# Tryptophan

Category: Amino acids

Also known as: L-tryptophan

Tryptophan is an essential amino acid whose metabolites, particularly serotonin, are necessary for growth and development but become pro-inflammatory and degenerative when present in excess after maturity. Peat argued that while tryptophan is indispensable during rapid growth…

10 passages · 3 authors · 2001–2022 · Most-cited: [Ray Peat](https://bioenergeticoracle.com/md/voices/ray-peat/index.md)

Canonical page: https://bioenergeticoracle.com/concepts/tryptophan

## Synthesis

**Tryptophan** is an essential amino acid whose metabolites, particularly serotonin, are necessary for growth and development but become **pro-inflammatory** and degenerative when present in excess after maturity. [Source 1, 8] Peat argued that while tryptophan is indispensable during rapid growth, its continued high intake in adulthood allows its excitable, oxidative properties to act as *random, excitatory, inflammation-promoting processes* throughout the organism. [Source 8] He identified tryptophan, along with cysteine and methionine, as a primary **anti-thyroid** amino acid that suppresses metabolism and contributes directly to the aging process. [Source 2, 4]

The primary danger of excess tryptophan lies in its conversion to serotonin, a molecule Peat characterized as a central mediator of stress, inflammation, and learned helplessness. [Source 9] Serotonin suppresses mitochondrial respiration, promotes lipid peroxidation and blood clotting, and stimulates the release of ACTH and cortisol, creating a self-perpetuating catabolic state. [Source 2, 7, 9] Peat noted that estrogen redirects tryptophan metabolism toward serotonin, making women particularly susceptible to its negative effects, and that hypothyroidism and cortisol both increase serotonin formation. [Source 1, 3] In contrast, adequate **vitamin B6** and **calcium** help direct tryptophan metabolism away from serotonin and toward the synthesis of niacinamide. [Source 3, 10]

Restriction of tryptophan has been shown to produce profound anti-aging effects. Peat cited studies where rats fed a diet lacking tryptophan or containing only one-fourth the normal amount maintained reproductive ability far longer and experienced significant increases in both average and maximum lifespan, looking and acting like younger animals. [Source 1] Georgi Dinkov has written that tryptophan is the only amino acid that is *directly carcinogenic*, likely through its ability to mimic estrogen in promoting prolactin release, and noted that it is always present in the smallest amounts in living organisms, indicating its potentially dangerous nature. [Source 4, 9] Dinkov also emphasized that tryptophan restriction, especially when combined with methionine and cysteine restriction, can increase maximum lifespan by 20 to 30 percent, dwarfing the effects of caloric restriction alone. [Source 4]

Peat recommended that adults limit their intake of tryptophan-rich foods, particularly muscle meats, which also contain high levels of pro-inflammatory cysteine, methionine, iron, and phosphate. [Source 5, 6] He advocated for the use of **gelatin** as a major dietary protein after growth is completed because it completely lacks tryptophan, cysteine, and methionine, thereby reducing the risk of inflammatory and degenerative diseases. [Source 8] He warned that overconsumption of meat protein can displace carbohydrate in the diet and liberate thyroid-suppressing amino acids, noting that Broda Barnes had to double his thyroid dose when eating a high-meat diet. [Source 6] The fatigue of over-training is likely produced by a tryptophan and serotonin overload resulting from muscle catabolism, and stress-induced free fatty acids increase tryptophan uptake into the brain, further driving serotonin synthesis. [Source 2]

## People also ask

### How does tryptophan contribute to aging and inflammation?

Peat argued that excess tryptophan in adulthood converts to serotonin, which suppresses mitochondrial respiration, promotes lipid peroxidation, and stimulates cortisol release, creating a pro-inflammatory, catabolic state that accelerates aging.

### Why did Peat recommend gelatin as a dietary protein?

Peat advocated for gelatin because it completely lacks tryptophan, cysteine, and methionine, the anti-thyroid amino acids he believed drive inflammation and degeneration when consumed in excess after growth is completed.

### What role does vitamin B6 play in tryptophan metabolism?

The corpus describes how adequate vitamin B6 helps direct tryptophan metabolism away from serotonin synthesis and toward the production of niacinamide, reducing the formation of pro-inflammatory serotonin.

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## Cited passages

Passage numbers match the `[Source N]` markers in the synthesis above.

