Hui Xin Wong - Senior Dietitian at St Luke's Hospital, Singapore

GABA (Gamma-Aminobutyric Acid)

GABA is an amino acid found in various foods such as vegetables (broccoli, spinach, tomato, potato, sweet potato), fruits (banana and berries), fermented foods (kimchi, miso, tempeh), tea (green, black, oolong tea), rice (white, black, red), and soy bean. It has been shown to reduce anxiety and stress, leading to better sleep quality. Yoshida et al. (2015) found a trend for improved feelings upon awakening in people who consumed GABA rice (17mg GABA) during and after the intervention. Additionally, Yamatsu et al. (2016) found that GABA supplementation of 100mg can shorten time to fall asleep (sleep latency) and increase deeper sleep (non-rapid eye movement sleep) which is beneficial for both brain and body rest. The study by Byun et al. (2018) also reported 300mg GABA tablet intake reduced sleep latency after the intervention in middle-aged adults having poor sleep. In conclusion, repeated use of 100–300 mg of GABA has been effective in reducing the time to fall asleep and improves early stages of sleep. Prolonged use of GABA (1-4 weeks) was considerably safe as there was no severe adverse effect reported across all studies. 

Ashwagandha

Ashwagandha, also known as Indian ginseng, has been used in traditional Indian Ayurvedic medicine for long. Ashwagandha root extract can improve memory and cognitive abilities in people with mild cognitive impairment, enhance the sexual function in both males and females, aid in weight management in adults as well as relieve stress and anxiety. Ashwagandha root extract has demonstrated improvements in sleep quality, particularly in those with insomnia. Studies show significant reductions in sleep onset latency, sleep efficiency, and wake after sleep onset, as well as improved mental alertness upon waking. These mean that an individual can fall asleep quickly, experience longer asleep duration with fewer time spent awake after falling asleep, leading to feeling refreshed when waking up. Higher doses (600 mg/day) and longer durations (8 weeks) of Ashwagandha supplementation have been more effective in improving sleep in individuals with insomnia. Ashwagandha root extract was well tolerated by all the participants regardless of their health condition and age. 

Passionflower Extract

Passionflower which has long been prescribed for various conditions such as anxiety, nervousness, constipation, abdominal cramps, mild infections and insomnia in American and European traditional medicine. Passionflower extract (Passiflora incarnata) has shown promise in improving subjective sleep quality, particularly in individuals with primary insomnia. However, clinical studies showed limited effects on objective measurements of sleep using polysomnography. The plant has a good safety profile and might be more effective for mild sleep issues.

Grape Seed Extract

Grape seed extract, rich in proanthocyanidins, has been studied for its effects on sleep in individuals with obstructive sleep apnea syndrome which is a common sleep-related breathing disorder. Studies indicate that grape seed extract improves sleep quality by reducing fatigue, sleepiness, and brief periods (3-15 seconds) of wakefulness during sleep, as well as increasing rapid eye movement sleep.

Melatonin

Melatonin is a hormone involved in regulating the internal body clock’s cycle of sleep and wakefulness. Despite some controversy and limited evidence in prior studies, 2019 review supports melatonin as an effective treatment for secondary sleep disorders due to sleep restriction. Based on more recent review in 2022, supplementation with melatonin has been shown to significantly improve sleep quality, especially in individuals with sleep disorders or those experiencing disruptions to circadian rhythms (e.g. shift workers, jet lag).  The sleep quality is as assessed by the Pittsburgh Sleep Quality Index (PSQI) which is an efficient tool for measuring the quality and patterns of sleep. Melatonin has been effective in enhancing sleep quality with remarkable improvements observed in subjects with respiratory diseases, metabolic disorders, and sleep disorders. Both doses (≤ 3 mg and > 3 mg) increased sleep quality significantly. 

In summary, these substances can promote better sleep by either reducing sleep onset latency, increasing non-rapid eye movement sleep, or improving sleep quality in general. Each substance has shown effectiveness under specific conditions or for particular types of sleep disturbances, with GABA and melatonin being the most extensively studied for their sleep-inducing effects.

Conjugated linoleic fatty acid (CLA) 

Recent research on conjugated linoleic acid suggests it may reduce body fat and improve lipid metabolism. CLA is also being used in sports for fat reduction and potential performance improvement. Other potential benefits include reduced inflammation and enhanced insulin effect.

