Influence of Nutrition on Aggression

This is a good article connecting nutrition and behavior. I'm not sure I can agree that a lower protein intake results in less aggression, as I am a long-time feeder of a raw diet backed up by my vet and even Best Friends Animal Sanctuary both of which recommend a raw diet for aggressive dog cases. However, it is very true that excess carbs can cause a ton of problems in both physical, mental, and emotional health.

Aggression is a topic that has been much investigated in behavioral research. Despite the large number of publications dealing with this subject, many aspects are still not understood. Recent studies have provided new endocrine and neurophysiologic insights into the underlying mechanisms resulting in the expression of aggression. In the past, the steroid hormone testosterone was believed to be the main endocrine activator of aggressive behavior and its expression rate. However, the importance of testosterone seems to lie in its neuromodulatory function, especially in the regulation of overall dominance and competitive aggression. In turn, unrestrained aggression, impulsivity and risk-taking behavior are associated with low central serotonin activity. Other centrally active molecules, such as vasopressin or dopamine are also key players in mediating aggressiveness. In a social context, aggression is mostly applied in competitive processes to obtain access to limited resources such as food and mating partners, or for the defense of resources. Intriguingly, diverse forms of aggression are probably triggered by environmental factors such as the availability and quality of food.

Clinical evidence indicates that, for some persons, diet may be associated with, or exacerbate, such conditions as learning disability, poor impulse control, intellectual deficits, a tendency toward violence, hyperactivity, and alcoholism and/or drug abuse, and behaviors associated with delinquent behavior. Recent studies of the relationship between diet and behavior involving offender populations have yielded evidence that a change in diet can result in significant reduction in aggressive or antisocial behavior. Much as humans feel offended at certain things and resort to aggression, dogs too respond similarly. Just as certain foods do not suit humans, there are many foods that should not be fed to dogs. There’s more to antisocial behavior than nutrition, but I would argue that it is an important missing link.

Recently, dietary recommendations have included reducing total protein intake to control aggression, blaming aggression on not having enough fat in the diet, and trying to prove that adding tryptophan to the diet will curb aggression. With regard to the effect of total dietary protein content on behavior in dogs, the results of one study suggest that a reduction in dietary protein content is not generally useful in the treatment of behavior problems in dogs, but may be appropriate in dogs with territorial aggression that is a result of fear. Fear-aggressive behavior was significantly reduced in dogs fed a low (17%) protein diet when compared to medium (25%) and high (32%) protein diets. This same study concluded that dietary protein had no effect on dominant-aggressive dogs. This study confirmed numerous earlier studies linking high protein levels with different types of aggression. The speculation is that high protein levels in the food provide an over-abundance of amino acids, essentially crowding out the amino acid tryptophan. Tryptophan is essential for seratonin production, which has a calming and stabilizing effect on canine behavior. Newer studies are trying to prove that tryptophan can help reduce aggression because of its relationship with the production of serotonin, which in turn helps produce calmness. For dogs with dominance aggression, the addition of tryptophan to high-protein diets or change to a low-protein diet may reduce aggression. For dogs with territorial aggression, tryptophan supplementation of a low-protein diet may be helpful in reducing aggression.

Amino acids are found in proteins, and dogs, as carnivores, specifically need animal based proteins. Plant proteins lack some of the amino acids, which dogs, as carnivores specifically need. This includes l-taurine (for heart health), and l-carnitine (also for the heart and organ health). When dogs get a full complement of amino acids, it is not only calming to them, but helps support their organs, skin, coat, eyes and brain. Meat is also rich in B vitamins and minerals, including iron (which is lacking in plant based foods). Therefore, dogs, being carnivores, need high quality protein derived from animals to remain calm and keep blood glucose levels stable. In a process called glyconeogenesis, amino acids and fats are converted to glucose. When dogs are fed low amounts of animal based protein, they use carbohydrates for energy. But this type of energy is not consistent and the blood sugars fluctuate, by going up and then falling. This, in turn, creates mood swings. Creating glucose from animal based proteins and fats creates a stable blood sugar level, which keeps a dog calm and focused. Feeding a dog a diet high in carbohydrates, especially starches and grains, will simply create less focus and blood sugar spikes. Additionally, when carbohydrates are higher than 35% of the diet, they have the potential to protein starve the dog, in that the dog, being a carnivore, is not getting all the amino acids necessary to sustain and maintain healthy organs, brain function, and healthy coat and skin. Therefore, one of the reasons your dog may be acting hyperactive, unfocused and out of control may be the predominantly grain based kibble that you might be feeding him. Actually, grain based diet should never be fed to a dog. It can ruin his digestive system because it is not his natural diet. As mentioned previously, the biological and physiological basis of this is related to blood sugar levels. Not only do high carbohydrate diets lead to wild swings in blood sugar levels, they can lead to insulin resistance and the development of diabetes mellitus. If you look at it from an evolutionary perspective, dogs evolved from wolves. While they are not obligate carnivores, they consume only minimal quantity of grains, roots and fruits, usually in the form of the already partially digested paste and juices in the intestines of their prey. In the wild if you see wolves and dogs eating an herbivore prey that they have killed, you may notice they first go for the stomach area of the carcass. That is where they will find roots, fruits, grains, seeds, leaves and berries.

Fats are also a component needed for calmness. Not only is fat satiating (helps make a dog feel full) and helps ward off dehydration, but it also contains essential fatty acids, the most important of which is DHA (docosahexaenoic acid). Research has shown dogs that display more aggressive tendencies have lower blood serum levels of DHA. It is important to give dogs animal based sources of DHA (such as fish oils), as dogs have difficultly converting the ALA found in plant based oils.

Other ingredients in dog food are suspected of causing aggressive behavior, but have not been extensively studied. Some experts suspect soy protein, which contains plant estrogens, may upset hormonal balances, thus causing hyperactivity and aggression. Some research has focused on the long-term effects of synthetic food colorants and preservatives on the physical and mental well-being of dogs. Feeding a high-quality dog food with few additives and natural preservatives alleviates some of these concerns. In conclusion, I would recommend a diet of highly bioavailable animal proteins, fat and Omega 3 fatty acids to help dogs remain calm and stable. While food and diet may certainly affect canine behavior, including aggression, merely changing the diet is only part of the solution. Enlist the help of a qualified trainer or behaviorist if you are concerned about your dog’s aggression.

Courtesy of http://www.animalmedcenter.com/news-and-press/article/the-influence-of-nutrition-on-aggression