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Table of Contents
Year : 2021  |  Volume : 18  |  Issue : 1  |  Page : 32-36

Investigation of the effect of food types on melatonin hormone level in human body

1 Department of Medical Lab. Techniques, Al-Esraa University College, Baghdad, Iraq
2 Ministry of Science and Technology/Food Pollution Research Center, Baghdad, Iraq

Date of Submission24-Oct-2020
Date of Acceptance26-Oct-2020
Date of Web Publication17-Mar-2021

Correspondence Address:
Isam Shaker Hamza
Department of Medical Lab. Techniques, Al-Esraa University College, Baghdad,
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/MJBL.MJBL_76_20

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Background: Melatonin, a neurohormone produced by the pineal gland, has recently been reported in foods, mainly of plant origin. Melatonin provides a number of benefits for human health. It has many important health benefits because it is a potent antioxidant and anti-inflammatory hormone. Objectives: The aim of this work is to investigate the relationship between malnutrition and food deprivation on melatonin levels in normal individuals in comparison with people suffering from gastrointestinal diseases. This study will focus on the nutritional factors apart from the intake of tryptophan that affects melatonin levels in humans. Materials and Methods: This study reported interests regarding the optimization, validation, and application of analytical liquid extraction and high-performance liquid chromatography (SYKAM) coupled to a fluorescence detector for the determination of melatonin in rice grains and blood samples. Results: In the present study, the results showed that there were significant differences between the three study groups, where the lowest values for melatonin hormone concentration were found in Group C as 2.033 ± 0.69 pg/mL which includes people suffering from famine, whereas the results of Group B showed clear differences of concentration than that in Group (C) as 3.520 ± 0.62 pg/mL which includes patients who were in hospital suffering from diseases and disorders of the digestive system, but at the same time their values were less than that of the healthy control Group A as 6.457 ± 0.59 pg/mL. Conclusion: Based on the present study, it can be concluded that melatonin hormone levels are highly deficient in people who are suffering from poverty, deprivation, and starvation compared to people with problems and disorders of the digestive system.

Keywords: Antioxidant, high-performance liquid chromatography, melatonin, Vitamin B6

How to cite this article:
Hamza IS, Ayyash MA, Mahmoud TY, Jarallah AL. Investigation of the effect of food types on melatonin hormone level in human body. Med J Babylon 2021;18:32-6

How to cite this URL:
Hamza IS, Ayyash MA, Mahmoud TY, Jarallah AL. Investigation of the effect of food types on melatonin hormone level in human body. Med J Babylon [serial online] 2021 [cited 2022 Nov 30];18:32-6. Available from: https://www.medjbabylon.org/text.asp?2021/18/1/32/311452

  Introduction Top

Melatonin (known scientifically as indoleamine N-acetyl-5-methoxytryptamine) is a hormone with neurotransmitter modulatory activity.[1] It is produced from the amino acid tryptophan in minute quantities by the pineal gland when the eyes detect no light (i.e., in darkness or blindness, or during sleep). Melatonin is also produced by the retina[2] and, in vastly greater amounts, by the gastrointestinal system.[3]

In fact, 400 times more melatonin can be found in the gastrointestinal system than that in the pineal gland or bloodstream,[4] where levels typically range from 0.1 to 10 nmol/L. Melatonin receptors are present in entral nervous tissues,[5] peripheral tissues,[6] and steroidogenic tissues,[7] including myometrial tissues of both pregnant and nonpregnant women.

Melatonin is also produced in plants where it functions as a first line of defense against oxidative stress.[8] In animals, melatonin is involved in the entrainment (synchronization) of the circadian rhythms including sleep–wake timing, blood pressure regulation, and seasonal reproduction.

Many of its biological effects in animals are produced through activation of melatonin receptors, while others are due to its role as an antioxidant, with a particular role in the protection of nuclear and mitochondrial DNA.[9] As a medicine, it is used for the treatment of insomnia; however, scientific evidence is insufficient to demonstrate a benefit in this area.[10] Melatonin is sold over the counter in the USA, Canada, and some European countries. In other countries, it may require a prescription or may be unavailable.[11]

The human hormone is the secretion of melatonin in the human body at night, that is, when in the dark, a person feels sleepy and desires to sleep, but if he/she is in room light, there will be reduced secretion of melatonin; hence, the amount of secretion is inversely proportional to the amount of light, if it regulates the biological clock of man, where Sleeps at night, and at the height of the sun increases the amount of light, decreases levels of melatonin, leading to vigilance.[12]

Antioxidants prevent high blood pressure and heart attacks, reduce the risk of cancer, have a role in the secretion of sex hormones, increase fertility and sexual desire, and work to calm down nerves and regulate the body's interactions, so called the hormone happiness, Insomnia, menstrual pain, Alzheimer's disease, and some psychiatric conditions.[13] The natural way to acquire melatonin is sleeping early in a dark room.

