Ultra-Processed Foods and Fertility: New Study Raises Concerns for Couples Trying to Conceive
A recent study has shed light on a potential link between the consumption of ultra-processed foods (UPFs) and difficulties in conceiving, particularly for men. These widely available food products, often found in items like mass-produced bread, breakfast cereals, crisps, and sweets, are characterised by a higher proportion of additives compared to natural ingredients. While UPFs have previously been associated with a broad spectrum of serious health issues, including type 2 diabetes, heart disease, dementia, and various cancers, this latest research delves into their impact on reproductive health.
The study, published in the Oxford Academic Human Reproduction journal, is the first to explore a correlation between UPF intake and fertility challenges. Researchers from the Netherlands meticulously observed 831 women and their 651 male partners, monitoring them from the pre-conception phase through to the early years of their child’s life.
Key Findings: Impact on Men and Early Foetal Development
The research uncovered a notable trend: future fathers who consumed higher volumes of UPFs faced an elevated risk of reduced fertility. Furthermore, the study indicated that in women with a higher UPF intake, the embryonic growth and yolk sac size of the foetus appeared to be smaller.
Dr. Gaillard, an epidemiology professor at Erasmus University Rotterdam and lead author of the study, emphasised the implications: “Our findings suggest that a diet low in UPFs would be best for both partners, not only for their own health, but also for their chances of pregnancy and the health of their unborn child.”
The comprehensive research tracked the participating couples between 2017 and 2021. During their pregnancies, at approximately 12 weeks gestation, parents were surveyed about their dietary habits. On average, women reported that 22 per cent of their diet consisted of UPFs, while men indicated a slightly higher proportion at 25 per cent. Alarmingly, over one in ten couples involved in the study consumed more than 30 per cent of their diet from UPFs.
While the results indicated an impact on both partners, the consumption of UPFs appeared to have a more pronounced effect on men.
- Increased Risk of Subfertility in Men: The study found that men with higher UPF consumption were, on average, associated with a 37 per cent greater risk of subfertility, meaning it could take longer for their partners to conceive.
- Significantly Higher Risk in High UPF Consumers: For men in the highest UPF consumption group, the risk of subfertility rose to an even more significant 69 per cent.
For women, who underwent transvaginal ultrasounds at seven, nine, and eleven weeks of pregnancy, a higher UPF intake was linked to a slightly diminished yolk sac size at the seven-week mark. This was also associated with smaller embryonic growth, although the study noted that these effects became less pronounced in subsequent ultrasounds.
Previous research has indicated that slower embryonic growth during this critical period can sometimes be a precursor to premature births, miscarriages, and an increased likelihood of heart and blood-related issues in childhood.
Celine Lin, a PhD student at Erasmus University Medical Center and the study’s first author, elaborated on these findings: “We observed that UPFs consumption in women was not consistently related to the risk of subfertility and time to pregnancy, but was associated with slightly smaller embryonic growth and yolk sac size by the seventh week of pregnancy. These differences in early human development were small, but are important from a research perspective and at population level, as we showed for the first time that UPF consumption is not only important for health of the mother, but may also be related to development of the offspring. In men, we observed that higher UPF consumption was related to a higher risk of subfertility and a longer duration until pregnancy was achieved, but not with early embryo development. This association may be explained by the sensitivity of sperm to dietary composition, whereas maternal UPF consumption may directly influence the environment in the womb in which the embryo develops from the start of life onwards.”
Moving Forward: A Call for Holistic Preconception Care
The authors were keen to stress that their study was observational, meaning it cannot definitively prove a direct causal link between UPF consumption and the observed outcomes. However, they highlighted the need for further investigation.
Dr. Gaillard reiterated the importance of a broader perspective: “We should move away from the idea that only the health and lifestyle of mothers-to-be is important for pregnancy and offspring outcomes, and recognise that the health and lifestyle of both the mother- and father-to-be play an important role. Our results highlight the need to pay more attention to male health in the preconception period, which has traditionally been overlooked.”
Expert Reactions and Cautious Interpretation
While experts welcomed the study’s findings, they also urged caution due to the limitations inherent in such research, especially concerning a sensitive topic like fertility.
Professor Channa Jayasena, a professor of reproductive endocrinology at Imperial College London, commented: “The results are interesting, but there are several reasons to be cautious interpreting them. First, we have no way of knowing whether it is UPF itself, or some other behaviour that is linked with the things they observed. Secondly, the differences observed are tiny, and hardly significant compared with measures such as weight loss. This means that even if UPF are causing reproductive problems, their impact on individuals appears very small indeed. We know from previous research that in general all couples should prioritise a healthy diet, exercise, and smoking cessation when trying to get pregnant. Whether avoiding UPF will offer additional benefits remains unresolved.”
Professor Gunter Kuhnle, a professor of nutrition and food science at the University of Reading, also voiced concerns: “Fertility is an important but very sensitive topic and should therefore be handled accordingly. He first raised concerns with the ‘several limitations’ of the questionnaire, which he says ‘does not appear to have been developed or validated for ultra-processed food’.”
Professor Kuhnle further added: “Given that the assessment of ultra-processed food intake has severe limitations, the conclusions of the study, and the recommendations, need to be interpreted carefully. The authors point out that their study is observational so cannot prove causality, but then they also suggest that ‘a diet low in UPFs would be best for both partners’, which could be interpreted as them suggesting they do assume causality. A concern is that such results may cause distress and self-blame in people who have unsuccessfully tried to conceive – and that it is used to give advice to people trying to conceive.”
The ongoing intrigue surrounding the health impacts of ultra-processed foods continues to grow, with this latest research adding another layer of concern for those planning a family. While direct causality remains to be definitively established, the findings underscore the potential benefits of prioritising a diet rich in whole, unprocessed foods for both partners when trying to conceive.
