Iron is a critical element in the metabolism of nearly every living organism. For humans, it’s an essential constituent in a vast array of proteins. Hemoglobin, the protein in red blood cells, holds about two thirds of the body’s iron. It is involved in the transport and storage of oxygen. Myoglobin in muscle cells helps to match the supply of oxygen to the demands of working muscles.
Cytochromes are iron-containing compounds critical to cellular respiration and the iron-containing enzymes, catalase and peroxidase, protect cells from the accumulation of hydrogen peroxide, a potentially damaging reactive oxygen compound. During development, iron is required to build myelin, the nerve insulation that makes signal transport efficient. Iron also is needed for brain chemicals, such as the neurotransmitter dopamine which sends signals within the brain.
For all that, iron deficiency is the most common nutrient deficiency in the U.S. and one of the causes of disability and death worldwide. Three stages of iron deficiency are generally identified—low iron stores, low functional iron, which affects red blood cell formation, and iron deficiency anemia, the most severe form.
In iron deficiency anemia red blood cells are smaller than normal (microcytic) and lower in hemoglobin (hypochromic), which impairs the delivery of oxygen to tissues. This results in typical symptoms of fatigue, rapid heart rate, palpitations, and rapid breathing upon exertion.
Iron deficiency can result from high growth rate, blood loss, restricted diet, or any combination of these factors. Infants and children up to 4 years old are at risk. Babies get iron from mother's milk, but rapid growth demands more iron after the first four to six months. Women who are pregnant or of child bearing age, and adolescents are particularly vulnerable, as are women who are dieting or highly physically active. Loss of blood and certain disease states, such as celiac disease, and H. pylori infection are associated with iron deficiency anemia. Vegetarians also may be at risk because iron from plant sources is less efficiently absorbed.
“To establish a food-fortification program, several important factors should be considered,” writes Ram Chaudhari, Ph.D., senior executive vice president and chief scientific officer for Fortitech Inc., Schenectady, N.Y. “This includes the choice of food vehicle and iron compound, the fortification level and ways to enhance iron bioavailability from the fortified food.
“Industrially produced infant formulas are usually fortified with highly bioavailable water-soluble iron compounds, such as ferrous sulfate, and they contain added ascorbic acid,” Chaudhari explains. “However, cereal products are difficult to fortify with such compounds due to unacceptable organoleptic changes (rancidity flavor/color changes) that occur during storage and/or preparation. Less-soluble and less-bioavailable iron compounds, such as elemental iron powders and ferric pyrophosphate, are commonly used.
“To overcome the obstacle of water-insolubility of certain iron compounds, alternative compounds such as ferrous fumarate, which is poorly soluble in water, is soluble in dilute acid such as gastric juice and cause less acceptable organoleptic changes in fortified cereal. In order to have appropriate compounds along with iron absorption, it is necessary to develop absorption-enhancer nutrient premixes to combat the most prevalent micronutrient deficiency in the world,” Chaudhari concludes.
Fortifying foods with iron continues to be a method of choice to address iron deficiency. “The fortification of foods and beverages is an ever increasing trend. In developing nations, it’s the least expensive way to bring badly needed nutrients to the populace,” says Max Motyka, director human product division, Albion Advanced Nutrition Inc., Clearfield, Utah.
Several technical problems complicate iron fortification in beverages. They include low bioavailability of iron compounds and the off taste that iron can impart to foods. Many iron sources also can accelerate oxidation, producing an unfavorable color and flavor in products and potentially causing irritation of the gastrointestinal system.
Companies making functional foods are turning to the more bioavailable form of minerals, such as Amino acid chelates to enhance nutrition delivery, according to Motyka. Albion’s Ferrochel ferrous glycinate has GRAS status, is CAS and FCC listed.
“Since iron bioavailability is closely associated with reactivity; the more available the iron the more likely it will have undesirable reactions in the food or beverage application,” says Kantha Shelke, Ph.D., principal for Corvus Blue, a Chicago-based nutrition science consultancy. “Iron is usually incorporated in food systems in either of three forms: elemental (Fe-0), ferrous (Fe+2), and ferric (Fe+3). Food systems largely dictate which form of iron will work best.”
Elemental iron, of low solubility, is relatively stable and has medium bioavailability. It is typically used in cereals and extruded foods. But, according to Shelke, ferrous iron, the cheapest and most bioavailable is also most reactive so ferrous-fortified foods are not very shelf stable and prone to rancidity. Ferric iron is less reactive and less soluble and therefore less bioavailable than ferrous. It is expensive and is typically used in packaged foods designed for long shelf life.
“The FDA mandate for iron fortification takes into consideration the RDA, not the bioavailability of iron,” Shelke adds. “Specific labeling guidelines for RDA require food applications to follow those guidelines to ensure they provide the specified RDA for iron. But increasing the dosage to compensate for low bioavailability can raise the cost significantly. Most iron-fortified foods, specifically cereal, provide less than 10 percent of the RDA.”
Akzo Nobel, Amsterdam, Netherlands, pioneered the manufacture and usage of sodium feredetate under the trade name Ferrazone. It has superior bioavailability without metallic taste or reactivity with other components. It also meets JECFA (Joint Expert Committee for Food Additives – WHO) specifications.
Most applications require about 20mg of Ferrazone on average to deliver the RDA for elemental iron – less than half as much as ferrous fumarate and ferrous sulfate and about a fifth as much as ferric pyrophosphate.
The development of mineral amino acid chelates represents a “reinvention” of the fortification processes, one that overcomes many of the technical problems. “TRAACS [The Real Amino Acid Chelate System], our patented brand of mineral amino acid chelates, exhibits very good organoleptic properties within a wide range of food and beverage products” says Motyka.
“Ready-to-drink liquid products and (dairy) foods such as yogurt can be somewhat challenging, [affecting] solubility and taste,” adds Motyka. “We find the mineral taste is more commonly an issue in beverages rather than food items. The additions of citric and/or malic acid to the mineral amino acid chelates will not only enhance the chelates’ solubility, but it also masks the taste.”
SunActive Fe, by Taiyo International Inc., Minneapolis, is a “micronized super-dispersible iron without iron flavor or color-changing potential.” This form of iron is stable against heat, salt, pH and oxidation and does not promote stomach upset or constipation. It also provides good absorption and bioavailability.
Iron is one of the oldest and most studied micronutrients. Its fortification is entering a new era, in which the technical problems are being solved, promising easier and more pleasant methods of avoiding iron deficiency.