Departament de Ciència Animal i dels Aliments, Universitat Autònoma de Barcelona, Bellaterra, Spain
Nutritional Issues with Nutraceuticals
There is a large amount of nutraceuticals in the market for a variety of purposes. Nutraceuticals are not regulated as medications; thus, many of them do not have studies or data on efficacy and safety, which is why a careful evaluation of their claims is important.1 Legislation regulating these substances varies from country to country.
Some nutraceuticals might have an impact upon the nutritional status of the animal and, as such, asking owners about their use is an important part of the screening nutritional evaluation found in the WSAVA Nutrition Toolkit (www.wsava.org/nutrition-toolkit).
Some, but not all, of the common issues that nutraceuticals have related to nutrition are as follows:
1. Provision of unaccounted calories
Some supplements provide energy. The most common energy-containing supplements are oils, such as fish oil, coconut oil, and oil blends. Fish oil is commonly used in a variety of diseases,2 such as renal disease, atopy, and osteoarthritis; while coconut oil has been proposed to be of use in fat malabsorption syndromes and weight management (among other unproven claims). Oil blends of omega 3 and 6 fatty acids are usually recommended for dermatological problems. Oils and fats have an approximate energy density of 9 kcal of metabolizable energy/gram. For example, a teaspoon of fish oil provides approximately 30 kcal.
Other nutraceuticals might provide calories due to flavouring, such as some of the joint supplements.
Adding calories to the daily intake can promote undesired weight gain. Calories coming from unbalanced (non complete) food items can create nutrient dilution (where the patient gets adequate calories, but the amount of some essential nutrients can fall below requirements).
To prevent these problems the energy content of any non-balanced food items, such as treats and nutraceuticals, provided to the pet must be accounted for and they should provide in total no more than 10% of the total daily caloric intake of the dog or cat.
2. Reaching toxic levels of nutrients
Some essential nutrients have maximum levels set due to their negative effects when provided in high amounts.
Depending on the size of the patient and the amount of nutraceutical provided, using some fish oil and multivitamin products can result in vitamin toxicity, particularly of vitamin D.
Human multivitamins provide high amounts of this vitamin (plus several other potentially toxic nutrients such as trace minerals) and their use on top of commercial diets should be discouraged for this reason. Pet multivitamins, if used, should be evaluated in each case to ensure no toxic levels are reached. Again, their use is not necessary in pets already receiving a complete and balanced diet.
When using fish oil, the amount of vitamins A and D provided by the oil should be obtained from the manufacturer and calculate the amount each patient would receive at the desired dose. This amount should be added to that provided by the regular diet and this should be compared to the safe upper limit of these vitamins.3
Another common problem is the use of calcium supplements for reproduction and growth in patients already receiving a complete diet. Excess calcium in these demanding lifestages can result in problems such as skeletal malformations and eclampsia.3 As such, their use should be discouraged as well.
Some nutraceuticals can be contaminated. There have been reports of mercury and dioxin contamination in fish oils,4 lead contamination in bone meal, and arsenic contamination in kelp. When wishing to use a nutritional supplement, it is recommended to contact the company and ask them for any potential contamination risks and how does the company screen for toxins in their products.
Some nutraceuticals have ingredients (in some cases to provide flavor, like in probiotics, prebiotics, joint supplements) that can be potentially antigenic to susceptible animals. This is especially important to consider in animals with suspected adverse reactions to foods or that are undergoing an elimination diet trial.
1. Dzanis DA. Nutraceuticals and dietary supplements. In: Fascetti AJ, Delaney SJ, eds. Applied Veterinary Clinical Nutrition. Chichester, West Sussex, UK: Wiley Blackwell; 2012: 57–67.
2. Bauer JE. Therapeutic use of fish oils in companion animals. J Am Vet Med Assoc. 2011;239(11):1441–1351
3. National Research Council. Nutrient requirements of dogs and cats. Washington, DC: The National Academies Press; 2006.
4. Lenox CE, Bauer JE. Potential adverse effects of omega-3 fatty acids in dogs and cats. J Vet Intern Med. 2013;27(2):217–226.