Dried fish are an affordable and readily available food across the tropics.
As they are often produced by small-scale fisheries and are usually traded informally, however, little was known about how widespread this food is produced, consumed or how nutritious it is.
In the first large-scale investigation of dried fish consumption, a team of researchers led by academics at Lancaster University provides evidence that dried fish contributes significantly to the recommended nutrient intakes for young children and women.
This research underlines the food's importance for global food security and nutrition.
Using modelling based on data from the multinational Living Standards Measurements Study conducted in Côte d’Ivoire, Ghana, Nigeria, Malawi, Tanzania and Uganda, the scientists behind the findings estimate that dried fish is eaten weekly by a third of households in these countries.
They also approximated that dried fish is consumed by 54% more people than fresh fish.
Dried fish are particularly important to the diets of those in poor households and those near coastlines or urban centres.
This, the researchers say, reinforces the importance of protecting fish catches for local consumption, rather than for international markets.
But just how nutritious are dried fish?
The researchers examined the nutrient content of some of the most readily available dried fish in East and West Africa, as well as the Indian Ocean, to determine their importance in providing nourishment.
They analysed 19 species of fish, including freshwater fish from the Great Lakes (such as the Lake Victoria sardine) and marine species from West Africa (including the Madeiran sardinella) and the Indian Ocean (such as rabbitfish).
Analysis of sun-dried and smoked fish revealed that dried fish are packed with nutrients: even small amounts of dried fish contribute significantly to recommended nutrient intakes for young children and women.
Processing of fish by sun-drying and smoking concentrates essential nutrients into smaller, shelf-stable portions, such that all dried fish forms were found to have a higher nutrient density than fresh fish, for equivalent portion sizes.
This was especially true for minerals that are key to public health, such as iron and zinc.
The study reveals that small portions of dried fish contribute more than 15% of recommended intakes for multiple essential dietary nutrients, including calcium, iodine, iron, selenium, zinc, vitamins B12 and D.
Dr James Robinson, Leverhulme Research Fellow at Lancaster University’s Lancaster Environment Centre, said: “Until now, the role and scale of dried fish in supporting food security and nutrition has often been undervalued and hidden, limiting our understanding of how dried fish contribute to healthy diets."
“Fish caught in oceans, lakes and rivers across Africa and Asia are dried, smoked or fried, providing large supplies of affordable and nutritious foods that can be stored for long periods of time and easily transported."
“The widespread prevalence of highly-nutritious dried fish shows these foods play critical roles in food security and nutrition, particularly for vulnerable populations such as women and children, households close to fisheries and even in places distant from fisheries.”
Future uses
Following these new insights, the researchers say their findings suggest dried fish could be used to prevent micronutrient deficiencies in women and young children in Africa.
Dried fish rich in omega-3 fatty acids, iodine and selenium could be powdered and mixed with other food products to produce highly nutritious meals for infants that can be used to treat and prevent malnutrition.
Dr Rucha Karkarey, co-author, Lancaster University, said: “Dried fish can fill nutrient gaps in seasonal seas, such as reef fish in Lakshadweep Islands that are caught and dried before the south-west monsoon."
"But here and across the tropics, policies are needed to protect supply for coastal communities against competing international markets.”
Marian Kjellevold, research professor at the Institute of Marine Research, Bergen, said: “High-quality analytical data on small processed fish is presently lacking in most African food composition tables, which limits our ability to fully understand and utilise their nutritional potential."
"This paper is an important step towards filling that gap, generating robust data that is essential for developing knowledge-based dietary guidelines and ensuring these nutrient-rich foods are used to improve public health.”