Mapping the conceptualisation, contributing factors and interventions of moral distress among healthcare providers in Africa: a scoping review.

The global population is aging rapidly, with the prevalence of chronic diseases such as dementia consistently increasing []. Dementia is a major public health concern with one new case diagnosed every three seconds [, ]. By 2030, cases are projected to reach 74.7 million, with healthcare costs of US$2 trillion each year []. The complex pathology of dementia combined with the limited efficacy of current pharmacological treatments necessitate multifaceted prevention and treatment approaches [, ]. The 2024 Lancet commission identified 14 modifiable risk factors that if addressed, could prevent up to 50% of dementia cases globally []. Although diet is not explicitly listed, it is linked to at least five of the listed cardiometabolic risk factors (diabetes, obesity, high cholesterol, hypertension, and alcohol intake); suggesting the potential role of nutrition in dementia prevention [, ]. Vitamin K is best known for its role in coagulation, with some evidence also pointing to benefits for bone and cardiovascular health []. Emerging research suggests that vitamin K may also be a contributor to cognitive health []. Such benefits may arise from the activation of vitamin K-dependent proteins (VKDPs), including pro-thrombotic proteins (coagulation factors II, VII, IX, and X) and anti-thrombotic factors (Protein S and Protein C) that influence dementia risk through their effects on thrombosis and cerebrovascular integrity [, ]. Other VKDPs such as osteocalcin, growth arrest-specific protein 6 (Gas6), and matrix Gla protein (MGP), may reduce neuroinflammation and Aβ plaque accumulation, suppress the formation of reactive oxygen species, and/or inhibit vascular calcification to maintain microvascular elasticity [, , ]. Warfarin, a vitamin K antagonist, is also associated with greater dementia risk, compared with direct oral anticoagulants (DOACs) []. Vitamin K exists in two main forms: vitamin K1 (phylloquinone, PK) is abundant in plant-based foods, particularly green leafy vegetables and plant oils, while vitamin K2 (menaquinone, MK) is primarily found in animal-derived products and fermented foods such as meat, cheese and yoghurt []. These MKs have side chains of varying length (MK-4 to MK-13), which influence their absorption, metabolism, and bioactivity []. Cross-sectional studies have reported lower dietary vitamin K1 intake in patients with early-stage Alzheimer’s disease compared to cognitively healthy individuals []. They have also found associations between higher dietary intake or serum concentrations of vitamin K1 and better cognitive performance [–]. Biomarkers of vitamin K insufficiency, such as undercarboxylated osteocalcin, have also been linked to greater odds of cognitive impairment []. However, findings from prospective studies are limited and inconsistent [, ], and most of this evidence has focused on vitamin K1 and total vitamin K. Vitamin K2 has been rarely examined despite having distinct dietary sources and/or biological functions that could differentially influence brain health []. This is likely attributed to the lack of comprehensive vitamin K2 food databases [] which have only recently become available [, ].