Dr. Snow's How to Stay Rollin': Obesity Gene & Multivitamin - Breast Cancer Studies

Multivitamin use and breast cancer incidence in a prospective cohort of Swedish women

Credit:
Am J Clin Nutr 91: 1268-1272, 2010. First published March 24, 2010; doi:10.3945/ajcn.2009.28837
American Journal of Clinical Nutrition, doi:10.3945/ajcn.2009.28837
Vol. 91, No. 5, 1268-1272, May 2010
© 2010 American Society for Clinical Nutrition
Susanna C Larsson, Agneta Åkesson, Leif Bergkvist and Alicja Wolk

1 From the Division of Nutritional Epidemiology, The National Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden (SCL, AÅ, and AW), and the Department of Surgery and Centre for Clinical Research, Central Hospital, Västerås, Sweden (LB).

2 Supported by research grants from the Swedish Cancer Foundation and the Swedish Research Council for Infrastructure.

3 Address correspondence to SC Larsson, Division of Nutritional Epidemiology, National Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE-17177 Stockholm, Sweden. E-mail: susanna.larsson@ki.se

Background: Many women use multivitamins in the belief that these supplements will prevent chronic diseases such as cancer and cardiovascular disease. However, whether the use of multivitamins affects the risk of breast cancer is unclear.

Objective: We prospectively examined the association between multivitamin use and the incidence of invasive breast cancer in the Swedish Mammography Cohort.

Design: In 1997, 35,329 cancer-free women completed a self-administered questionnaire that solicited information on multivitamin use as well as other breast cancer risk factors. Relative risks (RRs) and 95% CIs were calculated by using Cox proportional hazard models and adjusted for breast cancer risk factors.

Results: During a mean follow-up of 9.5 y, 974 women were diagnosed with incident breast cancer. Multivitamin use was associated with a statistically significant increased risk of breast cancer. The multivariable RR of women who reported the use of multivitamins was 1.19 (95% CI: 1.04, 1.37). The association did not differ significantly by hormone receptor status of the breast tumor.

Conclusions: These results suggest that multivitamin use is associated with an increased risk of breast cancer. This observed association is of concern and merits further investigation.

Exercise Can Beat Obesity Gene

By Michael Smith, North American Correspondent, MedPage Today
Published: April 05, 2010
Reviewed by Robert Jasmer, MD; Associate Clinical Professor of Medicine, University of California, San Francisco and
Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner

An hour a day of moderate to vigorous exercise can overcome the effect of a gene variant that predisposes people to obesity, researchers said.

In a cohort study of 752 European adolescents, those who had one or more copies of the variant -- but exercised daily -- were no more likely to be overweight than those who did not have the variant, according to Jonatan Ruiz, PhD, of Sweden's Karolinska Institute, and colleagues.

They implication, they said in the April issue of Archives of Pediatrics & Adolescent Medicine, is that recommended exercise levels can "ameliorate the deleterious effect" of the gene variant.

The gene variant in question -- dubbed rs9939609 -- is the so-called A allele of the fat mass- and obesity-associated gene, or FTO. Each copy of the A allele has been estimated to correspond with an extra 1.5 kilograms in body weight.

Some studies have shown that exercise benefits people carrying one or more copies of the allele, the researchers said, but others have not found an effect.

To help clarify the issue, they turned to a cross-sectional study known as Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA), designed to obtain data on nutrition and health-related parameters.

Of the 3,865 adolescents in the study, 752 adolescents (including 413 girls) had data on the FTO variant, body mass index, and physical activity as measured by accelerometers over a seven-day period.

The researchers divided the group according to whether they achieved the 60 minutes a day of moderate or vigorous exercise in recent guidelines for adolescents from the U.S. Department of Health and Human Services.

Overall, they found, 200 of the 339 boys and 111 of the 413 girls reached the recommended daily exercise level.

Of the 752 adolescents, 275 had no copies of the allele, 354 had one copy, and 123 had two, Ruiz and colleagues reported in the journal, but there was no significant difference among the FTO genotypes in terms of how many of the participants met the exercise cutoff.

On the other hand, among those who did not meet the cutoff, there was a significant effect on obesity-related factors. Specifically, after adjusting for center, sex, and age, the A allele was associated with higher:

    * Body mass index -- at plus 0.65 per copy, which was significant at P=0.005
    * Body fat percentage -- at plus 1.70% per copy, which was significant at P=0.003
    * Waist circumference -- at plus 1.15 centimeters per copy, which was significant at P=0.04

On the other hand, there were no significant differences in those parameters -- based on FTO status -- among participants who met the exercise level, the researchers said.

Results were similar in boys and girls and did not change when the researchers adjusted for pubertal stage, rather than age.

Ruiz and colleagues said the study is cross-sectional, so the findings should be interpreted with caution.

The study had support from the European Community Sixth RTD Framework Programme, the Spanish Ministry of Education, the Spanish Ministry of Health, the Swedish Council for Working Life and Social Research, and the ALPHA study (a European Union-funded study in the framework of the Public Health Programme).

The researchers made no financial disclosures.

Primary source: Archives of Pediatrics & Adolescent Medicine
Source reference:  Ruiz JR, et al "Attenuation of the effect of the FTO rs9939609 polymorphism on total and central body fat by physical activity in adolescents: The HELENA Study" Arch Pediatr Adolesc Med 2010; 164(4): 328-33.
http://archpedi. ama-assn. org/cgi/content/ short/164/ 4/328

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