Men who smoked before teens may father fatter sons

Smoking before puberty
may lead to men fathering fatter sons, suggesting that lifestyle factors can
have adverse impacts on the next generation, a study has found.

The research found that
men who smoked regularly before age 11 fathered sons who had five to ten
kilograms more body fat than the sons of men who did not smoke, or started
smoking after age 11. The researchers said this could indicate that
exposure to tobacco smoke before puberty might lead to epigenetic changes in metabolism
in the next generation, passed on through the male line.

Senior author of the study, Professor Marcus Pembrey,
said: 'This discovery of trans-generational effects has big implications for
research into the current rise in obesity and the evaluation of preventative
measures'. He added: 'It is
no longer acceptable to just study lifestyle factors in one generation'.

A similar
effect on increased Body Mass Index (BMI) was also observed in the daughters of fathers who
smoked before age 11, but to a much lesser extent. However, no such association
was found between when a mother started smoking and body fat of her children.

The
results of this study should be interpreted with caution as the authors
themselves state that there are a number of weaknesses in this study. In
particular, less than one percent of all the fathers questioned started smoking
regularly before age 11. Together these men fathered only 13 sons, leading
some experts to comment on the significance of the findings based on the small
sample size.

Dr Graham
Burdge, researcher of human nutrition at the University of Southampton, told Reuters the findings 'may potentially provide new insights into factors that may
influence development of obesity in childhood', but 'the findings only show associations and cannot be interpreted as indicating that paternal smoking at
an early age causes obesity in their sons'.

He added
that, 'A possible alternative interpretation is that that exposure of parent
and child to a common environment has an effect on the child's BMI that might
be influenced by the lifestyle of the father'.

Tim
Spector, a professor of genetic epidemiology at King's College London, commented
that: 'The data are persuasive but not yet definitive as we need to confirm the
same smoking related epigenetics changes in the kids' DNA'.