-adjusted OR = 0.77 [95% CI = 0.62–0.97]) (Table). Although the association appeared stronger in postmenopausal women (age-adjusted OR = 0.71 [0.55–0.92]) than premenopausal women (0.96 [0.62–1.49]) (Table), the multiplicative interaction between lecithin supplement use and menopausal status was not statistically significant (likelihood ratio test P interaction = 0.25).
;)
TABLE: Association Between Ever-use of Lecithin Supplements With Breast Cancer
All durations of intake were inversely associated with breast cancer risk overall and among postmenopausal women only; however, the pattern was not consistent with a dose-response relationship. The small number of users among premenopausal women limits our power to detect associations for this subgroup. Dose information was not collected, and the phosphatidylcholine content of lecithin supplements was not known. A potential limitation of this study is misclassification due to incomplete measurement of all choline and phosphatidylcholine sources. Soy lecithin is also added to foods as an emulsifier, and the amount obtained from cumulative exposure is unknown. Lastly, we cannot rule out the possibility that our findings are due to chance.
We believe this is the first report of a reduced risk of breast cancer associated with lecithin supplement use. This finding should thus be considered hypothesis-generating. Given the recent interest in choline and breast cancer risk,4–7 future studies that examine lecithin supplement use may be warranted.
Laura N. Anderson
Prevention and Cancer Control
Cancer Care Ontario
Toronto, Ontario
[email protected]
Michelle Cotterchio
Prevention and Cancer Control
Cancer Care Ontario
Toronto, Ontario
Dalla Lana School of Public Health
University of Toronto
Toronto, Ontario
Beatrice A. Boucher
Prevention and Cancer Control
Cancer Care Ontario
Toronto, Ontario
Department of Nutritional Sciences, and Dalla Lana School of Public Health
University of Toronto
Toronto, Ontario
REFERENCES
1. Millen AE, Dodd KW, Subar AF. Use of vitamin, mineral, nonvitamin, and nonmineral supplements in the United States: The 1987, 1992, and 2000 National Health Interview Survey results.
J Am Diet Assoc. 2004;104:942–950.
2. Institute of Medicine. Choline. In:
Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. Washington, DC; National Academy Press; 1998:390–422.
3. Zeisel SH, da Costa KA. Choline: an essential nutrient for public health.
Nutr Rev. 2009;67:615–623.
4. Xu X, Gammon MD, Zeisel SH, et al. Choline metabolism and risk of breast cancer in a population-based study.
FASEB J. 2008;22:2045–2052.
5. Xu X, Gammon MD, Zeisel SH, et al. High intakes of choline and betaine reduce breast cancer mortality in a population-based study.
FASEB J. 2009;23:4022–4028.
6. Cho E, Holmes MD, Hankinson SE, Willett WC. Choline and betaine intake and risk of breast cancer among post-menopausal women.
Br J Cancer. 2010;102:489–494.
7. Cho E, Holmes M, Hankinson SE, Willett WC. Nutrients involved in one-carbon metabolism and risk of breast cancer among premenopausal women.
Cancer Epidemiol Biomarkers Prev. 2007;16:2787–2790.
8. Cotterchio M, Boucher BA, Kreiger N, Mills CA, Thompson LU. Dietary phytoestrogen intake–lignans and isoflavones–and breast cancer risk (Canada).
Cancer Causes Control. 2008;19:259–272.
9. Thompson LU, Boucher BA, Liu Z, Cotterchio M, Kreiger N. Phytoestrogen content of foods consumed in Canada, including isoflavones, lignans, and coumestan.
Nutr Cancer. 2006;54:184–201.