### Source 1 — Tryptophan, serotonin, and aging

Ray Peat · Article · 2006 · https://raypeat.com/articles/aging/tryptophan-serotonin-aging.shtml

> Some research has been done on the amino acid requirements of rats over a significant part of their short lifespans. In rats and farm animals, the amount of tryptophan required decreases with time as the rate of growth slows. In some ways, rats never really mature, since they keep growing for nearly their whole lifespan. Their growth stops just a short time before they die, which is usually around the age of two or three years. (At this age, rats' cells still retain approximately the same high water content seen in the cells of a two year-old child.) They usually become infertile about half-way through their lifespan.
>
> If we try to draw conclusions about amino acid requirements from the rat studies, I think we would want to extrapolate the curve for the decreasing need for tryptophan, far beyond the point seen during the rat's short life. And those “requirements” were determined according to the amounts that produced a maximum rate of growth, using the index of the pig farmers, as if the rats were being studied for possible use as meat.
>
> When rats were fed a diet completely lacking tryptophan for a short period, or a diet containing only one fourth of the “normal” amount for a more prolonged period, the results were surprising: They kept the ability to reproduce up to the age of 36 months (versus 17 months for the rats on the usual diet), and both their average longevity and their maximum longevity increased significantly. They looked and acted like younger rats. (A methionine-poor diet also has dramatic longevity-increasing effects.)
>
> On the tryptophan-poor diet, the amount of serotonin in the brain decreased. When brain serotonin decreases, the level of testosterone in male animals increases. More than 20 years ago, a chemical (p-chlorophenylalanine) that inhibits serotonin synthesis was found to tremendously increase libido. In old age, the amount of serotonin in the brain increases. This undoubtedly is closely related to the relative inability to turn off cortisol production that is characteristic of old age (Sapolsky and Donnelly, 1985). Hypothyroidism increases the formation of serotonin, as does cortisol (Henley, et al., 1997, 1998; Neckers and Sze, 1976).
>
> In white hair, the amount of tryptophan is higher than in hair of any other color.

### Source 2 — Tryptophan, serotonin, and aging

Ray Peat · Article · 2006 · https://raypeat.com/articles/aging/tryptophan-serotonin-aging.shtml

> There are people who advocate the use of tryptophan supplementation or other means to increase serotonin in the tissues as a treatment for the fibromyalgia syndrome, but the evidence increasingly suggests that excessive serotonin, interfering with muscle mitochondria, is a major factor in the development of that syndrome. In 1965, Hans Selye showed that the injection of serotonin caused muscular dystrophy. Subsequent studies suggest that serotonin excess is involved in both muscular and nervous dystrophy or degeneration (O'Steen, 1967; Narukami, et al., 1991; Hanna and Peat, 1989).
>
> The fatigue produced by “over-training” is probably produced by a tryptophan and serotonin overload, resulting from catabolism of muscle proteins and stress-induced increases in serotonin. Muscle catabolism also releases a large amount of cysteine, and cysteine, methionine, and tryptophan suppress thyroid function (Carvalho, et al., 2000). Stress also liberates free fatty acids from storage, and these fatty acids increase the uptake of tryptophan into the brain, increasing the formation of serotonin. Since serotonin increases ACTH and cortisol secretion, the catabolic state tends to be self-perpetuating. This process is probably a factor influencing the rate of aging, and contributing to the physiological peculiarities of aging and depression.
>
> Malnutrition, and specifically protein deficiency, produces an inflammatory state that involves extreme serotonin dominance. Stress or malnutrition prenatally or in infancy leads to extreme serotonin dominance in adulthood. Other functions of tryptophan are reduced, as more of it is turned into serotonin. Decreasing tryptophan or decreasing serotonin improves learning and alertness, while increased serotonin impairs learning.
>
> Tryptophan is an essential amino acid for reproduction and growth of the young animal. Most research on the nutritional requirements for amino acids has been done on farm animals, because of the economic incentive to find the cheapest way to produce the fastest growth. Farmers aren't interested in the nutritional factors that would produce the longest-lived pigs.
>
> Some research has been done on the amino acid requirements of rats over a significant part of their short lifespans. In rats and farm animals, the amount of tryptophan required decreases with time as the rate of growth slows.

