Written by Jessica Patella, ND. An experiment in rats showed that supplementing their diet with melatonin improved bodyweight, systolic blood pressure, glucose tolerance, and cholesterol levels.
Metabolic Syndrome affects more than 25% of the population in developed areas of the world (1). The condition is related to an increased risk for cardiovascular disease, type 2 diabetes, obstructive sleep apnea, reproductive disorders, dementia, non-alcoholic fatty liver disease and some cancers (1,2). Recent research conducted in rats found that melatonin may be beneficial in reducing the effects of metabolic syndrome (1).
Metabolic syndrome is a cluster of signs, with at least three having to be present to be diagnosed with the syndrome:
- Waist circumference >102 cm in males and >88 cm in females
- Triglycerides >150 mg/
- HDL cholesterol <40 gm/dL
- Blood pressure >130/85 mmHg
- Fasting blood sugar (glucose) >110 mg/dl
The research included three separate experiments:
Experiment 1:
Rats were divided into 3 groups (8 in each group) for 8 weeks and given the same amount of food. The drink solutions varied per group with a 5% fructose drink, 10% fructose drink or a control group with tap water.
Compared to the control group, systolic blood pressure (p=0.012) and total cholesterol (p=0.017) significantly increased in both the 5% and 10% fructose groups. Compared to the control group, LDL or “bad cholesterol” (p=0.039), triglycerides (p<0.001) and body weight (p<0.007) also significantly increased, but only in the 10% fructose group (1). These results support that high fructose drinks result in signs of metabolic syndrome in rats (1).
Experiment 2:
Rats were divided into 4 groups (8 in each group) for 8 weeks and given the same amount of food. The drink solutions varied per group with a 5% fructose drink, 5% fructose drink plus melatonin (15 microg/mL in ethanol), melatonin (15 microg/mL in ethanol) or tap water.
Melatonin counteracted the effects of the fructose drink and significantly reduced systolic blood pressure (p<0.01), total cholesterol (p<0.02) and uric acid levels (markers for gout, p<0.04) in rats.
Experiment 3:
Rats were divided into 4 groups (8 in each group) for 8 weeks and given the same amount of food. The drink solutions varied per group with a 10% fructose drink, 10% fructose drink plus melatonin (15 microg/mL in ethanol), melatonin (15 microg/mL in ethanol) or tap water.
Melatonin counteracted the effects of the fructose drink and significantly reduced body weight (p<0.05), systolic blood pressure (p<0.03) and glucose tolerance (which shows an improved control of blood sugar; p<0.02)
In conclusion, melatonin showed beneficial effects on metabolic syndrome signs, including reducing body weight, systolic blood pressure, glucose tolerance, total cholesterol and uric acid levels in rats (1). It should be noted that melatonin is primarily used for regulating circadian rhythms, also known as the sleep cycle. Since rats are nocturnal animals and human studies have not been conducted yet, it is unclear if these results will remain the same in non-nocturnal animals (1). The doses used in the study were also very high. Currently for insomnia, melatonin is usually given in doses of 2-5 mg/day. In this study, the melatonin amounts given to the rats was the human equivalent dose of 21-35 mg/day for a 150 pound adult (1). Future research in humans is still needed.
Source: Cardinali, Daniel P., et al. “Melatonin may curtail the metabolic syndrome: studies on initial and fully established fructose-induced metabolic syndrome in rats.” International journal of molecular sciences 14.2 (2013): 2502-2514.
© 2013 by the authors; licensee Molecular Diversity Preservation International, Basel, Switzerland. Creative Commons Attribution license (http://creativecommons.org/licenses/by/3.0/).
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Posted March 25, 2013.
Jessica Patella, ND, is a naturopathic physician specializing in nutrition and homeopathic medicine and offers a holistic approach to health. She earned her ND from Southwest College of Naturopathic Medicine in Tempe, AZ, and is a member of the North Carolina Association of Naturopathic Physicians. Visit her website at www.awarenesswellness.com.
REFERENCES:
- Cardinali DP, et al. Melatonin May Curtail the Metabolic Syndrome: Studies on Initial and Fully Established Fructose-Induced Metabolic Syndrome in Rats. 2013 Int J Mol Sci 14: 2502-14; doi:10.3390/ijms14022502.
- Brown T, et al. Systematic review of long-term lifestyle interventions to prevent weight gain and morbidity in adults. Obes. Rev. 2009, 10, 627–638.
- Tappy L, et al. Fructose and metabolic diseases: New findings, new questions. Nutrition 2010, 26, 1044–1049.
