A herbal approach to digestive health

Words - Catherine Rudenko

Introduction

The use of herbs and plant extracts to manage digestive ailments in other species is well documented. Whilst equine specific research is somewhat limited, some research is available and shows promising results. The principle common to traditional herbal medicines, whichever system is adopted, is that the patient is considered as a whole. This includes taking into account age, current level of vitality, emotional state or personality, along with environmental challenges. 

The digestive system is considered of primary importance as digestive health influences other aspects of health within the body. That traditional view is one that is now upheld firmly in modern science, as we become increasingly aware of the influence of gut health on other body systems. Within the human food sector there now exists a multitude of supplements targeting gut function, changing the microbiome, and promoting various health benefits derived from such changes. 

Plants present an opportunity to do more to manage digestive health for horses in training but supply and safety are significant challenges. Not all herbs are approved for use in racing as they contain substances that are banned in racing, for example ephedrine commonly found in Indian snakeroot, or synephrine that is often found in bitter orange cultivars. Just because a herb is available online and marketed for equine does not mean it is safe to use in racing. There is also the consideration of supply chain, as the global herbal market does not operate with the racing industry in mind. Whilst many herbs are themselves safe for use in racing by their action or composition, the supply chain may expose them to contamination with herbs or other materials containing banned substances. It is therefore essential only to use herbs and blends from companies operating under codes of practice, such as BETA NOPS who are assessing and managing the risk of contamination with naturally occurring prohibited substances (NOPS). 

The information below discusses some of the plants most commonly used or better evidenced for their effects on aspects of digestive health. Research is other species unless specifically stating equine. The information below is designed to provide an introduction to herbs commonly used for digestive health, the majority of which are available through reputable brands. 

Herbs noted for antiulcer or antacid effects

Turmeric (Curcuma longa)

Traditionally used for symptoms including inflammation, gastritis and gastric ulcer. In a study looking at the effect of curcuma longa extract the effects noted were reduced gastric acid secretion and protection against gastric mucosal lesions (1). Effect noted as from blocking of H2 histamine receptors.

Chamomile (Matricaria recutita)

One of the most widely studied herbs. Well known for its antioxidant and inflammatory properties. It has also been studied for its effects on management of diarrhoea and gastric ulcers (2). Effect likely from antioxidant properties.

Milk Thistle (Silybum marianum)

Milk thistle has been reported as having protective effects against ulceration through its positive effects on mucosa.

Fenugreek Seeds (Trigonella foenum-graceum)

Traditionally used for a variety of digestive disorders. Fenugreek seeds have been studied and compared with omeprazole for their protective effects against ulcers. In one study the soluble gel extract from fenugreek seeds was found to be as effective as omeprazole for experimentally induced ulcers (3).

Licorice (Glycyrrhiza glabra)

Well known for its antiulcer properties in humans and documented as an effective antacid. Research has shown that licorice used in donkeys with glandular ulcers induced by phenylbutazone was effective at reducing ulcer severity. Licorice was also effective at preventing associated phenylbutazone induced hypoglycaemia (4).

There are other herbs also with reported ulcer benefits mostly from a healing perspective including corydalis, gotu kola and bacopa. 

Combinations

Herbs are most often prescribed in combination, as a cocktail of herbs will provide more than one mode of action, and will take into consideration other aspects of a state of disease. 

Herbal combinations for ulcers within equine research is limited but some studies exist for marketed products. An Italian company has shown efficacy of a combination of minerals and herbs, namely fenugreek, licorice aloe vera and fleawort extract at reducing ulcer severity score of thoroughbreds in training (5). 

Another commercial preparation trialled in humans based on bitter candytuft, melissa leaf matricaria flower, caraway fruit, peppermint leaf, angelica root, milk thistle, elan-dine herb and licorice root was proven effective at lowering gastric acidity and inhibiting serum gastrin levels (6).

Herbs noted for anti-inflammatory effects of digestive disorders

Although gastric ulcers are the most common concern for horses the remainder of the digestive tract is equally challenged by the training environment and needs for high energy feeds. Herbs are often used, and well documented, for the management of human digestive disorders. Whilst there is not always a direct equine equivalent the similarities in conditions makes a herbal approach an interesting consideration. 

Boswellia (Boswellia serrata)

A potent anti-inflammatory herb with evidence for use in management of inflammatory bowel disease (IBD) and Chron’s disease. In both cases, research proves Boswellia as effective as medication in some studies. 

Chamomile (Matricaria recuita)

A herb with multiple benefits, including carminative effects. Widely used for any inflammatory condition of the bowel and gastrointestinal spasms. 

