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Objectives

 To develop a better understanding of how to utilize home-prepared diets in practice.

 How to approach the subject of nutraceutical use in practice and questions to ask in order to better guide clients.

Key Points

 Home-prepared diets can be useful in the management of certain disease states.

 Many home-prepared diet recipes do not provide complete or balanced nutrition.

 Home-prepared diets should always be formulated or checked by a veterinary nutritionist.

 Veterinarians may assist their clients in evaluating the efficacy and safety of the nutraceuticals clients elect to use on their pets.

 Nutraceuticals are often marketed in the same manner as approved drugs, which may erroneously lead the consumer to assume a certain degree of safety and efficacy with their use.

Overview

The use of homemade diets by pet owners has grown rapidly in the past several years. As owners become increasingly aware of alternative therapies for themselves, they are beginning to explore these options for their pets. It is important that practitioners understand how to properly evaluate homemade diet recipes. Supplied with this information, the client may then make an informed decision concerning diet and product selection and utilization.

Additional Detail

With the advent of complete and balanced commercial pet foods the use of homemade diets has declined. However, over the past several years there has been a growing segment of pet owners that are electing to home cook for their pets. There are many reasons for this. Some of the more common ones included: the negative press against commercial pet foods (erroneous information in most cases), the belief that home cooked foods are better (more natural) than commercial pet foods, the feeling of a stronger bond between the owner and pet; the belief that home cooking is cheaper (not true in most cases) and the presence of a disease process that prohibits the use of a commercially available diet.

Most nutritionists agree it is in the animal's best interest to eat a commercially available food, if at all possible. A very important point to remember is that homemade diets typically have not undergone animal feeding trials or even laboratory analysis to confirm they support the life stage for which they were designed. Owners often substitute ingredients without first consulting their veterinarian or nutritionist. Frequently the recipes selected are from unknown or questionably reputable sources. Finally, ingredients (especially in recipes following dietary fads) are often difficult to acquire.

There are, however, a number of reasons to institute a homemade diet program in some patients. The major indication for placing an animal on a homemade diet is a medical condition that has special nutritional concerns not addressed in a commercial or veterinary therapeutic diet. One of the more common conditions where homemade diets have been extremely useful is in managing adverse food reactions. By feeding a homemade diet one can select a protein and carbohydrate source not available in commercial foods, avoid additives and preservatives, and maintain control over the type and amounts of ingredients used. Home cooked diets are often the only option for animals with multiple medical conditions. By selecting a commercial diet to treat one condition, the practitioner may be feeding in a method that is contraindicated for another. A common example is an animal with hyperlipidemia, or a history of severe recurrent pancreatitis, and calcium oxalate stones. Homemade diets are also useful for patients with medical conditions that necessitate the use of a prescription diet, but that diet is not well accepted by the pet for a variety of reasons.

A diet history should be obtained on every patient, each time they are seen in your practice. If a client mentions that they are home-cooking for their pet, it is recommended that a copy of the recipe (including the source of the information) be obtained from the owner. It is virtually impossible to determine if a recipe meets a patient's nutrient needs by inspection alone, however one can often identify areas of concern based on a quick overview. This type of review may often provide evidence for the recommendation to have the diet evaluated and revised by a veterinary nutritionist. During initial inspection of the diet, one should try to identify the fat, protein, carbohydrate, vitamin and mineral (especially calcium) source.¹ Other considerations should include evaluation of the carbohydrate source-cooked versus uncooked, and quantity in the recipe. What type and quality protein source is included? Is the protein source high in fat? What is supplying the vitamins and minerals? Does the diet contain taurine (especially in cats, but can also be critical in dogs eating certain dietary ingredients). ¹

Many veterinary practitioners successfully use homemade diets in the management of their patients. It is important to obtain homemade diet recipes from reputable sources, ideally formulated by properly trained individuals. There are a number of recipes in the veterinary literature, in textbooks and referred publications. Some of the major pet food companies have formulated and published homemade diet recipes. Be extremely cautious of recipes obtained from the Internet, or the multiple publications designed for use by the general public. Alternatively, a better option is to have a diet specially formulated for your patient. A custom-formulated diet accounts for the patient's specific needs and abnormalities, using ingredients the pet likes. Contact the veterinary teaching college in your area to see if their clinical nutritionist provides this service (often for a fee). There are also a number of veterinary nutritionists in the private consulting sector who will custom formulate diets for a fee. Board certified veterinary nutritionists may be located through the American College of Veterinary Nutrition (AVCN) at www.acvn.org.

