True lactose intolerance (symptoms stemming from lactose malabsorption) is less common than is widely perceived, and should be viewed as just one potential cause of cows’ milk intolerance. There is increasing evidence that A1 beta-casein, a protein produced by a major proportion of European-origin cattle but not purebred Asian or African cattle, is also associated with cows’ milk intolerance. In humans, digestion of bovine A1 beta-casein, but not the alternative A2 beta-casein, releases beta-casomorphin-7, which activates μ-opioid receptors expressed throughout the gastrointestinal tract and body. Studies in rodents show that milk containing A1 beta-casein significantly increases gastrointestinal transit time, production of dipeptidyl peptidase-4 and the inflammatory marker myeloperoxidase compared with milk containing A2 beta-casein. Co-administration of the opioid receptor antagonist naloxone blocks the myeloperoxidase and gastrointestinal motility effects, indicating opioid signaling pathway involvement. In humans, a double-blind, randomized cross-over study showed that participants consuming A1 beta-casein type cows’ milk experienced statistically significantly higher Bristol stool values compared with those receiving A2 beta-casein milk. Additionally, a statistically significant positive association between abdominal pain and stool consistency was observed when participants consumed the A1 but not the A2 diet. Further studies of the role of A1 beta-casein in milk intolerance are needed.

This is the first systematic review, to our knowledge, of published studies investigating the gastrointestinal effects of A1-type bovine β-casein (A1

Food-derived opioid peptides include digestive products derived from cereal and dairy diets. If these opioid peptides breach the intestinal barrier, typically linked to permeability and constrained biosynthesis of dipeptidyl peptidase-4 (DPP4), they can attach to opioid receptors. The widespread presence of opioid receptors spanning gut, brain, and internal organs is fundamental to the diverse and systemic effects of food-derived opioids, with effects being evidential across many health conditions. However, manifestation delays following low-intensity long-term exposure create major challenges for clinical trials. Accordingly, it has been easiest to demonstrate causal relationships in digestion-based research where some impacts occur rapidly. Within this environment, the role of the microbiome is evidential but challenging to further elucidate, with microbiome effects ranging across gut-condition indicators and modulators, and potentially as systemic causal factors. Elucidation requires a systemic framework that acknowledges that public-health effects of food-derived opioids are complex with varying genetic susceptibility and confounding factors, together with system-wide interactions and feedbacks. The specific role of the microbiome within this puzzle remains a medical frontier. The easiest albeit challenging nutritional strategy to modify risk is reduced intake of foods containing embedded opioids. In future, constituent modification within specific foods to reduce embedded opioids may become feasible.

Since the 1950s, Henan County on the Qinghai–Tibet Plateau (the Plateau) has experienced notable changes in its ecological and socio-economic environments, posing challenges to livelihood sustainability. Adopting a mixed method of qualitative interviews, field observations, and statistical data analysis, these changing livelihoods were investigated from a transdisciplinary systems perspective. The aim of this research was to develop an understanding of the relationships between changing land use and the livelihood dynamics on an ecologically fragile land. Results indicate that increasing human and animal populations, together with increasing connectivity between the Plateau and the lowlands, have led to increasing flows of nutrients to the lowlands. The increasing product flows, including the use of dung which is used for heating both on the Plateau and as a Plateau export, together with a lack of nutrients returning to the grasslands, have contributed to the present sustainability challenges. In this study, the transdisciplinary systems perspective provides an overarching integrative framework that transcends the individual socio-economic and biophysical system components, thereby providing key insights not available from within individual disciplines. More detailed analyses are now required, still within a transdisciplinary framework, to quantify specific relationships.

Transdisciplinary thinking lies at one end of a continuum within system thinking, with discipline-based approaches at the other end. Interdisciplinarity and multidisciplinarity are intermediate domains within this continuum. Transdisciplinary thinking is unique in always starting with problem-structuring related to contexts, in which people, typically with multiple and competing objectives, interact with a biophysical world. As such, transdisciplinary thinking is particularly relevant to pastoral systems where livelihoods and environmental issues intersect, and where multiple stakeholders are the norm. Integration, both within transdisciplinary thinking and consequent action, is particularly challenging. This is because there is no quantitative methodology that can capture the complex essence of transdisciplinary issues that encompass both human and biophysical disciplines. Nevertheless, a transdisciplinary approach provides a framework for civilised debate and communication within a broad framework of policy generation. We illustrate these issues with two highly contrasting studies, these being pastoralism at the country level in New Zealand and at the county level in Qinghai on the Qinghai-Tibet Plateau in Western China. Both case studies are characterised by complex property rights within a dynamic resource-constrained environment, in which environmental issues have planetary implications that extend well beyond the bounds of the pastoral system itself.