Most of these ingredients primarily affect appetite indirectly by managing stress, improving sleep, or influencing metabolism. GABA, Ashwagandha, Passionflower, Grape Seed Extract, and Melatonin are more likely to reduce stress and improve sleep, which can help in managing emotional or stress-induced eating, leading to a more balanced appetite.

References: 

Yamatsu, A., Yamashita, Y., Pandharipande, T., Maru, I., & Kim, M. (2016). Effect of oral γ-aminobutyric acid (GABA) administration on sleep and its absorption in humans. Food Science and Biotechnology, 25(2), 547–551. https://doi.org/10.1007/s10068-016-0076-9

Monti, J. M., Möhler, H., Pandi-Perumal, S. R., & Monti, J. M. (2010). GABA and Sleep: Molecular, Functional and Clinical Aspects (1. Aufl., pp. 1–486). Springer-Verlag. https://doi.org/10.1007/978-3-0346-0226-6

Hepsomali, P., Groeger, J. A., Nishihira, J., & Scholey, A. (2020). Effects of Oral Gamma-Aminobutyric Acid (GABA) Administration on Stress and Sleep in Humans: A Systematic Review. Frontiers in Neuroscience, 14, 923–923. https://doi.org/10.3389/fnins.2020.00923 

Cheah, K. L., Norhayati, M. N., Husniati Yaacob, L., & Abdul Rahman, R. (2021). Effect of Ashwagandha (Withania somnifera) extract on sleep: A systematic review and meta-analysis. PloS One, 16(9), e0257843–e0257843. https://doi.org/10.1371/journal.pone.0257843

Langade, D., Thakare, V., Kanchi, S., & Kelgane, S. (2021). Clinical evaluation of the pharmacological impact of ashwagandha root extract on sleep in healthy volunteers and insomnia patients: A double-blind, randomized, parallel-group, placebo-controlled study. Journal of Ethnopharmacology, 264(NA), 113276-. https://doi.org/10.1016/j.jep.2020.113276

Deshpande, A., Irani, N., Balkrishnan, R., & Benny, I. R. (2020). A randomized, double blind, placebo controlled study to evaluate the effects of ashwagandha (Withania somnifera) extract on sleep quality in healthy adults. Sleep Medicine, 72, 28–36. https://doi.org/10.1016/j.sleep.2020.03.012

Miroddi, M., Calapai, G., Navarra, M., Minciullo, P. L., & Gangemi, S. (2013). Passiflora incarnata L.: Ethnopharmacology, clinical application, safety and evaluation of clinical trials. Journal of Ethnopharmacology, 150(3), 791–804. https://doi.org/10.1016/j.jep.2013.09.047

李立群 郝正玮 戈艳蕾 赵雅宁 王红阳 郭霞. (2016). 葡萄籽原花青素对中老年OSAHS患者肺通气及炎症水平的影响. 实用预防医学, 23(7), 784–788. https://doi.org/10.3969/j.issn.1006-3110.2016.07.005

Kun, X., Cai Hong, H., & Subramanian, P. (2019). Melatonin and sleep. Biological Rhythm Research, 50(3), 490–493. https://doi.org/10.1080/09291016.2018.1443554

Fatemeh, G., Sajjad, M., Niloufar, R., Neda, S., Leila, S., & Khadijeh, M. (2022). Effect of melatonin supplementation on sleep quality: a systematic review and meta-analysis of randomized controlled trials. Journal of Neurology, 269(1), 205–216. https://doi.org/10.1007/s00415-020-10381-w

Li, T., Jiang, S., Han, M., Yang, Z., Lv, J., Deng, C., Reiter, R. J., & Yang, Y. (2019). Exogenous melatonin as a treatment for secondary sleep disorders: A systematic review and meta-analysis. Frontiers in Neuroendocrinology, 52, 22–28. https://doi.org/10.1016/j.yfrne.2018.06.004

Lehnen, T. E., da Silva, M. R., Camacho, A., Marcadenti, A., & Lehnen, A. M. (2015). A review on effects of conjugated linoleic fatty acid (CLA) upon body composition and energetic metabolism. Journal of the International Society of Sports Nutrition, 12(1 pp.36–36), 36–36. https://doi.org/10.1186/s12970-015-0097-4