These include red meat, poultry, fish, beans, lentils, tofu, tempeh, nuts, and seeds. An easy way to get more iron in your meals is to use cast iron utensils [ 12 ]. Refrain from drinking coffee, milk, cocoa, or green, black and herbal tea within an hour before or after a meal, as these decrease iron absorption from food. Phytates found in whole grains and legumes also decrease iron absorption. When you eat them, add foods rich in vitamin A and beta-carotene — research shows that they can increase iron absorption and can override the influence of phytates [ 19 , 20 , 21 ].
Foods rich in vitamin A and beta-carotene include carrots, sweet potatoes, fish, cantaloupe, bell peppers, squash, and grapefruit. Increase the amount of vitamin C-rich foods in your diet. Sprinkle some lemon juice on your steak and salads. If you are taking iron supplements, you can take them with orange juice. Vitamin C increases the bioavailability of iron and its absorption in the gut [ 22 ].
Avoid aspirin and nonsteroidal anti-inflammatory drugs NSAIDs , such as ibuprofen — they can cause gut injuries and increase the loss of blood and therefore iron [ 23 , 24 ].
Try not to take your iron-rich meals or iron supplements within 2 hours of antacids and heartburn medication [ 25 ].
Causes shown here are commonly associated with low transferrin levels. The most common cause of low transferrin levels is iron overload excess iron [ 26 , 10 ]. Iron overload can be due to iron poisoning acute , or due to chronic overload due to hereditary disorders such as hemochromatosis, thalassemia, or sickle cell anemia [ 27 , 9 ].
As mentioned above, transferrin is a negative acute phase protein. When the liver increases the production of inflammation-associated proteins e. CRP , ferritin it decreases the production of transferrin. A number of conditions such as infection and cancer can decrease transferrin levels [ 6 , 7 , 28 ].
Increased IBD activity and inflammation severity were associated with lower transferrin levels [ 29 ]. Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your healthcare provider. If you have a higher amount, you may have iron-deficiency anemia.
If you have a lower level, you may have another problem, such as liver disease and hemolytic anemia. Transferrin may also be measured using a value called total iron-binding capacity TIBC.
A higher level means that you may have iron-deficiency anemia. Another measurement, called transferrin saturation, checks how many places on your transferrin that can hold iron are actually doing so.
Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. If you have a lower level, you may have another problem, such as liver disease and hemolytic anemia.
Transferrin may also be measured using a value called total iron-binding capacity TIBC. A higher level means that you may have iron-deficiency anemia. Another measurement, called transferrin saturation, checks how many places on your transferrin that can hold iron are actually doing so. Many other medical conditions can cause high or low levels of transferrin. The results of these tests, and other tests, can help your healthcare provider determine the cause of your symptoms.
The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand. Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded.
When the needle pricks your arm or hand, you may feel a slight sting or pain. These explanations will help the reader gain a general overview of transferrin through these important chemistry topics. Transferrin contains two identical subunits that contain three domains: N-terminal cytoplasmic tail of 62 amino acid residues, transmembrane segment of 26 amino acid residues, and large extracellular C-terminal region which makes up the remaining polypeptide Figure 2.
These binding sites have a non-synergistic effect on each other. Figure 2. Left : The transferrin protein with two iron III metals bound. The transferrin protein is in the ribbon representation with the N-terminus represented as blue and the C-terminus represented as red.
There are two binding sites circled. Right : The binding sites of transferrin with iron III. The binding sites of transferrin with iron III consist of two tyrosines, one histidine, one aspartic acid, and one carbonate ion which are shown in stick representation. Iron III is the orange metal ball. A carbonate anion is an integral part of transferrin binding to iron III.
Carbonate attaches to transferrin by making hydrogen bonds with amino acid residues not directly involved in the coordination of iron III.
When carbonate binds to iron, it brings with it a large part of the protein. This can be accredited to the placement of hydrogen bonds between amino acid residues and carbonate. In addition to changing the shape of the protein, the coordination environment can now offer iron III a tighter more secure binding pocket. This better sized pocket enhances the binding of the other ligands to iron III in addition to aiding in the specificity of this pocket for the the atomic radius of iron III.
The reaction of iron III binding to transferrin is as follows Figure 3. The hormone hepcidin regulates iron II leaving a cell through ferroportin which is a protein that transports iron into and out of a cell.
Three protons are released due to ionization of two tyrosine residues and the release of the water molecule that was already bound to iron III. When iron III binds to the amino acid side chains, the pK a values decrease because there is a shift of electron density from the ligands toward the iron III which allows the amino acid side chains to deprotonate more easily.
When iron III is bound to transferrin, the pK a is lower than 7 for tyrosine. The conformational change also protonates aspartic acid and lysine As a result, a vesicle forms to help transport substances throughout the cell. Figure 3. The transferrin Tf protein has two active sites where iron III ions bind to two tyrosines, one histidine, one aspartic acid, and a carbonate. Once iron is bound, transferrin binds to transferrin receptor 2 TFR2 beginning endocytosis.
The release of iron is facilitated by the pH change that occurs in the formed endosome Figure 4. The endosome utilizes a hydrogen pump that changes the pH of the endosome to about 5. Figure 4. With the decrease of the pH, the histidine and carbonate ions are protonated, releasing iron III from the binding site.
This principle describes how change in concentration can predict what products will be made in order to get back to equilibrium. Equations one and two Figure 3 summarize the binding of iron III to transferrin. Equation one is the the first iron binding, and equation two is the second iron III binding. In both cases, a product of the reaction includes three hydrogen ions. These hydrogen ions are lost from the two tyrosine ligands and the histidine ligand. At an acidic pH, as is the case inside the endosome, there is an increase of hydrogen ions, and therefore an increase in the concentration of products.
The reactants in each case involve iron III no longer being bound to transferrin. This offers another explanation of what happens with transferrin in the acidic endosome. Some diseases may arise due to abnormal iron levels Figure 5.
Hemochromatosis is a chronic iron overload disease which can result from genetic mutations or environmental factors. Hereditary hemochromatosis arises from mutations in the transferrin receptor-2 TFR2. TFR2 is required for adequate hepatic expression of hepcidin. When TFR2 is impaired, hepcidin production decreases which can lead to hereditary hemochromatosis. There is an increase in ferroportin mediated iron efflux in the liver which causes the liver to store more iron.
Ferroportin is a transmembrane protein which transports iron from inside a cell into the outside of a cell. The excess iron produces reactive oxygen species ROSs which can lead to cell death and is associated with cardiomyopathic and endocrine disorders. Apo-transferrin is a transferrin molecule that does not have iron III bound to it. When the blood does not have enough iron to produce hemoglobin, iron-deficiency anemia occurs. Figure 5.
Diseases Related to Iron Levels. Left : Hemochromatosis. Hemochromatosis occurs due to the overaccumulation of iron. Right : Iron-Deficiency Anemia. Iron-deficiency anemia occurs due to the overproduction of transferrin and lowered iron III levels which causes more apo-transferrin to form.
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