Demulcent Herbs

This group of herbs is used to lubricate and protect digestive tract membranes. Some herbs in this group are also in the anti-ulcerogenic group, highlighting that herbs are often carry multiple benefits across categories. Their primary mode of action comes from mucilaginous substances, namely polysaccharide gels, that protect mucosal surfaces by adhering to them. They may also act as prebiotics and influence intestinal flora. 

Marshmallow (Althea officinalis)

Used in humans for the management of inflammation of gastric mucosa.

Slippery Elm (Ulmus fulva)

Used for inflammation and ulceration of the stomach and for cases of colitis. 

Licorice (Glycyrrhiza glabra)

Licorice has a similar effect, although slightly different mode of action, through increasing mucus production and promoting mucosal blood flow.

Fenugreek (Trigonella foenum-graceum)

Used in the management of gastritis. 

Antimicrobial Herbs

There are numerous herbs with antimicrobial effects. The mostly widely studied group for gastrointestinal infections are those containing the active component berberine. It has been found effective in treating diarrhoea caused by Escherichia coli, Shigella dysenteriae and Salmonella paratyphi B, amongst others. Berberine is found in plants such as goldenseal, Oregon grape root and coptis root. 

Chamomile and thyme are also in this category although not of the berberine group. Chamomile oil is reported as having antifungal activity and activity against gram positive bacteria. Thyme oil has antifungal activities against a wide range of organisms. 

Antiviral Herbs 

Whilst there are several herbs considered as having antiviral properties, such as Echinacea, there is little information specifically for efficacy against gastrointestinal viruses. The exception being for tormentil root, which has been investigated for its effects against rotavirus diarrhoea in children. Research has shown an extract of tormentil root was effective in shortening the duration of rotaviral diarrhoea. 

Considerations

There is a considerable amount of research and evidence around the efficacy of some herbs, along with increasing understanding of their modes of action. As is often the case, equine specific research is limited and research from other species must be relied on. 

Herbs that are well researched, are worth considering alongside a well-balanced approach to nutrition. The main challenge is not finding evidence of efficacy, but finding a source that is most appropriate to racing. Although herbs and extracts are readily available online it is important to purchase through companies that are aware of the risks of naturally occurring prohibited substances and are managing this risk with a focus on racing, and not to use any supplement containing known banned substances. 

References

1. Kim DC, Kim SH, Choi BH, Baek NI, Kim D, Kim MJ, Kim KT. Curcuma longa extract protects against gastric ulcers by blocking H2 histamine receptors. Biol Pharm Bull. 2005, Volume 28, Issue 12

2. Mohamed-Amine Jabri, Nadhem Aissani, Haifa Tounsi, Mohsen Sakly, Lamjed Marzouki, Hichem Sebai. Protective effect of chamomile (Matricaria recutita L.) decoction extract against alcohol-induced injury in rat gastric mucosa. Pathophysiology, 2017, Volume 24, Issue 1

3. R Suja Pandian, C.V Anuradha, P Viswanathan, Gastroprotective effect of fenugreek seeds (Trigonella foenum graecum) on experimental gastric ulcer in rats, Journal of Ethnopharmacology, 2002, Volume 81, Issue 3

4. Masoud Ahmadnejad, Ghader Jalilzadeh-Amin, Benjamin W Sykes. Prophylactic effects of Glycyrrhiza glabra root extract on phenylbutazone-induced Equine Glandular Gastric Disease (EGGD). Journal of Equine Veterinary Science, 2022, V olume118.

5. Stucchi,L. Enrica,Z. Alessia,S. Giovanni,S. Serena,C. Contura,B. Ferro,E. Ferrucci,F. Efficacy of the administration of a natural feed supplement in the management of equine gastric ulcer syndrome in 7 sport horses: a field trial. American Journal of Animal and Veterinary Sciences. 2017, Volume 12, Issue 3

6. M.T. Khayyal , M. Seif-El-Nasr , M.A. El-Ghazaly , S.N. Okpanyi , O. Kelber , D. Weiser. Mechanisms involved in the gastro-protective effect of STW5 (Iberogast) and its components against ulcers and rebound acidity. Phytomedicine. 2006, Volume 13, Issue 1

Equine Nutrition - be wary of false feeding economies

Article by Louise Jones

Many horses, especially performance horses, breeding stallions, and broodmares at certain stages of production, require additional calories in the form of hard feed. Whilst in the current economic climate, with rising costs and inflation, it might be tempting to look at lower cost feeding options; in reality, this could be a false economy. When choosing a feed, in order to ensure that you are getting the best value for money and are providing your horses with the essential nutrients they require, there are a number of factors to consider.

Quality 

The ingredients included in feed are referred to as the raw materials. These are usually listed on the feed bag or label in descending order by weight. Usually they are listed by name (e.g., oats, barley wheat) but in some cases are listed by category (e.g., cereals). Each raw material will be included for a specific nutritional purpose. For example, full-fat soya is a high-quality source of protein, whilst cereals such as oats are mainly included for their energy content, also contributing towards protein, fibre and to a lesser degree, fat intake.

