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mardi 15 septembre 2015

How a title could be misleading: warning, bad science often begins with inappropriate titles

Vitamin C: The Exercise Replacement?
Savannah, Ga. (September 4, 2015)—Overweight and obese adults are advised to exercise to improve their health, but more than 50 percent do not do so. New research to be presented at the 14th International Conference on Endothelin: Physiology, Pathophysiology and Therapeutics suggests that taking vitamin C supplements daily can have similar cardiovascular benefits as regular exercise in these adults.
The blood vessels of overweight and obese adults have elevated activity of the small vessel-constricting protein endothelin (ET)-1. Because of the high ET-1 activity, these vessels are more prone to constricting, becoming less responsive to blood flow demand and increasing risk of developing vascular disease. Exercise has been shown to reduce ET-1 activity, but incorporating an exercise regimen into a daily routine can be challenging. This study, conducted at the University of Colorado, Boulder, examined whether vitamin C supplements, which have been reported to improve vessel function, can also lower ET-1 activity. The researchers found that daily supplementation of vitamin C (500 mg/day, time-released) reduced ET-1-related vessel constriction as much as walking for exercise did. Vitamin C supplementation represents an effective lifestyle strategy for reducing ET-1-mediated vessel constriction in overweight and obese adults, the researchers wrote.
Caitlin Dow, PhD, postdoctoral research fellow at the University of Colorado, Boulder, will present “Vitamin C Supplementation Reduces ET-1 System Activity in Overweight and Obese Adults” at the poster session on Friday, September 4, from 1 to 2:30 PM in Ballroom BCDEF of the Hyatt Regency Savannah.

It seems that Endothelin is useless in men...
    • Session Title: Biomarkers

Abstract P292: Concentrations of Endothelin-1 Predict Coronary Heart Disease in Women in a Swedish Cohort Study

  1. Ulf Lindblad1
+Author Affiliations
  1. 1Medicine, Gothenburg, Sweden
  2. 2Lund Univ, Dept of Clinical Sciences, Malmö., Malmö, Sweden


Objecitves: Endothelin-1 has been linked to coronary heart disease (CHD) in retrospective studies. Although prospective studies in subjects with previous CHD also have shown a higher risk for a second event related to higher endothlin-1 concentration, prospective studies investigating the risk of a first event are still lacking. We accordingly aimed to investigate the risk of a first event of coronary heart disease (CHD) associated with concentrations of endothelin-1 in men and women separately.
Subjects and methods: A random sample of 2.818 Swedish men and women aged 30-74 years was surveyed in 2002-2005 (76% participation). Standard questionnaires were used to gain information on medical history and lifestyle and all participants conducted a physical examination. Endothelin-1 collected at baseline was successfully analysed in 2795 subjects (99%). All first events of CHD were retrieved by record linkage with the Swedish Cause of Death and Hospital Discharge Registers. After controlling for proportionality, Cox Proportional Hazards Regression was employed to investigate the associations between endothelin-1 and incident CHD.
Results: During a mean follow up of 8.1 years (± 0.96) there were 96 incident cases of CHD (men 71 and women 25). Concentrations of endothelin-1 were similar in men and women (2.3 pg/ml vs 2.4 pg/ml p=0.111). In age-adjusted Cox regressions, concentrations of endothelin-1 predicted CHD in women (HR=1.48 CI 1.1-1.8), albeit not in men (HR=1.0 CI 0.9-1.3). These findings remained in multivariable analyses adjusting for diabetes, waist-hip ratio, smoking habits, LDL-cholesterol and systolic blood pressure (HR in women=1.45 CI 1.1-2.0; HR in men=1.1 CI 0.9-1.3). The interaction term between sex and endothelin-1 in the fully adjusted analysis was borderline significant (p=0.055).
Conclusions: Endothelin-1 predicted CHD in women independent of traditional CHD risk factors. If these findings are confirmed in other populations there will be implications for risk evaluation in clinical practice.

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