Anti-Inflammatory Properties of Tart CherryJune 2013
By Michael Downey
On October 17, 2005, the FDA sent out warning letters to cherry growers insisting that they cease making substantiated health claims that specific chemicals found in cherries could reduce pain and inflammation.1,2
The FDA wanted cherry growers to stop citing published scientific studies showing that cherries are packed with unique anthocyanins and other compounds that naturally mediate the inflammatory process.3-6 These compounds deliver comparable anti-inflammatory activity to ibuprofen (Advil®) and naproxen (Aleve®)7—but without the significant side effects!
Standard treatment for muscle pain and inflammation has been with nonsteroidal anti-inflammatory drugs. With over 111 million prescriptions and accounting for around 60% of over-the-counter pain reliever sales in the USA alone, these are some of the most commonly used types of medications.8 But because they can have deadly side effects, including gastric bleeding, heart attack, and kidney failure, the search for natural agents that could prove more beneficial and safer has gained increased attention.9,10
The compounds found in cherries modulate numerous pathways to protect against other conditions associated with inflammation—including cancer, cardiovascular disease, metabolic syndrome, and Alzheimer’s disease.11-14 For example, tart cherry constituents can switch critical genes off and on;15,16 modulate cell-signaling molecules like tumor necrosis factor;17 and target multiple cardiovascular factors—producing, in one study model, an astounding 65% reduction in early mortality!18
In this article, you will learn of the multiple benefits found in cherries that the FDA did not want to be publicized.
Broad-Spectrum Tart Cherry Compounds
One of nature’s most potent classes of flavonoids is anthocyanins. These powerhouse nutrients are responsible for the deep colors in some berries, fruits, and vegetables. Naturally, like other anthocyanin-rich foods, tart cherries deliver substantial antioxidant and anti-inflammatory activity.3-6
But tart cherries are superior because they provide high levels of some novel anthocyanins that are absent from a number of other anthocyanin-rich foods, such as blueberries or bilberries!7
Also, the unique composition of tart cherries goes far beyond anthocyanins.
In fact, tart cherries were shown to contain much higher amounts of total phenolics than even their nutritious cousins, sweet cherries.19 Aside from a greater abundance of anthocyanins, tart cherries also deliver a cast of supporting compounds.
Tart cherries were ranked 14th among the top 50 foods for highest antioxidant content per serving—surpassing such well-known antioxidant sources as red wine and dark chocolate.20
This complex profile prompted researchers to investigate what turned out to be numerous biochemical pathways modulated by tart cherry compounds.3-7,12,21-26
The range of activity was breathtaking. Here’s a partial sampling: bioactive compounds found in tart cherries beneficially inhibit certain enzymes5,7 while boosting others,12,21,22 switch-on cancer defenses,23,24 down-regulate glucose,25 and enhance primary antioxidants.26 We’ll examine this multi-potent network of underlying mechanisms later.
But first, let’s learn about their resulting impact on degenerative conditions—starting with muscle inflammation.
High-intensity or prolonged physical activity of any kind typically causes muscle damage, resulting in oxidative stress, inflammation, and pain.27-29
As people age, muscle mass and strength tend to decrease, in a process called sarcopenia.30 Although exercise can help overcome this process, post-exercise pain and loss of strength tend to last much longer.
The observed anti-inflammatory benefits of tart cherries prompted researchers to investigate whether they could be used to protect muscles, lower pain, and accelerate muscle repair.
Research demonstrated that orally administered anthocyanins from tart cherries significantly lowered inflammation-induced pain in rats in a dose-dependent manner3 and that tart cherry juice blend lowered indicators of exercise-induced muscle damage in horses.31
Then researchers turned to controlled human trials, first testing the impact of tart cherries on the degree of pain following intense exercise.
The effects of tart cherry juice consumption were tested in a double-blind, randomized trial of runners participating in a 24-hour relay race. Runners drank two 355 milliliter beverages containing either tart cherry juice or a placebo beverage daily for one week prior to the race and during the race. (Two 355 mL bottles of tart cherry juice daily provides at least 80 mg anthocyanins which is the equivalent of 90 to 100 cherries.)32
Both groups reported pain after the race. But the runners who drank tart cherry juice experienced a substantially smaller pain increase after the race.32 This natural protection against acute muscle soreness suggested that tart cherries must be providing some defense against muscle damage.
