Nitrate and nitrite contamination in drinking water and cancer risk: A systematic review with meta-analysis.

BACKGROUND: Pollution of water sources, largely from wide-scale agricultural fertilizer use has resulted in nitrate and nitrite contamination of drinking water. The effects on human health of raised nitrate and nitrite levels in drinking water are currently unclear. OBJECTIVES: We conducted a systematic review of peer-reviewed literature on the association of nitrate and nitrite in drinking water with human health with a specific focus on cancer. METHODS: We searched eight databases from 1 January 1990 until 28 February 2021. Meta-analyses were conducted when studies had the same exposure metric and outcome. RESULTS: Of 9835 studies identified in the literature search, we found 111 studies reporting health outcomes, 60 of which reported cancer outcomes (38 case-control studies; 12 cohort studies; 10 other study designs). Most studies were set in the USA (24), Europe (20) and Taiwan (14), with only 3 studies from low and middle-income countries. Nitrate exposure in water (59 studies) was more commonly investigated than nitrite exposure (4 studies). Colorectal (15 studies) and gastric (13 studies) cancers were the most reported. In meta-analyses (4 studies) we identified a positive association of nitrate exposure with gastric cancer, OR = 1.91 (95%CI = 1.09-3.33) per 10 mg/L increment in nitrate ion. We found no association of nitrate exposure with colorectal cancer (10 studies; OR = 1.02 [95%CI = 0.96-1.08]) or cancers at any other site. CONCLUSIONS: We identified an association of nitrate in drinking water with gastric cancer but with no other cancer site. There is currently a paucity of robust studies from settings with high levels nitrate pollution in drinking water. Research into this area will be valuable to ascertain the true health burden of nitrate contamination of water and the need for public policies to protect human health.

What influences child feeding in the Northern Triangle? A mixed-methods systematic review.

Optimising child feeding behaviours could improve child health in Guatemala, Honduras and El Salvador, where undernutrition rates remain high. However, the design of interventions to improve child feeding behaviours is limited by piecemeal, theoretically underdeveloped evidence on factors that may influence these behaviours. Between July 2018 and January 2020, we systematically searched Cochrane, Medline, EMBASE, Global Health and LILACS databases, grey literature websites and reference lists, for evidence of region-specific causes of child feeding behaviours and the effectiveness of related interventions and policies. The Behaviour Change Wheel was used as a framework to synthesise and map the resulting literature. We identified 2,905 records and included 68 relevant studies of mixed quality, published between 1964 and 2019. Most (n = 50) were quantitative, 15 were qualitative and three used mixed methods. A total of 39 studies described causes of child feeding behaviour; 29 evaluated interventions or policies. Frequently cited barriers to breastfeeding included mothers' beliefs and perceptions of colostrum and breast milk sufficiency; fears around child illness; and familial and societal pressures, particularly from paternal grandmothers. Child diets were influenced by similar beliefs and mothers' lack of money, time and control over household finances and decisions. Interventions (n = 22) primarily provided foods or supplements with education, resulting in mixed effects on breastfeeding and child diets. Policy evaluations (n = 7) showed positive and null effects on child feeding practices. We conclude that interventions should address context-specific barriers to optimal feeding behaviours, use behaviour change theory to apply appropriate techniques and evaluate impact using robust research methods.

Intersections of climate change with food systems, nutrition, and health: an overview and evidence map.

Scientific research linking climate change to food systems, nutrition and nutrition-related health (FSNH) has proliferated, showing bidirectional and compounding dependencies that create cascading risks for human and planetary health. Within this proliferation, it is unclear which evidence to prioritise for action, and which research gaps, if filled, would catalyse most impact. We systematically searched for synthesis literature (i.e. reviews) related to FSNH, published after January 1, 2018. We screened and extracted characteristics of these reviews and mapped them in an interactive Evidence and Gap Map (EGM), supplemented by expert consultation. 844 synthesis reports met inclusion criteria (from 2,739 records) and were included in the EGM. The largest clusters of reports were those describing climate impacts on crop and animal source food (ASF) production, and emissions from such (86%). Comparatively few reports assessed climate change impacts on nutrition-related health, or food manufacture, processing, storage, and transportation. Reports focused on strategies of climate adaptation (40%), mitigation (29%), both (19%) or none (12%). Only one quarter of reports critically evaluated equity (25%), and fewer reports suggested that changes to equity and equitable practices would alter climate-FSNH dynamics (6%). The expert consultation mirrored the results of the EGM, and contextualised findings further. This novel map describes a wide research landscape linking climate change to FSNH. We identified four key research gaps, including 1) Research on whole food systems or post-harvest elements 2) Research evaluating relationships between climate change and nutrition-related health outcomes, especially among vulnerable populations; 3) Promising methods (and additional data required) that can a) identify inflection points or levers for intervention, b) incorporate complex dynamics and characterize trade-offs, c) be understood and applied in context-specific, localised ways for decision-making; and 4) Research undertaken through interdisciplinary collaborations that enables producing and translating evidence to action, especially those that inherently consider co-production and fairness.

