L-Tryptophan For Dogs And Cats: Is It Safe?

The amino acid tryptophan is commonly known as the reason we get drowsy after eating turkey. Once ingested and absorbed, human (and animal) bodies can use tryptophan to produce the neurotransmitter serotonin and the hormone melatonin. Melatonin enhances sleep by inducing feelings of drowsiness, and serotonin works in the body's neurological pathways to produce anti-anxiety and calming effects. A nutritionist first theorized in the 1980s that a high-protein meal, particularly one with high tryptophan quantities, the body produces more serotonin and melatonin, leading to reduced anxiety, drowsiness, and an overall calmer mind state. In recent years, L-tryptophan has gained popularity as a supplement to encourage calmness and reduce problem aggression. 

Many L-tryptophan supplements on the market today claim to reduce anxiety and calmness in dogs, most of which include other calming agents such as passionflower, ginger, or chamomile flower. This article discusses the science of L-tryptophan supplement, whether it's safe, and if it can be an effective supplement for dogs with anxiety.

Related: Best CBD oil for dogs

Does Turkey Make You Drowsy?

First, let's address the turkey myth. Consuming turkey does not actually make you drowsy or lower anxiety. Turkey meat fails to contain uniquely high tryptophan levels. Even the amount of tryptophan you consume after a high-protein meal that does have a lot of tryptophan is still not high enough to cause significant fluctuations in serotonin levels. Moreover, for tryptophan to be converted into serotonin (and eventually melatonin), the amino acid must first cross a highly selective blood-brain barrier to enter the brain. Tryptophan needs to compete with several other kinds of amino acids to go through the barrier, which means only a limited amount makes it into the brain. 

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Tryptophan And Dogs

While the turkey myth may not hold up, tryptophan may positively impact behavior and mental states when concentrated as a supplement. Tryptophan has been studied extensively as a serotonin precursor for use as a replacement or adjunct therapy for serotonin reuptake inhibitors (SSRIs), medications commonly used to treat human depression and occasionally used to treat anxiety in dogs. Below we highlight some studies reporting the effects of tryptophan supplementation in dogs:

Tryptophan To Treat Anxiety

Wageningen University in the Netherlands released a study of 138 dogs who suffered from behavior problems stemming from anxiety. Half of the dogs were fed standard dog food as a control, and the other half were given the same food but supplemented with L-tryptophan. It was a double-blind, placebo-controlled study known as the "gold standard" of research designs. The dog owners recorded their dog's behavior on the assigned diet for eight weeks, and the researchers also evaluated the dog's behavior at the end of the study.

Results: Although blood tryptophan levels went up by 37 percent in the study group, neither owners nor researchers noticed any significant behavioral differences between the control dogs and the supplemental group of dogs. While there were moderate behavioral changes over time, this change can be attributed to a placebo effect. The study found that supplementing L-tryptophan produced no anxiety-reducing effects in dogs. 

dog staring at you with anxious eyes

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Tryptophan To Treat Abnormal/Repetitive Behaviors

In this double-blind and placebo-controlled study, 29 dogs presenting some form of abnormal-repetitive behavior such as light chasing/shadow staring, anxiety-related lick granuloma, or stool eating were studied. The researchers also used a "crossover" design where half of the dogs are initially fed the control, and the other half are initially given the test diet for a period of time. Then both groups are switched to the alternate diet for a second study period. This study design is well-accepted in academia to control for the placebo effect and when the researcher has a limited amount of subjects. 

Results: The researchers found that supplementing L-tryptophan had no effects on the intensity or frequency of abnormal/repetitive behaviors. While the owners reported mild upticks in improvement, this happened both when the dogs were eating the control diet and receiving the supplemental tryptophan, making it another placebo effect. 

Tryptophan-Enhanced Diet To Treat Anxiety

In a single-blind, crossover study, dogs in the study group with anxiety-related behavior problems were given a control food supplemented with L-tryptophan and alpha-capsazepine (a peptide found in milk protein). Both groups of dogs were first given the control diet for eight weeks and then switched to the test diet for another eight weeks. Since the treatment and the control group were both given the supplement, it is difficult to distinguish between the supplement effect and placebo effect, a serious design flaw that is only briefly addressed. 

Results: Owners reported a small improvement in anxiety-related behaviors, but it's important to note that the severity of the problems was very low from the beginning. Though the change was statistically significant, it was rated as numerically very small. Moreover, since the food was supplemented with two test supplements, L-tryptophan's effects are not conclusive. 

What This Means For Pet Owners

One major takeaway is that while quality turkey is a great meat to feed your dog, the amounts of L-tryptophan in turkey are not substantial enough to have any impact on your dog, as turkey doesn't contain more tryptophan than other types of protein. Giving your dog turkey will not calm them down, except for the regular calming effects a treat or good meal may have (on your dog or yourself). 

The second major takeaway is that while L-tryptophan IS safe to give your dog as a supplement, it doesn't have any major effects on treating hyperactivity and most probably no effects on anxiety or aggression. The two placebo-controlled studies we detailed above reported negligible effects on calming dominance-related aggression and anxiety-related behavioral problems. The small amount of behavioral change in the third study did not satisfactorily address the placebo effect. 

Related: How Much Sleep Do Dogs Need?

CBD May Be More Effective

If you are a dog owner looking for holistic ways to calm your pet's anxiety, CBD might be your best option. Many recent studies are uncovering the myriad ways CBD can benefit dogs, such as reducing anxiety, lowering inflammation, managing seizures, and helping with pain management and stress. Dope Dog offers a range of natural, organic CBD dog products using 100% pure CBD isolate, sourced from organic hemp grown right here in the U.S. Our customers report significant improvements in their dogs' anxiety and quality of life. Order some treats for your furry best friend from Dope Dog today!

sweet fluffy puppy with one ear up

Looking for high-quality CBD dog products?
Order from Dope Dog today.

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