Phytate in Feed— Ways to Reduce Negative Impacts

Dr. Jayanta Bhattacharya, DGM-Techno-commercial (SA& SEA), Bentoli Inc

Phytic acid is a chelated organic molecule which steals vital nutrients like minerals, vitamins, and amino acids that animals could have absorbed from intestine and used in body. Hence it is considered as antinutritional factor in feed.

We find phytate in most of the plant-based feed ingredients like seeds, beans, grains, corn. Enzymatic break down of phytate in feed results in improving availability and absorption of essential minerals like phosphorus and other trace minerals.

What is phytate?

Phytic acid is a six-fold dihydrogen phosphate ester of inositol, also called inositol hexakisphosphate or inositol polyphosphate. It can form complexes with metals or proteins and, therefore, reduce their bioavailability in the gastrointestinal tract. Phytate or phytic acid is the principal storage form of phosphorus in many plant tissues, especially bran and seeds.

Basic principle of phytic acid is to protect the seeds from sprouting in unfavourable environments. It is usually found right next to or in the peel. In favourable environmental conditions specially in presence of water, phytate breaks and releases phosphorus required for sprouting of seeds. 

Negative Effect

The effects of the phytate inside our body are mostly negative, as it chelates minerals. It binds strongly to nutrients such as calcium, magnesium, zinc, iron, vitamin B3 and does not allow the body to use these. Phytate also affects efficacy of digestive enzymes. In tests outside of the body it has been seen that it strongly diminishes the ability of amylase to do its job and break down starch. It also seems to affect pepsin and trypsin, enzymes that our body uses to break down proteins.

Positive Effect

• Phytate is also able to bind to radioactive substances and heavy metals. By doing so it can help us eliminate these through bowel movements. However, there are other, healthier ways of eliminating heavy metals.
• Phytate can also act as a type of antioxidant and thereby eliminate some free radicals.
• Phytate contains phosphorus and enzymatic breaking of phytate releases phosphorus and decreases cost of feed by reducing the inclusion of phosphorus rich ingredients like dicalcium phosphate etc.

How can we reduce the amount of phytate and get positive benefits?

Enzyme phytase breaks complex phytate molecule and makes the phosphorus and other nutrients available for animals to use. Phytase is already present in the seeds, but to be activated it needs primarily water. It works best at temperatures that are a little higher than the body temperature (41⁰C) and pH-ranges around 5, which is a slightly acidic environment.

Phytase becomes inactive at temperatures higher than 55⁰C (131⁰F).  It can even be destroyed if the seed (grain) is grounded so that the temperature in the grinding process rises above 55⁰C (131⁰F).

Phytase also becomes inactive if it is frozen or stored during prolonged periods. Though it is not practically possible and feasible even in animal feed manufacturing, this method could be used wherever suitable in high value frozen food.

Apart from using phytase, several other methods could be explored as combined strategies along with regular usage of phytase in feed

1. Organic acid: adding organic acid in diet may reduce the pH of the feed and helps in activating phytase to break phytate molecules

2. Probiotics: It has been seen that probiotics, especially lactobacillus, tends to produce phytase. Adding probiotic in feed is an increasing trend which releases several enzymes including phytase in gut. Phytase produced by probiotic complements phytase enzymes and augments enzymatic break down of phytate to release phosphorus

3. Fermentation: By further fermenting our food we can often greatly reduce or even eliminate the phytic acid.

Formulating feed considering phytate content in feed ingredient is another choice to reduce the presence of phytate in feed. High phytate of course exhibits negative impacts on intestine and reduces the performance. On the other hand, using phytase along with probiotic and acidifier would be the combined strategies to explore bound nutrients specially phosphorus and other trace minerals.

References:

(1) Famularo G et al, “Probiotic lactobacilli: an innovative tool to correct the malabsorption syndrome of vegetarians?”, Medical Hypotheses 2005 65(6):1132–5.

(2) Davidsson L, 2003, “Approaches to Improve Iron Bioavailability from Complementary Foods’, Journal of Clincal Nutrition, 133:1560S-1562S

(3) Anna Ptak et al., 2015, Phytase Modulates Ileal Microbiota and Enhances Growth Performance of the Broiler Chickens, https://doi.org/10.1371/journal.pone.0119770