Systematic evidence and gap map of research linking food security and nutrition to mental health.

Connections between food security and nutrition (FSN) and mental health have been analytically investigated, but conclusions are difficult to draw given the breadth of literature. Furthermore, there is little guidance for continued research. We searched three databases for analytical studies linking FSN to mental health. Out of 30,896 records, we characterized and mapped 1945 studies onto an interactive Evidence and Gap Map (EGM). In these studies, anthropometry (especially BMI) and diets were most linked to mental health (predominantly depression). There were fewer studies on infant and young child feeding, birth outcomes, and nutrient biomarkers related to anxiety, stress, and mental well-being. Two-thirds of studies hypothesized FSN measures as the exposure influencing mental health outcomes. Most studies were observational, followed by systematic reviews as the next largest category of study. One-third of studies were carried out in low- and middle-income countries. This map visualizes the extent and nature of analytical studies relating FSN to mental health and may be useful in guiding future research.

Trust and responsibility in food systems transformation. Engaging with Big Food: marriage or mirage?

Concentration of power among transnational 'Big Food' companies has contributed to food systems that are unsustainable, unhealthy and inequitable for people and planet. Given these commercial determinants of health, if 'food systems transformation' is to be authentic-more than a passing narrative-then leveraging Big Food is paramount. To this end, researchers, practitioners and policy-makers are increasingly encouraged to engage with these powerful entities. However, given the conflicts of interest at stake, engagement relies on trust and transparency, that all stakeholders take responsibility for their actions and demonstrate commitment to do no harm. Given Big Food's track record in influencing policy, shifting costs and responsibility for their harms-and while profit primarily drives business decision making-we question whether it is logical to expect trust.This analysis explores concepts of responsibility and trust in relation to food systems transformation involving public-private partnerships. Through short cautionary case studies-looking at the United Nations Food Systems Summit, and Big Food's plastic burden-it argues that unless such companies take responsibility for their cross-cutting effects and earn authentic trust through demonstrably doing no harm, their participation in evidence generation and policy processes should be limited to responding to information requests and adhering to regulation. Any involvement in research agenda-setting or formulating policy solutions introduces conflicts of interest, legitimises corporate irresponsibility and jeopardises scientific integrity. Big Food has dynamism and power to address food system problems, but while it contributes to so many of these problems it should follow-not formulate-transformational evidence, policies and regulations.

A systematic scoping review of environmental, food security and health impacts of food system plastics.

Plastic pollution arising from food systems is driving policies for reduction, removal, reuse and recycling, but literature on plastic uses and outcomes across subsectors is fragmented. We use a systematic scoping review to describe the extent, range and nature of published evidence since 2000 on seven major plastic types used at any point within food systems and their quantifiable effects on the environment, food security and human health. Although the majority of publications focus on agricultural production, relatively fewer consider retail, household and food waste disposal plastics. Gaps in the research include evidence from low- and middle-income countries, health or food security and/or economic outcomes generated from human population studies-and the subsequent environmental and human health effects. A greater understanding of this disparate evidence landscape is essential to formulate coherent research strategies to inform potential policy actions and assess trade-offs across economic and environmental targets, human health and food security.

Global Mental Health and Nutrition: Moving Toward a Convergent Research Agenda.

Both malnutrition and poor mental health are leading sources of global mortality, disease, and disability. The fields of global food security and nutrition (FSN) and mental health have historically been seen as separate fields of research. Each have undergone substantial transformation, especially from clinical, primary care orientations to wider, sociopolitical approaches to achieve Sustainable Development Goals. In recent years, the trajectories of research on mental health and FSN are further evolving into an intersection of evidence. FSN impacts mental health through various pathways such as food insecurity and nutrients important for neurotransmission. Mental health drives FSN outcomes, for example through loss of motivation and caregiving capacities. They are also linked through a complex and interrelated set of determinants. However, the heterogeneity of the evidence base limits inferences about these important dynamics. Furthermore, interdisciplinary projects and programmes are gaining ground in methodology and impact, but further guidance in integration is much needed. An evidence-driven conceptual framework should inform hypothesis testing and programme implementation. The intersection of mental health and FSN can be an opportunity to invest holistically in advancing thinking in both fields.