Waste by-products from human food processing are sometimes used in the manufacture of horse feed. Whilst it is true that they do still hold a nutritional value, in most cases they are predominantly providing fibre but contain poor levels of other essential nutrients. Two of the most commonly used by-products are oatfeed and distillers grains. Oatfeed is the fibrous husks and outer layer of the oat and it mainly provides fibre. Distillers grains are what is left over after yeast fermentation of cereal grains used to produce alcohol. The leftover grain is dried and used in the feed industry as a protein source. Distillers grains can be high in mycotoxins, which are toxic chemicals produced by fungi in certain crops, including maize. Furthermore, despite being used as a protein source, distillers grains are typically low in lysine. As one of the first limiting amino acids, lysine is a very important part of the horse’s diet; horses in work, pregnant mares and youngstock all have increased lysine requirements.

Another ingredient to look out for on the back of your bag of feed is nutritionally improved straw, often referred to as “NIS”. This is straw that has been treated with chemicals such as sodium hydroxide (caustic soda) to break down the structural fibre (lignins) and increase its digestibility. Straw is a good example of a forage which contains filler fibre; in fact, you can think of it as the horse’s equivalent of humans eating celery. Traditionally, oat straw was used to make NIS, however many manufacturers now use cheaper wheat or barley straw due to the rising cost of good quality oat straw.  Not all companies state what straw is used and instead use generic terms such as cereal straw, which again, allows them to vary the ingredients used depending on cost and availability. 

By law, feed manufacturers must declare certain nutrients on the feed bag, one of which is the percentage crude protein. This tells you how much protein the feed contains. However, not all protein is created equal; some protein is of very high quality, whilst other proteins can be so low in quality that they will limit a horse’s ability to grow, reproduce, perform or build muscle. Protein ‘quality’ is often measured by the levels of essential amino acids (e.g., lysine, methionine) it contains. In most cases feed manufacturers do not have to list the amount of these essential amino acids; but looking at the ingredient list will give you a clue as to how good the protein quality is. Good sources of high-quality protein include legumes and soybean meal, whereas by-products often contain moderate- or low-quality protein, even though they may be relatively high in crude protein. 

Understanding more about the ingredients in your bag of horse feed will help you to assess whether they are providing good, quality nutrition. Feeds containing large proportions of lower quality ingredients will obviously be cheaper, but this could compromise quality of the products. The goal therefore is to ensure that the nutritional makeup of the products remains high quality and consistent. 

Cooking for digestibility 

Digestibility is a term used to describe the amount of nutrients that are actually absorbed by a horse and are therefore available for growth, reproduction, and performance. Understanding digestibility of energy sources—such as fibre, fat, starch, and sugar as well as protein, vitamin and mineral digestibility—is important when devising optimal diets for horses. 

Most of the energy in grains is contained in the starch; however, horses cannot fully digest starch from uncooked (raw) grains in the small intestine, which results in this undigested starch traveling into the hindgut where it will ferment and potentially cause hindgut acidosis. Therefore, in order to maximise pre-caecal digestibility, feed manufacturers cook the grain. Similarly, soya beans must be carefully processed prior to feeding them to horses. This is because raw soybeans contain a specific enzyme that blocks the action of trypsin, an enzyme needed for protein absorption.

There are various methods of cooking including pelleting, micronizing, extrusion, and steam-flaking.  This is a fine art as, for example, undercooking soya beans will not deactivate the enzymes correctly, thus resulting in reduced protein absorption. On the other hand, overcooking will destroy essential amino acids such as lysine, methionine, threonine, and possibly others.

Variation in cooking methods, and hence digestibility, can have a direct impact on how the finished product performs. Your individual feed manufacturer should be able to tell you more about the cooking processes they use to maximise digestibility.

Micronutrient and functional ingredients specification

The back of your bag of feed should list the inclusion of vitamins, such as vitamin E, and minerals including copper and zinc. A lower vitamin and mineral specification is one way feed companies can keep the cost of their products down. For example, the vitamin E level in one unbranded Stud Cube is just 200 iu/kg—50% lower than in a branded alternative.

For most vitamins and minerals, the levels declared on the back of the bag/label only tell the amount actually added and do not include any background levels provided by the raw materials. In other marketing materials, such as brochures, some companies will combine the added figure with the amount provided by other raw materials in order to elevate the overall figure. For example, a feed with 50 mg/kg of added copper may list the total copper as 60 mg/kg on their website or brochure.  Whilst it is perfectly acceptable to do this, it is equally important to recognise that background levels in different raw materials can vary and hence should not be relied upon to meet requirements. To complicate this slightly further, chelated minerals (e.g., cupric chelate of amino acids hydrate, a copper chelate) may be included. Chelated minerals have a higher bioavailability, and so a feed with a high inclusion of chelated copper may perform as well as one that has an even higher overall copper level but does not include any chelates.

