How much does a mother’s diet affect her children’s health?

Every step a parent takes leaves a mark on their children’s path. Even before conception, their habits will lead the way, and, like an invisible thread, this influence extends throughout childhood and adolescence. Where they live, who they live with, the family income or the education of the mom and dad; everything plays a decisive part. Diet, too: during pregnancy, due to the direct link created by the umbilical cord, and during child-rearing, due to the replication of patterns, among other factors. A study published in the British Medical Journal (BMJ) alludes to this idea and suggests that the maternal consumption of ultra-processed food during the child-rearing period is associated with an increased risk of overweight or obesity in their offspring.

There is “a transgenerational association” between maternal consumption of ultra-processed foods and the body weight of their children, explains a group of researchers from Harvard Medical School in the publication. They confirmed this after studying the dietary and behavioral data of a cohort of nearly 20,000 children born to more than 14,500 mothers in the United States. Being only observational, a causality cannot be established from this study, but the analysis of the patterns of ultra-processed food consumption in the mothers does find that, irrespective of other lifestyle risk factors (such as smoking, marital status, the partner’s education or physical activity), the children of women who consume more ultra-processed foods have up to a 26% higher risk of developing overweight or obesity than the offspring of the mothers who eat less.

By “ultra-processed” scientists mean products like “bacon, cola, energy bars, and ice cream that have undergone intensive industrial processing.” That is, those that, according to the NOVA classification system (which ranks foods according to their level of processing) are configured as “industrial formulations” that include substances like sweeteners, dyes or additives, among others, that give them a certain appearance or taste or that make them durable, accessible or ready to eat. The scale is controversial within the scientific community and not all ultra-processed foods have the same impact on health, experts warned, but they do agree that many of these products tend to have a lower nutritional profile.

According to the Harvard researchers, their findings “suggest that mothers might benefit from limiting intake of ultra-processed foods to prevent offspring overweight.” “Dietary recommendations should be refined and financial and social barriers removed to improve nutrition for women of child bearing age and to reduce childhood obesity,” they concluded. The study found a link during childhood and adolescence, but, interestingly, not during pregnancy: there was a trend in the same direction, but it was not statistically significant.

The researchers believe that “maternal diet during child-rearing is likely to shape offspring’s diet and lifestyle choices.” In fact, according to the scientists, it has already been proven that interventions only in the parents are also effective for the child to lose weight. However, they leave the door open to more hypotheses that explain the persistence of this sort of invisible umbilical cord and suggest that other avenues need to be explored further. They also admitted that part of the risk may be due to unmeasured factors.

A limited consumption

Independent experts say that the study is reliable and, despite the limitations that the authors themselves admitted (such as the fact that causality cannot be established, that some data were self-reported and could be inaccurate, or that the results cannot be generalized because the mothers in the cohort were predominantly white). Javier Aranceta, president of the Spanish Academy of Nutrition and of the Scientific Committee of the Spanish Society of Community Nutrition, pointed out that the research follows a trend: “There are precedents, concordant results, although they were less potent. Ultra-processed foods have a negative effect on body composition; they pose a risk of obesity, which is square one for many diseases. Now there is enough evidence to propose a limited consumption [of these products].”

The evidence regarding the influence of the parents’ diet on their offspring continues to grow, at all stages. A study in animal models found that an adverse maternal environment during pregnancy predisposes the offspring to suffer from metabolic syndrome, with an increased risk of obesity and diabetes, and although the causes are not clear, the researchers point to epigenetic changes in neurons of the hypothalamus, responsible for regulating the energy balance of the descendant. Another analysis of seven European cohorts also revealed that a poor-quality maternal prenatal diet can negatively influence offspring body composition as well as the risk of overweight and obesity. And research in schools in Alabama and Texas found that children were almost twice as likely to have a body mass index percentile above 95% if their caregiver was obese.

A shared responsibility

A scientific review published in the journal Biomolecules takes into account the influence of the habits of both parents — not only the mother — on the health of their children: “An increased risk of birth defects (...) has been reported in offspring when both the parents were overweight. Furthermore, parental pre-conception obesity is predictive of an increased offspring BMI from childhood to adolescence and adolescence to adulthood.” In the BMJ investigation, the scientists admitted, precisely, “the possibility that mothers are not solely responsible for household foods.”

The researchers do not lose focus that the risk factors for developing obesity or overweight are not isolated, but intertwined: it is not only the diet in itself, but also the ease of access to certain products, food education or the time available to cook and eat. Libertad González, professor of health economics at Pompeu Fabra University, lamented that the Harvard researchers did not delve into the causes that explain this phenomenon, and insisted that the consumption of ultra-processed foods is correlated with other variables, such as income or living in places where it is more difficult to get healthy products.

González also considers it a disadvantage that the cohort, despite being of good quality, only includes women, even though she herself has led studies that confirm that the weight of the family food operations falls on the women. Duane Mellor, a dietician and professor at Aston University, also criticized that the BMJ study did not take into account the mother’s food intake at other times in her life, as well as the food intake of the other parent.

According to the World Health Organization, around 39 million children under the age of five were obese or overweight in 2020. Aranceta points out that the problem — and the responsibility — is global: “After the breastfeeding period, everyone is responsible. We have to be responsible and the parents and grandparents have to realize that we have to improve the food aspect. The healthiest is more expensive and less comfortable, but more time in the kitchen means less time in the clinic.”

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