A pregnant person holds their belly with one hand and a half eaten donut, an ultra-processed food, in the otherShare on Pinterest
A parent’s diet may affect the obesity risk of their children. enigma_images/Getty Images
  • Ultra-processed foods are those that have undergone significant levels of industrial processing and modification during preparation and contain only small amounts of whole foods, if any.
  • A recent study shows that the consumption of ultra-processed foods by mothers during the child-rearing period was linked to an increased risk of overweight or obesity in their offspring during childhood or adolescence.
  • These findings suggest that women of reproductive age should limit the intake of ultra-processed food to reduce the risk of overweight and obesity in their children.

Childhood obesity is a major health issue and is associated with an increased risk of cardiovascular disease and diabetes later in life. The prevalence of childhood and adolescent obesity was nearly 20% in the United States between 2017–2020, accounting for about 14.7 million children and adolescents.

A new study published in BMJ shows that higher levels of maternal intake of ultra-processed foods during childhood and adolescence was associated with an increased risk of overweight or obesity in their offspring between 7–18 years of age, independent of the offspring’s consumption of ultra-processed foods.

“Our research highlights the importance of the diet of the mother on not only her health but also the health of her children. Until now, we tended to focus on dietary counseling for middle-aged and older adults to reduce the risk of chronic disease. This clearly shows that we need to encourage healthy eating across the life course.”
Dr. Andrew Chan, study author and professor of medicine at the Harvard Medical School

“From a public health standpoint, we also need to emphasize access to healthy foods for family units to reduce the epidemic of childhood and adult obesity,” Dr. Chan told Medical News Today.

“We also need to understand that one of the manifestations of social disparities in health is not only differential access to health care but also differential access to healthy, minimally processed foods. This requires deliberate and thoughtful policy-making that addresses not only a basic human right to food but also a right to healthy food,” he added.

Until recently, public health guidelines for obesity prevention and treatment have generally emphasized the importance of maintaining healthy eating patterns. These approaches promote the consumption of certain foods such as whole grains, nuts, fruits and vegetables, and fish while limiting the intake of other foods such as saturated fats, sugar, and sodium.

The obesity epidemic has been accompanied by a steady increase in the consumption of highly processed foods worldwide. Moreover, studies have shown that consumption of ultra-processed food is associated with an increased risk of obesity, diabetes, and cardiovascular diseases. This has led to the emergence of an alternative public health strategy that emphasizes limiting foods that are ultra-processed instead of nutrient intake.

Ultra-processed foods are foods that have undergone significant industrial processing and modification and thus contain only a small amount of whole foods. Thus, ultra-processed foods tend to contain food additives such as preservatives, emulsifiers, stabilizers, and sweeteners that are typically not used in domestic cooking. These foods are generally ready to consume or require little preparation and have a long shelf-life.

Due to the industrial manufacturing processes used for making these types of foods, ultra-processed foods are generally highly palatable, inexpensive, and high in calories, sugar, salt, and saturated fat. Some examples of ultra-processed foods include mass-produced bread and bakery items, ready-to-eat meals, packaged sweets, desserts, and snacks.

Several studies have consistently shown that the consumption of ultra-processed foods is associated with overweight and obesity in adults and children. Moreover, studies have shown that a mother’s diet during pregnancy and even during childhood and adolescence, i.e. during the child-rearing period, can influence the risk of obesity in the offspring.

These studies have examined the association between maternal adherence to specific dietary patterns, such as the DASH diet, or the quality of diet consumed by the mother and the risk of childhood obesity. However, there is a lack of research specifically examining the link between the maternal consumption of ultra-processed food and the incidence of obesity in their offspring during childhood and adolescence.

In the present study, the researchers used data on mother-child pairs to examine the impact of the consumption of ultra-processed food by mothers during pregnancy and the child-rearing period on the development of obesity or overweight in their offspring during childhood or adolescence.

The present study used data from mothers enrolled in the Nurses’ Health Study II (NHS II) and their children participating in the Growing Up Today Study (GUTS I and II), The NHS II is a longitudinal study examining risk factors associated with chronic conditions in nurses aged between 25–42 years at the time of enrollment.

GUTS-1 and GUTS-11 are longitudinal studies involving children of NHS participants aged between 7–17 years at enrollment, with an objective to examine the long-term impact of diet and exercise on an individual’s weight.