To confirm this, scientists conducted a controlled trial on indices of muscle recovery. Participants were given either tart cherry juice or a control drink for five days before, on the day of, and for two days after a marathon race.
Runners in the tart cherry group had significantly lower inflammation biomarkers (Interleukin-6 and C-reactive protein) compared to the placebo group. The tart cherry group also recovered isometric strength faster than the control runners, demonstrating an accelerated recovery following strenuous exercise.33
To further assess the potential decrease in muscle injury and strength loss, another research team gave 14 male college students who never exercised 12 ounces of either a tart cherry juice blend or a placebo twice daily for eight consecutive days. Then participants performed a type of repeated arm exercise (elbow flexion eccentric exercise) that typically induces muscle damage. Isometric elbow flexion strength, pain, and muscle soreness were measured before, and for four days after, the protocol.
After 24 hours, the control group’s arm strength was decreased by 30%—while the tart cherry group’s arm strength was diminished by only 12%. After four days, the control group’s arm strength was still down by over 10% while, remarkably, the tart cherry group’s arm strength had increased by 6%!34
The research team concluded that tart cherry significantly reduced the typical pain and loss of strength induced by exercise—and produced marked preservation of muscle function.34
The most recent trial on muscle injury and recovery included ten males, half of whom drank one ounce of a tart cherry beverage twice daily for ten days, while the other half drank the same amount of a placebo beverage during this period. All subjects completed two sets of an intensive, unilateral leg exercise—first, one set with one leg before the ten-day beverage consumption period, and then another set with the other leg after the beverage period.
Faster recovery of the knee extension (maximum voluntary contraction force) was observed with the tart cherry juice protocol versus control. The researchers concluded that the improved muscle recovery time may have been due to attenuation of oxidative damage.35
The study author suggested that tart cherry components produce a significant myoprotective—or muscle-protecting—benefit.35
Experts estimate that one out of every two Americans will develop symptomatic osteoarthritis at some point in their lifetime.36 Osteoarthritis is a chronic condition characterized by a breakdown of joint cartilage that leads to pain and injury.37
The Arthritis Foundation reports that the risk of developing osteoarthritis is greater among those of increased age, those who are athletic or regularly engage in repetitive-motion work, and those who are obese.38
Osteoarthritis has a strong inflammatory component.39 Acetaminophen is the most commonly used osteoarthritis pain medication.40 However, this pain-reliever does not help lower inflammation,40 and its side effects can include kidney or liver damage.41
In a 2007 pilot study, researchers at Baylor Research Institute gave tart cherries in pill form to patients with osteoarthritis of the knee. They documented that, after 8 weeks, more than half the subjects experienced a significant improvement in pain and function.42
Then, in 2012, a double-blind, randomized, placebo-controlled trial was presented at the annual meeting of the American College of Sports Medicine, ahead of publication. Scientists measured the impacts of tart cherry on serum inflammatory biomarkers among inflammatory osteoarthritis patients. (Patients with inflammatory or erosive osteoarthritis are those who suffer from sudden signs of inflammation, such as redness, pain, and swelling.)
The trial included 20 female participants between 40 and 70 years old who experienced at least moderate pain from osteoarthritis. The participants consumed two 10.5-ounce bottles of either tart cherry juice or a control beverage for 3 weeks.
Among those patients consuming the tart cherry juice, there was a statistically significant decrease in inflammation, indicated by reduced levels of C-reactive protein (CRP). The impact was greatest for those women who had shown the highest inflammation levels at the start of the investigation.43
This research demonstrates that tart cherry juice provides osteoarthritis patients with anti-inflammatory activity without the adverse effects and risks of traditional arthritis medications.
