Phytase is a naturally occurring enzyme found in plants, microorganisms, and some animal tissues. This enzyme belongs to a class of phosphatases that catalyzes the breakdown of phytic acid, or phytate. Phytase unlocks phosphorus and other minerals chemically bound within plant-based foods, thereby improving their nutritional value. Understanding how this enzyme works reveals its broad applications, from enhancing animal nutrition to improving human mineral absorption.
The Problem with Phytic Acid
Phytic acid (phytate) is the primary way phosphorus is stored in many plant seeds, grains, and legumes, often accounting for 60 to 90 percent of the total phosphorus content. The molecule has six phosphate groups attached to an inositol ring, giving it a strong negative charge. This charge allows it to readily bind to essential minerals, such as iron, zinc, calcium, and magnesium, in the digestive tract.
When phytic acid binds to these minerals, it forms insoluble complexes that the digestive systems of humans and many animals cannot break down. These complexes resist absorption in the small intestine, leading to the excretion of the bound minerals and phosphorus. Because it blocks mineral absorption, phytic acid is classified as an anti-nutrient, reducing the nutritional benefit of plant-heavy diets.
How Phytase Breaks Down Phytate
Phytase solves the anti-nutrient problem by dismantling the phytic acid molecule through hydrolysis. As a phosphatase enzyme, phytase uses water to cleave the six phosphate groups sequentially from the inositol ring structure of the phytate molecule.
The breakdown of phytic acid releases inorganic phosphorus, making it readily available for absorption and utilization by the body. This hydrolysis also liberates chelated minerals, such as iron and zinc, previously locked within the insoluble phytate complex. The action of phytase directly increases the bioavailability of phosphorus and other trace elements from plant-based ingredients.
Enhancing Animal Feed Efficiency and Sustainability
Phytase is widely used in the livestock and poultry industries as a feed additive. Simple-stomached animals (monogastrics) like pigs, chickens, and fish produce little to no natural phytase. Since their diets rely heavily on plant materials like corn and soy, a significant portion of consumed phosphorus remains bound as phytate and passes through undigested.
Supplementing feed with commercially produced microbial phytase allows animals to utilize the phosphorus already present in the feedstuffs. Increasing the efficiency of phosphorus absorption reduces the need to add expensive inorganic phosphorus supplements. This nutritional improvement leads to better bone development, growth rates, and feed conversion ratios.
Phytase also provides a significant environmental benefit by reducing phosphorus excretion. When animals excrete undigested phytate, the phosphorus runoff from waste accumulates in waterways, contributing to eutrophication. Eutrophication causes excessive algae growth that depletes oxygen and harms aquatic ecosystems. By increasing phosphorus utilization, phytase can reduce phosphorus content in manure by 15 to 30 percent, mitigating water pollution.
Improving Mineral Absorption in Human Diets
Phytase is important in human nutrition, particularly for those whose diets are rich in whole grains, seeds, and legumes. While humans produce very little of the enzyme, it is naturally present in many plant foods. In grains like wheat and rye, phytase is activated during traditional food preparation methods.
Techniques such as soaking, sprouting, and fermentation increase the activity of native phytase. For instance, the long fermentation process for sourdough bread utilizes natural phytase to break down phytate, making minerals more accessible. These methods help ensure sufficient absorption of minerals like iron, zinc, and calcium. Phytase is also available as a dietary supplement to reduce the anti-nutritional effect of phytic acid.