Nutritional Availability to Rats of Selenium in Tuna, Beef Kidney, and Wheat

Abstract

Weanling male rats were fed a selenium (Se)-deficient 40% Torula yeast diet for 4 weeks and were then continued on depletion for another 4 weeks or were repleted with 0.1, 0.2, or 0.3 ppm Se as sodium selenite or 0.2 ppm Se as tuna, beef kidney, or high-Se wheat. There were no significant differences in young red blood cell Se, unfractionated red blood cell Se, or liver Se levels in groups fed diets containing 0.2 ppm Se. Glutathione peroxidase (GSH-Px) activity in young red blood cells was lower in the three groups fed food Se than in the group fed selenite (0.2 ppm Se). Young red blood cell GSH-Px was significantly lower in rats fed tuna than in rats fed wheat. Unfractionated red blood cell GSH-Px was lower in rats fed tuna than in rats fed selenite, but did not differ significantly among groups fed food Se sources. Liver GSH-Px was significantly lower in rats fed tuna than in rats fed kidney, wheat, or selenite. Availability of Se was only 54-58% as great from tuna as from selenite for induction of GSH-Px in liver and in red blood cell populations. Therefore, low availability of Se from fish may have to be considered when assessing Se status of human beings from dietary intake.

Determination of nutritional efficiency of selenium contained in processed skipjack meat by comparison with selenite.

“…In particular, Se in fish, which is one of the principal Se sources in the Japanese diet, has lesser bioavailability (13)(14)(15)(16). Thus, evaluation of the nutritional eficiency2 of fish-Se is important in qualitative assessment of Se intake in Japan.…”

Comparative Utilization of Fish Selenium and Inorganic Selenite by Rats of Normal Selenium Status

“…Most studies examining the bioavailabil ity of selenium in fish find that it is relatively low compared with other food products [2,6,7,10]. However, using the test of restoring blood plasma glutathione peroxidase activity of selenium-depleted chicks, the selenium in fish meal was found to be more available than selenium in soyabean and gluten meal [14].…”

“…Different parame ters such as intestinal absorption [32], reten tion [8,21], glutathione peroxidase activity [2,10] and the curative effect on certain dis eases [6,7] have been used to test the bio availability of selenium compounds. A di etary response to the glutathione peroxidase activity in different tissues is often used, but this effect depends on a low selenium status of the test animals [9,18]; and other methods should be preferred in establishing the avail ability of selenium compounds in man and animals of normal selenium status [28], The retention of selenium in different tis sues depends on the dietary supply of the ele ment [8,22], Therefore, the retention and distribution of selenium in the tissues may give information on the utilization of sele nium from different foodstuffs.…”

“…Fish is known as a rich source of selenium, but the bioavailability of selenium in fish is reported to be low compared to different vegetable selenium sources [2,6,7,10]. Other reports have shown different bioavail abilities of selenium in fish, varying with the method used [14,21,30].…”

Selenium in Seafood Materials

“…57,58) Although the selenium content in fish is high, there are fewer reports on the bioavailability of selenium from seafood than that from wheat, cereal, eggs, meats, etc. [59][60][61][62] In some cases, fish is not a rich source of bioavailable selenium, due in part to its high mercury content and other heavy metals, which bind to selenium. 10) Due to the formation of an insoluble complex with heavy metals, such as mercury, selenium from seafood, e.g., tuna, was thought to be less bioavailable than that from beef and wheat.…”