Combined impact of lifestyle factors on mortality: prospective cohort study in US women
BMJ 2008; 337 doi: https://doi.org/10.1136/bmj.a1440 (Published 16 September 2008) Cite this as: BMJ 2008;337:a1440
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Rob M van Dam and colleagues have defined low risk physical activity
as an average of at least 30 minutes a day of activity of at least
moderate intensity (requiring 3 metabolic equivalents an hour, including
brisk walking), consistent with existing guidelines and reference to the
work from Patt and colleagues.
I do have 2 questions that I hope could find an answer in their data.
The first may be seen as being slightly provocative: does regular vigorous
exercise deserve allocation to a distinct risk class. In particular, may
extremely vigorous exercise protracted for decades (lifestyle) have
effects that could not be only positive when looking into mortality and
morbidity (the latter not being assessed by your study).
The second question is about diet supplement and exercise training. I do
assume that some of the most active participants may have been using
supplements (Vitamin C could have been one).
This could have some impact, at the least theoretically, as very well
known free-radicals scavenger.
Have they been able to clear-up the data from this possible confounding
factor?
Competing interests:
None declared
Competing interests: No competing interests
Would the Nurses health study be able to tell us how quickly the benefits of a change in lifestyle appear?
This study shows the benefit of adhering to lifestyle guidance in
middle aged women. Over the time period of the study the benefits of a
healthy lifestyle have become more apparent and presumably more women have
adopted a healthy lifestyle. The long term follow up of doctors has given
estimates for a diminishing risk of death following smoking cessation but
data around change to a healthy lifestyle regarding diet and physical
activity is less available. Would examining the data from the Nurses
Health study be able to answer how quickly the benefits appear when
lifestyle is changed? In essence how long does it take for the
attributable risk take to revert to that of those who followed healthy
guidelines throughout? Evidence on this would be helpful in assessing
impact and outcomes to support commissioning for healthy lifestyles.
anita.roy@wdpct.nhs.uk
Competing interests:
None declared
Competing interests: No competing interests