Serotonin – the “Happy Hormone”
Serotonin is the neurotransmitter often thought of as our “happy hormone” – especially because its production increases when we’re exposed to natural sunlight.
Part of the way it does this is because it transmits a signal that tells the body when to shut down and rest. This is more important than many people know in our fast paced society. A body that doesn’t get enough time to re-coup or repair itself is not going to function as well.
Serotonin is a natural mood regulator. It makes you feel emotionally stable, less anxious, more tranquil and even more focused and energetic.(1)
Serotonin exerts powerful influences over:
Mood, emotions and self-esteem,
Cravings and appetite (especially for carbohydrates),
Inducing natural sleep,
Reduce pain sensitivity,
A non-drug anti-depressant for depression,
Pain tolerance – especially in alleviating migraines,
Reduce anxiety and tension.
Sexual desire and function.
Unfortunately, deficient (and sometimes, excessive) intake of various dietary minerals and vitamins can lead to disturbed levels of serotonin. It can disrupt either the production or re-uptake processes. Care must be taken in attempting to increase serotonin levels, as a dangerous condition known as serotonin syndrome may result.(2-3) This is why we strive to have a balanced approach to Serotonin in our “4 Brain Chemicals” approach.
Serotonin – the Appetite Suppressant
Serotonin is also nature’s own appetite suppressant. It is one or the 4 essential brain chemicals that curbs food cravings and shuts off appetite. It makes you feel satisfied (not necessarily full) even if you are not full. The result is eating less and losing weight – a big hurrah for many!
One of the ways serotonin does this is by controlling ghrelin levels. When you haven’t eaten in a while, your stomach and intestines produce a protein called ghrelin. They also do this when you don’t get enough sleep – making you extra hungry the next day! (4)
This is one of our four powerful brain chemicals that curbs cravings and shuts off the appetite. It can help you feel satisfied even if your stomach is not full. The result, again, is eating less and losing weight!
Tryptophan and 5-HTP – the Building Blocks of Serotonin
Serotonin, taken orally, is not passed into the serotonin pathways of the brain. This may be because serotonin is such an important regulating chemical. The blood-brain barrier prevents serotonin in the blood stream from directly affecting serotonin levels in the brain and over-dosing it.(5)
Serotonin, itself, cannot cross the blood-brain barrier,
It must be produced within the brain to be used there.
This means that simply taking serotonin is not sufficient for our weight loss purposes. It may help sleep and other things but it has to be sufficient in the brain to help with the weight loss! We have to understand the process and how to co-operate with to get out results.
The majority of serotonin is produced in our digestive tract but we are interested here in what is produced in the brain. Technically, serotonin is created when:
1. The body combines tryptophan with tryptophan hydroxylase to form 5-hydroxyltryptamine (5-HT).
2. The 5-HTP then is converted into serotonin.(6)
Tryptophan, the beginning building block of serotonin, can only get into the brain after some sweet or starchy carbohydrates are eaten. Carbohydrates turn into glucose which triggers insulin that redirects the other amino acids to other places. Now the tryptophan can pass by the blood/brain barrier. It is converted to 5-htp which is converted into serotonin and the soothing and appetite controlling effects are soon felt.
This means that, with tryptophan, a pre-meal carbohydrate drink or snack results in more serotonin and people become less hungry. (A protein drink or snack does not produce a decrease in the appetite.)
Many of you have experienced serotonin slowing your appetite when you munched a roll, carb treat (or wine) while waiting for the main course. If 20 minutes had gone by, a common feeling when the meal is served is: “Hmm, I don’t feel that hungry now”.
Eating a low fat and protein (a few grams are ok) carbohydrate snack increases serotonin’s ability to help you feel less hungry. You will eat less, feel more satisfied and lose weight. The carbohydrates can be sweet or cracker or pretzel starchy, avoiding high-fiber fruits because they slow digestion.
However, the amino acid tryptophan produces a metabolite 5-hydroxytryptophan (5-HTP) from which serotonin is synthesized and that is capable of crossing the blood-brain barrier!
Although tryptophan is an amino acid found in all protein, eating protein can prevent tryptophan from passing through the blood/brain barrier. The reason is pretty simple: when we eat protein, there are more of the other protein amino acids in the blood than tryptophan. Tryptophan loses out in the race to get through the blood/brain barrier and very little gets in after a protein meal – even a yogurt snack!
2. 5-HTP Advantages
5-HTP has some advantages over tryptophan that make it work faster and more effectively to boost your brain serotonin to optimal levels:
• Much of the L-Tryptophan is used for other purposes so only a small fraction is available to the brain to make serotonin.
• 5-HTP is a step closer to serotonin in the synthesis process, making it possibly more efficient.
• L-Tryptophan has to compete with other amino acids to enter the brain, whereas 5-HTP doesn’t have to compete.
• 5-HTP is more efficient so an effective dose of 5-HTP taken is 100 mg, whereas the equivalent dose of L-Tryptophan is 500 mg.
• 5-HTP seems to have fewer risks and side-effects than L-Tryptophan.
In addition, 5-HTP treatment was associated with a decrease in appetite and food intake (resulting in weight loss) without significantly affecting mood state.(7) (It should be noted that 5-HTP is said to reduce cravings for carbohydrates in particular.(8)
After serotonin is released by a neuron it activates receptors located on adjacent neurons. Serotonin can be recycled a bit by the neuron that released it, for reuse. Some drugs inhibit this re-uptake of serotonin, making it stay in the synapse longer.
• Tricyclic antidepressants inhibit the re-uptake of both serotonin and norepinephrine.
• Selective Serotonin Re-uptake Inhibitors (SSRIs) have fewer (though still numerous) side effects and fewer interactions with other drugs.(9) Numerous double-blind studies show that 5-HTP is equal to SSRIs and tricyclic antidepressants in terms of effectiveness, but is less expensive, better tolerated with much fewer side effects. However, 5-HTP shouldnot be taken with any neurological drug that has been prescribed for antidepressant or other cognitive purposes unless cleared by a medical doctor.
1. New York Times news article, accessed 17 July 2014.
2. Recognition and treatment of serotonin syndrome, Dr. C. Frank, Canadian Family Physician, published July 2008, accessed 17 July 2014, article.
3. Mayo Clinic Serotonin syndrome: Definition, accessed 17 July 2014.
4. Balasubramanyan A. “Ghrelin and PYY: Rising Stars in Appetite Regulation” The Endocrine Society 2003, 85th Annual Meeting.
5. Turner EH, Loftis JM, Blackwell AD. Serotonin a la carte: supplementation with the serotonin precursor 5-hydroxytryptophan. Pharmacol Ther. (2006)
6. About.com Psychology What is serotonin?, accessed 17 July 2014.
7. Ceci F, et al. The effects of oral 5-hydroxytryptophan administration on feeding behavior in obese adult female subjects. J Neural Transm. (1989)
8. Wurtman RJ, Wurtman JJ. Brain serotonin, carbohydrate-craving, obesity and depression. Obes Res. (1995)
9. Mayo Clinic Selective serotonin reuptake inhibitors (SSRIs), accessed 17 July 2014.
(A good source: How to increase serotonin in the human brain without drugs, Dr. S. Young, Journal of Psychiatry and Neuroscience, published November 2007, accessed 17 July 2014.)