Recently, in addition to cooked, home-prepared diets, many owners have started to feed raw food diets to their animals. Nutritional therapy has always had a strong appeal to many owners because it is viewed as natural and therefore, but not always correctly, safe. Proponents of raw food diets proclaim many health benefits associated with this feeding regime. Arguments include that dogs and cats are carnivores, that they evolved eating raw food, and that the processing of commercial diets alters or destroys nutrients essential for these animals. While these arguments initially appear scientifically plausible and are occasionally reinforced by examples, they often do not stand up to scrutiny or are supported by strong scientific advice.

Currently there are three major categories of raw food diets fed to dogs and cats. The first are commercially available, "complete" foods, intended to be the sole source of nutrition. Combination diets are the second type of raw food diet commonly used. The client purchases a commercially available grain and supplement mix, that they then combine with raw meat at home. Home-prepared complete raw food diets are a third option. These diets are often referred to by the acronym "BARF" (bones and raw food diet), although other approaches are available.

The concerns and questions surrounding this feeding approach are many. Upon closer scrutiny many of the recommended feeding regimes are not balanced or do not provide all of the required nutrients. This is of particular concern during the growth period. Other problems that may arise from this feeding approach include gastrointestinal obstructions and perforations, bacterial contamination and zoonotic diseases.

Many clients who wish to prepare home-cooked diets for their pets often like to include dietary supplements in their pet's daily regime. In order for practitioners to adequately evaluate these products and provide sound advice, it is necessary that they thoroughly understand the definitions and recent regulatory issues concerning nutraceuticals.

Currently there is no legal definition for either nutraceutical or nutritional supplement. The term nutraceutical was developed to refer to a product marketed under the premise of being a dietary supplement (i.e., a food), but with the intent to treat or prevent disease.² A nutritional supplement is a product that provides known essential nutrients to augment the diet to meet recognized physiologic needs and prevent nutritional deficiencies.³ So the question arises, is a nutraceutical a food or a drug? The Food and Drug Administration's (FDA) Food, Drug, and Cosmetic Act (FDCA) has legally defined a food as an article used for food or drink for man or other animals and includes any article that provides taste, aroma, or nutritive value.⁴ The FDA considers foods to be "generally recognized as safe." On the other hand, food additives are not generally recognized as safe, and like drugs are subject to premarket approval.⁴

A drug is defined by the FDA as any substance, food or nonfood, that is used to treat, cure, mitigate, or prevent a disease, and any nonfood substance that is intended to affect the structure or function of man or animals. ⁴ This definition also includes veterinary feed directive drugs and any substance given by injection. ⁴ Based on the above definition, it may appear that nutraceuticals are indeed drugs; however, one important distinction exists. Under the law a new drug must undergo an approval process before marketing, which includes the submission of adequate data from controlled scientific studies to demonstrate the product is safe and effective for its intended use. This process is often very costly to the manufacturer and takes an extended period of time to complete. Therefore, nutraceuticals are not drugs because they have not undergone this approval process. Subsequently, nutraceuticals cannot be marketed with a label that states or implies they are intended for medical use. Intent is very difficult to establish beyond a label claim to prevent or treat a medical condition. Intent may be implied through advertising, promotional brochures, or verbal communications with sales representatives.

In 1990, the Nutrition and Labeling and Education Act (NLEA) was designed to include regulation of dietary supplements, particularly health claims made by the manufacturers of these products. However, public and private response to this act was extremely negative, which prompted the passage of the Dietary Supplement Health and Education Act (DSHEA) of 1994. This Act severely limited the FDA's ability to regulate the dietary supplement industry. According to the DSHEA, dietary supplements include amino acids, vitamins, minerals, herbal products, and substances that supplement the diet by increasing total dietary intake. The DSHEA defines these substances as "foods" and thereby protects them from FDA regulation. The burden of proof of safety and efficacy resides with the manufacturer of a drug or food additive. This same burden of proof lies with the FDA for dietary supplements as a result of the DSHEA. The passage of the DSHEA has led to some interesting situations. For instance, if a substance was first marketed as a supplement or a food and subsequently approved as a new drug by the FDA, it may continue to be sold as a supplement. However, if the FDA first approved that same substance as a drug, it cannot be sold as a supplement or food. This is the reason that estrogen and thyroxin are not dietary supplements but other hormones are, such as melatonin.²

