MONTMORENCY TART CHERRY RESEARCH
Tart cherries are one of the few known food sources of melatonin, a potent antioxidant that helps improve the body’s circadian rhythms and natural sleep patterns (Burkhardt 2001).
A study conducted by Reiter and colleagues at the University of Texas Health Science Center found that tart cherries contain substantial amounts of melatonin, at levels higher than normally found in human blood. Montmorency cherries, contain 13.5 nanograms (ng) of melatonin per gram (Burkhardt 2001). Produced naturally by the body’s pineal gland at the apex of the brain, melatonin has been shown to do much more than regulate our sleep-wake cycle. Studies suggest that melatonin may help protect the vascular system, lessen inflammation, and reduce ischemia and reperfusion injury associated with surgery (Tan 2000, 2003, Cuzzocrea 2001, Lissoni 1997, Reiter 2001, 2000).
A study conducted by Reiter and researchers from St. Marianna University of School of Medicine in Japan found that feeding chicks a diet containing plants rich in melatonin raised blood levels of melatonin, indicating that melatonin ingested from the diet is absorbed and enters the general circulation, after which it is capable of binding to sites in the brain and other tissues (Hattori 1995).
Reiter and colleagues speculate that eating just a handful of tart cherries will increase melatonin levels in blood, thereby improving the body’s natural sleep patterns and potentially providing other health benefits.
ARTHRITIS AND GOUT
For decades, tart cherries have quietly grown a devoted fan base of arthritis sufferers who routinely consumed the fruit to help soothe their symptoms. At the time, the only evidence was anecdotal. Today, however, there appears to be science behind the cherry folklore.
The suspicion that cherries might help with arthritis and gout was first proposed in 1950 (Blau 1950). This preliminary study found that daily cherry consumption helped to relieve “gout attacks” and the pain associated with arthritis. After eating the cherries, the patients in the study had lower blood levels of uric acid. Elevated levels of uric acid are associated with the onset and progression of gout.
Since then, several studies have confirmed this link, including a study from USDA’s Human Nutrition Research Center at the University of California, Davis where researchers found that healthy women (ages 20 to 40 years) who consumed two servings or 280 grams of cherries after an overnight fast showed a 15 percent reduction in uric acid levels, as well as lowered nitric oxide and C-reactive protein levels (Jacob 2003).
The researchers conclude that “…compounds in cherries may inhibit inflammatory pathways” associated with gout. Additional studies suggest that consumption of cherries may be beneficial for the management and prevention of inflammatory diseases (Kelley 2006, van Acker 1995), including inflammatory pain (Tall 2004).
Tart cherries and their compounds appear to aid in diabetes control and in reducing the complications associated with this disease.
In a study from Michigan State University, partially funded by the U. S. Department of Agriculture, the effects of extracts of anthocyanins from tart cherries were tested on mouse pancreatic cells, which produce the hormone insulin in the presence of glucose (sugar). Results showed that anthocyanin-exposed cells increased insulin production by 50 percent compared to cells not exposed to anthocyanins. The researchers conclude that cherries might be useful in the prevention of type 2 diabetes Jayaprakasam 2005).
In another study on rats, a single dose of anthocyanins decreased fasting blood glucose levels by 19 percent and improved glucose tolerance by 29 percent. After one month of treatment with anthocyanins, fasting blood glucose levels had dropped to half of the pre-treatment levels and glucose tolerance had improved by up to 41 percent (Cherian 1992).
Small blood vessels, called capillaries, are damaged in diabetes as a result of elevated blood sugar levels. Collagen proteins become linked to the elevated sugar and form abnormal complexes that damage tissues and blood vessels.
One study on rats found that anthocyanins significantly reduced the formation of these abnormal protein complexes (Cohen-Boulakia 2000).
Retinopathy is a serious complication of diabetes, resulting from the overproduction of abnormal proteins produced when the body attempts to repair damaged capillaries. Anthocyanins appear to prevent this damage to blood vessels and also might prevent production of abnormal proteins. In one study, this damage was significantly reduced in 12 diabetic patients who consumed 600 milligrams of anthocyanins a day for two months (Boniface 1996). In another study, 31 patients with diabetic retinopathy showed marked improvement in permeability and a reduced tendency to hemorrhage when treated with anthocyanins (Scharrer 1981).