### Source 3 — Ray Peat KMUD: 12-10-13 Aging and Energy Full Interview

Ray Peat · Interview · Jan 25, 2017 · https://www.youtube.com/watch?v=DEdDTAyZuJU

> **Ray Peat:** Yeah, women in particular are very susceptible to too much tryptophan. They used to be the victims of pellagra much more often than men. That's because estrogen redirects the metabolism of tryptophan into serotonin rather than niacin or niacinamide. When corn is treated with alkali to make hominy or tortillas, the chemistry shifts it over in that pathway, makes niacin out of it, and doesn't let so much serotonin be formed.
>
> **Andrew Murray:** Okay, because there was another chemical, aspartic acid. I also saw that was a good source from which NAD can be synthesized, and that was from asparagus and asparagus juice in particular.
>
> **Ray Peat:** Well, you don't want to take plain aspartic acid or even with minerals because it's an excitotoxin in itself.
>
> **Andrew Murray:** How about asparagus juice as a source of it, I wonder?
>
> **Ray Peat:** Oh, it's fine.
>
> **Andrew Murray:** Yeah,
>
> **Ray Peat:** okay. And another amino acid that's being promoted a lot in the Internet world is either arginine or citrulline to increase your nitric oxide. That's going exactly in the wrong direction epigenetically. Vitamin B6 is needed to prevent tryptophan being turned into too much serotonin and to help turn it into niacinamide. And simply supplementing niacinamide is a very direct way to help reverse these epigenetic problems. Five years ago, when the Harvard people were starting A drug company, I think it was called Sirtis, S-I-R-T-I-S, which was bought by a big drug company, Glaxo, and they dumped it this year and went on to something else.

### Source 4 — Animal-based vs. Ray Peat diet, a conversation with Georgi Dinkov

Georgi Dinkov · Interview · Dec 20, 2022 · https://www.youtube.com/watch?v=9ZM9sCfmAGc

> **Georgi Dinkov:** um and then in addition tryptophan is the only amino acid that is directly carcinogenic it is not a coincidence that if you look in nature whether it's an animal or plant and whatnot tryptophan is always present at the smallest amount compared to any other amino acid and in the composition of what it's a plant an animal any kind of a living organism tryptophan will be the tiniest amount of them all um and i can give it like in a let's say you get a glass of milk and get a couple of grams of like some amino acids tryptophan will be probably on the amount on the on the uh something in the range of like 50 milligrams so it's two orders of magnitude lower than what the other amino acids are present and that gives you a good indication that uh in general that's not something you probably want to overload with right so now we know it's a precursor to serotonin it is directly carcinogenic right um and it's also anti-thyroid it's a glitrogen you can cause hypothyroidism by feeding too much tryptophan there are animal studies on that yeah methionine and cysteine Now, both of them are also anti-thyroid, but methionine has this unique effect. It's a methyl donor, right? It is an essential amino acid. Cysteine can get synthesized from methionine. But some of the studies on lifespan extension...

### Source 5 — One Radio Network: The True Nature of a Virus (September 21, 2020)

Ray Peat · Interview · Sep 21, 2020

> **Ray Peat:** Oh, yeah. I think liver should be limited to about one serving per week. Too much meat, people who eat a pound of meat every day are going to overload not only on the pro-inflammatory iron, but also the pro-inflammatory tryptophan, cysteine, and methionine that are very high in the meat, and the extremely high ratio of phosphate to calcium in the meat. All of these are pro-inflammatory that are able to accelerate the aging inflammatory process.
>
> **Patrick Timpone:** But isn't tryptophan more to settle people down to help them sleep and they even do IVs for tryptophan?
>
> **Ray Peat:** They might do it, but I think it's very dangerous. Cysteine and tryptophan are very closely connected to the inflammatory processes, including brain inflammation.
>
> **Patrick Timpone:** Oh, okay. So you don't want to do that to go to sleep, right?
>
> **Ray Peat:** No.
>
> **Patrick Timpone:** This is Ben from Oregon. Hi, Dr. Peat. I'm currently on two grains of natrothroid, which just recently has been pulled from the shelves, yet again would like to start taking Sinoplus like you do. How many Sinoplus 120-30 microgram tablets would equal two grains of natrothroid?