Melatonin does not secrete during day time sleep. High melatonin concentrations are found in seeds and some fruits such as tart cherries, bananas, and tomatoes. Foods that help the pineal gland to produce melatonin are bananas, cocoa or dark chocolate, tomatoes, ginger, oats, corn, rice, and barley.[14]

In general, melatonin-induced drugs are recommended to people suffering from insomnia and depression, especially for older people, who can sleep 8 h a day.[15] Lack of secretion of melatonin is attributed to stimulants such as coffee, tea, and soft drinks, which should not be taken at night because they reduce the secretion of melatonin.[16] Spending time in front of the computer screen before sleeping also reduces the secretion of melatonin because the bright screen light affects melatonin secretion. Instead of a hearty dinner, a light dinner is recommended early because full stomach causes insomnia aging.[17]

  Materials and Methods Top

Sample collection

Rice grain samples

Rice grains were collected from the local markets of Baghdad city, then washed carefully under tap water to get rid of impurities and dust, later washed again with distilled water, washed, and the cleaned samples were dried and stored in polyvinyl bags until the time of analysis.

Blood samples

  • Control Group A: It includes samples of healthy men.[18] They were collected from normal staff, who consume natural foods, who were free from signs and symptoms of diabetes and hypertension, who were nonsmokers, and those whose age ranged from 25 to 50 years
  • Patient Group B: Fifteen samples were collected from people suffering from gastrointestinal diseases and admitted at Yarmouk Hospital
  • Patient Group C: Fifteen samples which were collected from impecunious families.

Sample preparation

Blood samples were collected in the early morning (before 9 a.m.), the time when generally melatonin levels are reasonably high and allow for evaluating differences between individuals without using any anticoagulant. The samples were subjected to centrifugation at 3000 rpm for 10 min at 4°C to obtain serum. The collected serum was stored at −20°C immediately after separation in multiple Eppendorf tubes till analysis.

Chemicals and reagent

Melatonin standard was purchased from Sigma Chemical. The following chemicals (highly purified) used were obtained from thoughtful international companies: acetonitrile (C2H3N), methanol (CH3OH), and ethanol (C2H6O) for high-performance liquid chromatography (HPLC) analysis. Apart from the chemicals mentioned above, other chemicals used included hydrochloric acid (HCL), tartaric acid (C4H6O6), ethyl acetate (C4H8O2), and ortho-phosphoric acid (H3PO4). Ultra-pure water used in the study was purified for HPLC.

Determination of melatonin by high-performance liquid chromatography

HPLC method is used in particular for the detection of melatonin in food and other samples. Measurement is performed using a fluorescence detector, which is characterized by a high sensitivity, a high specificity, and a high selectivity for many of the compounds and in particular the melatonin.[19] The conditions of separation are listed in [Table 1].
Table 1: Conditions of melatonin separation by high-performance liquid chromatography

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Preparation of standard solution

Standard solution of melatonin was prepared by weighing out the desired mass of 0.01 g dissolved in 100-mL methanol grade for HPLC. Several dilutions were performed on the standard solution to obtain the required and appropriate concentration values for the desired analysis.

Preparation of samples

Rice samples (100 mg) were frozen in liquid nitrogen and finely ground, followed by extraction with 1-mL Acetonitrile solution (ACN) at 4°C for 12 h in dark (1.0 ng/g), and were added to the samples as internal standards. After centrifugation at 12,000 rpm and 4°C for 10 min, the supernatants were sequentially evaporated under mild nitrogen stream.

The evaporated samples were re-dissolved in 100-μL 0.1 M HCl, and then extracted with ether (1 mL). The ether phase was collected, dried under nitrogen gas, and reconstituted in 100-μL H2O/MeOH (80/20, v/v) for further analysis, as shown in [Figure 1].[20]
Figure 1: The general scheme for the analysis of melatonin (MLT)

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Instruments and analytical conditions

HPLC model (SYKAM) Germany, pump model: S 2100 Quaternary Gradient Pump, autosampler model: S 5200, and detector: ultraviolet (S 1150).

