Can Diets Fight Chronic Pain? The Science Isn't There

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Claims that strawberries and other foods rich in antioxidants can reduce inflammation and pain aren't backed up by much research.

Diets and supplements that claim to cure inflammation from everyday aches and pains, heart disease, arthritis, Alzheimer's and cancer aren't supported by much scientific evidence. The biggest impact of any diet on arthritis pain may have more to do with calories than antioxidants.

The Internet is littered with diets and supplements that claim to cure everything from everyday aches and pains to heart disease, arthritis, Alzheimer's disease and cancer — all by reducing inflammation.

Alternative medicine guru Andrew Weil recommends an anti-inflammation diet, and plans like The Zone and the Mediterranean diet are also built on the principles of the anti-inflammation theory.

"When you talk about a diet that emphasizes antioxidants or a diet that emphasizes foods that are said to have an anti-inflammatory effect, the diets are going to look very, very similar," says Lisa Cimperman, a dietitian at University Hospitals in Cleveland.

Each diet emphasizes slightly different things, but they all have plenty of antioxidant-rich fruits and vegetables, fish or small amounts of lean meat, whole grains, little to no processed or refined foods, and an emphasis on omega-3 fatty acids like those found in fish oil.

The idea is to eliminate foods that promote inflammation, like omega-6 acids found in vegetable and corn oils, processed foods and animal fats. Meanwhile, increasing foods like fresh fruits and vegetables, omega-3 fatty acids found in fish and nuts rich in antioxidants and phytochemicals allegedly can prevent or reverse conditions involving inflammation and pain.

Cimperman says there's no question that what we put in our mouths — and how much of it — has a big influence on our health. But no one diet has been shown to prevent inflammatory-linked diseases.

"We are not at the point yet that we can say that diet directly modifies the inflammatory process," she says.

Not The Gold Standard

The problem is that the majority of studies linking diet to disease either are too small or are retrospective — that is, they ask people what they ate in the past and then try to correlate that to their current-day health. And studies have shown that people don't accurately recall what they've eaten in the past.

"What they are doing is taking maybe some smaller study or a study that wasn't as rigorous, and they are using that as a jumping point for making these claims," Cimperman explains. "Beyond a good healthy diet in general, those claims that you see out there are largely overblown."

The gold standard study — a prospective, randomized, placebo-controlled, double-blind study — takes two groups of similar people, some eating normally, and others eating an anti-inflammatory diet, and compares the changes in their health over time. And the entire time, neither the doctors nor the patients know which diets they're on. It's the way most pharmaceutical drugs are evaluated, but studies looking at diet or nutritional supplements are rarely held to this standard.

But that doesn't mean anti-inflammatory diets are all bad. In fact, Cimperman points out that these diets are simply variations of the same healthy diet she would recommend to anyone. But patients shouldn't expect a miracle cure.

"It might be healthy, but it may not have the effects that they're promising," Cimperman says.

Modest Effects Of Certain Foods

But what about the people who do experience a benefit?

Eric Matteson, a rheumatologist at the Mayo Clinic, says people with sensitivities to certain foods, like wheat gluten or milk proteins, can benefit from eliminating them. But those cases are very rare, he says.

He argues that the biggest effect a diet can have on arthritis pain comes in the form of calories, not antioxidants.

"The most important thing to consider is the effect of having too much of anything in your diet," Matteson says. "A big contributor to the worsening of arthritis is body weight."

Matteson says the claims that certain foods have anti-inflammatory properties isn't all hype: Proper clinical studies have shown that omega-3 fatty acids and herbs like turmeric work the same way in the body as ibuprofen to reduce inflammation and pain. But he says the effects are subtle at best.

"In general, we could say that using the turmeric or using the fish oil might be equivalent to taking 200 to 400 milligrams of ibuprofen. It does vary a little from study to study what that effect actually is, but the effects are very modest," says Matteson.

Experts say a healthy diet, weight loss and exercise are likely to make everyone feel better, including those with chronic pain. But they warn that diet is meant to enhance, not replace treatments that have been shown to work, and it's something patients should discuss with their doctors.

Copyright 2011 National Public Radio. To see more, visit http://www.npr.org/.

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