Selenium, the best-kept secret of canned tuna

FAO reports that the Pacific, Indian and Atlantic Oceans provide large quantities of tropical tunas for canned tuna processing. The species with the highest catches according to this organization are: skipjack tuna, yellowfin tuna, bigeye, albacore and bluefin.

Canning is a combination of the traditional and the modern, with practices that guarantee the food safety of the product. In these processes all the undesirable parts of the tuna are removed and only the loin is kept to preserve its nutritional value. Heat is the only resource used to offer a sterilized food, without any type of preservatives, and ready to be placed on supermarket shelves.

Canned tuna is a staple food in the diet but, nevertheless, knowledge about its nutritional properties is low. Tuna contains a considerable amount of proteins that have an important variety of essential amino acids. In addition, it also offers long-chain omega-3 fatty acids (EPA+DHA), vitamins B, D and E as well as minerals such as phosphorus, potassium, iodine and selenium.

The food we eat, as in the case of tuna, is influenced by the interaction of several elements present in its composition. This interaction is key to the absorption of substances at the intestinal level, and will also determine how physiological mechanisms develop within the human organism. This is where selenium comes into play, which has the ability to block the absorption of mercury and has a protective effect.

More than a decade ago, the American Nicholas Ralston, together with John Kaneko, was commissioned to initiate a study with in vivo models to measure the protective effect of selenium against mercury. The work carried out led to the creation of the HBVSe ratio by the aforementioned scientist, which allowed for a much more realistic sweep of fish consumption. In addition, other experts of various nationalities contributed their own findings to give breadth and depth to the initial work.

Due to the fact that selenium would play an essential role in our organism, and being linked to the levels of mercury we consume with food, there is a relationship between both substances. It was this correspondence that led to high fish intake significantly reducing the risk of immune-related diseases for the longest-lived inhabitants of the country.

The results of recent measurements to determine the relationship of mercury to selenium in tuna, stored for canning, show that selenium is very highly present. According to scientists, selenium outweighs mercury tenfold, which justifies the above conclusions about its quantity.
The SELATUN project discovered by ANFACO-CECOPESCA revealed the average contribution of 12 times more selenium than mercury in Spanish canned products available on the market. This means that the consumer can be sure that the sizes of fish used for canning meet the standards. Thus, their food protection is ensured.