Iron Inhibitors & Promoters
Ascorbic acid or vitamin C occurs naturally in vegetables and fruits, especially citrus. Ascorbic acid can also be synthesized for use in supplements. Ascorbic acid enhances the absorption of nutrients such as iron. In studies about effects of ascorbic acid on iron absorption, 100 milligrams of ascorbic acid increased iron absorption from a specific meal by 4.14 times.
Although alcohol can enhance the absorption of iron, no one is encouraged to drink alcohol as a means of improving iron status. Moderate consumption of alcohol has known health benefits but heavy or abusive drinking, especially when in combination with high body iron levels increases the risk for liver damage, liver cancer and blood cell production. Approximately 20-30% of those who are heavy consumers of alcohol acquire up to twice the amount of dietary iron as do moderate or light drinkers, but alcohol abuse increased the risk of liver disease such as cirrhosis. A standard drink is defined as 13.5 grams of alcohol: or 12oz beer, 5oz wine, 1.5oz distilled spirits. Moderate consumption is defined as two drinks per day for an adult male; one drink per day for females or those older than 65 regardless of gender.
Beta-Carotene is one of more than 100 carotenoids that occur naturally in plants and animals. Carotenoids are yellow to red pigments that are contained in foods such as apricots, beets and beet greens, carrots, collard greens, corn, red grapes, oranges, peaches, prunes, red peppers, spinach, sweet potatoes, tomatoes, turnip greens and yellow squash. Beta-carotene enables the body to produce vitamin A. In studies of the effects of vitamin A and beta-carotene on absorption of iron, vitamin A did not significantly increase iron absorption under the experimental conditions employed. However, beta-carotene significantly increased absorption of the metal. Moreover, in the presence of phytates or tannic acid, beta-carotene generally overcame the inhibitory effects of both compounds depending on their concentrations. Like vitamin E, beta-carotene is an excellent anti-oxidant, but one should take any of these judiciously. Studies have shown that taking vitamin A habitually in amounts of 25,000 IU can cause liver problems, and that taking supplemental beta-carotene can enhance the progression of some cancers. The best source of these nutrients is whole foods.
EDTA+fe and Ferrochel are additive iron compounds and are emerging as candidates for fortification by major food manufacturers. Both additives were found to exceed absorption capabilities of the commonly used fortificant ferrous sulfate.
Hydrochloric acid (HCI) present in the stomach, frees nutrients from foods so that they can be absorbed.
Especially red meat increases the absorption of nonheme iron. Beef, lamb and venison contain the highest amounts of heme as compared to pork or chicken which contains low amounts of heme. It has been calculated that one gram of meat (about 20 percent protein) has an enhancing effect on nonheme iron absorption equivalent to that of 1 milligram of ascorbic acid. A Latin American-type meal (maize, rice, and black beans) with a low iron bioavailability had the same improved bioavailability when either 75 g meat or 50 mg of ascorbic acid was added
As part of the Framingham Heart Study, a National Institutes of Health project, investigators looked at the factors that increased iron stores such as diet and iron supplementation. Participants included more than six hundred elderly patients. Those who took supplemental iron along with fruit had higher iron stores, some as much as three times. No one is encouraged to consume sugar to improve iron absorption. Too much sugar can lead to other health problems, such as obesity and diabetes. Refined white sugar has no nutritional value except calories. However, eating fruits or adding honey or black-strap molasses to foods such as cereals can boost iron absorption and add nutrients that are lacking in refined sugar.
Smoking cessation gums can increase serum ferritin levels
Medications that reduce the amount of acid in the stomach such as antacids or proton pump inhibitors can lead to hypochlorhydria (low stomach acid) or achlorhydria which is the complete absence of stomach acid.
Calcium (like iron) is an essential mineral, which means the body gets this nutrient from diet. Calcium is found in foods such as milk, yogurt, cheese, sardines, canned salmon, tofu, broccoli, almonds, figs, turnip greens and rhubarb and is the only known substance to inhibit absorption of both non-heme and heme iron. Where 50 milligrams or less of calcium has little if any effect on iron absorption, calcium in amounts 300-600 milligrams inhibit the absorption of heme iron similarly to nonheme iron. One cup of skimmed milk contains about 300 milligrams of calcium. When calcium is recommended by a healthcare provider, as is often the case for women trying to prevent bone loss, these supplements can be taken at bedtime. Calcium supplements are best taken with vitamin D and in a citrate rather than carbonate form.
Eggs contain a compound that impairs absorption of iron. Phosphoprotein called phosvitin is a protein with a iron binding capacity that may be responsible for the low bioavailability of iron from eggs. This iron inhibiting characteristic of eggs is called the “egg factor”. The egg factor has been observed in several separate studies. One boiled egg can reduce absorption of iron in a meal by as much as 28%
Oxalates impair the absorption of nonheme iron. Oxalates are compounds derived from oxalic acid and found in foods such as spinach, kale, beets, nuts, chocolate, tea, wheat bran, rhubarb, strawberries and herbs such as oregano, basil, and parsley. The presence of oxalates in spinach explains why the iron in spinach is not absorbed. In fact, it is reported that the iron from spinach that does get absorbed is probably from the minute particles of sand or dirt clinging to the plant rather than the iron contained in the plant.
Polyphenols are major inhibitors of iron absorption. Polyphenols or phenolic compounds include chlorogenic acid found in cocoa, coffee and some herbs. Phenolic acid found in apples, peppermint and some herbal teas, and tannins found in black teas, coffee, cocoa, spices, walnuts, fruits such as apples, blackberries, raspberries and blueberries all have the ability to inhibit iron absorption. Of the polyphenols, Swedish cocoa and certain teas demonstrate the most powerful iron absorption inhibiting capabilities, in some cases up to 90%. Coffee is high in tannin and chlorogenic acid; one cup of certain types of coffee can inhibit iron absorption by as much as 60%. These foods or substance should not be consumed within two hours prior to and following your main iron-rich meal
Phytate is a compound contained in soy protein and fiber. Even low levels of phytate (about 5 percent of the amounts in cereal whole flours) have a strong inhibitory effect on iron bioavailability. Phytate is found in walnuts, almonds, sesame, dried beans, lentils and peas, and cereals and whole grains. Phytate compounds can reduce iron absorption by 50 to 65 percent.
Eating plans to help boost iron levels or reduce iron levels must be individualized. Two handouts provided by the Iron Disorders Institute entitled Boost Your Ferritin and Lower Your Ferritin are good starting points for construction of an eating plan for adults that helps to achieve iron replenishment or iron reduction.
If iron is appropriately distributed throughout the body in hemoglobin, muscles, ferritin, bone marrow and elsewhere in the body, one’s diet can be geared toward iron balance and disease prevention. Fresh fruits, vegetables, whole grains, adequate protein, limited dairy, animal fats and processed sugars form the basis for a good eating plan.
Whenever possible, consume whole foods as opposed to “foods in a pill.” Our bodies are not geared to managing large doses of supplements that can tax the liver, kidneys or disrupt the balance of other nutrients.
This page is dedicated to the late Dr. John L. Beard, Ph.D. Professor of Nutritional Sciences, Penn State University, Member of The Iron Disorders Institute (IDI) 1998-2009 and The late Mary Frances Picciano, Ph.D., Senior Nutrition Research Scientist at the Office of Dietary Supplements (ODS), National Institutes of Health (NIH),