Gout is another type of inflammatory arthritis, and it is associated with higher risks of cardiovascular disease and mortality.44 High blood concentration of uric acid is considered its main pathway.45
Typically, drugs such as allopurinol and probenecid are used to help lower uric acid levels. But the side effects of these drugs can include difficulty breathing, unusual bleeding, vomiting, nausea, or severe skin rash.46,47 They may even interfere with other medications.48,49
Fortunately, research has spotlighted a safe alternative. For decades, gout sufferers have consumed tart cherry juice for symptomatic relief, on the basis of anecdotal evidence. Now, rigid science has begun to support this tradition.
A study conducted by scientists at Boston University found that intake of cherry extract reduced the risk of gout attacks in those who suffered recurrent gout attacks by 45%.50 Additionally, the researchers discovered that when cherry intake was combined with allopurinol use, the risk for gout attacks was reduced by 75% versus no intervention. What’s more, these results persisted even across subgroups stratified for sex, obesity status, purine intake, and alcohol use.50 Tart cherries appear to be a natural—and safe—way to inhibit the key gout pathway.
Quelling the Chronic Inflammation of Obesity
Chronic inflammation significantly boosts the risk of a number of conditions, including cancer and heart disease.51 But few people realize that obesity can be both a cause—and a consequence—of chronic low-level inflammation.52,53
Adipose cells are not simply fat stores—they are chemically active cells.52 In obese individuals, belly fat deposits generate a torrent of pro-inflammatory cell-signaling molecules known as cytokines.54 Left unchecked, these cytokines trigger a cascade of destruction that can lead to a number of degenerative diseases.55,56
Researchers demonstrated that obese or overweight human adults who consumed 8 ounces daily of tart cherry juice for 4 weeks exhibited significantly lowered inflammation. This was evidenced by marked decreases in erythrocyte sedimentation rate, tumor necrosis factor levels, and monocyte chemotactic protein—all key indicators of inflammation.44
Tart cherries are clearly a potent tool for inhibiting the chronic, often obesity-related, low-level inflammation that can lead to many disorders—and they could even inhibit obesity itself!
Cardiovascular Disease Prevention
Elevated readings of low-density lipoprotein (LDL) cholesterol are a factor in the onset of atherosclerosis and other cardiovascular diseases.57
To help decrease low-density lipoprotein to a safer range, the standard medical approach is to prescribe statins or fibrates to decrease blood lipid levels.58 However, some patients encounter side effects with these drugs that range from muscle pain (myalgia) to very serious complications such as liver dysfunction and rhabdomyolysis, a condition in which damaged skeletal muscle is broken down, sometimes resulting in kidney failure.59,60
A series of studies on rats concluded that diets enriched with tart cherries improved multiple cardiovascular risk factors. These included a reduction in cholesterol, body fat, weight, and abdominal fat. Tart cherries also calmed inflammation at sites—such as the belly and heart—specifically linked to heart disease risk.61-63
Then, in 2011, scientists reported a 26% decrease in cholesterol in mice given tart cherry powder, as well as a 65% reduction in early death. This lower mortality was believed to be due to improved cardiovascular health.62
Turning their attention to humans, researchers investigated the impact of tart cherry juice on serum triglycerides. They reported in 2011 that consuming 8-ounce-daily of tart cherry juice lowered triglycerides levels by over 17% on average!44
Together, these studies suggest that tart cherries promote cardiovascular health by safely lowering levels of cholesterol and triglycerides, as well as other risk factors.
Studies have shown that berry anthocyanins—found in tart cherries—can switch off genes involved in the multiple pathways of cancer.
These include genes for cell proliferation and inflammation, and for angiogenesis (the growth of new blood vessels that feed a tumor).14,64,65
Anthocyanins can also trigger apoptosis, the programmed cell death that causes pre-cancerous cells to self-destruct.64,66
These studies establish that anthocyanins work through a network of mechanisms to promote a broad spectrum of natural anticancer protection. And because there is a unique synergy among the anthocyanins and phenolic acids in tart cherries, scientists have been investigating them for their anticancer benefits.7
In mice, a diet of tart cherries inhibited both the incidence and size of adenomas (benign tumors) of the cecum, an area at the beginning of the large intestine that is a common site for colon cancer. In the same study, the growth of human colon cancer cell lines was shown to be reduced by tart cherry anthocyanins.67
Finally, in 2011, a review of past studies concluded that cherries exert a variety of anti-carcinogenic effects.11