Table 1.
Biological functions and dietary characteristics of ETEs.
| ETE | Enzymes Using ETE as Cofactors | Biological Functions | Food Sources | RDA for Pregnant Women | Refs |
|---|---|---|---|---|---|
| Co | Methionine synthase L-methyl-malonylCoA mutase |
Component of Vitamin B12 (Vit B12, cobalamin); metabolism of folates and purines;synthesis of methionine |
Fresh cereals and green vegetables (0.2–0.6 µg Co/g dry mass) | Not available for Co; Vit B12: 2.6 µg/day, which corresponds to about 0.1 µg of Co |
[6,7,8,9] |
| Cu | Oxireductases (e.g., copper/zinc superoxide dismutase and cytochrome oxidase) | Cellular respiration; antioxidant defense; neuropeptide synthesis | Shellfish, nuts, sunflower seeds, cocoa, bran cereals, whole grain products, beef liver and other organ meats | 1000 µg/day | [10,11,12,13,14,15,16] |
| Mn | Metalloenzymes (e.g., arginase, glutaminase synthetase and phosphoenolpyruvate decarboxylase) Oxireductases (manganese superoxide dismutase) |
Carbohydrate, protein, amino acid and lipid metabolism; antioxidant defense |
Whole grains, legumes, nuts, seeds, tea, wheat, brown rice, and spinach | Not available | [16,17,18,19] |
| Mo | Sulfite oxidase, xanthine oxidoreductase, aldehyde oxidase, and mitochondrial amidoxime-reducing component | Metabolism of sulfur amino acids and heterocyclic compounds (e.g., purines and pyridines) Production of uric acid and in detoxification |
Beans, oat, rice, nuts, and dark-leafy vegetables | 50 μg/day | [16,20,21] |
| Zn | Over 300 metalloenzymes (e.g., carbonic anhydrase and alkaline phosphatases and) Oxireductases (e.g., copper/zinc superoxide dismutase) |
Protein synthesis; antioxidant defense |
Meat, seafood, dairy products, eggs, seeds, and nuts | 11 mg/day | [16,22,23,24] |
Legend: Co: cobalt; Cu: copper; ETEs: essential trace elements; Mn: manganese; Mo: molybdenum; Zn: zinc.