How A Tryptophan Deficiency Makes You Old

tryptophan deficiency

You get old when a tryptophan deficiency lets inflammation in your body get out of control; meaning, that it becomes chronic, or systemic. Unfortunately, chronic inflammation is a fact of life for most people as they age. Find out what to do about it.

tryptophan deficiency

A tryptophan deficiency makes you old for a variety of reasons, but a new study showed that too little of this amino acid can disrupt the microbiome balance in your gut that helps keep chronic inflammation at bay.

Inflammation is a big part of aging poorly. To age slowly, or become biologically younger, you must address inflammation, or as scientists call it, inflammaging.

So, this new “Tryptophan-Deficient Diet” study reported in the International Journal of Molecular Sciences by researchers in the Medical College of Georgia Department of Medicine discovered that eight weeks on a low-tryptophan diet results in some unhealthy changes in the trillions of bacteria that comprise the gut microbiota and higher levels of systemic inflammation in aged mice.

What does this have to do with us humans, you ask?

Well, this is important news for us for three reasons:

  1. Although we’re not mice, we share about 90% of the same genetics, and thereby — although by no means conclusive — what happens to mice in a lab has a decent chance of happening to us.
  2. Our gut bacteria affect our health in a myriad of ways, from inflammation to depression.
  3. We can control our tryptophan levels in our body, and therefore help our gut microbiota work to make us healthy, rather than old and sick.

Before we go any further, it would be helpful to tell you what tryptophan is, and then I’ll get into what it affects other than inflammation, and how to get more tryptophan in your diet…..

Let’s dig in…


What Is Tryptophan?

tryptophan deficiency

Tryptophan is an amino acid. Amino acids are the so-called “building blocks of protein.” Proteins determine the function of cells, and consequently the function of our organs and tissues.

In humans, tryptophan is not stored for long periods; consequently, it has the lowest concentration in the body among all the amino acids. It also declines as we age. That can be problematic given that tryptophan plays a key role in our mood, energy level and immune response.

Much of how tryptophan affects us is through its reciprocal relationship with our microbiota: We consume tryptophan via certain foods and supplements, along with fibrous foods that keep our gut microbes healthy, and in return they help make us healthy.

What you need to know about microbiota and the microbiome


Why Can A Tryptophan Deficiency Make You Old?

A tryptophan deficiency can lead to chronic inflammation

The focus of the Tryptophan-Deficient Diet study is about how an insufficient amount of tryptophan in your diet can increase chronic inflammation through altering the relative population sizes of four particular types of gut microbes, Clostridium sp, Acetatifactor, Mucispirillum and Blautia.

Clostridium sp is the bacterium that metabolizes the essential amino acid tryptophan enabling production of good products like serotonin in the gut, which can not happen sufficiently if tryptophan is deficient.

In contrast, the Acetatifactor population, a bacterium associated with intestinal inflammation, increases three-fold during a tryptophan deficiency.

Mucispirillum and Blautia play a big role in maintaining microbiota health in humans and animals. They also have been found to be significantly decreased in patients with Crohn’s and colitis, where inflammation can be rampant. Mucispirillum, for example, resists oxidative “bursts” associated with inflammation and produces numerous factors associated with reducing reactive oxygen species and consequently inflammation.

This is a big deal, because inflammation ages you, which is why scientists coined the term, inflammaging. In my post, How You Can Beat Chronic Inflammation (and Age Better) with Exercise, Food and Supplements, I wrote that scientists have made these observations:

  • The prevalence of harmful gut bacteria can result in a dramatic alteration of the symbiotic relationship between gut bacteria and the host, thereby contributing to metabolic diseases via stimulation of low-grade, chronic inflammation.
  • Diet is the main contributing factor to obesity-associated changes in the gut microbiota that alter the ratio between beneficial bacteria and harmful bacteria (the Firmicutes:Bacteroidetes ratio). In fact, a fecal transplant (which has gut bacteria) from a lean person into an obese person will cause weight loss in the recipient (the obese person).
  • Gram-negative bacteria (those that cause many types of infections) start the inflammation-related processes associated with the onset of obesity and insulin resistance (which can lead to diabetes).

