Is more always better?

Link between health and nutrition

Despite strict food regulations which dictate that any health-related nutritional claims on products must be substantiated by huge volumes of data and long approval cycles, few people would deny that nutrition impacts health in humans. At least 75% of visits to doctors have a nutrition-related root, and it is not much different for pets, especially since many issues in pet health or disease can be connected to the overall food regime (pet food plus treats/ scraps/supplements, et cetera) that a consumer follows for their pet.

Linear response is rare

Typically, nutritional research has focused on titrations or levels of a nutrient given in various situations (dry, canned, soft-moist, supplements) measuring a specific parameter of health or performance. Often, the response will increase and perhaps plateau and then decline. With most nutrients, there would appear to be an optimal range of effectiveness, with the potential of too much leading to toxicity or health concerns. It is rare to find steadily increasing nutrient levels producing a linear response in terms of health or performance.

Just how much protein is needed? Every pet owner wants reassurance that they are choosing the best possible food products for their pets. Unlike true carnivores such as cats, which in the wild mostly feed on meat and bones from their prey, dogs are not carnivores but omnivores. In other words, they are capable of obtaining their energy and nutrients from both plant and animal sources. Wild dogs eat whatever comes their way – berries, insects, roots, vegetables – and certainly do not represent a shining nutritional example for domestic animals to follow. In contrast, a pet dog’s intake is driven by meat flavours, liver hydrolysates, fats, oils and sugar. 

In my many years in the veterinary industry, I have seen the launch of dog food comprising 40%, 45% or even 50% protein. Manufacturers seem to be trying to outdo one another, yet according to the Association of American Feed Control Officials (AAFCO), dog nutritional profiles require a minimum of 22.5% protein for growth, gestation, lactation and only 18.0% for maintenance. So what’s the point of foods with 40% to 50% protein?

Striking the right balance

In car mechanics, it is obvious; too much fuel or oil will flood the engine. In food, too much of any nutrient can essentially do the same, which is why nutrition is focused on finding the ‘optimum balance’. Foods can be fortified to achieve the intended shelf life, and certain near-nutrients such as L-carnitine, omega-3 fatty acids, fibre, and taurine (for dogs) are fortified to support overall health and nutritional performance – even though it is not always permissible to make a claim about the health impact of a nutrient on the product packaging.

Increasing the level of certain nutrients can dramatically impact the absorption and/or performance of others. Calcium must be balanced with phosphorus in a ratio of between 1:1 and 2:1. However, too much calcium can affect absorption of many other trace minerals. For example, utilisation of a zinc source that has low bioavailability for a high-calcium food will severely reduce the amount of zinc actually absorbed. I have often observed that animals on high-calcium food usually have the poorest-quality skin, hair and coats, irrespective of the balance in the rest of the food. 

When reporting a food allergy to a specific food, consumers rarely understand that it is really ‘too much’ of a specific nutrient or an imbalance. 

A similar impact can be seen in the case of too much phosphorus leading to kidney disease, or too much sodium resulting in hypertension and heart disease.

Focus on what is optimal

When creating formulas, nutritionists should be free to choose the ideal amount of each ingredient in order to provide the best nutritional balance and fortification for long-term health and performance – that should always be the first objective. 

The amount a pet is fed should depend on its life stage, gender, health condition, amount of exercise, and so on. In human nutrition, with the trend towards mega doses of many nutrients/near-nutrients, the train of thought has often been that if something is good for health, more of it must be even better. In my opinion, we need to turn our attention back to what is optimal. After all, more is not always better, it is just more.