### Source 6 — #55: Bioenergetic Nutrition Basics  |  "The Ray Peat Diet"  |  Appetite and Metabolism with Ray Peat

Ray Peat · Interview · Apr 25, 2021

> ## Dietary Basics: Protein
>
> **Danny Roddy:** Is there any way for somebody to gauge if they're becoming too deficient on tryptophan?
>
> **Ray Peat:** Digestion is usually the first thing to go wrong. They'll start getting gas or some digestive symptom, which could be that they're not replacing the lining of the intestine fast enough.

### Source 7 — Thought and energy, mood and metabolism

Ray Peat · Article · 2001

> Tryptophan is turned into serotonin, which promotes lipid peroxidation, blood clotting, and certain patterns of nerve activity. Serotonin can suppress mitochondrial respiration, and along with the reduced body temperature that it produces, a pattern of torpor or helplessness tends to be produced.
>
> But another pattern can be produced by stress, in which adrenaline and related substances maintain body temperature and alertness, despite the metabolic inefficiency. In hypothyroidism, it is common for adrenaline or noradrenaline to be produced in very large amounts. The brain and pituitary hormones (thyroid stimulating hormone, TSH, and its release hormone, TRH) that tend to increase in hypothyroidism, have their own brain modifying effects, increasing alertness and attention. Hypothyroidism can also cause hypersecretion of ACTH, adrenocorticotropin, which is also a powerful brain stimulant.
>
> These two different reactions to stress, viz., torpor or tension, depression or hyper-alertness, are often seen as reactions to over-sleeping, or under-sleeping. On a Sunday, when a person sleeps an extra hour or two, it's common to feel lethargic for the rest of the day. And when a person has to get up several hours too early, there is often the feeling of being over-stimulated. Many years ago, someone noticed that depressed people who missed a night's sleep, or who were wakened several hours earlier than normal, came out of their depression, until they caught up on their sleep. Sleep deprivation has become a recognized treatment for depression.
>
> Manic-depressive ("bipolar") people typically seem to need very little sleep during their manic periods. In depression, there is excessive influence of serotonin, in mania, excessive influence of adrenaline. These chemicals are links between energy metabolism and many specific adaptive physiological processes. One pattern of nerve activity, corresponding to these metabolic patterns, inclines a person to see the impossibility or futility of everything, the other causes an inclination to overlook impediments and undesirable consequences. In either state, important parts of reality are excluded.
>
> Apart from these moods that can be induced by the interactions of diet, hormones, and the demands or opportunities of the environment, the liveliness and vigor of metabolism influence the rhythms of thought and behavior, and the richness of experience and the appropriateness of activities.

### Source 8 — Ask the Herb Doctor: Tryptophan

Ray Peat · Interview · Nov 15, 2019

> ## Tryptophan and Serotonin
>
> **Andrew Murray:** Carrying on from where we left off last month, I had some questions about tryptophan and serotonin. Given that serotonin is formed from the amino acid tryptophan, and the premise is that serotonin is an inflammatory molecule responsible for many negative effects, how best can we avoid tryptophan ingestion to limit the serotonin formed from it?
>
> **Ray Peat:** Tryptophan and its metabolites, including serotonin, are essential for life. Every kind of organism is built with proteins containing tryptophan. Albert Szent-Györgyi demonstrated the electronic nature of life—fluorescence, luminescence, and electronic conductivity of living systems. Tryptophan is the amino acid that gives proteins that basic property which, according to Szent-Györgyi, is the essential mechanism of life that lets it sense and move. This electronic property is at the heart of sensation, movement, secretion, and consciousness. When something goes wrong with tryptophan or its metabolites, it disturbs life at its deepest level. Cell division and all other functions depend on this excitability of tryptophan. In the muscle protein myosin, there is one particular tryptophan which is most sensitive electronically. This tryptophan interacts with cysteine, an oxidizable sulfur protein. These are the "electric motor" of life processes, and they are essential during the growth process. However, if you keep the same ratio coming in via your diet after you stop growing, they are no longer being consumed for growth. They become free actors which can spread excitability and oxidizability randomly in the organism. During the growth period, you need the full balanced range of amino acids. But when growth stops, all you need is to maintain the renewal of skin, intestine lining, lungs, and brain proteins. That is a very small amount of growth compared to infancy. Those amino acids are now at risk of becoming random, excitatory, inflammation-promoting processes. Gelatin is a major protein used for building connective tissues, and it has a complete lack of these excitable proteins: cysteine, methionine, and tryptophan. If gelatin becomes a major dietary protein when growth is completed, you reduce the risk of inflammatory and degenerative diseases.

