NEW YORK (Reuters Health) – Granddaughters and great granddaughters of men who started to smoke cigarettes before puberty are apt to have more body fat than expected, a transgenerational analysis shows.

“Our results reflect on the possible causes of accumulation of body fat,” Dr. Jean Golding of Bristol University, UK. “At this stage, they are unlikely to have clinical relevance but may be useful in the public health field by indicating how potentially dangerous it may be to future generations if children are exposed to harmful substances before puberty, such as cigarettes.”

“If our study is correct, it is the exposure (to cigarettes smoking) before the gonads have fully developed that is key to the physical development of subsequent generations,” she noted. “We assume that such exposures will leave some sort of epigenetic mark on the sperm that will subsequently develop.”

“From published information on the ways in which animals have been shown to also demonstrate transgenerational influences, I would suggest that exposures to substances such as pesticides, or traumatic events such as abusive family homes, may well be shown to have demonstrable consequences down the generations,” she added.

The group’s 2014 report on more than 14,000 individuals showed that sons of fathers who had started smoking regularly before puberty (<13 years) had increased fat mass during childhood, adolescence, and early adulthood.

In the current study, published in Scientific Reports, they show in an analysis of data from questionnaires that if the paternal grandfather had started smoking pre-puberty versus later in childhood (13-16 years), his granddaughters, but not grandsons, showed excess fat mass at age 17 (mean difference, + 3.54 kg) and age 24 (mean difference, + 5.49 kg).

Further, when fathers of maternal grandfathers started smoking pre-puberty, their great-granddaughters, but not great-grandsons, had excess body fat at ages 17 (+ 5.35 kg) and 24 (+ 6.10 kg).

A sensitivity analysis showed no associations with lean mass.

To determine whether the results were due to the later generations starting to smoke pre-puberty, the researchers omitted individuals who had smoked regularly starting before age 13 from further analyses – and the findings were similar.

The authors conclude, “If these associations are confirmed in another dataset or using biomarkers, this will be one of the first human demonstrations of transgenerational effects of an environmental exposure across four generations.”

Can preconception paternal smoking exert similar effects on a newborn offspring’s body fat? Probably not – but possibly.

In a study published in JAMA Network Open, Dr. Ravi Retnakaran of Mount Sinai Hospital in Toronto and colleagues studied 1,174 newly-married women and their partners in Liuyang, China. They assessed these couples at a median of 23.3 weeks before a singleton pregnancy, then followed them across gestation for neonatal and obstetrical outcomes.

“In this preconception cohort, the prevalence of smoking was high in men (45.8%) but very low in women (0.4%),” Dr. Retnakaran told Reuters Health by email. “Despite its low prevalence, maternal smoking predicted lower infant birthweight. In contrast, however, paternal smoking prior to conception was not associated with infant birthweight or length of gestation. Moreover, there was no evidence of interaction between the father’s smoking status and BMI on either of these outcomes.”

“While it is reassuring that paternal smoking prior to conception was not associated with adverse neonatal outcomes at delivery, it is important to recognize that these findings do not rule out the possibility, per the Paternal Origins of Health and Disease paradigm, that programming effects of preconception paternal smoking may emerge later in life in childhood or adulthood,” he noted.

“Indeed,” he added, “the latter concept – i.e., a programming effect that is then passed on to subsequent generations – may well fit with the findings of the paper in Scientific Reports.”

Dr. Matthew Suderman of Bristol University, principal author of the Scientific Reports study, agrees, noting by email that in his group’s studies, “the effect of prepubertal smoking on fat mass in descendants increases as they transition from childhood to early adulthood.”

SOURCES: https://go.nature.com/3utKDpg Scientific Reports, online January 21, 2022

https://bit.ly/34tPWuf JAMA Network Open, online January 21, 2002

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