環境科学：ブルーフードの可能性を深く掘り下げて調べる

Increasing the production of blue foods — plants, animals and algae from freshwater and marine environments — has the potential to increase consumption and improve diets, a study in Nature suggests. Some categories of aquatic food are found to be more nutritious than beef, lamb, goat, chicken or pork, when averaging across the assessed nutrients (omega-3, vitamins A and B12, calcium, iodine, iron and zinc). The paper is part of the Blue Food collection of research papers, comments and opinion pieces published in Nature, Nature Food and Nature Communications, which offers insights into the contribution that aquatic foods can make to future food systems and the challenges that need to be tackled if these contributions are to be realized.

Aquatic foods may have the potential to improve both human nutrition and the sustainability of food production, but are often underrepresented in nutritional and environmental assessments of food systems. The Blue Food Assessment explores the part that aquatic foods can play in building healthy, sustainable and equitable food systems.

A global database comprising macro- and micro-nutrient composition profiles from 3,753 aquatic food taxa (including fish, crustaceans, and seaweeds/algae) is presented by Christopher Golden and colleagues in Nature. Comparing values with land-based food sources, their analysis indicates that all of the top seven categories of nutrient-rich animal-source foods are aquatic foods, including pelagic fish (such as tuna and herring), shellfish and salmonids (the family that includes salmon and trout). They modelled the effect of an approximately 8% increase in global blue food production by 2030 and predict that this could reduce prices by 26%, potentially improving micronutrient uptake in up to 166 million people. Even with only a moderate increase in production, the models indicate that aquatic foods could provide a higher supply of calcium (8% higher; median across countries), iron (4%), the omega-3 fatty acids DHA and EPA (186%), zinc (4%), and vitamin B12 (13%), although vitamin A is projected to decline by 1%. The study also suggests that there is nearly a three times greater benefit to females than males of increased aquatic food consumption, providing a potential pathway for nutritional equity.

In a second Nature paper, Jessica Gephart and colleagues assess the environmental impact of blue food production. They analyse 23 species groups of aquatic food that represent nearly three-quarters of global production, providing standardized estimates of greenhouse gas emissions, nitrogen and phosphorus pollution, and freshwater and land use. Farmed bivalves (such as clams and oysters) and seaweeds perform best, producing lower emissions than their captured counterparts. The findings highlight opportunities to improve environmental performance, advance data-poor environmental assessments, and inform sustainable diets.

The collection will be available via the following link after the embargo has ended: https://www.nature.com/collections/fijabaiach