All this leads Dr. Carlos M. Isales, co-director of the MCG Center for Healthy Aging and chief of the MCG Division of Endocrinology, Diabetes and Metabolism, to say:

We think the microbiome plays an important role in the aging process and we think one of those players in the aging is tryptophan, which produces metabolites that affect every organ function

When those unwanted metabolites proliferate our microbiota becomes unhealthy, because a tryptophan deficiency has a negative impact on inflammation (increasing it), as well as on the production of the neurotransmitter serotonin (important for reducing depression) and melatonin (helpful for restorative sleep).

The unhealthy changes the scientists saw in the microbiota made them suspect that this resulted from the increased release of inflammation-promoting signaling molecules called cytokines, hypothesizing that microbiota changes might induce release of the molecules body-wide. They examined an array of specific inflammation-promoting cytokines and found they were more prevalent in the mice who were tryptophan deficient, concluding that a low-tryptophan diet set the stage for inflammation body-wide, which is chronic or systemic inflammation.

“Basically your immune system has been dysregulated, you have continued inflammation from damaged tissue by the processes that normally keep you healthy,” Dr. Isales says, as chronic inflammation can replace the classic episodic immune response that fights infection and enables healing.

What Dr. Isales calls this “unnatural” process of aging is associated with chronic disease conditions like impaired digestive health, declining cognitive function and a compromised immune system. Turns out that the gut microbiota is a significant modulator of these.

The good news is the mice study were able resolve the unhealthy changes in their body once they resumed a healthy tryptophan intake in just a few days.

But there’s a caveat to this story!

Increasing tryptophan did not always correct the health issues; in fact, some tryptophan metabolites are actually harmful. The best option, the scientists found, was to ensure that the mice were not tryptophan deficient to begin with, so that their microbiota maintained optimal function, rather than attempt a tryptophan rescue.


Additional Health Benefits of Tryptophan

tryptophan deficiency prevents several benefical health effects


In addition to reducing systemic inflammation, tryptophan may be able to help with:

  • Restorative sleep
  • PMS
  • Smoking cessation
  • Depression
  • Appetite
  • Dementia
  • Exercise

Read on to find out the particulars, but note that all of the studies referenced below were conducted on a small group of subjects, and therefore more research is needed to conclusively demonstrate these benefits of tryptophan.

Restorative Sleep

Tryptophan produces melatonin in the brain’s pineal gland, the gut, the retina, and immune cells. Melatonin regulates the circadian rhythm and sleep patterns and is used as a supplement itself to help people sleep [1, 2].

Studies have shown that:

  • Tryptophan supplementation increased average total sleep and made test subjects drowsy within a half hour before sleep [3].
  • Insomniac patients increased total sleep by 28% by Tryptophan supplementation, and decreased early-morning wakefulness by an average of 37 minutes [4].
  • 250 mg of Tryptophan increased stage 4 sleep (deep sleep). Given that normal dietary intake is between one-half and one gram of Tryptophan, it appears that even small amounts may increase deep sleep [5].
  • Tryptophan supplementation may also improve obstructive sleep apnea (airflow blockage during sleep) during non-REM sleep: however, patients with central sleep apnea showed no improvements [6].


The breakdown of tryptophan into various metabolites is affected by the phase of the menstrual cycle, which can also indirectly affect serotonin production  [7].

Tryptophan supplementation (6 grams daily) improved the following symptoms in women suffering from premenstrual dysphoria (a severe type of PMS) [8]:

  • Mood swings
  • Tension
  • Irritability

Mood improved by 34.5% in those given L-tryptophan supplements.

Smoking Cessation

People who were given tryptophan supplements, had a high-carbohydrate diet and  regular smoke-ceasing therapies smoked fewer cigarettes compared to placebo, and experienced decreased anxiety and withdrawal symptoms [9].


