Studies on modifiable risk factors and fertility are important as patients are interested in what they can do to improve their outcomes. Diet is something many patients ask about. Answering their questions can be difficult as no one had formal training in nutrition and fertility during medical school. Further, dietary behaviors are complex, and studies of diet and health outcomes can be difficult to interpret regardless of study design. The good news is that the field of nutritional epidemiology has advanced considerably in recent years, and for reproductive medicine, in particular, analyses out the Environment and Reproductive Health (EARTH) Study are providing helpful insights (
1
).An example of the informative work coming out of the EARTH Study is in this month’s issue of F&S Reports by Mitsunami et al. (
2
) in their prospective cohort study, dietary patterns associated with semen quality were investigated in 296 men. From this, a dietary score was applied to male dietary patterns in 231 couples undergoing in vitro fertilization (IVF). They found that the dietary score was not related to any clinical outcomes after IVF. This finding held after excluding couples with a diagnosis of male factor infertility and intracytoplasmic sperm injection cycles. If this study had stopped at semen quality, the findings would have been misleading. By looking at the primary outcome of live birth, the investigators find that we can tell our male patients that they do not need to change their diets to have a good outcome after IVF, a finding that many will find reassuring.What can we tell women who ask about diet and IVF outcomes? Previously published work from Dr. Audrey Gaskins and the EARTH Study team shows that women with high compliance to a “profertility” diet have higher chances of pregnancy than women with low compliance (
3
). In presenting this work, the investigators provide compelling, biologically plausible arguments to support their findings, but as clinicians, we need to be careful interpreting the data and using it to counsel women who ask for information about interventions to improve fertility.There are a number of points to consider in interpreting findings from the EARTH Study’s profertility diet and women’s IVF outcomes. First, before this study, the “profertility” diet had not been described. The pattern was constructed from dietary factors identified primarily by the EARTH Study investigators to be associated with IVF outcomes in a cohort of women recruited from the Boston area. Accordingly, there is no profertility-recipe book with measurements or proportions to follow or a profertility diet menu for women to implement into their daily routine. Second, women who did not complete the food frequency questionnaire were excluded from the study. Was their diet different? More variability, perhaps, so they had a difficult time completing the survey? Were their outcomes different? In cohort studies, it is critical to consider if there were unmeasured confounders that might change the findings. Most importantly, a cohort study like this doesn’t tell us if short-term profertility dietary interventions improve IVF outcomes for women who are actively trying to become pregnant and deliver a child, so it’s not clear how or if it should influence our counseling.
The bulk of data we do have on dietary interventions for women and reproductive outcomes is for overweight and obese women with or without polycystic ovary syndrome (PCOS). While overweight and obesity are associated with lower ovulation and IVF success rates, weight-loss interventions have failed to show improved live birth rates (
4
). On the other hand, elevated body mass index is linked to a number of chronic diseases and an increased risk of all-cause mortality. Therefore, when we have the opportunity to motivate and counsel these women, we should, but how do we do this when weight loss is a topic many of us are not well versed in?There is not a single, most effective diet for weight loss in all patients, but an easily accessed, patient-specific approach with data to back it up would be a welcoming place to start. For women with PCOS, the intervention piloted by Missel et al. (
5
) is encouraging. It focuses not only on outcomes associated with the long-term health sequelae associated with PCOS but also on immediate concerns like hirsutism and mental health. The investigators state that “larger, long-term, randomized controlled trials comparing our diet to other dietary approaches are necessary to understand better the long-term feasibility and efficacy of this approach to treatment for PCOS.” This is true for drawing broad conclusions, but for individuals, the truth is that they should try what they think will work for them. They may have to try again with something else, but if they are going to find success after hitting a roadblock, they need options.Overall, it’s important to keep the quality of the data in mind when counseling patients about dietary interventions and reproductive outcomes. Based on the work by Missel et al. (
5
), for overweight and obese women with PCOS looking to lose weight, their intervention shows promise and is worth a try. Based on the study by Mitsunami et al. (2
), diet does not seem to be tied to IVF outcomes in men. For most of our patients who are otherwise healthy, the data on diet and fertility outcomes is difficult to interpret and should be taken with a grain of salt.References
- The environment and reproductive health (EARTH) study: a prospective preconception cohort.Hum Reprod Open. 2018; 2018
- A dietary score representing the overall relation of men’s diet with semen quality in relation to outcomes of infertility treatment with assisted reproduction.F S Rep. 2021; 2: 396-404
- Dietary patterns and outcomes of assisted reproduction.Am J Obstet Gynecol. 2019; 220: 567.e1-567.e18
- Randomized trial of a lifestyle program in obese infertile women.N Engl J Med. 2016; 374: 1942-1953
- Impact of an online multicomponent very low-carbohydrate program in women with polycystic ovary syndrome: a pilot study.F S Rep. 2021; 2: 386-395
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Published online: September 29, 2021
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- A dietary score representing the overall relation of men’s diet with semen quality in relation to outcomes of infertility treatment with assisted reproductionF&S ReportsVol. 2Issue 4Open Access
- Impact of an online multicomponent very-low-carbohydrate program in women with polycystic ovary syndrome: a pilot studyF&S ReportsVol. 2Issue 4Open Access
