I am not an nutritional expert, but I am happy to share my experiences and understanding. It seems there is a little conflicting evidence, but for the most part it takes about 3 weeks to see a difference when using yeast. It probably would be worth a try. I can say that yeast supplements have been used in the cattle industry, and it appears that it really improves milk productivity and other things in cattle. The bottom line appears to be – if you are not going to feed good forage, then this isn’t going to help. I contacted Dr Coleman about where to get the best product, and we will see what he says. I know years ago I used a probiotic that was used successfully in the cattle industry. I really saw no visible difference, and I tried it for over 2 years! I did find one that really has helped when horses get a sour stomach, after foaling and it works great on foals right after birth – especially at foal heat or anytime they get diarrhea. Horses do not have a multi-compartmented stomach like cattle so I am not certain they both benefit from the same supplements. I spoke with Dr Coleman on this topic. He said that a yeast supplement is one product that is based on good science. He also added that it is one product he used when he worked in the feed industry.