### Source 9 — Serotonin, depression, and aggression - The problem of brain energy.

Ray Peat · Article · 2012 · https://raypeat.com/articles/articles/serotonin-depression-aggression.shtml

> Since the other large neutral amino acids compete with tryptophan for entry into cells, the branched chain amino acids have some anti-serotonin activity, and this could be a justification for their use by athletes, since tryptophan and serotonin decrease glycogen stores and reduce endurance.
>
> The only amino acid that has ever been found to be carcinogenic is tryptophan. Its ability to mimic estrogen in promoting the release of prolactin is probably responsible.
>
> A large carbohydrate meal increases the ratio of tryptophan to the competing amino acids, and it has been proposed that this can shift the body’s balance toward increased serotonin. In an animal study, bromocriptine, which shifts the balance away from serotonin, reduced obesity and insulin and free fatty acids, and improved glucose tolerance.
>
> All of these observations are easiest to understand in terms of the suppression of cellular energy. Serotonin, like estrogen, lowers cellular ATP and interferes with oxidative metabolism.
>
> Serotonin, like histamine, has its proper physiological functions, but it is a mediator of stress that has to be systematically balanced by the systems that support high energy respiratory metabolism. The use of supplements of tryptophan, hydroxytryptophan, or of the serotonin promoting antidepressant drugs, seems to be biologically inappropriate.
>
> Many of the symptoms produced by excess serotonin are also the symptoms of hypothyroidism. Thyroid, progesterone, and high quality protein nutrition are central to protection against the serotonin syndromes. (Progesterone, like LSD, can inhibit the firing of serotonergic nerves, but an overdose, unlike LSD, never produces hallucinations.)
>
> One of the many actions of the "SSRI" (such as fluoxetine, Prozac), which aren’t related to their effect on serotonin, is to increase the concentration of allopregnanolone in the brain, imitating the action of increased progesterone. Following this discovery, Lilly got Prozac approved as a treatment for premenstrual syndrome. Since the production of allopregnanolone and progesterone depends on the availability of pregnenolone and cholesterol, a low cholesterol level would be one of the factors making this an inappropriate way to treat PMS.

### Source 10 — Reader Comment Q&A — Danny Roddy on Robb Wolf and Chris Kresser’s Paleologix Supplements

Danny Roddy · Forum Q&A · Jan 19, 2013 · https://180degreehealth.com/danny-roddy-on-robb-wolf-and-chris-kressers-paleologix-supplements/

> **Danny Roddy:** (2013-01-21) @Natter, “I’m trying to eat more "Ray Peat-like", but I too noticed that some problems came back, namely an itchy, dandruff-laden scalp and minor acne.” Some people need more vitamin A (and sometimes zinc) when they increase their dairy consumption. “I am kind of turned off at the "aspirin and thyroid hormone" plan. Any diet, plan, or concept that puts emphasis on a drug or peculiar supplement is always suspect.” I’m not sure what you’re talking about. “Then there’s milk, which is an odd recommendation, since many people are lactose-intolerant, including myself. I cannot drink store-bought pasteurized milk. I can only tolerate cultured milk and yogurt and cheese. To acknowledge this caveat more often would be nice.” Peat talks about it in his article on calcium, I’ve written about it on my site several times, and I’ve addressed it in this thread as well. “Then there’s coffee. I’ve looked around and could find no convincing data that drinking coffee is a good source of magnesium; not to mention the fact that it is a diuretic, which promotes the loss of minerals to begin with, especially potassium, and even magnesium itself!” Peat wrote a good article on caffeine/coffee. Context is needed to critically evaluate its usefulness. http://raypeat.com/articles/articles/caffeine.shtml “Just another example: "Tryptophan is bad, but drink milk and consume dairy. Dairy is a high source of tryptophan"” Tryptophan can be converted into the b-vitamin niacin or serotonin. Calcium can help direct tryptophan metabolism towards niacin.

_Generated 2026-07-20 from the Bioenergetic Oracle corpus._