Efficacy and Safety

Veterinarians may assist their clients in evaluating the efficacy and safety of the nutraceuticals clients elect to use on their pets. Nutraceuticals are often marketed in the same manner as approved drugs, which may erroneously lead the consumer to assume a certain degree of safety and efficacy with their use. Consumers are often unaware of the lack of scientific support behind the marketing.

Safety and efficacy are both important, but of the two, safety is perhaps more important. An exception would be an instance when an alternative therapy, with unproved efficacy, was used in place of a proven medical treatment. In some cases, the delay in providing appropriate medical treatment may be fatal. The natural appeal of alternative therapies is a major selling point for many consumers. However, one must remember that natural does not necessarily equate with safe. Aflatoxin is a natural product, but not a safe one. An Associated Press analysis of Food and Drug Administration records reveals more than 2500 reported side effects and 79 deaths associated with dietary supplements.⁵ Dietary supplements containing ephedrine alkaloids to promote weight loss or bodybuilding were responsible for more than 800 reports of adverse side effects to the FDA in a 4-year period (1993 to 1997).⁶ There is a recent report in the veterinary literature describing 47 dogs with suspected caffeine and ephedrine toxicosis resulting from ingestion of an herbal supplement containing guarana and ma huang. ⁷

No compound, including a FDA-approved drug, is necessarily free of adverse side effects, even if safety studies have been conducted. However, with drugs, information concerning potential side effects is provided to the prescribing doctor. Nutraceuticals frequently do not provide a list of potential side effects associated with their use. Moreover, a well-established reporting system by which undesirable side effects are reported and shared with users currently is lacking for nutraceuticals.

Considerations for Use in Clinical Practice

Regardless of whether veterinarians actively use complementary therapies in their practice, it is vital they open the lines of communication with their clients concerning these approaches. A recent survey of dietary supplement use in humans demonstrated that 50% of people who used nutraceuticals did not report them to their healthcare provider on a written questionnaire, though this information was specifically requested.⁸ In another report, 72% of respondents with serious medical conditions who used unconventional therapies did not report them to their medical doctor.⁹ Fear of disapproval and/or the belief that their physician is not knowledgeable about alternative therapies are two of the many reasons clients withhold this information. Even if a question about nutraceutical use is included as part of a comprehensive medical questionnaire in your practice, clients should be specifically asked this question in the course of reviewing the animal's medical and dietary history. By opening the line of communication between you and the client, the client will feel more comfortable discussing these concerns with you.

It is important to review with clients that nutraceutical manufacturers have no burden of proof when it comes to establishing either the safety or efficacy of their products. A careful review of each patient's medical history should be completed. Careful consideration should be given to a patient receiving other medications, as there is the potential that drug interactions may occur. For example, elevated serum digoxin concentrations have been documented in patients concurrently taking ginseng.¹⁰

Because of the regulatory oversight of nutraceuticals, it becomes the clinician's burden to conduct a personal review of the nutraceutical in question if he recommends it. Most information on a specific product is likely to be obtained from the manufacturer, but a thorough investigation should also include a review of the scientific literature and the pursuit of opinions from unbiased experts. There are multiple publications one can consult to find details on particular herbs, and following Web sites listed may provide additional information:

1.  www.quackwatch.com

2.  www.herbalgram.org

3.  http:// nccam.nih.gov

4.  www.navigator.tufts.edu/index.html

5.  www.consumerlab.com

6.  www.biovalidity.com

7.  www.mskcc.org

When retrieving information from some textbooks and publications, as well as the Internet, one must keep in mind that these sources are often not peer-reviewed or referred. Therefore, the validity of the information they provide cannot be guaranteed.

When faced with determining the potential efficacy of a nutraceutical, the practitioner should ask the following questions before making a recommendation.^11-13

1.  "Does the product do what it claims to do?" "What studies have been done to prove this, or are testimonials the only proof?"

2.  "Does the product contain what it claims it does, and if so, is the product bioavailable?"