Alleviating depression through tryptophan is a mixed bag. Some studies confirm its value in improving depression, others are inconclusive and some show it’s unhelpful.

For instance:

  • Depressed people who also have insomnia could be aided by tryptophan supplementation [10,5].
  • A randomized study of 25 young adults showed that high tryptophan diets increased mood and decreased depressive symptoms and anxiety [11].
  • In a study of 24 patients, clomipramine (a drug for depression) and L-tryptophan were more effective in improving depressed mood, suicidal intent, and anxiety compared to clomipramine alone [12].
  • A meta-analysis of tryptophan’s effects on depression confirmed some positive effects, but the authors underlined the low evidence quality, and avoided making conclusions [13].
  • A study of depressed patients showed that L-tryptophan supplementation did not help and the patients needed further treatment before release [14].


In a study of 15 healthy volunteers, those receiving Tryptophan supplementation ate 20% fewer calories and ate more protein than carbohydrates [15].

A rat study showed that after 24 hours of fasting, those given Tryptophan ate less on their first meal, and their meal intervals (time between meals) were longer [16].

Also, it could be that reduced tryptophan levels and absorption into the brain might be responsible for carbohydrate cravings [17].


A study of dementia patients showed that serotonin levels in the brain were significantly lower in dementia patients compared to healthy people [18].

The same study showed that patients with dementia had less tryptophan absorption than healthy individuals. Mental improvement in those with tryptophan deficiency occurred when supplemented with tryptophan [19].


Tryptophan supplements given to athletes improved their total exercise time by 49%, and lowered their perceived exertion, most likely due to the increased pain tolerance [20].

In 20 volunteers, tryptophan (300 mg, twice a day for 3 days) improved power output during the last 20 minutes of exercise when added to a sugar and electrolyte drink [21].

Tryptophan had no effects on the performance of endurance athletes [22].


Beware of the Downside of Consuming Tryptophan

Tryptophan is not for everyone. Although it’s an essential amino acid, the body does not produce it, so it must come from exogenous sources, such as food and supplements. But how much is key, and for some how much is important to know.

It’s always a good idea to consult with your doctor before taking tryptophan.

For a review of tryptophan safety suggestions and precautions, check out this Mayo Clinic page.


Sources of Dietary Tryptophan

You can ensure you do not get a tryptophan deficiency by eating tryptophan rich foods, such as oats, nuts, seeds (flax, hemp, chia), tofu, beans and lentils.

The form of tryptophan is called L-tryptophan. The usual dosage of L-tryptophan is 500 mg, but many people take more.

Less than 8 grams per day for eight weeks shouldn’t produce any side effects. That said, an upper limit for tryptophan supplementation is still uncertain [40].

L-tryptophan is often combined with other compounds, such as melatonin or 5- HTP. If you want pure L-tryptophan, among the highest rated on Amazon is Superior Labs Pure L-Tryptophan in capsules, or BulkSupplements L-Tryptophan in powder form.


Your Takeaway

Remember these five things:

  1. Tryptophan is an amino acid that helps make the microbiota in your gut healthy.
  2. Specifically, tryptophan helps gut microbes prevent chronic inflammation, one of the big deleterious effects of aging.
  3. Trytophan can also help with sleep, PMS, smoking cessation, depression, appetite, dementia and exercise — although the studies on all of these aren’t conclusive.
  4. Talk to your doctor before supplementing with tryptophan, because it’s not for everyone; also, it’s a good idea to take it before you become chronically inflamed.
  5. Rid yourself of a tryptophan deficiency by eating tryptophan rich foods, such as oats, nuts, seeds (flax, hemp, chia), tofu, beans and lentils. Or use a supplement.

Last Updated on November 8, 2022 by Joe Garma

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Joe Garma

I help people live with more vitality and strength. I'm a big believer in sustainability, and am a bit nutty about optimizing my diet, supplements, hormones and exercise. To get exclusive Updates, tips and be on your way to a stronger, more youthful body, join my weekly Newsletter. You can also find me on LinkedIn, Twitter and Instagram.

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