Science Podcasts

Naked Scientists episode

Sun, 28th Sep 2008

Young at Heart - Healthy Ageing

This week, how to live longer and look younger with the science of ageing!  We discover how repairing damage to DNA could prevent the diseases associated with old age, and find out how to keep your skin looking younger for longer.  Also, doing just four things could add fourteen years to your life - so find out what they are, right here!  Plus, how gene therapy could cure one from of blindness, how to get more distance from a tank of diesel and counting insects - how bees can count up to four, but not five.  Also, in Kitchen Science, we explore the stretchy science of rubber bands!

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In this edition of Naked Scientists

Full Transcript

  • 19:47 - Damaged DNA

    DNA damage leads to many of the diseases we associate with ageing, so if we could stop DNA from being damaged, or repair existing damage - could we stay young forever?

  • 27:01 - Younger Looking Skin

    Meera finds out how to keep your skin looking young and healthy...

  • 33:30 - How to Live Longer

    You may be surprised to hear that some very simple lifestyle changes can extend your life by 14 years! We find out how to live longer...

  • 45:00 - Why does hair grow out of control in older people?

    Why do eyebrows start to grow out of control in old people? I was at the barbers last weekend, and after cutting his hair, the barber asked the elderly gentleman in front of me if he wanted his eyebrows trimmed (they did need it!).

  • 54:23 - How do our cells know how old they are?

    I heard that our cells replace themselves every 18 months which means our bodies are actually only 18 months old. How do the cells, the new cells carry the information about our real chronological age forward into the next generation of cells?

  • 55:21 - Why does hair lighten in the Sun?

    If melanin causes the colour of our skin and our hair why does our skin go dark and our hair go light in the sun?

 

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Thats interesting I did not realize that our DNA could change! Karen W., Sun, 28th Sep 2008

Brad Tittle contacted the naked scientists after the show to say:

"Hi Chris,

I refer you to the following counter analysis to the EPIC study reporting 14 extra years if you do the right thing.

http://junkfoodscience.blogspot.com/2008/01/if-only-it-were-true.html

It truly amazes me that a bunch of smart people like you embrace this malarky. How about a little of the scientific rigor in analyzing the results.

As Sandy points out, there was no difference between doing 4, 3, or 2 of the healthy habits. Only when the final item was added was their a difference.

I admire your work most of the time, just not when it comes to evaluating epidemiological data.

What one should get out of this study is that most of the "bad" behaviors aren't really that bad. We may yet find the fountain of youth, but epidemiology probably won't be part of the process.

Sorry. I hate criticizing the work you do."

Nicks response is to follow. BRValsler, Tue, 21st Oct 2008

Nick Wareham replied with this comment:

"Thank you for inviting me onto your show on Sunday. Thanks also for the feedback comments from your listener. We appreciate the opportunity to respond to their comments and to react to the claims that were made on the website to which they refer since this makes a series of negative and largely incorrect statements about our paper published in PLOS Medicine.

Your correspondent and the author of the website suggest that we were claiming a level of causal inference that was beyond the limits of our data. However, we were very in our paper to state that the magnitude of association between the four key lifestyle factors was estimated to be equivalent to that of 14 years in chronological age. We did not claim that we had observed a causal relationship. We were careful in the discussion section of our paper to consider alternative explanations for the observed associations, particularly chance, bias and confounding.

The author of the website seems to have a problem with the whole notion of epidemiology as a point of principle, which is not a reasonable stance. Some critics have argued that observational epidemiology is so limited that only randomized controlled trials can be used to inform public health policy.

However, this viewpoint also has major problems and we would remind the author of the website, as an example, that there is no randomized controlled trial data concerning smoking and chronic disease endpoints, and public health policy is based on observational data.

There are a number of serious factual inaccuracies on the website blog. I have reproduced a few of their mistakes together with a response below.


"Their key finding, which has not been reported, was they were unable to find a tenable correlation between any of the health behaviors and mortality: all-cause, cardiovascular disease, cancer or any other cause of death. The relative risks all hugged either side of 1 - null findings."

This is completely incorrect. Table 3 of our paper clearly shows that each of the four behaviours is strongly and statistically significantly association with all-cause. cardiovascular and cancer mortality independently of age, sex, BMI and social class. The statement they make is wrong.

"Compared with those who'd reported doing four healthy behaviors more than a decade earlier, they found no tenable correlation with higher all-cause mortality among those reporting only three healthy behaviors more than a decade earlier ... nor among those reporting only two healthy behaviors ... nor among those reporting only one healthy behavior. Only among those who reported no healthy behavior at all at the time of enrollment (49 deaths) did the relative risks for mortality go above chance or statistical error."

Again this is completely incorrect. Table 4 of our paper clearly shows that for all-cause, cardiovascular,  cancer and non-cvd/non-cancer mortality the relative risks were statistically significantly different from 1 in those doing 3, 2, 1 or none of the behaviours compared to those doing 4 which was the reference category. The statement above which implies that the effect was only demonstrable in the small top category is completely wrong.

I am perfectly willing to come back onto your show to discuss with anyone who wishes to put a contrary view the arguments about the merits or otherwise of epidemiology as the foundation stone of public health.  As for the claims made on the website which imply that our science is poor, this is simply wrong and are not a matter of debate." BRValsler, Tue, 21st Oct 2008

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