In the March 17, 2009 issue of Life Extension Update, we reported the finding from the Sister Study, a cohort of healthy sisters of breast cancer patients, of a beneficial association between multivitamin use and telomere length, a biomarker of aging. Telomeres, which are repeating DNA sequences that cap the ends of chromosomes, shorten with increased cellular aging.
In articles published in the February and March, 2009 issues of the journal Cancer Epidemiology Biomarkers and Prevention, further findings from the Sister Study concerning the impact of lifestyle on telomere length were revealed.
In the February, 2009 issue, Christine Parks, PhD, of the National Institute of Environmental Health Sciences of the National Institutes of Health (NIH) and her associates evaluated the effect of stress on telomere length in 647 Sister Study participants. Telomere length in DNA from blood samples was measured, and stress hormone levels in urine were assessed. Questionnaires completed by the subjects provided information on perceived stress levels.
Study participants, on average, reported low stress levels. "Even so, women who reported above-average stress had somewhat shorter telomeres, but the difference in telomere length was most striking when we looked at the relationship between perceived stress and telomere length among women with the highest levels of stress hormones," Dr Parks observed. "Among women with both higher perceived stress and elevated levels of the stress hormone epinephrine, the difference in telomere length was equivalent to or greater than the effects of being obese, smoking or 10 years of aging."
In the report that appeared in the March, 2009 issue of the journal, the effect of past and current body mass index (BMI) on telomere length was examined. Sister Study participants whose BMI categorized them as overweight or obese before or during their thirties and whose weight status was maintained were found to have shorter telomeres compared to subjects who became overweight at an older age. "This suggests that duration of obesity may be more important than weight change per se, although other measures of overweight and obesity were also important," stated lead author Sangmi Kim, PhD, also of the National Institute of Environmental Health Sciences. "Our results support the hypothesis that obesity accelerates the aging process".
"We anticipate a wealth of information to come out of the Sister Study," predicted Dale Sandler, PhD, chief of the Epidemiology Branch at the National Institute of Environmental Health Sciences and principal investigator of the Sister Study. "Not only do we hope to find out more about the environmental and genetic factors that might lead to breast cancer, we also want to learn more about how factors such as stress, diet and exercise might impact cancer and other disease risks."
"Together these two studies reinforce the need to start a healthy lifestyle early and maintain it," National Institute of Environmental Health Sciences director Linda Birnbaum, PhD, concluded. "These papers remind us that there are things people can do to modify their behavior and live healthier lives, such as maintain a healthy weight and cultivate healthy responses to stress."
Related Health Concern: Obesity
The risk of death from all causes, including cardiovascular disease and cancer, increases with rising obesity in both men and women in all age groups, and the risk associated with a high BMI is greater for whites than for blacks (Calle et al 1999).
Obesity increases the risk of developing metabolic syndrome and coronary heart disease (Shirai 2004); type 2 diabetes (Mensah et al 2004); osteoarthritis of major load-bearing joints, such as the knee (Felson et al 1997); hypertension (high blood pressure); sleep apnea (periods of suspended breathing during sleep; Wolk et al 2003); and gall bladder disease (Petroni 2000).
The International Agency for Research on Cancer has classified obesity as a critical causal risk factor for cancers of the colon, breast (postmenopausal women), endometrium, kidney (renal cell), and esophagus (adenocarcinoma) (Calle et al 2004).
A study reported in the Journal of the American Medical Association suggests that obesity causes 111,909 deaths annually (Flegal et al 2005), while epidemiological evidence shows that a lower body weight is associated with lower mortality risk (Stevens 2000). In the well-known Framingham Heart Study, risk of death increased by 1 percent for each extra pound (0.45 kg) of weight between age 30 and 42 and increased by 2 percent between age 50 and 62 (Solomon et al 1997; Kopelman 2000).
Metformin is a prescription drug used to treat type 2 diabetes. Published research shows that it also helps nondiabetics lose weight (Paolisso et al 1998). Metformin reduces the release of glucose (sugar) stored in the liver as glycogen. This prevents blood glucose levels from rising too high, so the body does not need to produce as much insulin (Davidson et al 1997; Maggs 1997; Pugh 1997). Metformin also prevents some of the detrimental effects associated with normal aging (Kiho et al 2005).
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