The researchers used data collected from lifestyle and health questionnaires that were administered on a regular basis during the three studies. This included data from food frequency questionnaires, which were used to assess the average daily consumption of various ultra-processed food items.

The researchers tracked 19,958 mother-child pairs over an average of 4 years to analyze the association between maternal ultra-processed food consumption during child rearing and the development of overweight or obesity in their offspring between 7-18 years of age.

They found that the intake of ultra-processed food by mothers during the child-rearing period was associated with an increased risk of overweight or obesity in their offspring during childhood or adolescence.

The researchers then divided the mothers into five groups based on their daily consumption of ultra-processed food during the child-rearing period. They compared the risk of obesity or overweight among these groups after adjusting for maternal risk factors such as physical activity levels, energy intake, body weight, socioeconomic factors, and offspring-related factors such as consumption of ultra-processed food, sedentary time, and physical activity levels.

The offspring of mothers who consumed the highest levels of ultra-processed food during the child-rearing period were at a 26% higher risk of developing overweight or obesity.

Among the different types of ultra-processed foods, maternal consumption of ultra-processed bread and breakfast items was associated with an increased risk of obesity or overweight in the offspring.

The researchers then examined the impact of the intake of ultra-processed food during pregnancy. They analyzed data from dietary assessments covering a period of one year that included at least some part of the pregnancy.

Consumption of ultra-processed foods during pregnancy was not associated with an increased risk of childhood overweight or obesity. However, the researchers found an increased risk of developing overweight or obesity in the offspring of mothers who consumed more ultra-processed dairy-based desserts and sweetened beverages during pregnancy.

Interestingly, a slight decrease in the amount of ultra-processed food consumed by the mothers in the study was noted to have occurred between 1991 and 2015.

Previous studies have linked maternal inflammation during pregnancy to childhood obesity. Evidence suggests that additives such as emulsifiers commonly used in dairy-based desserts can alter gut microbiota and promote chronic maternal inflammation, subsequently resulting in childhood obesity.

Alternatively, consumption of ultra-processed foods during pregnancy could alter the long-term expression of genes associated with growth and energy balance in the fetus, increasing the risk of obesity during childhood.

The researchers noted that the study had an observational design and does not establish causation between maternal ultra-processed food consumption and the incidence of obesity or overweight in their offspring. In other words, the results observed in the study could be due to factors that were not accounted for in the study.

They also noted that their analysis used self-reported measures of body weight and diet, which could be susceptible to bias. Moreover, the women included in the study had similar socioeconomic backgrounds and education levels and this could limit the generalizability of these results to the broader population.

Other researchers have voiced skepticism about the NOVA classification system, which was used to categorize foods according to the extent and type of processing. Dr. Duane Mellor, registered dietitian and senior teaching fellow at Aston University, says:

“The potentially subjective description of ultra-processed foods can introduce bias and errors. Something made at home from ingredients may not be considered to be ultra-processed, but when the identical product is bought in a shop it is not, but after all a cake is still a cake, shop bought or home baked.”

Dr. Hilda Mulrooney, associate professor of nutrition at Kingston University, says there was “a lot of disagreement” about the NOVA classification system for ultra-processed foods.

“The NOVA system is not agreed on in the literature and suggests that the level of processing rather than the nutritional quality of the food, is more important for health. This is not universally agreed in nutritional science, which relates the risk of ill-health to intakes of nutrients,” she said, pointing out that ultra-processed foods are often high in calories, fat, salt and/or sugar.

Are all processed foods bad?

Dr. Gunter Kuhnle, professor of nutrition and food science at the University of Reading, notes that “[The study participants] with the highest intake of ultra-processed food have the overall lowest diet quality, most likely to smoke, have a lower income and lower educational attainment—it is therefore very likely that socio-economic factors can explain at least some of the results.”

“In my opinion, such studies detract from the real problem by focusing on a fashionable but wrong definition. Many of the foods classed as ‘ultra-processed’ can be part of a healthy diet and there is no need to avoid them. As they often have a long shelf-life and make much better use of resources—for example, fish fingers—they are more affordable and can reduce food waste,” Prof. Kuhnle added.

“Instead of demonizing foods and making people feel guilty for not being able to afford more expensive foods, it would be better to understand the physiological reasons and find ways to mitigate those. Ultimately, this would also require addressing existing health disparities.”
— Dr. Gunter Kuhnle