New research has shown that consumption of walnuts can boost blood levels of melatonin and antioxidants in rats. Melatonin is a hormone that is naturally produced in humans by the pineal gland. It is most commonly associated with inducing and regulating sleep, since it is produced during the hours of darkness.
Researchers investigated whether melatonin is present in walnuts, and whether eating walnuts has an effect on levels of melatonin and antioxidants in the blood. For the study they first extracted melatonin from walnuts and quantified it using HPLC (high-performance liquid chromatography). The amount of melatonin in the nuts was found to be between 2.5 and 4.5 nanograms per gram.
Researchers then fed either walnuts or regular chow to rats, after having restricted their diet prior to the study. Their serum melatonin levels and 'total antioxidant power' were measured. The walnuts were seen to increase blood melatonin concentrations threefold in the rats that ate them, compared with those on the regular chow. Serum antioxidant power also increased.
Thus researchers say that studies demonstrate that walnuts contain melatonin and that it is absorbed when it is eaten, and it is found to improves our ability to resist oxidative stress caused by toxic molecules called free radicals.
Although it is not clear how many walnuts humans would need to eat in order to benefit, in theory researchers say they expect it to reduce the incidence of cancer, delay or make less severe neurodegenerative diseases of aging, including Parkinsonism, Alzheimer's disease and reduce the severity of cardiovascular disease.