FEAS[Singletons]T

The nutritional statues of parents, wherein excess or inadequate intake of certain dietary factors prior to conceiving a child, causes variable health outcomes for the child throughout the life course.  Fairly well-developed understandings of this connection in mothers and mothers-to-be has led to specified international dietary guidelines for periconception and preconception care. However, recommendations for fathers-to-be are substantially absent due to gaps in knowledge surrounding how paternal diet prior to conception influences the downstream health status of the next generation. Studying the epigenome of the male germline and the influence of nutritional status in men on the sperm epigenetic landscape is the first step in providing insight into the mechanistic link between paternal diet and subsequent offspring health.

In this study, we aim to elucidate the role of acute dietary intake in male populations, and its impact on spermatozoa quality, integrity, content and epigenetic programming. We hypothesize that exposure of men to a conventionally healthy (unprocessed diet at calorically adequate and excessive quantities) versus a conventionally unhealthy diet (processed diet at calorically adequate and excessive quantities) will induce epigenetic changes to the sperm at genomic regions involved in development and metabolism.

We will conduct a dual-arm cross-over design clinical nutrition intervention using a cohort of young health men in Copenhagen where participants will firstly be randomised to an adequate calorie or an excessive calorie arm of the study. Within the two study arms, participants will be further randomised to receive a three-week intervention of either a processed or unprocessed diet. Each participant will then undergo a twelve-week washout period followed up by a within-arm crossover to the alternative dietary treatment.

Participants in the adequate calorie diet groups will receive food allocations in accordance with their nutritional needs and participants in the excessive calorie groups will receive food allocations 500 kcal in excess of their nutritional needs per day. The processed diet is based on the typical dietary intake patterns of American men aged 19-30. Food and beverage products provided will fall into the category of processed foods and ultra-processed foods in accordance with the NOVA food processing classification system. The unprocessed diets will meet the Nordic and Australian dietary guidelines for food groups and micronutrients. Food and beverage products provided will fall into the category of unprocessed/minimally processed foods and processed culinary ingredients in accordance with the NOVA food processing classification system.

We have designed these diets to be macronutrient matched, wherein both the processed and unprocessed diets provide 49% of kcal from carbohydrates, 35% from fat, and 16% from protein, to control for macronutrient variability as a confounding factor, and focus on the quality and content of food products provided on the induced effects.

Biological specimens and survey information from participants will be collected at several time points throughout the study.  This includes assessment of anthropometric characteristics, survey information surrounding lifestyle, physical, and mental health, classical semen quality characteristics, serum metabolic markers, reproductive hormones, and appetite hormones.  Biological samples collected include blood, semen and saliva.  Following conclusion of the intervention, the fraction of mature spermatozoa will be further analysed for epigenetic features.  Specifically, we will conduct smallRNA sequencing, reduced representation bisulfite sequencing and ATAC-sequencing in order to determine how the sperm epigenome is remodelled following the acute dietary interventions.