Your liver is a vital organ and essential part of your body’s detoxification system.
Melatonin taken as an oral supplement (such as gummies or tablets) must pass through your digestive system- and therefore your liver- before it's absorbed. It’s worth wondering what kind of effect melatonin has on your liver- but also if your liver is affecting the efficiency of your melatonin supplement.
Overview: your liver
One of the liver's main functions is to metabolize substances and chemicals that pass through your body's digestive system, breaking them down into parts that are easier for your body to absorb (or excrete) before it circulates your bloodstream.
For example, your liver converts alcohol, which is toxic to your body, into acetate, which other tissues can safely break down into carbon dioxide and water.
In the case of alcohol, your liver is still able to break it down. But extended or heavy alcohol consumption can inflame your liver, resulting in liver damage. Over time, it could lead to alcoholic liver disease, where the scarring to your organ is irreversible and impairs your liver’s ability to function properly.
Does melatonin affect your liver?
Most studies show no significant negative impact to your liver from ingesting melatonin supplements, even long-term. This study found that melatonin showed no implication in exacerbating clinical liver injuries.
In fact, one clinical study found that melatonin actually had an improvement on some factors related to non-alcoholic fatty liver disease, including blood pressure and liver enzyme elevation.
A separate study found that melatonin had protective effects against liver injuries, albeit the potential clinical applications for liver disease were limited in research.
Similar studies lend to the suggestion that melatonin is not entirely harmful to the liver, and that oral supplements can be taken safely for most healthy adults. By comparison, melatonin is generally not as dangerous to your liver as alcohol is (although you should avoid mixing the two).
However, those with a liver condition should still consult with their physician before they take supplements that might affect their liver function.
Does your liver affect how effectively supplements work?
While melatonin might not impact your liver, your liver does have an impact on how well your melatonin supplement works.
Like all other substances ingested orally, drugs and supplements are heavily metabolized by the liver prior to being absorbed. Of course, this applies to oral melatonin as well.
When metabolized by the liver, oral melatonin is subject to the first-pass effect. The first-pass effect describes when a drug or hormone, like melatonin, is metabolized, reducing its concentration before it enters circulation.
Because of this first-pass effect, only a fraction of the melatonin you ingest gets actually absorbed, and the rest is degraded.
Less effective after being metabolized
Bioavailability is how much of a substance or drug is actually absorbed, compared to the amount you take. Because of the first-pass effect taking place in your liver, only a fraction of the melatonin that you ingest is actually absorbed.
The bioavailability of oral melatonin especially is poor; a study found that the bioavailability of oral melatonin was found to be less than 20%. Most people absorb less than half of the melatonin they're taking, which is incredibly inefficient.
In addition, it takes time for your body to break down and absorb oral melatonin. Typical oral melatonin supplements take around an hour or even longer for effects to peak.
Efficiency of nasal melatonin vs. oral melatonin.
Normally, melatonin is produced in your brain's pineal gland. Natural melatonin production in your body is primarily affected by the amount of light exposure in your eye. In the absence of light exposure, your brain’s pineal gland increases melatonin production.
Melatonin produced naturally does not go through the first-pass effect from being metabolized by your liver. However, oral melatonin supplements cannot bypass that effect.
A more efficient method of absorption is using nasal melatonin, such as Ascent Instant Sleep.
Intranasal application offers a more direct pathway to your brain, bypassing any barriers that would delay it from being absorbed or degraded such as the blood-brain barrier. This barrier typically filters substances from reaching your brain and
A study comparing methods of absorption found the greatest potential in intranasal absorption, which was absorbed much more quickly compared to other methods including oral and transdermal melatonin.
Overall, harmless but less effective
In an overview, taking melatonin orally does not appear to have a negative impact on your liver albeit at the cost of efficiency.
Alternative forms of taking melatonin- such as nasal supplements which aren’t processed through your liver- will have better bioavailability than those oral supplements without impact to your liver.