Fish has a special nutritional role

Fish are the healthiest of meats, their farmed production has a far smaller carbon footprint than livestock, and they are also huge providers of the micronutrients people need.

Beyond the energy and protein they supply, they lower the risk of coronary heart disease and improve cardio-vascular health. Fish are also supreme suppliers of long-chain n-3 poly unsaturated fatty acids (LC n-3 PUFA), which are demonstrably linked to better cognitive development as measured by reading skills up to the age of 12.

“Fish is not just food,” said Jogeir Toppe, a FAO officer and expert on fish and nutrition. He cited the case of the mola, a pond fish in Bangladesh that has exceptionally high levels of zinc and iron and Vitamin A as well as 80 times the calcium content as tilapia. Similar pelagic species elsewhere, such as African lake sardines, have similar micronutrient profiles, but many indigenous fish have yet to be studied.

Those attributes are invaluable as 800,000 child deaths each year are attributable to zinc deficiency, 250 million children worldwide are at risk of vitamin A deficiency, and almost a third of the world’s population is iron deficient. Seafood is also practically the only natural source of iodine.

However, the new study noted that households with rising incomes often shift away from such humble types – what the industry calls “trash fish” – towards fattier and filet-friendly species such as carp which are less efficient providers of micronutrients. One reason is that the higher-status fish are often eaten as filets while the mola and its kin are typically eaten whole.

“The highest iron, zinc and calcium content of fish lies in their heads, bones and guts, which is often the part that gets thrown away, as with tuna,” said Toppe. Somewhat ironically, byproducts such as fish heads or the back-bones of Nile perch whose fresh fillets are exported may often be of higher nutritional value than the main product, he added.