Optimizing Ingredients

How to Improve Ingredient Bioavailability

Bioavailability is defined as the fraction of the ingested nutrient that is absorbed and subsequently utilized for normal physiological functions. For some of the elements this is the incorporation into various metalloproteins, such as Iron in hemoglobin. Most elements are an integral part of a wide range of enzyme systems. For example, Selenium functions as a component of glutathione peroxidase, an antioxidant. Bioavailability of essential nutrients is a must when developing formulations. Today’s consumers are well informed, they understand nutrient bioavailability, they are reading labels and are selective about which finish products they will choose. While price may attract some consumers others select ingredients based on their net benefits and some use bioavailability of nutrients as a determining factor. The old concept of more is better is no longer acceptable. In most cases smaller quantities of a nutrient may be more bioavailable than larger quantities, dependent on the form of course.

Absorption of selenium and copper is much lower in ruminants (cows, sheep, goats) than in nonruminants (humans, poultry, pigs). The low absorption of these minerals in ruminants is due to modifications that occur in the rumen environment. Selenium bioavailability is reduced by high dietary sulfur and the presence of cyanogenetic glycosides in certain legumes. Feeding organic selenium from selenomethionine or selenized yeast results in much higher tissue and milk selenium concentrations than are obtained with selenite. High dietary molybdenum in combination with moderate to high dietary sulfur results in formation of thiomolybdates in the rumen. Thiomolybdates greatly reduce copper absorption, and certain thiomolybdate species can be absorbed and interfere systemically with copper metabolism. Independent of molybdenum, high dietary sulfur reduces copper absorption perhaps via formation of copper sulfide. High dietary iron also reduces copper bioavailability. Dietary factors that affect bioavailability of zinc in ruminants are not well defined. Phytate does not affect zinc absorption in ruminants because microbial phytase in the rumen degrades phytate. Manganese is very poorly absorbed in ruminants, and limited research suggests that high dietary calcium and phosphorus may reduce manganese absorption.

Efficiency of absorption of many trace minerals and dietary factors that affect bioavailability of minerals differ greatly between ruminants and nonruminants. In ruminants, microbial digestion in the rumen and reticulum precedes mammalian digestion in the abomasum and small intestine. Ruminant diets are usually high in fiber, and considerable digestion of fiber occurs via microbial fermentation in the rumen. However, association of minerals with fiber fractions in feedstuffs and/or binding of minerals to undigested fiber constituents in the gastrointestinal tract may alter bioavailability of some trace minerals in ruminants. The pH in the rumen environment is only slightly acidic (6.0–6.8), and in the rumen, many trace minerals exist largely in an insoluble form. At least some of the metal complexes that are formed in the rumen remain insoluble even under the acidic conditions found in the abomasum.

Iron deficiency is widespread in the United States and is a major cause of anemia in susceptible populations, especially in those whose demand for iron is high, such as growing children or pregnant women. Many factors, including dietary components (phytates, tannins, phosphates, and high calcium intake), exercise, menstruation, and maturity may increase or reduce iron availability. Iron absorption and utilization increase as iron stores are depleted, but inhibiting factors in such foods and beverages as soybeans and tea can impair iron absorption. Copper deficiency can result in anemia, bone disease, and diminished immune competence. Excessive intake of copper can lead to toxic effects, especially vascular problems such as low blood pressure and high blood-cholesterol levels. The bioavailability of copper is affected by a variety of factors. Among those which decrease bioavailability are suboptimal levels of acid in the gastrointestinal tract; the boiling of foods, which may leach away copper; and the consumption of uncooked protein foods. Copper bioavailability may also be reduced by interaction with other minerals such as iron, zinc, lead, cadmium, and selenium. Microencapsulation/encapsulation is a tool that can be used to protect each Copper particle and prevent its interaction with minerals such as iron and zinc thereby increasing the bioavailability of Copper. This technology can also be used to protect iron, prevent its interaction with other minerals and enhance its bioavailability.

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