Nutrition Strategies to Improve Sleep: How the evening meal and kiwifruit can help

Why is it so common to get drowsy after a solid Thanksgiving meal with high carbohydrate, high simple carbohydrate (sugars) and high L-tryptophan protein? We can use these anecdotal situations added to research to improve sleep. The concept of incorporating carbohydrate (CHO) of higher glycemic index for the evening meal might improve quantity and quality of sleep. An example of a meal which could positively impact sleep would be a large serving of rice, with a small portion of turkey and either milk/ cheese/ yogurt which would be consumed within 2-3 hours before going to sleep.

The higher glycemic CHO results in a significant spike in insulin. Insulin results in increased amino acids absorbed by skeletal muscle which decreases the concentration of LNAA (large neutral amino acids) which prevent quantity and rate of L-tryptophan that can cross the blood brain barrier to be further metabolized into serotonin and melatonin. The turkey would contain higher concentrations of L-tryptophan. The dairy serving since it is known to increase sleep duration and may be due to melatonin content. Overall, the need to support healthy sleep patterns is of upmost importance for health and performance as evidence by poor sleep being the top predictor of injuries in adolescents (Doherty et al., 2019).

Modulating sleep in athletes could be helped with a few dietary and/or supplemental strategies like melatonin via tart cherry juice to support appropriate changes in lowing of core body temperature necessary for quality sleep (Howatson et al., 2012). Consumption of antioxidants from foods, like tart cherries, has been demonstrated to mitigate pro-inflammatory cytokines and sleep quality can be negatively impacted by elevated levels of pro-inflammatory cytokines (Howatson et al., 2012). Thus, in periods of the season where intense activity or overreaching is occurring, antioxidants could help sleep.

Furthermore, the article by Doherty et al. (2019) explained that soreness and fatigue post strenuous exercise negatively impacts sleep quality and quantity. Interesting, tart cherry supplementation (30ml 2x/day for 8 days) reduced DOMS (delayed onset muscle soreness) and recovered faster in agility training among semi-professional male soccer players (Bell et al., 2016). Thus, in periods of high-volume training or double-header games, tart cherry supplementation may help with prolonging agility and max explosiveness, while at the same time reducing magnitude of DOMS whereby indirectly improving sleep.

Eating Golden kiwifruit before bed and resulting benefits for improved sleep duration have a few possible understood mechanisms (Doherty et al., 2019). Yes, kiwifruit is high in vitamin C and E making it have antioxidant and anti-inflammatory properties. It also has twice the serotonin content as tomatoes, but is that enough by itself to cause notable impacts on sleep? One explanation of the sleep effects of gold kiwifruit is due additionally because of its higher folate content with over 30 micrograms per serving. Estimates of 20-30% of people have MTHFR gene mutation, so the ability to synthesize folate (active form) from folic acid is impaired in a significant part of the population. So why is folate critically important for sleep? Apparently, insomnia conditions can be due to folate deficiency (Lin et al., 2011). Thus, those with insomnia or significantly fragmented sleep might consider folate via food/ supplements and consider genetic testing to evaluate if they have a variant MTHFR gene mutation.

The reason why folate is needed to facilitate sleep is how it is involved in the synthesis of melatonin. The simplified pathway is:

• Tryptophan

  • 5-HTP (5-hydroxytrophtophan)

    • Serotonin

      • NAT (N-acetylserotonin)

        • melatonin

So where is folate in this pathway? It is needed to convert NAT to melatonin. Folate is required to convert homocysteine to methionine. Methionine gets modified to SAM (S-adeonsyl Methionine) which is needed to add a methyl (CH3) group to NAT to convert it to melatonin. Hope that makes sense! In essence, if one is low in folate, they likely will have lower melatonin concentrations which explains the conclusions by Lin et al. (2011) that folate deficiency can be a valid reason for insomnia.

A brief summary can be viewed below:

https://www.youtube.com/watch?v=kc9jHOyfO-Q

References:

Bell, P. G., Stevenson, E., Davison, G. W., & Howatson, G. (2016). The Effects of Montmorency Tart Cherry Concentrate Supplementation on Recovery Following Prolonged, Intermittent Exercise. Nutrients, 8(7), 441. https://doi.org/10.3390/nu8070441

Doherty, R., Madigan, S., Warrington, G., & Ellis, J. (2019). Sleep and Nutrition Interactions: Implications for Athletes. Nutrients, 11(4), 822. https://doi.org/10.3390/nu11040822

Doherty, R., Madigan, S. M., Nevill, A., Warrington, G., & Ellis, J. G. (2021). The Sleep and Recovery Practices of Athletes. Nutrients, 13(4), 1330. https://doi.org/10.3390/nu13041330

Howatson, G., Bell, P. G., Tallent, J., Middleton, B., McHugh, M. P., & Ellis, J. (2012). Effect of tart cherry juice (Prunus cerasus) on melatonin levels and enhanced sleep quality. European journal of nutrition, 51(8), 909–916. https://doi.org/10.1007/s00394-011-0263-7

Lin, H.-H., Tsai, P.-S., Fang, S.-C., & Liu, J.-F. (2011). Effect of Kiwifruit Consumption on Sleep Quality in Adults with Sleep Problems. Asia Pacific Journal of Clinical Nutrition, 20(2), 169–174. https://doi.org/10.6133/apjcn.2011.20.2.05