3.  "If studies have been conducted on the compound, were they in vivo or in vitro?"

4.  "Were the studies done in the target species?"

5.  "Did the studies employ the same dose as is contained in the product?"

6.  "Were the studies well-controlled?"

7.  "Were the studies published in a peer-reviewed journal or similarly reputable source?"

8.  "What are the active ingredients in products containing multiple substances, and what is the potential they may interact in a negative manner?"

9.  "What other medications is my patient receiving, and how might the nutraceutical in question interact with them?"

10. "What work has been done to verify the safety at the dosage of intended use?"

11. "Has a margin of safety (the difference between effective dose and maximum safe dose) been established?"

If the clinician or client decides to proceed with the use of the nutraceutical after a thorough review of the literature, it should be done with caution. The client should be informed of the controversial nature of the treatment and permitted to make an informed decision. Alternatively, the practitioner should be willing to advise against the use of a nutraceutical for which there are inadequate data to support its effectiveness and safety. The patient should be monitored frequently for treatment efficacy and unforeseen adverse side effects. Should any adverse side effects occur, these should be immediately reported.¹³

Another option for veterinarians that do not feel comfortable using nutraceuticals is to refer the client to a practitioner that limits their practice to alternative medicine. However, unlike other disciplines, there are no AVMA-recognized specialists in complementary veterinary medicine because board certification in these therapies does not currently exist.

Summary

Clearly, there is a need for increased scientific research in this area of medicine, focusing on the mechanism of action, efficacy, and safety of nutraceuticals. The development and use of a standard for these compounds would facilitate their use in double-blind controlled studies and clinical efficacy trials. The use of a standard would permit direct comparisons to be made among different studies. That being the case, the current lack of scientific evidence should not always be seen as the fatal flaw of these products. As in other areas of veterinary medicine, the edict "above all else, do no harm" applies here as well. ¹⁴

References

1.  Remillard RL et al. Making pet foods at home. In Hand MS et al. ed., Small Animal Clinical Nutrition (4^th edition), Topeka, KS; Mark Morris Institute, 2000: 163-182.

2.  Dzanis, DA. Nutraceuticals: Food or Drug?, Proc North Am Vet Conferenc,. Orlando, FL, 1998: 430-431.

3.  Dzanis, DA. The evaluation of the use of nutritional supplements and nutraceutical compounds for therapy of disease., Proc Am Coll Vet Intern Med Meeting, San Diego, CA, 1998: 83-84.

4.  Boothe, DM. Nutraceuticals in veterinary medicine, Part I: Definitions and regulations. Compend Contin Educ Pract Vet, 19, 1997: 1248-1255.

5.  Neergaard, L. Dietary Supplement Dange. Daily News, February 22, 1998.

6.  Bartels, CL and Miller, SJ. Herbal and related remedies. Nut Clin Pract, 1998; 12: 5-19.

7.  Ooms TG, Khan SA and Means C. Suspected caffeine and ephedrine toxicosis resulting from ingestion of an herbal supplement containing guarana and ma huang in dogs: 47 cases (1997-1999). JAVMA, 2001; 218: 225-229.

8.  Hensrud DD, Engle DD and Scheitel SM. Underreporting the use of dietary supplements and non-prescription medications among patients undergoing a periodic health examination. Mayo Clin Proc, 1999; 74(5): 443-447.

9.  Eisenberg DM, Kessler RC, Foster C, et al. Unconventional medicine in the United States: Prevalence, costs, and patterns of use. New Engl J Med, 1993; 328(4): 246-252.

10. McRae, S. Elevated serum digoxin levels in a patient taking digoxin and Siberian ginseng. Can Med Assoc J, 1996; 155: 293-295.

11. Dzanis, DA. Nutraceuticals: Where's the beef? Proc North Am Vet Conference, Orlando, FL, 1998: 432-433.

12. Fascetti, AJ. Nutraceuticals: Considerations for use in clinical practice", Adv Sm Anim Med Surg, 1999; 12: 1-2.

13. Dzanis, DA. Nutraceuticals in veterinary medicine. Aust Vet J, 1999; 77: 238-239.

14. Boothe, DM. Pharmacology: Nutraceuticals: The good, the bad, and the ugly. Proc Am Coll Vet Intern Med Meeting, San Diego, CA, 1998: 292-295.