Melatonin is a hormone produced by the pineal gland in the brain that helps regulate sleep and wake cycles. It has become a popular supplement in recent years as a natural sleep aid. Some foods, like rice, have been claimed to be high in melatonin and beneficial for sleep. But is there any truth to the claim that rice is high in this sleep-regulating hormone? Let’s take a closer look at the facts.
What is Melatonin?
Melatonin is a hormone produced by the brain’s pineal gland that helps control our circadian rhythm – our internal body clock. Light exposure, especially from the blue light emitted by screens like phones and computers, inhibits melatonin production. When it gets dark, melatonin levels naturally rise to induce sleepiness. Melatonin supplements provide extra melatonin to mimic this natural rise in the hormone.
Some of melatonin’s roles include:
- Regulating sleep and wake cycles
- Inducing and improving sleep
- Fighting jet lag
- Supporting immune function
- Protecting against oxidative stress
Given melatonin’s sleep-promoting effects, there is significant interest in dietary sources of melatonin like rice. But it’s important to understand typical melatonin levels in foods versus supplements.
Melatonin Levels in Rice vs. Supplements
While some rice contains melatonin, the levels are far below typical melatonin supplements.
One study analyzed the melatonin content in 31 varieties of rice. The researchers found:[1]
- Melatonin levels ranged from 0.21-12.0 nanograms per gram (ng/g)
- The average melatonin level was 2.15 ng/g
In comparison, melatonin supplements often provide:[2]
- 0.5 mg to 5 mg per supplement (500,000 to 5,000,000 ng)
This means a typical melatonin supplement provides over 100,000 times more melatonin than rice. Clearly, melatonin supplements are a far more potent source.
While rice provides a miniscule amount of melatonin compared to supplements, it likely does not provide enough to significantly impact sleep or circadian rhythms.
Factors that May Impact Melatonin Levels in Rice
While rice is a poor source of melatonin compared to supplements, some factors may impact melatonin levels to a small degree:[1]
- Rice variety: In the analysis of 31 rice types, melatonin ranged over 10-fold from 0.21 to 12 ng/g.
- Growing conditions: Stressors like high UV radiation may increase melatonin production in rice.
- Processing: Milling and cooking may decrease melatonin levels in rice.
- Timing of harvest: Harvesting rice at night increased melatonin levels by 168% in one study.
So while these factors may alter melatonin content, rice still only provides trace melatonin compared to supplements.
Does Eating Rice Promote Sleep?
While rice is low in melatonin, some research has still linked rice consumption, especially at night, with improved sleep quality.
However, these benefits are likely explained by rice’s high carbohydrate content. Rice is mostly starch, providing a large dose of carbohydrates that can induce sleepiness. Studies show foods with a high glycemic index, like white rice, can improve sleep by altering tryptophan and serotonin levels in the brain.[3]
This suggests the sleep benefits of nighttime rice meals are due to carbohydrates rather than the miniscule melatonin content.
Other Food Sources of Melatonin
While no food provides melatonin levels close to supplements, some other foods contain higher levels than rice:[4]
| Food | Melatonin (ng/g) |
|---|---|
| Tart cherry juice | 4.5-18.1 |
| Walnuts | 3.5-4.2 |
| Sweet corn | 1.5-3.9 |
| Banana | 0.5-1.9 |
| Tomatoes | 0.3-1.9 |
While these foods contain slightly more melatonin than rice, typical melatonin supplements still provide over 100,000 times greater amounts. Dietary melatonin from food may provide minimal support for circadian rhythms and sleep, but supplements deliver vastly higher levels.
Conclusion
In conclusion, while rice provides trace amounts of the sleep-related hormone melatonin, levels are thousands of times lower than melatonin supplements. Rice likely does not contain enough melatonin to alter sleep or circadian rhythms to a significant degree. However, rice still appears to provide some sleep benefits, likely due to its high carbohydrate content.
While no food comes close to supplemental doses, tart cherry juice, walnuts, sweet corn, bananas and tomatoes provide slightly higher melatonin levels than rice. But evidence does not support rice as a potent source of melatonin. Those seeking melatonin’s sleep-promoting effects should prioritize evidence-based supplements over dietary sources.