Ethical consideration

The study was conducted in accordance with the ethical principles that have their origin in the Declaration of Helsinki. The study was carried out with patients' verbal approval before sample was collected. The study protocol, subject information, and consent form were reviewed and approved by a local ethics committee.

  Results Top

Melatonin levels

Melatonin levels were estimated by using HPLC which added a new dimension to the investigation of organic compounds in different samples with the ability to obtain both qualitative and accurate quantitative data in one operation and the speed of analysis. The identification of melatonin in samples was based on retention time in comparison with pure commercial standard material [Table 2].
Table 2: The mean±standard deviation of melatonin concentration of subject groups by high-performance liquid chromatography

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[Figure 2],[Figure 3],[Figure 4],[Figure 5],[Figure 6] show that a complete baseline of separation was obtained within the standard, rice, and serum samples of subject groups.
Figure 2: High-performance liquid chromatography chromatogram of standard melatonin. Its retention time is 6.604

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Figure 3: High-performance liquid chromatography chromatogram of melatonin level in rice sample, its retention time is 6.453

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Figure 4: High-performance liquid chromatography chromatogram of melatonin level in serum sample of Group A (control), its retention time is 6.456

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Figure 5: High-performance liquid chromatography chromatogram of melatonin level in serum sample of Group B, its retention time is 6.453

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Figure 6: High-performance liquid chromatography chromatogram of melatonin level in serum sample of Group C, its retention time is 6.453

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In human body, hormones help recognize the onset of darkness and respond accordingly to initiate sleep and perform other actions. Rice was chosen as a food source rich in melatonin, which is considered one of the favorite and main foods on the Iraqi table. The results of the current study showed that there were significant differences between those groups, where the mean of melatonin hormone levels in healthy people (control Group A) was 6.457 ± 0.59 pg/mL, whereas the mean hormone level of patients who are in hospital and suffering from diseases and disorders of the digestive system (Group B) was 3.520 ± 0.62 pg/mL, which was lower than that of Group A. While the results showed that the mean of melatonin levels in Group C (including poor and impecunious families) was 2.033 ± 0.69 pg/mL, who do not have enough food for their daily life, which was lower than that of patients in Group B.

  Discussion Top

Synthesis of melatonin requires tryptophan as a precursor as well as a functioning of several enzyme-based reactions, first to compose serotonin and subsequently melatonin. Several vitamins and minerals act as co-factors and activators in these processes, so the deficiency of needed nutrients may restrict the synthesis of melatonin. Fluctuating melatonin levels can be boosted by ingesting products containing melatonin. The bioavailability of plant-based melatonin is evident, and could explain some health benefits of vegetables, fruits, and grain products.[2]

Other health-related lifestyle factors such as body weight, which is related to diet, may have as much effect on melatonin levels as specific dietary choices. Thus, the health benefits of diet-driven melatonin boosts seem not to be the product of any single food or nutrients present in the diet. In general, diets rich in vegetables, fruits, and grain products contain considerable levels of dietary melatonin. Vitamins and minerals contribute to the synthesis of endogenous melatonin while the body is active.[8]

Melatonin deficiency can have a significant negative effect on the human body. Through the results obtained from the current study, which showed clear significant differences, we can attribute it for several reasons, in which the most important is the lack or absence of sources that supply the body with what it needs from the primary materials and compounds such as tryptophan that are necessary to synthesize and produce melatonin hormone at the natural levels that keep the vital activities of the human body calm and rest. Drowsiness and sleep in addition to many physiological activities such as physiological well-being, including sleep regulation, maintenance of blood pressure, and reproductive activities, are related to this hormone. This means low levels of antioxidants in people with low concentrations of melatonin, as the foods they depend on have very little concentration of melatonin.[13]

  Conclusion Top

Melatonin has many important functions to play in the human body, most of which are yet to be understood. It is most helpful for sleep regulation; maintenance of blood pressure, reproductive activities, and antioxidant system; as well as anxiety reduction. It also seems that melatonin might be useful in the treatment of some diseases. Based on the present study, it can be concluded that melatonin hormone levels are highly deficient in people who are suffering from poverty, deprivation, and starvation compared to people with problems and disorders of the digestive system.


The author is grateful to and sincerely acknowledges all the patients who participated in this study. His special thanks for Food Pollution Research Center/Ministry of Science and Technology, and other researchers at the chemistry department for their help and continued support.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

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  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]

  [Table 1], [Table 2]


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