Nutrition and health
More than two billion people worldwide, particularly in developing countries, are estimated to be deficient in essential vitamins and minerals, especially vitamin A, iron and zinc. Micronutrient deficiencies occurring at particular stages of human life (pregnancy, lactation, and early childhood) can severely affect health and development, often leading to irreversible effects.
One means for alleviating this problems is to increase the availability, affordability and consumption of animal-source foods (ASFs), particularly fish, meat and eggs. ASFs are a key component in a balanced and nutritious diet for most people and inadequate supplies often result in malnutrition, especially among women and children.
For many developing country communities, especially those living close to coastal and inland waters, fish are the dominant animal source food. In some of Asia’s poorest countries (Bangladesh and Cambodia, for example) people derive as much as 75% of their daily protein from fish. In many other low-income food deficient (LIFD) countries and regions the figure is less, but still considerable; in West Africa, for example, fish accounts for 30% of animal protein intake.
Sustaining and increasing fish consumption in LIFDs where it is a preferred food source is important because of the protein they provide and the range and bioavailability of the nutrients that many fish species contain. Many types of fish, for example, have especially rich and bioavailable sources of calcium, zinc, iron and many vitamins.
To better understand the contribution to nutrition that fish can make, WorldFish scientists have been studying the nutritional value of different species. They have also been working with partners to better understand and improve food purchasing and consumption patterns among vulnerable groups.
The nutritional value of fish
The contribution that fish makes to human nutrition, and its positive impact on health, has received different emphasis in developed and developing countries. In the former, the focus has been on fish as a healthy alternative to other sources of protein, especially red meat. Fish and fish oils (especially from marine sources) contain high levels of polyunsaturated fatty acids which lower blood pressure, reduce the risk of heart disease, and boost infant growth and cognitive development. In contrast, in developing countries the focus has been on the role of fish in tackling undernutrition and micronutrient deficiencies.
For the most part, fish also contain more nutritious protein and micronutrients than staple foods such as cereals, rice and maize. This is because plant foods generally contain low concentrations of lysine and protein absorption by the human gut is relatively limited. In contrast, proteins from animal sources, such as fish, are more easily absorbed and have more balanced concentrations of all the essential amino acids and concentrations of lysine are particularly high.
Foods from animal sources, such as fish, meat and dairy products are also usually richer in zinc, an especially important dietary requirement for women in the third trimester of pregnancy and during lactation. In contrast, cereals and legumes contain inhibitors of zinc absorption, such as phytic acid. So when diets are dominated by staple foods, as they are for most poor people, there is little zinc uptake. Fortunately, adding even a small amount of fish to a plant-based diet can greatly increase zinc intake and compensate for the low bioavailability caused by the phytic acid content of staple foods.
Other important micronutrients supplied by fish include the minerals iron, calcium, iodine (from marine fish), phosphorus, selenium and fluorine, and vitamins A, B (thiamine, riboflavin, niacin), and D, with a little vitamin C if consumed fresh.
Not all fish are equally nutritious
It has been shown that some small fish, eaten whole, provide a particularly rich source of calcium, vitamin A, iron and zinc. This feature, coupled with the fact that small fish are more frequently consumed by the poor and are more likely to be distributed evenly among household members, makes them a promising focus for attention. We estimate, for example, that production of only 10 kg/pond of the vitamin-rich small fish mola, which is already present in 1.3 million small fish ponds in Bangladesh, could meet the annual recommended vitamin A intake for two million children.
WorldFish researchers are examining this potential to improve nutrition through a project titled: “Linking Fisheries and Nutrition: Promoting Innovative Fish Production Technologies in Ponds and Wetlands with Nutrient-Rich Small Fish Species in Bangladesh.”In the northwest of the country, 1,500 target households with small ponds are being selected to culture small nutrient dense fish in highly efficient, low risk polyculture systems that include a variety of high value fish including carps and freshwater prawns.
Improving nutritional status and household food security
Research done by WorldFish scientists in Bangladesh has identified the pathways that exist between fish-related livelihoods (small-scale fisheries, fish farming) and household nutritional security. The study identified and explored three key pathways:
- A consumption pathway where small-scale fisheries and aquaculture contribute to household nutritional security through the consumption of fish captured or produced by household members;
- An income pathway where small-scale fisheries and aquaculture contribute to household nutritional security through the income generated by these activities that is then used to purchase other foodstuffs;
- A distribution pathway where small-scale fisheries and aquaculture contribute to empowering women, resulting in better nutritional outcomes at the household level.
Although specific data on the linkage between improved diet and nutritional status has been scarce, this study shows that expanding aquaculture and supporting small-scale fisheries have potential as sustainable ways of improving nutritional status and household food security through these pathways.
Acting on these findings, WorldFish has partnered with Save the Children for a five year USAID-funded Nobo Jibon Multi-Year Assistance Program in the Barisal district of Bangladesh, an area of chronic poverty, transitory food insecurity. The project will work to expand adaptive small-scale aquaculture to provide employment and reduce the incidence of malnutrition in children. By addressing market-based income generation, poor and extremely poor households will have increased purchasing power and improved access to food. WorldFish’s role is to provide technical support for the dissemination of five key technologies relating to carp aquaculture, cage aquaculture, prawn aquaculture, integrated aquaculture-agriculture and aquaculture nurseries and to study their effectiveness.
Fisheries and Health
A number of complex relationships exist between the actors in the fisheries sector, their health, diet and the social conditions in which they live. WorldFish and partners are researching the impact of HIV/AIDS on the fisheries sector, specifically in Africa.
Studies by WorldFish and others have shown that HIV prevalence among fisherfolk in Africa is particularly high and their increased vulnerability is caused by a complex combination of factors specific to the small-scale fisheries sector in sub-Saharan African countries. WorldFish and partners are researching the impact of HIV/AIDS on the fisheries sector in Africa, and how sub-populations in fishing communities, especially female fish traders, are vulnerable to disease.
The program “Fisheries and HIV/AIDS in Africa: investing in sustainable solutions” is assessing the key risk factors among highly vulnerable target groups through surveys and qualitative research. Partners are piloting business-based interventions that will address some of the risk factors such as lack of services and transactional sex in the context of fish marketing.
The potential of nutrient-rich small fish species in aquaculture to improve human nutrition and health
Culture of mola (Amblypharyngodon mola) in polyculture with carps: experience from a field trial in Bangladesh