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Several studies have now confirmed that cherries not only increase sleep duration and sleep quality, but they are anti-inflammatory.
The newest study comes from researchers at Spain's University of Extremadura. They tested 30 people – ten between 20 and 30 years old, ten between 35 and 55 years old and ten between 65 and 85 years old.
The researchers randomly divided the subjects into two groups. They were given either a tart cherry juice drink or a placebo with cherry flavor twice a day. Those who drank the cherry juice experienced substantially better sleep quality – measured by sleep efficiency, awakenings, and total sleep time.
Moreover, the researchers found that the older group experienced better improvements in sleep quality that the younger groups.
Another study included scientists from the United States (Nicholas Institute of Sports Medicine), the UK (Northumbria University and the University of Surrey) and South Africa (University of Johannesburg). This study followed 20 healthy men and women with an average age of 27 years old.
Half of the group was randomly assigned to drink tart cherry juice concentrate and the other half drank a placebo for seven days. The juice concentrate was made from tart Montmorency cherries (Prunus cerasus).
The results determined that the cherry group slept an average of 34 minutes more per night and had a 5-6% increase in sleep efficiency. Sleep efficiency is the time spent asleep as a proportion of time in bed.
They also found that the internal melatonin levels among the cherry group increased significantly, while the placebo group did not have any melatonin increase. Within 48 hours of cherry juice consumption, the urine of the cherry drinkers showed increased levels of 6-sulfatoxymelatonin – the primary melatonin metabolite. The researchers also measured melatonin levels by studying the subjects' circadian rhythms.
The researchers concluded:
these data suggest that consumption of a tart cherry juice concentrate provides an increase in exogenous melatonin that is beneficial in improving sleep duration and quality in healthy men and women and might be of benefit in managing disturbed sleep.
Cherries contain natural melatonin
Earlier research confirmed that Montmorency cherries contain melatonin. Research led by Dr. Russel Reiter from the University of Texas Health Science Center in San Antonio, Texas determined that the tart cherries will contain up to contain up to 13.5 nanograms (ng) of melatonin per gram of cherries. This is typically more than the levels found in the bloodstream.
Another study, this from Spain's University of Extremadura, also found that sleep quality and duration increased among elderly adults who consumed Jerte Valley cherries – another variety of tart cherries.
While cherries significantly spike melatonin levels and increase sleep quality, research on supplemental synthetic melatonin or melatonin extracted from the pineal glands of cows has been conflicting. These exogenous forms have been shown to improve sleep-phase disorders, but sleep quality results have been equivocal.
The difference may well lie in cherries' phytochemical content. Researchers from this most recent study stated:
cherry juice has been shown to decrease oxidative stress and inflammation following strenuous exercise making it possible that these antioxidant and/or anti-inflammatory properties modulated indices of sleep in this study...
Cherries reduce inflammation
The newest research comes from the USDA's Western Human Nutrition Research Center at the University of California at Davis.
This study tested 18 men and women between 45 and 61 years old. They were given 280 grams per day of Bing sweet cherries for 28 days.
After 28 days, the subjects had significantly lower levels of several inflammatory factors. Their CRP levels, ferritin levels plasminogen activator inhibitor-1 (PAI-1) levels were all about 20 percent lower, while their endothelin-1 levels were 14 percent lower, and their epidermal growth factor was 13 percent lower. Their IL-1 levels were 28 percent lower, and their advanced glycation end product receptor levels were 29 percent lower. All of these reductions indicated reduced inflammation within the body.
This result is confirmed by research from Oregon Health & Science University. This study utilized tart cherries. The research was presented at the American College of Sports Medicine Conference (ACSM) in San Francisco, Calif.
In this study, 20 women between 40 and 70 years old with inflammatory osteoarthritis were tested. The results found that drinking tart cherry juice twice daily for three weeks led to significant reductions in inflammation markers. The reductions were more significant among women with the highest inflammation levels at the beginning of the study.
"With millions of Americans looking for ways to naturally manage pain, it's promising that tart cherries can help, without the possible side effects often associated with arthritis medications," said lead researcher Kerry Kuehl, M.D. of Oregon Health & Science University. "I'm intrigued by the potential for a real food to offer such a powerful anti-inflammatory benefit – especially for active adults."
Osteoarthritis is the most common form of arthritis. Athletes can be at risk for developing osteoarthritis, and may benefit greatly from cherries. In a previous study, Dr. Kuehl found that athletes who drank tart cherry juice during training reported significantly less pain after exercise than those who didn't.
The antioxidant compounds in tart cherries are called anthocyanins. Their anti-inflammatory levels have been shown to be comparable to some well-known pain medications. Research from Baylor Research Institute found that daily tart cherry extract reduced osteoarthritis pain by over 20 percent for a majority of those studied.
According to University of Pennsylvania Medical Center for Sports Medicine Director of Sports Nutrition Leslie Bonci, MPH, RD, CSSD, LDN, incorporating tart cherries into the training menu of professional athletes and active clients has helped manage pain:
Why not eat red when there's so much science to support the anti-inflammatory benefits of this Super Fruit? And for athletes whose palates prefer the tart-sweet flavor profile of tart cherries, it's the optimal ingredient.
Whether the reduced inflammation is related to the increase in sleep quality remains in question.
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