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SKEPTOID BLOG:

Tart Cherries - Little Evidence For The Hype

by Eric Hall

July 13, 2013

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Donate A popular Twitter chat on running recently did a sponsored chat which touted the supposed effects of tart cherry products. It immediately set off my skeptical radar. It is pretty rare when a food or other ingestible product is capable of dramatic health effects, without significant distillation of the active ingredients. I have heard or read more than once that tart cherries are good for inflammation and related conditions such as arthritis. I took a quick look at the evidence.

Tart cherries are different than the standard cherry you may buy fresh in the supermarket. As this NPR story points out, they are much more delicate and cannot be transported very far. The product is canned or frozen and used in various forms from there. Due to the increased popularity as a health supplement, tart cherry shows up in juice, tablets, and other forms all claiming a way to replace your NSAID. The number of growers is also increasing.

Growers of the cherries have been making these claims for awhile. David Gorski wrote about the FDA's warning to growers as far back as 2005:
In it are documented claims by Amon Orchards that cherries prevent cancer. Not only that, but, according to Amon Orchards, they also contain a "natural chemical that not only flushes cancer-causing substances out of the body, but also helps stunt the growth of cancerous cells" and "anti-inflammatory pain relievers 10 times stronger than aspirin or ibuprofen," that can "relieve aches and pains."
Gorski also links to another grower who at the time the blog was written (in 2011) made similar claims, but in a passive-aggressive way saying the FDA said they couldn't make those claims. Hilarious. You can read more in Gorski's post.

The grower linked apparently has backed off some on the claims. In the FAQ section, to the question "Are the health claims about cherries reliable?" they answer:
So many outlandish claims are being made for the health benefits of various foods and supplements, that we have all become a little suspicious, and with good reason. For your assurance we have taken a number of steps: we are committed to offering only the highest quality; we have have presented on this site the documentation and research into the benefits of tart cherries; we avoid making claims and promising "too good to be true" results.
The site does tout the nutritional content of the fruit. A quick look at that page seems fairly reasonable, and they don't make any specific health claims.

A search of PubMed shows very limited research, and only a couple very small studies in humans. There are studies of antioxidant content, a few mouse studies, and a few on the growing of the cherries. Looking at the human studies, the evidence is extremely limited.

One of the recent studies was done on 58 patients with arthritis in their knees. The participants were separated into 2 groups, with each group getting a turn with either the cherry juice or a placebo. An interesting point was during the study, the participants were allowed to use acetaminophen, which was self-reported. That might make sense ethically, but one has to wonder how that might affect the results. The conclusion is written in an odd way:
Tart cherry juice provided symptom relief for patients with mild to moderate knee [osteoarthritis], but this effect was not significantly greater than placebo.
In other words, it had nothing to do with the cherry juice.

A couple of the studies were targeted at runners. One study took 20 "recreational" marathon runners and had them consume either cherry juice or a placebo for the 5 days previous, the day of, and 2 days after a marathon. The study showed "total antioxidant status (TAS)" as being about 10% higher in the cherry juice group. Also interesting was the isometric strength recovered significantly faster in the cherry juice group. However, there should be several cautions. The study is very small, so it is possible the cherry juice group simply had better training or a better recovery plan. The abstract also doesn't point out the ages of either group, which certainly could affect the results. I wouldn't bank on cherry juice based on this one study.

A similar study followed 54 runners a week up to and the day of the race. The runners were then asked to rate their pain before the drinks, before the race, and after the race. Here again the number of people in the study is small. The pain data also shows a significant crossover in the error bars. I couldn't find the full text of the study, but I question the data being as significant as claimed with the large crossover. The study again also fails to mention age or level of training leading up to the race. Without such data, the study is interesting, but far from conclusive as to cherry juice being a wonder drug for muscle recovery.

The common claim across these few studies and more so in the commentaries and the websites selling the stuff is the antioxidant content of the cherries. Antioxidants have been a buzz word for a long time, and certainly our body does use them to prevent and repair damage in our body. But do they work? Studies do not live up to the hype. As Dr. Steven Novella wrote a few years ago about a comprehensive study on antioxidants:
The science behind the role of oxidative stress in aging and neurodegenerative disorders and the modulation of oxidative stress by nutritional antioxidants is complex and has not yielded many confident therapeutic recommendations. And yet, by contrast, antioxidants are sold to the public with dramatic health claims as if they were well established. It is common for marketing hype to out pace scientific reality, especially when the science is complex and preliminary so that there is as yet no firm scientific consensus.
I would read Dr. Novella's entire post. It's good!

Tart cherries would seem to be much like other "superfoods" - certainly not harmful in normal quantities and a nice treat of fruit as part of a healthy diet. I enjoy the jams made from the fruit, as well as the dried versions as a good, fairly low-calorie snack. However, the science doesn't provide evidence of special healing properties or health benefits far above that which a balanced, healthy diet provides. If you have inflammation or pain, it is best to talk to your doctor. WebMD has a nice article on muscle soreness. You can also follow the NIH's basic rules on muscle aches:
For muscle pain from overuse or injury, rest that body part and take acetaminophen or ibuprofen. Apply ice for the first 24 - 72 hours of an injury to reduce pain and inflammation. After that, heat often feels more soothing...Be sure to get plenty of sleep and try to reduce stress.
I don't expect tart cherries to help me run better. Only more running will do that.

by Eric Hall

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