Equally important is the need to verify that any specific functional ingredients such as prebiotics or yeast are included at levels that are likely to be efficacious. 

Feeding rates

Whilst the cost of a bag of feed is undeniably important, another aspect that should be considered is the amount of feed required to achieve the desired body condition and provide a balanced diet. Feeding higher volumes of hard feed not only presents a challenge from a gastrointestinal health point of view but also increases the cost per day of feeding an individual. For example, the daily cost of feeding 8kg of a feed costing £400/€460 per tonne vs 5¼ kg of a feed costing £600/€680 per tonne are exactly the same. Plus, the lower feeding rate of the more expensive product will be a better option in terms of the horse’s digestive health, which is linked to overall health and performance. To keep feeding costs in perspective, look at the cost of feeding a horse per day rather than relying on individual product prices.

Consistency 

When a nutritionist creates a recipe for a horse feed, they can either create a ‘set recipe’ for the feed or a ‘least cost formulation’. A set recipe is one that doesn’t change and will use exactly the same ingredients in the same quantities. The benefit of this is that you can rest assured that each bag will deliver the same nutritional profile as the next. However, the downside is that if the price of a specific ingredient increases, unfortunately, so will the cost of the product.

On the other hand, least-cost formulations use software to make short-term recipes based on the cost of available ingredients. It will use the cheapest ingredient available. When done correctly, they will provide the amount of calories (energy), crude protein, vitamins and minerals as specified on the label. However, the ingredients will change, and protein quality can be compromised. Often feed companies using least-cost formulations will print their ingredients on a label, rather than the bag itself, as the label can be amended quickly and cheaply, should they alter the recipe.

Checking the list of ingredients in your feed regularly should alert you to any formulation changes.  Equally look out for feeds that include vague ingredient listings such as ‘cereal grains and grain by-products, vegetable protein meals and vegetable oil’; these terms are often used to give the flexibility to change the ingredients depending on how costly they are.

Peace of mind

Another important issue is that some companies producing lower-cost feeds may not have invested in the resources required to carry out testing for naturally occurring prohibited substances (NOPS) such as theophylline, banned substances (e.g., zilpaterol - an anabolic steroid) or mycotoxins (e.g., zearalenone). It is true that, even with the most stringent testing regime, identifying potential contamination is difficult; and over recent years, a number of feed companies have had issues.  However, by choosing a feed manufacturer who is at the top of their game in terms of testing and monitoring for the presence of such substances will give you peace of mind that they are aware of the threat these substances pose, and they are taking significant precautions to prevent their presence in their products. It is important to source horse feed from a BETA NOPS registered feed manufacturer at a minimum. It may also be prudent to ask questions about the feed manufacturer’s testing regime and frequency of testing.  

Supplements – to use or not to use?

A good nutritionist will be able to assess any supplements that are fed, making note of why each is added to the diet and the key nutrients they provide. It is easy to get stuck into the trap of feeding multiple supplements that contain the same nutrients, effectively doubling up on intake. Whilst in many cases this isn’t nutritionally an issue, it is an ineffective financial spend. For example, B vitamins can be a very useful addition to the diet, but if provided in levels much higher than the horse needs, they will simply be excreted in the urine. Reviewing the supplements you are feeding with your nutritionist to ensure they are essential and eliminating nutritional double-ups is one of the simplest ways to shave off some expense.

Review and revise

A periodic review of your horse’s diet ensures that you’re providing the best nutrition in the most cost-effective way. This will require the expertise of a nutritionist. Seeking advice on online forums and social media is not recommended as this can lead to misinformed, biased advice or frankly, dangerous recommendations. On the other hand, a properly qualified and experienced nutritionist will be able to undertake a thorough diet evaluation, carefully collecting information about forages, concentrates, and supplements. 

Working with a nutritionist has many advantages; they will be able to work with you to ensure optimal nutrition, whilst also helping to limit needless expenses. Some nutritionists are better than others, so choose wisely. (Does the person in question have the level of qualifications?) Bear in mind that while qualifications can assure you that the nutritionist has rigorous science-based training, experience is also exceptionally important. Ask them about their industry experience and what other clients they work with to ensure they have the right skill set for your needs. In addition, a competent nutritionist will be willing and able to interact with your vet where and when required to ensure that the health, well-being, and nutrition of your horses is as good as it can be. 

There are independent nutritionists available, but you will likely incur a charge—often quite a significant one. On the other hand, the majority of feed companies employ qualified, experienced nutritionists and offer their advice, free of charge.