What Is Tryptophan? Function, Effects, and Uses
In this article:
Tryptophan is an essential amino acid the body needs to produce serotonin – a neurotransmitter that influences mood, sleep, and overall wellbeing. L‑tryptophan is the biologically active form that the body can convert into serotonin and melatonin.
In dogs, cats, and horses, the right amount of L‑tryptophan can help take the edge off anxiety, support focus, and promote a more balanced response in stressful situations.
What’s the difference between tryptophan and L‑tryptophan?
Tryptophan occurs naturally in protein‑rich foods and must be supplied through the diet because the body cannot produce it. L‑tryptophan is the form of the amino acid that the body converts into serotonin and melatonin. This conversion plays a central role in regulating both emotional and physical responses.
Tryptophan
The umbrella term for the amino acid in all its forms.
L‑tryptophan
The biologically active form, most effective in feeds and supplements.
Key functions of tryptophan
• Serotonin production – supports emotional balance, reduces anxiety, and promotes a steadier mood.
• Melatonin production – supports a healthy sleep–wake cycle and better sleep quality.
• Stress regulation – helps the nervous system handle challenging situations without causing drowsiness.
• Focus and performance – may improve concentration during training and competition.
• Synergy with other ingredients – often works best alongside magnesium, B vitamins, and calming herbs such as chamomile and passionflower.
Read more about B vitamins and why they matter.
Tryptophan for Dogs
Tryptophan is an essential amino acid that dogs cannot produce themselves – it must be obtained through their diet. In the body, tryptophan is converted into serotonin, a neurotransmitter that plays a key role in mood, sleep, and stress management. For dogs, a balanced serotonin system can help reduce anxiety and support recovery during stressful situations.
Several studies on dogs have shown that tryptophan supplementation can have a calming effect and reduce stress-related behaviours, particularly when given regularly and combined with training or environmental adjustments.
Why L-tryptophan is used for dogs
Serotonin influences how dogs respond to stress, how quickly they recover, and how emotionally stable they are in daily life. An additional supply of tryptophan can be beneficial when a dog faces challenging situations, such as:
• Changes in environment
• Travel and transportation
• Training and competition
• Separation or being left alone
• Loud noises such as thunderstorms or fireworks
Signs of anxiety and stress in dogs:
- Excessive barking
- Restlessness or difficulty relaxing
- Panting without physical exertion
- Reduced appetite
Combined ingredients for enhanced effect
Tryptophan often works even better alongside other ingredients that support the nervous system:
• B vitamins – important for energy metabolism and nerve function
• Magnesium – supports muscle relaxation and stress reduction
• Natural extracts – such as chamomile, passionflower, and green tea (L-theanine), which offer a gentle calming effect
All our products contain carefully selected ingredients that work in synergy to give your dog effective, well-rounded support.
Calming products for dogs
FAQ: Tryptophan for Dogs
The effect of L-tryptophan can vary depending on the product. We offer several supplements designed to deliver noticeable results within 30–60 minutes, making them ideal for short-term, stressful situations. Other products, such as Nutracalm, are intended for longer-term use and work best when given daily over time.
Yes, L-tryptophan is safe for dogs – it’s an essential amino acid that provides significant benefits for both body and mind. However, excessive amounts of any ingredient or supplement are not recommended, and it should always be given as part of a balanced diet.
When given at the recommended dosage, tryptophan is generally safe for dogs. Some may experience mild digestive issues such as gas or loose stools at first. Always consult your vet if your dog has a strong or unusual reaction.
Tryptophan for Cats
Tryptophan is an essential amino acid that plays a key role in a cat’s mental balance and overall well-being. As the body cannot produce it naturally, it must be obtained through diet. In its active form, L-tryptophan, it serves as a building block for serotonin – a neurotransmitter that influences mood, stress levels, and sleep.
Why L-tryptophan is used for cats
L-tryptophan helps regulate nerve signals and the body’s stress response through serotonin production. Research shows that the right amount of tryptophan can help reduce anxiety and promote steadier behaviour in cats, without causing drowsiness.
L-tryptophan supplements may be beneficial in situations such as:
• Environmental changes (moving house, a new family member, travelling)
• Separation or loneliness
• Noise sensitivity (fireworks, construction noise)
• Excessive territorial behaviour or aggression
• Understimulation and restlessness
Signs of anxiety or stress in cats:
- Hiding more than usual
- Excessive grooming or hair loss
- Changes in appetite (eating more or less)
- Urinating outside the litter tray
Combining ingredients for greater effect
For optimal results, tryptophan is often combined with other calming ingredients such as magnesium, B vitamins, L-theanine, GABA, chamomile, and green tea extract. These work together to support a balanced nervous system and promote relaxation in cats.
All our calming products for cats are carefully formulated with synergistic ingredients to help promote security and well-being.
Calmin products for cats
FAQ: Tryptophan for Cats
Yes, L-tryptophan is a safe and natural amino acid when given in the correct dose.
Some products may have a noticeable effect within 30–60 minutes, while others deliver the best results with regular use over time.
Yes, as long as you follow the recommended dosage on the product and it is given as part of a balanced diet.
Because it is a natural building block of serotonin, which helps cats manage stress and anxiety in a gentle way.
Tryptophan for Horses
L-tryptophan is an essential amino acid that plays an important role in a horse’s nervous system and overall well-being. The body uses tryptophan to produce serotonin – a neurotransmitter that affects mood, stress response, and mental balance. As horses cannot produce tryptophan themselves, it must be provided through feed or supplements.
Unlike some calming substances, L-tryptophan does not make horses drowsy. Instead, it supports a balanced nervous system and improves their ability to focus, even in challenging situations.
Why L-tryptophan is used for horses
Tryptophan can be valuable in situations that may cause worry, nervousness, or tension, such as:
• Transport and competition travel
• Moving yards or environmental changes
• Training and competition
• Separation from other horses
Combined ingredients for greater effect
In our calming product for horses, AnxiKalm, L-tryptophan is combined with magnesium and B vitamins – a blend that supports the nervous system, muscle function, and mental balance without reducing performance.
This combination can help horses manage stress more effectively and maintain focus, even under pressure. All our products contain carefully selected ingredients that work together to provide broad and effective support.
AnxiKalm
✔️ L-tryptophan
✔️ Magnesium
✔️ Vitamins B1, B6, B2, and B9
✔️ Effects within 3–4 hours
✔️ No competition withdrawal period
FAQ: Tryptophan for Horses
In most cases, L-tryptophan is permitted, but regulations can vary between competition organisations. Our product, AnxiKalm, has no competition withdrawal period.
Some horses may show noticeable improvements within a few hours, especially with fast-acting products. For longer-term support, the supplement can be given daily over a period of time.
No, L-tryptophan should not cause drowsiness. It supports a balanced nervous system and helps the horse cope with stress without reducing energy or willingness to perform.